Why does the ground shake?

EDUCATIONAL GUIDE Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY BOOK REVIEW SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) Sevilla 2020 Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? PERSISTAH Project (Projetos de Escolas Resilientes aos SISmos no Território do Algarve e de Huelva) Mónica Amaral Ferreira Carlos Sousa Oliveira, João Estêvão, Antonio Morales Esteban, Beatriz Zapico Blanco, Emilio Romero Sánchez, Jaime de Miguel Rodríguez, María Victoria Requena García de la Cruz y Luís Sá SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) Collection Ediciones especiales Illustrations and cover design: Hugo O’Neill All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher (Editorial Universidad de Sevilla). Editorial Committee José Beltrán Fortes (Editorial Universidad de Sevilla Director) Araceli López Serena (Deputy Director) Concepción Barrero Rodríguez Rafael Fernández Chacón María Gracia García Martín Ana Ilundáin Larrañeta María del Pópulo Pablo-Romero Gil-Delgado Manuel Padilla Cruz Marta Palenque Sánchez María Eugenia Petit-Breuilh Sepúlveda José-Leonardo Ruiz Sánchez Antonio Tejedor Cabrera © Editorial Universidad de Sevilla 2020 c/ Porvenir, 27 - 41013 Sevilla Tlf. 954 487 447; 954 487 451 - Fax 954 487 443 Correo electrónico: [email protected] Web: <https://editorial.us.es> © Mónica Amaral Ferreira y Beatriz Zapico Blanco (coords.) 2020 © Mónica Amaral Ferreira (Instituto Superior Técnico/Universidade do Algarve), Carlos Sousa Oliveira (Instituto Superior Técnico), João Estêvão (Universidade do Algarve), Antonio Morales Esteban (Universidad de Sevilla), Beatriz Zapico Blanco (Universidad de Sevilla), Emilio Romero Sánchez (Universidad de Sevilla), Jaime de Miguel Rodríguez (Universidad de Sevilla), María Victoria Requena García de la Cruz (Universidad de Sevilla) y Luís Sá (Autoridade Nacional de Emergência e Proteção Civil) 2020 ISBN-e: 978-84-472-3047-1 DOI: http://dx.doi.org/10.12795/9788447230471 Layout and digital edition: Dosgraphic, S.L. ([email protected]) Ferreira, M.A.; Zapico Blanco, B.; Oliveira, C.S.; Estêvão, J.; Morales-Esteban, A.M.; Romero, E.; Requena, M.V.; de Miguel, J.; Sá, L. Why does the Ground shake?, Ferreira, M.A.; Zapico Blanco, B. (coords.), Sevilla, Editorial Universidad de Sevilla, 2020. This work has been developed within the framework of the PERSISTAH project, Projetos de Escolas Resilientes aos Seismos no Território do Algarve e de Huelva (0313_PERSISTAH_5_P), developed jointly by the universities of the Algarve and Seville and funded by the European Commission through the call EP – INTERREG VA Spain Portugal (POCTEP). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) Digital edition of the printed edition 2020 Review: Patrícia Gramaxo (PhD in Education Sciences, Primary Teacher) Acknowledgments: Dora Castelo (Museu de São Roque, Santa Casa da Misericórdia de Lisboa) Luís Nobre (Museu de São Roque, Santa Casa da Misericórdia de Lisboa) Carla Almeida (Serviço Municipal de Proteção Civil de Portimão, Primary Teacher) Rui Carrilho Gomes (IST Lisbon) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) Sumary Chapter 1. Introduction ............................................................... 11 1.1. Education for risk reduction ........................................................... 11 1.2. About the educational guide ........................................................... 11 Chapter 2. What is an earthquake? ............................................... 15 Chapter 3. How do we measure earthquakes? ............................... 21 3.1. Richter scale .................................................................................. 22 3.2. Mercalli scale .................................................................................. 23 Chapter 4. What generates a tsunami? .......................................... 27 Chapter 5. Are we in danger here? .............................................. 29 5.1. Most destructive earthquake and tsunamis in the iberian peninsula .. 33 5.2. Earthquake and tsunami of 1755 ..................................................... 36 Chapter 6. Why does my house shake? ......................................... 39 6.1. How do buildings withstand earthquakes? ....................................... 40 6.2. The relevance of non-structural elements ........................................ 42 6.3. How to reduce non-structural risk? ................................................ 43 Chapter 7. What to do in the case of an earthquake or tsunami? ..... 47 7.1. If I am at school and an earthquake begins, where must i go? .......... 47 7.2. Which are the most dangerous places inside a building? ................... 47 7.3. If I am outside and feel an earthquake, what must i do? ................... 47 7.4. What must i do after an earthquake? ............................................... 48 7.5. In case of tsunami, what must i do? ................................................. 48 Chapter 8. Activities .................................................................... 51 8.1. Puzzle of tectonic plates.................................................................. 51 8.2. Troubles always come in thress ........................................................ 54 8.3. Locate earthquakes around the world .............................................. 56 8.4. Locate tsunamis around the world ................................................... 58 8.5. Simulate a tsunami .......................................................................... 59 WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 16 If we cut a boiled egg (the Earth) in two, we found the nucleus (or yolk) inside. The nucleus is slightly larger than the moon and extremely hot. The nucleus is composed by iron, nickel and other metals. The egg white corresponds to the mantle, which is a cap with almost 3 000 kilometres of very dense rock, rich in iron and magnesium. Magma is formed when temperatures within the mantle are very hot. When a volcano erupts, the magma rises and overflows. The Earth’s crust (where we live), which forms the continents and the seabed, is the most external layer. It is composed by several huge pieces (similar to the pieces of a cracked eggshell), which fit like a puzzle. Their name is tectonic plates (or lithosphere). Heat causes movement in the mantle and, consequently the tectonic plates move. When they clash with each other cause earthquakes (seisms or tremors). There are around 20 plates along the surface of the Earth, which move continuously and slowly over each other. An earthquake occurs when the plates approach or separate (example of the hands / knuckles, Figure 4). Imagine your hands as “tectonic plates” and your knuckles as “plate edges”. Bring your hands together. The more you push your knuckles together, the more difficult the sliding movement of your fists will be, and the larger the pressure you feel in your knuckles. If you keep pressing for a while, a “plate” will slide, releasing the accumulated energy in your hands. It is an earthquake. Figure 4. Tectonic plate collision representations (Mónica Amaral Ferreira and Hugo O’Neill). You can also use a pencil to show the phenomenon. Hold a pencil horizontally. Apply force in both pencil ends, pushing down, and you will see that the pencil forms a curve. If you keep pushing, the pencil breaks in half, releasing the stress you put on it. The Earth crust behaves in the same way. When the crash occur, the tension is released and the energy moves through the ground in the form of waves, which we can feel as an earthquake (Figure 5). