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 ） .