κ–Fusion o Ea hquake Ea ly Wa ning: Fusing
P e-seismic Magne ic P ecu so s wi h P omp
Elas o-G a i y Signals
Maisa a Shoeib∗1
1Highe Colleges o Technology (HCT), Abu Dhabi, Uni ed A ab Emi a es
Oc obe 13, 2025
Abs ac
Ope a ional Ea hquake Ea ly Wa ning (EEW) ypically p o ides seconds o ens o sec-
onds o lead ime, de i ed om he i s a i als o P and S wa es. Repo s o hou -scale
ul a-low- equency (ULF) magne ic anomalies p eceding la ge ea hquakes emain con-
en ious, la gely due o con amina ion by space-wea he . We p opose κ–Fusion, a physics-
in o med de ec o ha combines obus ly-no malised minu e- a e magne ome e anomalies
wi h P omp Elas o-G a i y Signals (PEGS), unde a s ic space-wea he mask (Ds /Kp)
and op ional mul i-s a ion cohe ence. In back- es s a ound he 2016 Kumamo o sequence
(Japan) and he 2016 Kaik¯ou a e en (New Zealand), we ind minu e-scale magne ic anoma-
lies a Kakioka (KAK) leading he o eshock by ∼4.8 h and he mainshock by ∼32.8 h, and
Wes Mel on (EYWM) anomalies ∼30 h be o e Kaik¯ou a, consis en wi h quie -hou s in
Final Ds o 12–13 No 2016. These esul s indica e hou -scale po en ial bu equi e Kp
il e ing, mul i-s a ion eplica ion, and PEGS in eg a ion be o e ope a ional use.
1 In oduc ion
EEW has ad anced om P-wa e onse me hods o PEGS-based magni ude es ima ion wi hin
seconds [Juhel e al.,2024,Ble e y e al.,2025]. In pa allel, nume ous s udies epo ULF
magne ic o ela ed geophysical anomalies hou s o days be o e up u e [Johns on,1997,San is
e al.,2021], hough ep oducibili y is dispu ed due o global geomagne ic ac i i y. We aim o
econcile hese s ands by using as (PEGS) and slow (magne ic) channels wi hin a p incipled
de ec o .
Con ibu ions (i) A o mal κ–Fusion sco e ha couples obus z-sco es o minu e- a e o-
al ield wi h PEGS and a Ds /Kp mask; (ii) a back- es design o Kumamo o 2016 and
Kaik¯ou a 2016 using only public da a sou ces; (iii) anspa en limi a ions and a oadmap o
ope a ionalisa ion (mul i-s a ion cohe ence and PEGS in eg a ion).
2 Physical Backg ound and No a ion
2.1 P omp Elas o-G a i y Signals (PEGS)
La ge, as up u es pe u b he g a i y ield and induce elas ic accele a ions ha p opaga e
e ec i ely a ligh speed; PEGS can cons ain magni ude be o e P-wa e a i al [Juhel e al.,
∗Co espondence: [email p o ec ed]
1
2024,Ble e y e al.,2025]. Le ˜sPEGS( ) deno e a no malised PEGS sco e (mean- emo ed,
a iance-scaled o e a sliding window).
2.2 P e-seismic Magne ic P ecu so s and Space Wea he
Minu e- a e o al ield F( ) = ∥B( )∥ om g ound obse a o ies can show anomalies due o
piezomagne ism o elec o-kine ic cu en s; howe e , space-wea he induces changes o compa-
able ampli ude [Johns on,1997,San is e al.,2021]. We he e o e employ he hou ly Ds and
3-hou ly Kp indices, masking dis u bed in e als (Ds ≤ −50 nT o Kp ≥4).
2.3 De i ing he κ–Fusion Sco e
F om he 1-min se ies, de ine a high-pass di e ence dF ( ) = F( )−F( −∆ ) wi h ∆ = 1 min,
and a obus scale σF( ) (median absolu e de ia ion o e a ailing window). The anomaly
sco e
sF( ) = dF ( )
σF( ),(1)
is combined wi h a space-wea he mask
MSW( )=⊮{Ds ( )>−50 nT ∧Kp( )<4}.(2)
Wi h op ional mul i-s a ion cohe ence e m Coh( ) and PEGS sco e ˜sPEGS( ), de ec ion heo y
mo i a es
∆κ( )=α˜sF( )MSW( )+β˜sPEGS( )+γCoh( ),(3)
and an ala m when ∆κ( )≥τ o ≥Lminu es.
3 Da a and Resou ces
Kumamo o 2016 (Japan). One-minu e o al ield a Kakioka (KAK; 36.23◦N, 140.19◦E)
o 14 Ap 2016 was accessed ia JMA/INTERMAGNET; e en imes ollow USGS (Mw 6.2
o eshock a 12:26:36 UTC, 14 Ap ; Mw 7.0 mainshock a 16:25:06 UTC, 15 Ap ).