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 17 Plates crash. When the stress reaches a limit, the fracture appears and the energy is released. The vibration spreads across the ground in all directions. It is an earthquake. Figure 5. Explanation “the ground shakes” (Hugo O’Neill). The plate boundaries are very active areas in terms of earthquakes and volcanoes. Depending on the plate movement, the boundaries (or limits) between them can be: divergent, convergent or transform (Figure 6). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 18 Divergent Convergent Transform Figure 6. Chocolate snack representing plate boundaries motion (Mónica Amaral Ferreira and Hugo O’Neill). —Divergent limit / boundaries: when two plates are moving apart. Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges. The best-known example of a divergent plate boundary is the Mid-Atlantic Ridge, an undersea ridge that runs under the Atlantic Ocean and the Arctic Ocean. In some points of the ocean, it is possible to see elevations of this Atlantic ridge, forming island. Among such points are Iceland, Bermudas and the Azores, where the highst point of the ridge is located, at Pico Island (2 351 meters of altitude). —Convergent limit / boundaries: when two plates are colliding and cause subduction (Figure 7), i.e., when one plate (oceanic crust) slides under the other (continental or oceanic plate). Earthquakes and volcanoes are common around convergent limits. Most of the tsunamis are caused by the earthquakes generated in the subduction area. —Transform limit / boundaries: when two plates slide parallel to eachother, in opposite directions. Earthquakes can be originated inland or offshore. If a strong earthquake (magnitude greater than 7) occurs, and we are near the coast, there is risk of tsunami, which is a giant wave that can be the height of a building and reach the speed of an airplane (see chapter “What generates a tsunami?”). In the Iberian Peninsula both earthquakes types can take place, which means that there is also a risk of tsunami. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 19 Figure 7. Example of fault, subduction, trench, oceanic crust and continental crust (source: <http://www.lneg.pt/CienciaParaTodos/edicoes_online/diversos/guiao_tec- tonica_placas/texto>). At the end of this chapter, teachers could propose the following activities to their pupils: Suggested activities The Earth planet model in playdough Figure 2 The boiled egg Figure 3 Chocolate snack representing the plates boundaries Figure 6 Puzzle of the tectonic plates Page 49 WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 20 SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 21 More than one million earthquakes take place on Earth every year. Most of them are of very low magnitude, and we can not feel them. In Portugal, around 25 earthquakes per year are felt, and in Spain, around 12 earthquakes with a magnitude greater than 3 take place. Earthquakes can be weak, but they can also be very strong. How do we measure earthquakes? The instrument which records the seismic waves that move through the ground is called Seismograph. Movements are recorded in seismographs, which generate graphics called seismograms. Seismologists can obtain information from seismograms, such as the location of the hypocentre and the magnitude of the earthquake. The hypocentre, or underground focus point of an earthquake, is the point inside the Earth (lithosphere) where the seismic movement starts, i.e., where the fracture takes place. The epicentre is the projection of the hypocentre in the Earth’s surface, where the earthquake is felt most intensely and the largest damages in buildings and people are produced (Figure 8). Figure 8. Hypocentre vs. Epicentre (Emilio Romero Sánchez). Chapter 3. How do we measure earthquakes? SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 22 3.1. RICHTER SCALE In seismology, two scales are used to measure an earthquake: Ritchter and Mercali. The Richter scale, which was created in 1935 by the scientist Charles Francis Richter, measures the magnitude (released energy) of an earthquake. The Ritcher scale is not a linear scale, it is a logarithmic one; that is, multiplied by 10. Each number represents a magnitude 10 times greater than the previous one. For example, magnitude 5 is 10 000 times larger than magnitude 1 (Figure 9). Figure 9. Richter is a logarithmic scale (Emilio Romero Sánchez). For the soil to move ten times more, the amount of energy released needs to be 32 times higher (Figure 10). That is, an increase of one step in the logarithmic scale of magnitude corresponds to 101.5 ≈ 32 times more energy released. An increase of two steps corresponds to 103 = 1 000 times more energy. Thus, an earthquake of magnitude Mw = 7 releases 1 000 times more energy than one of magnitude 5, and approximately 32 times more than one of magnitude 6. Figure 10. Released energy (Emilio Romero Sánchez). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 23 Just to give you an idea, the Hiroshima bomb was equivalent to an earthquake of magnitude 6, and the meteorite which exterminated the dinosaurs, was equivalent to an earthquake of magnitude 13. The largest recorded earthquake was of magnitude 9,5 and took place in 1960 in Chile. There is not a theoretical limit for an earthquake magnitude, but it is estimated that an earthquake with a magnitude 15 would destroy the planet, dividing it in two. Earthquakes with a magnitude 5 or above, can cause minor to moderate damages in vulnerable buildings, while most buildings would suffer severe damages or even collapse when hit by an earthquake of magnitude larger than7 (Figure 11). MAGNITUDE 5 MAGNITUDE 7 Figure 11. What is the effect of earthquakes on buildings? (Hugo O’Neill). 3.2. MERCALLI SCALE The Mercalli scale was created in 1902 by the Italian seismologist Giuseppe Mercalli. It is used to measure intensity, that is, the earthquake effects in the population and buildings. It is a scale of 12 degrees (in roman numbers) where each degree represents the earthquake severity, from imperceptible to totally catastrophic (Figure 12). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 24 Figure 12. Modified Mercalli scale (Hugo O’Neill). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 25 The following list sumarizes the most relevant earthquakes in history: 1. Valdivia, Chile, May 22, 1960 (magnitude 9,5). It caused around 1 600 deaths in Chile, together with a tsunami which caused death and damages in places as far as Hawai, Japan and Filipinas. Two days after the earthquake, the Puyehue volcano erupted. 2. Alaska, March 28, 1964 (magnitude 9,2). The earthquake was felt mainly in Alaska, as well as in some places in Canada. This earthquake triggered a tsunami which caused damages in locations as far as Hawai. 