Tsunami analyses of great interplate earthquakes along the central Kurile subduction zone
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Transcript of Tsunami analyses of great interplate earthquakes along the central Kurile subduction zone
Tsunami analyses of great interplate earthquakes along the central Kurile subduction zone
Yuichiro Tanioka and Kei Ioki
Hokkaido University, Japan
NOAA-NGDC Paula Dunbar and Kelly Stroker
Russian Data Victor M. Kaystrenko
Recent large interplate earthquakes along the Kurile-Kamchatka subduction zone
Source models for the 2006 central Kurile earthquake
The slip distribution estimated using teleseismic body waves ( Yamanaka, ERI note, 2006)
The slip distribution estimated using tsunami waveforms (Fujii and Satake, 2007)
Source area of the 2006 Kurile earthquake
Source area of the 1963 Kurile earthquake estimated by Kanamori (1970)
Russia Alaska
Japan
Tsunami waveforms at tide gauges at Islands in Pacific were obtained from NOAA-NGDC
Source area of the 2006 Kurile earthquake
subfaults
length 50km width 50km
strike 223 °dip 22 °rake 90 °
Subfault
Slip (m)
error (m)
1 0.0 0.002 1.2 0.523 1.3 0.574 0.0 0.005 0.0 0.416 2.0 0.407 0.5 0.508 2.3 0.729 0.6 0.6310 3.0 0.6811 1.0 0.5712 3.8 0.7613 2.2 0.7814 2.5 0.4615 2.0 0.4516 0.2 0.2617 0.0 0.3518 1.1 0.4319 1.4 0.5020 0.9 0.4521 0.3 0.33
°
32
54 10
8
1112
1314
15
1
9
6
7
16
17
18
2120
19
subfault numbers
Comparison of observed and computed tsunami waveforms. The horizontal axis is time in minutes from the origin time of the earthquake. The vertical axis is amplitude in cm.
observed waveform
computed waveform
data used in the inversion
Comparison of observed and computed tsunami waveforms. The horizontal axis is time in minutes from the origin time of the earthquake. The vertical axis is amplitude in cm.
observed waveform
computed waveform
data used in the inversion
Total seismic moment estimated from the slip distribution was 4.6×1021 Nm (Mw 8.4).
Where the 1918 central Kurile earthquake occurred ?
Tsunami waveforms at tide gauges in Japan and USA
USA tide gauge records are collected from NOAA-NGDC
Choshi Chichijima Honolulu San Francisco
1963 Kurile earthquake
Source models for the1918 Kurile earthquake
12
34
5
2006 central Kurile earthquake
Five source models for the 1918 Kurile earthquake
fault length 100km
fault width 100km
strike 230°
dip 20°
rake 90°
The best source model is model 2
The differences between observed and computed arrival times are less than 20 minutes
Chi
Chichijima Choshi
Honolulu San Francisco
1963 Kurile earthquake
Source models for the1918 Kurile earthquake
12
34
5
2006 central Kurile earthquake
Model 5
Observed tsunami arrival times at Chichijima and Honolulu are not explained at all by computed ones, although those at Choshi and San Francisco are explained well.
Chichijima Choshi
Honolulu San Francisco
The source area of the 1918 Kurile earthquake is closer to that of the 2006 Kurile earthquake than that of the 1963 Kurile earthquake.
The slip amount estimated from the comparison of observed and tsunami waveforms for the 1918 Kurile earthquake is 6.6 m.
The seismic moment for the 1918 Kurile earthquake is calculated to be 4.6 x 1021Nm ( Mw 8.4 ) .
1963 Kurile earthquake
1918 Kurile earthquake
2006 central Kurile earthquake
Conclusions
The 1963 Kurile earthquake
1) The large slip occurred the plate interface near the trench.
2) The large slip area is the same as the source area estimated by Kamamori (1970).
3) Total seismic moment estimated from the slip distribution was 4.6×1021 Nm (Mw 8.4).
The 1918 Kurile earthquake
1) The source area of the 1918 Kurile earthquake is closer to that of the 2006 Kurile earthquake
2) The seismic moment for the 1918 Kurile earthquake is calculated to be 4.6 x 1021Nm ( Mw 8.4 ) .