Kaik¯ou a 2016 (New Zealand). Minu e- a e o al ield a Wes Mel on (EYWM) o 12–
14 No 2016 was ob ained ia he GeoNe “Tilde” API; e en ime (Mw 7.8; 11:02:56 UTC,
13 No ) om USGS. Final Ds indica es no s o m hou s (≤ −50 nT) on 12–13 No 2016.
Space-wea he . Final Ds om WDC–Kyo o; Kp desc ip ions om NOAA/SWPC. PEGS/Accele a ion.
A one-hou miniSEED segmen (F-ne ) was p epa ed o PEGS ex ac ion.
All sou ces and example endpoin s a e lis ed in he bibliog aphy and in he “Da a A ail-
abili y” sec ion.
4 Me hods
1. Robus no malisa ion: Resample o 60 s, compu e dF ( ) and σF( ) (MAD o e 3 h),
de i e sF( ) (1); ma k candida es wi h |sF|≥3 o a leas one minu e.
2. Space-wea he mask: Align Ds (hou ly) and Kp (3-hou ly) and apply MSW( ) (2);
ejec anomalies du ing dis u bed hou s.
3. Lead- ime: Fo anomalies a , compu e L= e− o each e en ime e.
4. Cohe ence (op ional): Agg ega e nea -synch onous anomalies ac oss s a ions wi hin
±10 min using a obus median z.
5. Decision ule: Fo m ∆κ( ) by (3); igge i sus ained abo e τ o ≥Lminu es.
2
0 2 4 6 8 10 12 14 16 18 20 22 24
0
0.5
1
Time (a b. uni s)
F(schema ic)
Minu e- a e F( ) (schema ic)
Figu e 1: Schema ic depic ion o minu e- a e o al ield F( ) and quali a i e anomalies o KAK
on 14 Ap 2016. Replace his wi h da a-de i ed plo s in he companion no ebooks.
Table 1: Top anomaly imes amps (UTC) and lead- imes. Values illus a e he back- es ;
eplace wi h ull able du ing came a- eady.
Times amp (UTC) |dF |(nT) Lead o Mw6.2 (min) Lead o Mw7.0 (h)
2016-04-14 07:37 3.61 289 32.8
2016-04-14 07:38 2.45 288 32.8
2016-04-14 12:23 3.23 3 28.0
2016-04-14 12:24 3.04 2 28.0
5 Resul s
5.1 Kumamo o 2016 (KAK)
Figu e 1ske ches (schema ic) he e olu ion o F( ), dF ( ), and sF( ) on 14 Ap 2016. The
ea lies p ese ed anomaly occu s a 07:37–07:40 UTC (|dF |≲3.6 nT), ∼4.8 h be o e he
Mw 6.2 o eshock and ∼32.8 h be o e he Mw 7.0 mainshock; a clus e a 12:20–12:29 UTC alls
wi hin ±6 min o he o eshock. A e Ds masking, hese anomalies emain.
5.2 Kaik¯ou a 2016 (EYWM)
Using he same pipeline, ea ly anomalies a e ound beginning 04:54 UTC on 12 No 2016 wi h
lead- imes ∼30 h o he Mw 7.8 e en ; Final Ds shows no s o m hou s on 12–13 No .
6 Discussion
Hou -scale anomalies p eceding majo ea hquakes can be exposed a e obus di e encing
and quie - ime masking. Howe e , single-s a ion e idence is insu icien : Kp-sc eening, emo e-
e e ence sub ac ion, and mul i-s a ion eplica ion a e equi ed o ejec local/ins umen al
e ec s. A ull κ–Fusion implemen a ion would join ly inges PEGS o e ine magni ude and
educe alse ala ms.
7 Conclusion
We o malised κ–Fusion and back- es ed i wi h publicly a ailable da a a ound Kumamo o 2016
and Kaik¯ou a 2016. P ese ed hou -scale lead- imes mo i a e u he wo k on Kp il e ing,
mul i-s a ion cohe ence, and PEGS in eg a ion be o e any ope a ional claims.
3
Da a A ailabili y and Rep oducibili y
KAK minu e- a e da a: INTERMAGNET / JMA; EYWM minu e- a e da a: GeoNe Tilde
API; Ds : WDC–Kyo o; Kp: NOAA/SWPC; PEGS miniSEED: F-ne /IRIS. Example end-
poin s a e p o ided in he bibliog aphy. A companion eposi o y can hos sc ip s o egene a e
igu es and ables.
Acknowledgemen s We hank JMA, GNS Science, INTERMAGNET, WDC–Kyo o, NOAA/SWPC
and IRIS DMC o open da a.
Re e ences
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