3. Sumatra, Indonesia, December 26, 2004 (magnitude 9,3). The second largest earthquake ever recorded, after the earthquake in Chile in 1960. The earthquake and tsunami caused 335 000 deaths and 150 000 students lost their school buildings. Few hours after the quake, the tsnumai devasted the east coast of Thailand, as well as Sri Lanka, India and the west cost of the Maldives. 4. Tohoku, Japan, Mars 11, 2011 (magnitude 9,0). The tsunami caused a nuclear disaster in Fukushima, which produced the indefinite evacuation of thousands of people, in a 20 kilometers radius. Around 200 school buildings were destroyed and more than 700 were significantly damaged by the tsunami. 5. Kamchatka, Russia, November 4, 1952 (magnitude 9,0). This earthquake generated a tsunami which caused widespread damages in the Hawuaiian islands. The tsnunami arrived in Alaska, Chile and New Zeland. 6. Maule, Chile, February 27, 2010 (magnitude 8,8). This earthquake and tsunami killed at least 521 people and wounded 12 000. More than 800 000 people were evacuated. The earthquake and tsunami destroyed or damaged more than 3 000 schools in Chile, affecting up to 1,25 millon students. A small tsunami crossed the Pacific Ocean, causing damages in ships located as far as in San Diego, California. 7. Ecuador Coast, January 31, 1906 (magnitude 8,8). The earthquake triggered a tsnunami which caused between 500 and 1 500 victims in Ecuador and Colombia. The tsunami hit the west coast of the United States (San Francisco), Hawai and Japan. It took the tsunami about 12 hours to cross the Pacific and get to Hilo, Hawaii. 8. Portugal, November 1, 1755 (magnitude 8,7-9,0). The earthquake was felt strongly in Lisboa, Algarve, south of Spain and Marroco. It was also felt in the Azores although without damages. Damages in buildings were however observed in Ponta Delgada (San Miguel), Angra do Heroísmo and Praia da Vitória (Terceira), Madeira and almost all Europe. The total number of victims is very uncertain, with estimates ranging from 20 000 to 40 000 people. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 32 Figure 17. Seismic hazard in mainland Portugal (Regulamento de segurança e ações para estruturas de edificios e pontes. 1983). SEISMIC HAZARD IN MAINLAND PORTUGAL Seismic hazard Reduced Low Moderate High SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 33 5.1. MOST DESTRUCTIVE EARTHQUAKE AND TSUNAMIS IN THE IBERIAN PENINSULA The following events shaped the seismological history of the Iberian Peninsula: — September 22, 1522. With an estimated magnitude of 6,5, this earthquake had its epicentre in the area of Algham, Almería. It affected severely the city of Almeria, and caused important damage in nearby towns, such as Vera, Baza, Guadix or Ugijar (Granada). It is considered the most damaging seism in the Spanish history. — January 26, 1531. This quake hit the centre of mainland Portugal, specially the region of Lisbon. The epicentre was located, probably, in the Benavente region (fault of the inferior Tajo valley). Its magnitude is believed to be 6,5, and some agitation was felt in the Tajo waters. — October 9, 1680. Known as the 1680 Malaga earthquake, it had its epicenter west of the city of Malaga and a maximum intensity of VIII-IX. The shake was felt in the city of Malaga and in other cities in central Spain, such as Toledo, Madrid and even Valladolid, more than 500 km away. — December 27, 1722. This seismic event caused great damage (human and material) from cape S. Vicente to Castro Marim affecting Tavira, Faro and Loulé. The epicentre was located offshore, and local tsunami was generated. — November 1, 1755. Also known as the Lisbon earthquake, this is the largest seismic event ever documented. It was strongly felt in Lisbon, the Algarve, south of Spain and Morocco. It was also felt in Azores, causing damages in Ponta Delgada (San Miguel) Cala del Heroismo and Playa de Vitória (Terceira) and Madeira. The mega-seism, with an estimated magnitude of 8,7 to 9,0, reached an intensity of X (Mercally) in the Algarve region. The total number of fatalities is estimated between the 20 000 and 40 000. Only in Lisbon, 20 000 of the 200 000 could have been killed. Of the 20 000 existing buildings, only 3 000 could be occupied after the event. Huge damage or collapse was found in 32 churches, 60 chapels, 31 monasteries, 15 convents and 53 palaces. Despite the quick response to the catastrophe, the reconstruccion of the city of Lisbon took more than a hundred years. — January 13, 1804. This earthquake had a magnitude of 6,7, and epicentre in the Mar de Alborán. It was followed by several aftershocks that struck the city of Motril. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 34 — March 21, 1829. With a magnitude of 6,6 and epicentre in Benejúzar, Rojales and Torrevieja, this seism caused 389 fatalities, 377 wounded, the collapse of 2 965 residential buildings and severe damages of 2 396 of them and the collapse of the bridges over the Segura river in Almoradí, Benejúzar, Dolores and Guardamar. Its effects reached to the populations of Almoradí, Algorfa, Rafal, Torrelamata, Daya Vieja, Guardamar, Dolores, Redován, San Fulgencio and San Miguel de Salinas. Half of those killed were in Almoradí, a village with narrow streets and tall buildings that collapsed on each other. The period between 1820 and 1830 was the most seismically intense in the south of the province of Alicante, due to the activity of the seismotectonic lines of Bajo Segura, including the faults of Benejúzar-Benijófar, Guardamar del Segura and Torrevieja. In general, the coast of Alicante is sunk about 10 meters below the Torrevieja fault. — November 11, 1858. Originated at the underwater valley of Sado, it was one of the main earthquakes that affected Portugal. It reached an intensity of X in Setúbal, causing great destruction in several towns. — December 25, 1884. With a magnitude of 6,5 and epicentre at Arenas del Rey, this earthquake caused the total devastation of several towns in the province of Granada, leaving 839 dead, 13 000 injured and 4 400 buildings destroyed. — April 23, 1909. With epicentre in the Benavente area (fault of the lower Tagus valley) this seism had a duration of approximately 20 seconds. Of magnitude 6,0, the maximum intensity was experienced in Benavente (IX) and Lisbon (VII), the eastern part of this city being the most damaged, with fallen chimneys and cracks in facades and walls. — February 21, 1964. A seismic crisis shook the western part of the island of S. Jorge (Azores), with a magnitude of 5,5, registering maximum intensities of VIII / IX in the Rosais. It was associated with an underwater eruption near the Rosais. Pico reached the maximum intensity of VI in the Piedade area, and in Faial there were maximum intensities of V in Horta, Ribeirinha and Cedros. — February 28, 1969. An earthquake of magnitude 7,9, with epicentre in the abyssal plain of Ferradura, was felt in large part of the peninsula, reaching a maximum intensity of VIII in the west of Windward, with significant damage to some old masonry constructions. In Lisbon, hundreds of chimneys were damaged, including collapses. There was