Earthquake Early warning and possible precursor from seismicity
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Transcript of Earthquake Early warning and possible precursor from seismicity
EARTHQUAKE EARLY WARNING AND POSSIBLE PRECURSOR FROM SEISMICITY
By NTU Palert, CWB & NCDR teams
1994 1995 1996 1997 1998 1999 2000
200
300
400
500
600
700
Even
ts (M
L > 2
.0)
1994 1995 1996 1997 1998 1999 2000
0.7
0.8
0.9
1
1.1
1.2
1.3
b va
lues
Chi-Chi Mw7.6
A
B
Aveage 435 events / 30 dayss.d.v. 78 events
Aveage = 0.97s.d.v. 0.10
1994 1995 1996 1997 1998 1999 2000Year
0
4
8
12
16
Even
ts (M
L>4.
0)
CAveage = 5.5s.d.v. 2.6
Wu and Chiao (2006)
Background 1994 to Chi-ChiM>=2.0Radius 20 kmDepth <= 40 km
Background1994 to 2003/12/09M>=McB value (Aki)Radius 25 kmDepth <= 35 kmRelocated catalogWu et al. (2008)
Chan et al. (2012)
PALERT EEW
- 3 0 3 6 9 1 2 1 5 1 8 2 1Tim e after P arrival (second)
-12
-8
-4
0
4
8
Dis
plac
emen
t (cm
)
-20
-10
0
10
20
Velo
city
(cm
/sec
)
-200
0
200
400A
ccel
erat
ion
(gal
)
Pd
PGA
PGV
PGD
c
M w6.6, focal depth 10 kmKnet Station NIG018Epicentral distance 14 km
0.5 cm
Pd threshold warning
4 5 6 7 8M w
0 . 1
1
1 0
c (s
ec)
Taiwan 11 eventsSouthern California 26 eventsJapan 17 events
log (c) = 0.296 M w - 1.716Sdv=0.122, R=0.933
0.001 0.01 0.1 1 10Pd (cm)
0 . 1
1
1 0
1 0 0
PGV
(cm
/sec
)
Taiwan 507 recordsSouthern California 199 recordsJapan 74 records
Linear regression over 780 recordslog(PGV )=0.920 log(Pd) + 1.642SDV = 0.326
For both onsite & regional early warning purposes
iTouch for backup power (4 hrs), display and sound warning
345 stations
CWB and Palert real-time strong motion stations
CWBSN & Palert Shaking maps
• Use 5 km as grid spacing and use inverse square distance as weighting factor to calculate each point PGA.
• One point represents 25 square km area.
Grid setting
Case 1
8 3822
Case 2
8 20
40
Thanks for your attention