Masumi Yamada, Kyoto University

How to Preparefor a Strong Shaking?

Earthquake Early Warning in Japan

2011 Tohoku EQEarthquake

P-wave detected

Location and Magnitude determinedEarthquake Early Warning issued

Observed Seismic Intensity reported

Tsunami Warning issued

0sec

19sec

27sec

3min

3.5min

27 bullet trains were stopped without derailments.

- March 11, 2011

Damage to bullet trains・ Damage to cable column 540・ Damage to cable 470・ Damage to column 100・ Damage to rail track 20

AERA Mook 震災と鉄道全記録

ProvidingEarthquake Early Warning

needs

ProvidingEarthquake Early Warning

needs

infrastructure

Seismic Stations

http://iisee.kenken.go.jp/net/shiva/update/India(IMD)0619.pdf

300km

ProvidingEarthquake Early Warning

needs

infrastructure

ProvidingEarthquake Early Warning

needs

infrastructure information technology

sensor

sensor

sensor

JapanMeteorologic

alAgency

TV

radiocell

phonetown

speaker

provider

train

factory<1sec

“Earthquake occurred off Fukushima.Prepare for strong shaking.”(Japan Meteorological Agency)

http://www.data.jma.go.jp/svd/eqev/data/study-panel/eew-hyoka/05/shiryou4-1.pdf

5th meeting of EEW improvement

Automated Responses to EEW

0 10 20 30 40 50 60

Public announcement

Elevator: emergency stop

Warning (alarm)

Warning (flashing lights)

Show alert on monitors

Secure evacuation route

Control machine

Other

Nothing

ProvidingEarthquake Early Warning

needs

infrastructure information technology

ProvidingEarthquake Early Warning

needs

seismologyinformation technology

infrastructure

Kanamori (2005)

How to estimate shaking?

http://www.seisvol.kishou.go.jp/eq/EEW/Meeting_HYOUKA/t02/index.html

Step1: Estimate location from P-

arrival times

Step2: Estimate Mag. from

displacement (Ad) & R

Step3: Estimate Shaking intensity

from M & R

log10PGV=0.58Mw+0.0038D – 1.29 – log10 (R+0.0028*100.5Mw) – 0.002Rlog10ARV =1.83 – 0.66 log10AVS30SI = 2.68 +1.72log10 (PGV*ARV)

Threshold of shaking to give EEW

The intensity is computed from acceleration waveforms.

5- 5+ 6- 6+ 7

0 1 2 3 4

(JMA Website)

2001 Gujarat Earthquake

Create Dataset | displacement amp.

Amplitude σ=±30%Vp and Vs σ=±10%

Location Estimation

Time History of Warnings

Earthquake

1st P-wave triggered @Bhuj

2nd P-wave triggered @ BhavnagarLocation and Magnitude determined

0sec

10sec

40sec

Time History of Warnings

Bhuj

Bhavnagar

Time History of Warnings

Earthquake

1st P-wave triggered @Bhuj

2nd P-wave triggered @ BhavnagarLocation and Magnitude determined

3nd P-wave triggered @ JaisalmerLocation error <10km

0sec

10sec

40sec

60sec

Time History of Warnings

Bhuj

Bhavnagar

Jaisalmer

Japanese EEWFacts and Figures

http://www.data.jma.go.jp/svd/eqev/data/study-panel/eew-hyoka/06/shiryou1.pdf

6th meeting of EEW improvement

Number of warnings

0 20 40 60 80 100

93%

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

44%

Accuracy

False alarm for 2011 Tohoku aftershock

False alarm for 2011 Tohoku aftershock

2013 False alarm

EEW M7.8Reality M2.3

M2.3

Disconnection of data

Noise

M7.8

http://www.data.jma.go.jp/svd/eqev/data/study-panel/eew-hyoka/05/shiryou3-2.pdf

Feedback on the False AlarmUpset

Not upset, but concerned

No choice

Unconcerned

Disinterested

Other

0 10 20 30 40

3%

28%

40%

5th meeting of EEW improvement

Summary

Earthquake Early Warning System needs:Infrastructure

InformationTechnology

Seismology Education× × ×

Examples:2001 Gujarat earthquake in India2011 Tohoku earthquake in Japan2013 False alarm in Japan

Problem1 : Underestimation

http://www.natureasia.com/japan/nature/specials/earthquake/nature_comment_051211-4.php

7070Warnings

AfterTohoku

Problem2 : False Alarms

http://www.jma.go.jp/jma/press/1104/28b/eew_hyouka_2.pdf

BeforeTohoku 1717

Warnings

55Exp.-Obs. ≧ 2

4444Intensity Error (Exp.-

Obs.)≧ 2

12123232multiple events others

Failure of Hypocenter Relocation

Good! Bad…

3/11 M9 3/12 M6

JMA website

Current Approach

Shake!

Shake!

Our Approach

Shake!

Shake!

No shake

No shake

No shake

7070Warnings

AfterTohoku

Performances

http://www.jma.go.jp/jma/press/1104/28b/eew_hyouka_2.pdf

BeforeTohoku 1717

Warnings

55Exp.-Obs. ≧ 2

4444Intensity Error (Exp.-

Obs.)≧ 2

44 2626This Study