slight to moderate damage in several churches and chapels in the south SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 35 of Lisbon. In Huelva, 4 people perished and 18 houses were declared uninhabitable. — November 23, 1973. The earthquakes took place on the 23rd of November and 11th of December of 1973. With magnitudes of 5,8 anf 5,6 respectively, they were felt in the islands of Pico and Faial. They caused 61 deaths and severe damages, including partially collapsed buildings and blocked roads. — January 1, 1980. This earthquake affected the islands of Terceira, S.Jorge and Graciosa (M 7,2), and caused great damage in the city of Angra do Heroísmo, mainly in one or two-story buildings in traditional stone masonry, damaging 15 000 homes (50% of the existing ones) of which 5 000 collapsed. The earthquake also generated a small tsunami. The earthquake caused 61 deaths, many of them due to landslides on the island of S. Jorge. The reconstruction of the destroyed areas was the largest operation carried out in Portugal in the last 100 years. — July 9, 1998. This swarm of earthquakes began on July 9, 1998, with an epicenter about 15 km NE of Horta and magnitude 5,9. About 10 600 aftershocks were recorded and lasted approximately 4 months. The earthquake caused 8 deaths, 100 injuries and 2 500 displaced people, affecting around 35% of the buildings in Faial and 10% in Pico. — February 12, 2007. With a magnitude of 6,1, this was the strongest quake felt in Spain after 1969. The epicentre was located at 200 km from the Portuguese cape of S. Vicent. The shaking was felt in most of the peninsula, and caused the dislodge of many buildings. On August 12th 2007, a second earthquake of 5,1 with epicentre in Ciudad Real was recorded. Is was again felt in most of the peninsula, and, although no personal damage was caused, the conference hall of the Municipal Theater of Almagro, a 19th-century building, was destroyed. — December 17, 2009. This earthquake, with a magnitude of 6,3 in the Richter scale, affected the region of Andalucía. It caused chaos and panic among the population, afraid of the possibility of an associated tsunami, which luckily did not take place. The quake caused relevant damages in many residential buildings. — May 11, 2011. This earthquake shacked mainly the locality of Lorca, in the region of Murcia. Its epicentre was located in the Alhama fault, and it had a magnitude of 5,1. It was preceded by a premonitory earthquake of 4,5 a few hours earlier on the same day. The shake was also felt in the provinces of Almería, Albacete, Granada, Jaén, Málaga, Alicante, Ciudad Real and some areas of the city of Madrid, where, due SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 36 to the soil type, the ground accelerations got amplified. Multiple aftershocks occurred after the main earthquake. The Region of Murcia, in which Lorca is located, is the most active seismological zone in Spain, although this locality, specifically, is not among the most dangerous within it. — January 25, 2016. Also known as the Alhucemas earthquake, of magnitude 6,3 and epicentre in the Alboran Sea, 77 km northwest of the autonomous city of Melilla, this earthquake was perceived with greater intensity in the northern area of Morocco (in addition to Alhucemas, particularly in the towns of Tirhanimine and Imzouren that are respectively 64 and 69 km from the epicentre) and in the autonomous city of Melilla. To a lesser extent, it was also felt in Gibraltar, along the coast of Almeria, Granada and Malaga. The tremor was also noticeable in more remote provinces, such as Cordoba and Seville. In total, the emergency telephone number 112 received in Spain more than 600 calls in which incidents were reported and advice of various kinds was requested. 5.2. EARTHQUAKE AND TSUNAMI OF 1755 The earthquake of 1755 is considered as the largest earthquake recorded up to this date. It was felt strongly in Lisbon, the Algarve, southern Spain and Morocco. Although causing no damages, it was also felt in most of Europe, the Azores and Madeira. The tsunami hit North Africa, northern Europe, affected the Azores and Madeira and reached as far away as Antigua, Martinique and Barbados. A strong earthquake, with epicentre at sea in the Gorringe area, took place on a Saturday morning, November 1st, 1755, All Saints Day, around 9:40a.m. Shortly after the earthquake, a fire started, mainly caused by stoves and candles fallen by the earthquake (Figure 18). The population tried to escape from the fire in the direction of the Tagus River. The waters of the Tagus initially descended, taking with them the ships moored at the dock. Around 11a.m. the waters began to level up, climbed the walls of the pier and advanced through the Baixa 300 to 400 m (Terreiro do Paço and streets near the river banks). According to the captain of an English ship, the waters rose about 16 feet three times in a row for 15 minutes. Only at 7 a.m. on Sunday would the tide return to normal. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 37 The impact of the 1755 earthquake is described in many contemporary accounts, such as the following (included in the Lisbon Emergency Plan for Seismic Risk): “(…) Behold, suddenly, that the sea enters through the barrier with a strong August flood. (…) However, when it exceeded its old limits, it hit many buildings and flooded the neighbourhood of S. Paulo (…)” (Mendonça, 1758), “(…) and it flooded partially with its ebb and the edge of the waters flowed, leaving its former bed and flooding Alfândega, Terreiro and Vedoria (…)”. According to Baptista et al. (1998), the Baixa da Cidade was flooded, with a penetration of 250 m, and the wall “Fernandina” (remade by King Felipe I) acted as a strong barrier to the passage of water. The area between the old Ribeira das Naus, Terreiro do Paço and Jardim do Tabaco was completely flooded. Another reference reports that “Bugio Castle was so covered in water that the garrison fired SOS shots and everyone was forced to retreat to the highest part of the tower”. According to contemporary reports, building damage began in the second phase of the earthquake, reaching its peak in the third. Some people had time to flee their homes between the first and second phases, but many of them were trapped by landslides. The movement of people was quite random. Shortly after the earthquake, there was a concentration in Largo de S. Paulo, where the tsunami wave arrived at 11:00 a.m., causing great losses (Oliveira, 2005). The total number of victims of this earthquake is estimated in 20 000 to 40 000 people. In Lisbon alone, it is believed that, of the 200 000 inhabitants of the time, 20 000 would have died. Of the 20 000 existing buildings, only 3 000 could be reoccupied after the earthquake. 32 churches, 60 chapels, 31 Figure 18. Artistic recreation of the Lisbon tsunami of 1755 (source: Getty Images). WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 38 monasteries, 15 convents and 53 palaces were totally destroyed or severely damaged. The reports of the time are not very consistent, which makes it difficult to calculate the exact number of victims due to the earthquake, tsunami and fire. The damage caused by the fire, which lasted approximately 6 days, was greater than that caused by the earthquake and the tsunami themselves (Santos, 2008). The complete reconstruction of the city of Lisbon took more than 100 years. At the end of this chapter, teachers could propose the following activities to their pupils: Suggested activities Simulate a tsunami Page 57 SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 39 WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) The earth is constantly moving, and that is why small earthquakes are happening all the time. We do not feel them and they do not cause any damage. Only special measuring devices (sismographs) can capture such small movements. However, a stronger earthquake would be felt, and could bring down trees and buildings. Still, earthquakes do not cause any problems by themselves. Imagine an earthquake taking place in the middle of the desert: what could happen? Nothing. What causes victims and damages are our buildings, if they are not properly prepared to resist earthquakes. We cannot predict when the earth will move, but we can reduce the effects and damage a shaking can cause if we know what to do at home, at school or on the street, before and during an earthquake. When an earthquake occurs, its waves propagate through the ground in all directions. Buildings are generally design to withstand vertical forces due to their weight and gravity. This does not automatically mean that they can withstand the horizontal forces transmitted by earthquakes. These horizontal loads make walls, floors, pillars, beams and the connections between them vibrate and move (Figure 19). The difference in displacement between different parts of the structure results in very high stresses in its members, causing damage and even collapse. Chapter 6. Why does my house shake? Figure 19. Building behaviour under an earthquake. If the building undergoes a large displacement, the structural elements such as beams, columns and walls could become damaged, making the building not safe (Emilio Romero Sánchez). Displacement Ground shaking SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 40 6.1. HOW DO BUILDINGS WITHSTAND EARTHQUAKES? Several factors affect the seismic behaviour of buildings, such as their year of construction, materials, foundation type, symmetry, number of floors, etc. Buildings can be designed in order to, with a given level of probability: endure an earthquake protecting their occupants, being used directly after the shake, or even keep on being operative during the event (like hospitals, for example). It is important to underline that, as we learn more about earthquakes and building dynamics, buildings that once were regarded to as safe, could be reconsidered as un-safe under the light of new knowledge. Some schemes employed to help the buildings endure earthquakes are related to the creation of a lateral load path, able to redistribute the seismic forces among the building structural elements. Braces are an example of such scheme (see Figure 20). These techniques are also employed in the rehabilitation of existing buildings, in order to reduce their vulnerability. In this case they are known as structural retrofitting. We can also reduce the damages caused in a building under seismic action by limiting its deformations which, as has been explained before, can result in large stresses in the structural elements. Base isolation is an example of this scheme: the building is constructed on top of elastomeric bearings which isolate the structure from the ground. When the earthquake takes place, all the deformation concentrates in these elastomeric bearings, while the rest of the building behaves as a rigid body and moving as a single block. Buildings with base isolation are more prone to withstand a strong earthquake with little damage, and to can be occupied directly after the event (Figure 21). Figure 20. Use of braces for the creation of a lateral load path (Emilio Romero Sánchez). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 41 Figure 21. Base isolation (Emilio Romero Sánchez). At the end of this chapter, teachers could propose the following activities to their pupils: Suggested activities The Treme-Treme house Page 58 SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 48 7.4. WHAT MUST I DO AFTER AN EARTHQUAKE? After the earthquake has finished, turn off the electricity and the gas. Go outside calmly, seek an open space away from buildings, trees and electricity poles. If you are close to the sea, go to a high place away from the coast. 7.5. IN CASE OF TSUNAMI, WHAT MUST I DO? After an earthquake and if you are in the house, at school or at work, bear in mind that in coastal zones (high-risk) you have few minutes to act (5 to 10 minutes), that’s to say, to start the evacuation (Figure 23). Once the earthquake has finished, evacuate the quickest possible on foot. Always follow the indications of the evacuation plan (horizontal and vertical). Some beaches have evacuation signs in the case of a tsunami (Figure 24) and sirens. Figure 23. Risk of tsunami (source: <www.tsunamizone.org>). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 49 Figure 24. What to do in coastal zones after an earthquake? (source: <www.tsunamizone.org>). At the end of this chapter, teachers could propose the following activities to their pupils: Suggested activities Locate tsunamis around the world Page 56 Simulate a tsunami Page 57 WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 50 SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 51 8.1. PUZZLE OF TECTONIC PLATES In this activity the students will assemble a puzzle/map showing the countries, the continents and the tectonic plates. The image can be printed and pasted onto cardboard, in order to create a large puzzle that allows to carry out the activity in groups. Alternatively, it can be printed in a smaller format, for individual use. The map is an excellent work tool because, allowing to visualize the location of the tectonic plates in relation to the oceans and the continents. Materials: — Cutout world map. — LEGO or wood blocks. Discussion: At the end of the activity the students will be able to: — demonstrate how the tectonic plates which cover the Earth fit as pieces in a puzzle; — locate Spain, Portugal and other countries in their puzzle; — note that Japan and California are located at the limit of the same tectonic plate (Pacific plate), in a zone of convergence called the Pacific Ring of Fire; — note that Australia, as it is located in the middle of a plate and far from the limits, does not suffer from earthquakes; Chapter 8. Activities SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 52 — give a simple explanation of the relation between the tectonic plates and the distribution of the earthquakes in the world, for example in the Iberian Peninsula; — give a simple explanation about the formation of volcanos in the archipelagos of the Azores and the Canary Islands, among others; — if they place a small LEGO or wood construction on the puzzle and knock under the table, the students will understand that the interior of the Earth moves what is above its surface. Figure 25. Primary school students putting the puzzle together individually (Patrícia Gramaxo). Figure 26. The same activity developed in groups (Beatriz Zapico Blanco). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 53 WORLD MAP Figure 27. Puzzle/world map (to be printed and cut). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 54 8.2. TROUBLES ALWAYS COME IN THRESS To find out the seismicity of our country, it is essential to identify the zones at greatest risk. This activity proposes combining hazard with creativity, manual skills, the coordination of colours, etc. (see section 5: “Are we in danger here?”). Other risks are associated with earthquakes can be discussed, such as tidal waves, landslides or fires, and things to do in order to be safer against them could be proposed. Figure 28. Spanish regions (adapted from <www.ign.es>). Materials: — Map of the Iberian Peninsula. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 55 Procedure: — Locate in the map the region where you live. — Paint the regions according to the seismic risk: red (high-risk), orange (moderate), yellow (low) and green (very low). — In what seismic and tsunami risk zone is the region where you live? ___ High ___ Moderate ___ Low ___ Very low SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 56 8.3. LOCATE EARTHQUAKES AROUND THE WORLD More than a million earthquakes occur every year on Earth! Most are of a very low magnitude, so low that we don’t even feel them. In Spain there are around 12 main earthquakes of a magnitude over 3,0 per year. It is important to find out exactly where an earthquake takes place. This information can help seismologists to identify and map the danger, as well as helping scientists to understand the location and the movement of the tectonic plaques. Figure 29. Examples of the activity development (Hugo O’Neill). Materials: — Map of Spain, Portugal or the world. — Computer and internet connection. — Coloured stickers or pins (it is important to have at least three different colours but there can be more). Procedure: Assign a magnitude range to each colour. We can take advantage of an earthquake in any place in the world to reflect and carry out critical thinking in the classroom. You can visit the site European-Mediterranean Seismological Centre (EMSC, <https://www.emsc-csem.org>). Investigate where earthquakes have occurred today and ask the students to place red circles to identify the earthquakes of greater magnitude, yellow circles for those of moderate magnitude and green for those of less magnitude. Do this activity weekly, for example, and in the course of three months, and you will observe how the limits of the tectonic plates are drawn. This is a good way for the students to discover where earthquakes can happen. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 57 Discussion: — Discover patterns of earthquakes all over the world. — How many earthquakes happened today? — Identify in the map where the earthquakes of greater magnitude happened today. — Why do earthquakes happen more in some places than in others? — What have earthquakes to do with the tectonic plaques? SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 64 SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 65 8.7. HUNTING FOR NON-STRUCTURAL RISKS You are going to do, with the help of your family, a visual inspection card of the potential hazards existing in your house (living room, dining room, kitchen, bedrooms) that may cause damage or injury during an earthquake. Architects and engineers often carry out this task to check the safety of structures and make plans to prevent damage in case of an earthquake. You can make a film, a presentation, an interview or a drawing with what you have identified. Also, indicate some solutions to make your house safer in the case of an earthquake. You can use this work to present your observations and suggestions to the person in charge of the school to help improving the safety in the classroom and in the school. Materials: — Evaluation sheet. Discussion: — Ask students what they know about non-structural elements and non-structural risk. — Identify the safest areas of the house. — Where can protection measures be applied? — Which solutions can be applied to reduce non-structural risk? SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 66 EVALUATION SHEET Evaluator:_________________________________ Date:___________ Identify the room: living room ❑ dining room ❑ kitchen ❑ bedroom ❑ bathroom ❑ other ❑ Identify: Ceilings and external elements Are there any? Yes No Suspended ceilings Air conditioners / ceiling heaters Suspended objects (lamps, vases, plants…) Decorative ceiling moldings Pipes / conducts Roof tiles (exterior) Balconies Chimneys Furniture and equipment Are there any? Are they well secured? Yes No Cupboards, wardrobes Filing cabinets Shels Picture on the walls, wall lamps Decorative elements fixed on the wall, such as statues, sculptures Televisions, projectors, microphones, speakers Computers, printers, photocopiers Fire extinguishers Game consoles Furnitures / equipment on wheels Art pieces / plant pots in high places Aquariums Glass windows / doors Ventilators Kitchen equipment (stoves, oven, fridge, washing machine, dishwasher) Doors of wardrobes or cupboards with security locks SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 67 8.8. MODEL: MOVE, PROTECT AND SECURE In teams, students will build a small model to simulate an indoor environment (bedroom, living room, kitchen, classroom, etc.) which they will later “shake up” to show how the non-structural elements will be affected (objects, decorative items, glass, furniture, etc.). First, place the furniture and the decorations. Then, identify the non-struc- tural risks and finally apply protection measures (by using glue, changing the arrangement of the furniture, adding blinds or curtains, etc.). Materials: — 1 shoebox with no lid; — leftover foam from a mattress or pillow; — small boxes (turn them over and paint them) to make furniture; — small round mirrors of different sizes; — small Lego pieces or doll-house furniture can also be used, if available. Figure 34. Examples of the activity using doll house (Beatriz Zapico Blanco). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 68 The activity can also be carried out in groups using other materials such as KLine, MDF, etc. Figure 35. Constructing the models with the kids (Photos: Nuno Patrício, RTP. Marta Vicente, Delta S. Silva [KnowRISK project, 2017]). Discussion: — Identify the main non-structural risks. — Identify the corresponding protection measures. — Discuss the topic and apply it to other environments. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 69 8.9. SPOT THE DIFFERENCES: REDUCE THE RISK IN YOUR SURROUNDINGS This activity can be carried out in small groups, by printing or projecting images of the ‘home’ and ‘school’ environments so that the whole class can identify the differences. In general, the discussion becomes more intense when children start to tell their own stories related to the topic or describe the state of their own bedroom. Discussion: In this activity, by spotting the differences between the images, the aims are to: — identify the non-structural risks in the bedroom or classroom; — provide solutions to reduce the risk; — involve the whole class in the discussion of the topic. Look at the pictures and ask: what risks can you identify in the classroom? Put a circle around them. How can these risks be reduced? Figure 36. Spot the differences (Hugo O’Neill). SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 70 Figure 37. Steps to reduce the seismic risk. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 71 8.10. TREME-TREME COMPUTER GAME This educational video game make children aware of seismic risk in a playfully way. It transmits knowledge and encourages new generations to become aware of and prepared for earthquakes. The game, available in Portuguese, English, Italian, French and Spanish, is freely distributed online. The application is available for Windows, macOS and Android. Visit <www.treme-treme.com> and install the game on your school or home computer. Figure 38. Treme-Treme computer game. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 72 8.11. TREME-TREME COOTIE This activity is related to the Treme-Treme game (<www.treme-treme.pt>) and its aim is to show some of the objects that must form part of an emergency kit. The children ask for a number, they say it aloud, they pick an object and then have to guess whether or not it belongs to an emergency kit. The answer is on the back of the question card. Materials: — “Treme-Treme” cootie (in the next page); — scissors. Discussion: — Select which objects belong in an emergency kit. — Explain why we must take some and reject others. — Encourage the students to play the Treme-Treme game (<www.tremetreme.pt>) at school or at home, as all the items in the kit are used in the game. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 73 Figure 39. Treme-Treme cootie. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 80 3. Predictions Indicate with a cross the options that you think will answer the questionproblem. Earthquakes occur… … due to the movements of the Earth around the Sun … because the Earth has a lot of water and the ground moves … because the surface of the Earth is formed by plates that move 4. Material a) Modelling the planet Earth in modelling clay. b) Puzzle and construction pieces. c) Chocolate bars that represent the Earth's crust. 5. Method 1. Observe the internal structure of the Earth through a model made of modelling clay. 2. Create the puzzle that represents the planet’s surface and identify the pieces as the tectonic plates that constitute the earth's crust. 3. Make the two extremites of the chocolate bar collide with each other and observe what happens. 4. Join the ends of the chocolate bar and make them move in parallel in the opposite direction and observe what happens. 5. Move the two halves away from the chocolate bar and observe what happens. 6. Results When we use chocolate bars, we observe that the extremities are modified according to the movements we perform. The same goes for the boundaries of tectonic plates. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 81 Convergent plates slide in parallel. Divergent plates collide. Transforming plates move away. Join by a line. 7. Conclusions Indicate with a cross (X) if the statements are true (V) or false (F). a) Through this experience, we can conclude that: V F Earthquakes occur because the interior of the Earth is made of constantly moving materials Earthquakes occur because the tectonic plates do not move Tectonic plates move because the interior of the Earth is always in motion b) With this exercise, we learn that: V F Earthquake, shake and tremors are antonyms The interior of the Earth is formed by nucleus, mantle and crust The surface of the Earth looks like a puzzle of plates that fit together The crust is formed by several ergonomic plates Tectonic plates can collide, move away or slide in parallel We can use chocolate bars to represent the boundaries of tectonic plates, so we can carry out this activity alone WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 82 c) Correct the statements you indicated as false in the previous exercises. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 83 WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) — Did you know that an earthquake could be named as seism, earth tremor or quake? These words are synonyms. — Each year, more than one million earthquakes occur on the Earth. — Just to have an idea, the tectonic plates move around 8 centimetres per year. This is the speed at which a nail grows! — The Euro-Asian plate moves away from the North-American plate at an average speed of 2,5 centimetres per year (this is 25 kilometres in a million years!). — The largest mountain range in the world is underwater. The mid-Atlantic ridge (Figure 43) is the largest mountain range in the world, with about 15 000 km of length. — The highest mountains in the world are still in formation! The Himalayan Mountains beging their formation about 60 million years ago, when the Indian plate collided with the Eurasian plate. Currently, both plates are still in convergence and the Himalayan Mountains are in constant transformation. — In the Pacific Ocean, more than 80% of the earthquakes occur in the socalled "Ring of Fire". This is an area of high geological instability, whose shape is similar to a horseshoe. The ring spreads along this ocean, which is the largest in the world. This area is characterized by the presence of several tectonic plates, which leads to a high frequency of occurrence of earthquakes and tsunamis. — Did you know that a tsunami could reach 800 km/h? This is the speed at which airplanes fly. Chapter 11. Trivia WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 84 Figure 42. Mid-Atlantic ridge. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 85 WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) Chagas, I. (1993). Aprendizagem não formal/formal das ciências: Relações entre museus de ciência e escolas. Revista de Educação, 3 (1), 51-59. Lisboa. Correia, V. (1995). Recursos didácticos. Aveiro: Companhia Nacional de Serviços, S. A. Earthquake teaching tools for the classroom (University of California Television [UCTV]): <https://www.youtube.com/watch?v=GQQCvsxHtJo>. Ferreira, M.A. (2012). Risco sísmico em sistemas urbanos. Tese de doutoramento. Instituto Superior Técnico, Universidade de Lisboa Ferreira, M.A., Oliveira, C.S., Mota de Sá, F., Lopes, M., Pais, I. (2018). KnowRISK Portfolio of solutions: for the reduction of seismic risk through non-structural elements. KnowRISK project (<https://knowriskproject.com/portfolio/>). Graells, P. M. (2000). Los medios didácticos. <http://peremarques.pangea.org/medios.htm>. Instituto Geográfico Nacional. (2017). Mapa de fallas activas cuaternarias. Inventors of Tomorrow: <https://inventorsoftomorrow.com/2017/01/30/earth_quakes-2/>. KnowRISK (2017). Know your city, Reduce seISmic risK through non-structural elements. European Commission’s Humanitarian Aid and Civil Protection Grant agreement ECHO/SUB/2015/718655/PREV2. <www.knowriskproject.com>. Magic Makers: <https://www.youtube.com/watch?v=lTMahL6xPRE>. Morales-Esteban, A., Martínez-Álvarez, F., Scitovski, S., Scitovski, R. (2014). A fast partitioning algorithm using adaptive Mahalanobis clustering with application to seismic zoning. Computers and Geosciences, 73, 132-141. <https://doi.org/10.1016/j.cageo. 2014.09.003>. Sá, L., Morales-Esteban, A., Durand Neyra, P. (2018). The 1531 earthquake revisited: loss estimation in a historical perspective. Bulletin of Earthquake Engineering, 16(10), 4533-4559. <https://doi.org/10.1007/s10518-018-0367-z>. Santos, M.C. (2008). Estudo dos danos ocorridos em Lisboa causados pelo terramoto de 1755: Quantificação e discussão. Tese de Mestrado. Universidade Técnica de Lisboa Instituto Superior Técnico, Lisboa, 166 pp. Saúde, A., Costa, E., Fernandes, J., Esteves, M., Amaral, M., Almeida, P., André, T. (2015). Referencial de educação para o Risco -Educação Pré-Escolar, Ensino Básico (1º, 2º e 3º ciclos) e Ensino Secundário. Ministério da Educação e Ciência, Lisboa. Treme-Treme, jogo educativo, <http://treme-treme.pt/>. References WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 86 Understanding earthquakes in the primary classroom: <https://www.sciencelearn.org.nz/ resources/2247-understanding-earthquakes-in-the-primary-classroom>. UPStrat-MAFA (2013). Urban disaster prevention strategies using macroseismic fields and fault sources. EU Project Num. 230301/2011/613486/SUB/A5), DG ECHO Unit A5. SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 87 WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) Figure 1. Organization of the Risk Education Framework ..................... 12 Figure 2. Models of the internal structure of Earth, using playdough of several colours (right image: <http://cienciasideiaxxi.blogspot.com>) ................................ 15 Figure 3. Structure of the Earth. Example using a boiled egg ................. 15 Figure 4. Tectonic plate collision representations (Mónica Amaral Ferreira and Hugo O’Neill) .................................................... 16 Figure 5. Explanation “the ground shakes” (Hugo O’Neill) .................... 17 Figure 6. Chocolate snack representing plate boundaries motion (Mónica Amaral Ferreira and Hugo O’Neill) .......................... 18 Figure 7. Example of fault, subduction, trench, oceanic crust and continental crust (source: <http://www.lneg.pt/ CienciaParaTodos/edicoes_online/diversos/guiao_tectonica_ placas/texto>) ........................................................................ 19 Figure 8. Hypocentre vs. Epicentre (Emilio Romero Sánchez) ............... 21 Figure 9. Richter is a logarithmic scale (Emilio Romero Sánchez) ......... 22 Figure 10. Released energy (Emilio Romero Sánchez) ............................ 22 Figure 11. What is the effect of earthquakes on buildings? (Hugo O’Neill) .. 23 Figure 12. Modified Mercalli scale (Hugo O’Neill) ................................. 24 Figure 13. Tsunami generation (Emilio Romero Sánchez) ....................... 27 Figure 14. Tsunami natural warning signs (Hugo O’Neill) ...................... 28 Figure 15. Spanish seismic hazard map (Norma de Construcción Sismorresistente, NCSE-02) ...................................................... 30 Figure 16. Quaternary active faults in the Iberian Peninsula and magnitude of earthquake .................................................. 31 Figure 17. Seismic hazard in mainland Portugal (Regulamento de segurança e ações para estruturas de edificios e pontes. 1983) ......... 32 Figure 18. Artistic recreation of the Lisbon tsunami of 1755 (source: Getty Images) .............................................................. 37 List of figures SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 88 Figure 19. Building behaviour under an earthquake. If the building undergoes a large displacement, the structural elements such as beams, columns and walls could become damaged, making the building not safe (Emilio Romero Sánchez) .......... 39 Figure 20. Use of braces for the creation of a lateral load path (Emilio Romero Sánchez) ...................................................... 40 Figure 21. Base isolation (Emilio Romero Sánchez) ................................ 41 Figure 22. Non-structural protection measures that can be adopted at school, at work or at home: move, protect, secure and retrofit. For more information, see the Practical Guide to KnowRISK, <https://knowriskproject.com/> ................... 44 Figure 23. Risk of tsunami (source: <www.tsunamizone.org>) ................ 48 Figure 24. What to do in coastal zones after an earthquake? (source: <www.tsunamizone.org>) ......................................... 49 Figure 25. Primary school students putting the puzzle together individually (Pa trícia Gramaxo)............................................... 52 Figure 26. The same activity developed in groups (Beatriz Zapico Blanco) .. 52 Figure 27. Puzzle/world map (to be printed and cut) .............................. 53 Figure 28. Spanish regions (adapted from <www.ign.es>) ....................... 54 Figure 29. Examples of the activity development (Hugo O’Neill) ............ 56 Figure 30. Earth globe (Hugo O’Neill) ................................................... 58 Figure 31. Example of the activity using spaghetti and marshmallows (Mónica Amaral Ferreira) ........................................................ 60 Figure 32. Example of the activity using straws and day (<https:// pbskids.org/designsquad/build/seismic-shake-up/>) ............... 61 Figure 33. Building the Shaking Paper House (Photo: Mónica Amaral Ferreira) ............................................. 61 Figure 34. Examples of the activity using doll house (Beatriz Zapico Blanco) .......................................................... 67 Figure 35. Constructing the models with the kids (Photos: Nuno Patrício, RTP. Marta Vicente, Delta S. Silva [KnowRISK project, 2017]) .................................................... 68 Figure 36. Spot the differences (Hugo O’Neill) ....................................... 69 Figure 37. Steps to reduce the seismic risk ............................................... 70 Figure 38. Treme-Treme computer game ................................................ 71 Figure 39. Treme-Treme cootie .............................................................. 73 Figure 40. KnowRISK board game ......................................................... 75 Figure 41. Seismic safety at school: non-structural elements (Hugo O’Neill) ...................................................................... 78 Figure 42. Mid-Atlantic ridge ................................................................. 84 SUMARY WHY DOES THE GROUND SHAKE? Mónica Amaral Ferreira Beatriz Zapico Blanco (coords.) 89 The aim of this guide is to integrate a set of activities about seismic risk in the first cycle of basic education in order to enhance the awareness of the population regarding this risk. The contents of this guide are intended for teachers. instructors and technical educative staff who would like to perform seismic risk related activities in schools or non-formal educational environments. The educational project “Why does the ground shake?” was conceived in the frame of the project PERSISTAH- Projectos de Escolas Resilientes aos Sismos no Território do Algarve e de Huelva. BOOK COVER