Information message about the destructive earthquake near the Western coast of Honshu Island, Japan, March 25, 2007 |
| The strong earthquake with М=7.0 victims and destructions has happened on March 25, 2007 at 00:41 GMT (04:41 Moscow time) near the Western coast of Honshu Island, Japan. |
| Parameters of the earthquake
have been determined in the Alert Service (AS) of Information
Processing Center (IPC) of Geophysical Survey of RAS in Obninsk with station data
obtained from digital and analog seismic stations of Russia, countries of CIS
and from abroad. Alert message on this earthquake has been delivered in 60 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 36 stations, accurate processing - with data 47 stations. |
| Figure 1 presents fragments of records obtained from digital stations Vladivostok (∆ 6.9º), Erimo (∆ 7º), Yuzhno-Sakhalinsk (∆ 10.8º), Hailar (∆ 17.1º), Petropavlovsk (∆ 22º). Figure 2 presents fragments of records obtained from digital stations Magadan (∆ 24º), Talaya (∆ 25º), Tiksi (∆ 27º), Bilibino (∆ 35º), Kurchatov (∆ 43º). |
Figure 1
| 
Figure 2
|
|
| IPC GS RAS also has obtained information with parameters of this event from some seismological centers, these data are given in table 1: |
| Table 1 |
| NN |
Time in origin h-min-s (GMT) |
Lat degr. |
Lon degr. |
Depth km |
N s/st |
Ms/ N |
mb/ N |
I0 calc |
GAP |
Center | | 1 |
00-41-55.4 |
37.25 |
136.52 |
10 |
47 |
7/15 | 6.4/13 | 10 | 96 | IPC GS RAS (Accurate) | | 2 |
00-41-59.3 |
37.31 |
136.46 |
33 |
36 |
7.1/7 | 6.4/11 | 8.5 | 135 | IPC GS RAS (Preliminary) | | 3 |
00-41-57.2 |
37.45 |
136.52 |
10 |
387 |
6.9Mw | | | 62 | CSEM | | 4 |
00-42-02.9 |
37.54 |
136.44 |
32.7 |
102 |
| 6.2/62 | | | NEIC (Preliminary) | | 5 |
00-41-57.3 |
37.28 |
136.6 |
5 |
114 |
6.7Mw | 6.3/78 | | 43 | NEIC (Accurate) | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| CSEM - European - Mediterranean seismological center |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Epicenter |
| In accordance with more accurate data from Meteorological Department of Japan epicenter of this earthquake was located in Japanese Sea with the origin at the depth of 11 km.
Figure 3 presents the map with epicenters of this earthquake obtained from data of various seismological centers and published at the site CSEM (European Mediterranean Seismological Center)
|
Figure 3 |
|
| Aftershock |
| This earthquake was accompanied with numerous aftershocks. In accordance with information obtained from Meteorological Department of Japan more than 50 repeating shocks have been registered in Isikawa region. Below one can find most significant of these aftershocks in accordance with GS RAS:
|
| N |
Date & Time (GMT)
yy-mm-dd hh:mm:sec |
Lat
degr. |
Lon
degr. |
Depth
km |
N
station |
Ms/ N |
mb/ N |
Io
calc. |
Region |
| 20071130 | 2007-03-25 06:43:43.0 | 37.93 | 136.84 | 100 | 13 | - | 4.4/ 4 | - | Near west coast of Honshu, Japan | | 20071131 | 2007-03-25 09:11:45.0 | 37.23 | 136.7 | 33 | 22 | - | 5.8/ 9 | 5.5 | Near west coast of Honshu, Japan | | 20071140 | 2007-03-25 22:16:38.0 | 37.03 | 136.44 | 33 | 19 | - | 5.4/ 8 | 4.5 | Near west coast of Honshu, Japan | | 20071145 | 2007-03-26 05:46:32.0 | 37.06 | 136.37 | 10 | 18 | - | 5.0/ 6 | 5-5.5 | Near west coast of Honshu, Japan | |
| Macroseismic manifestations |
| Powerful underground shock created the zone of disaster in the region of Japanese cities located at the Western Peninsula Noto in Isikawa prefecture. The number of victims reached 200 people. One woman was killed. The earthquake caused insignificant waves of tsunami with the height 10-20 cm.
Vibrations have been felt on the vast territory – from the most Northern Island Hokkaido to the south –western end of Honshu Island. Most significant destructions were registered in the cities Vadzima and Nanao. This is the region with the most destructions and victims, especially in Vadzima city, where nearly 50 living buildings were almost totally destroyed. Hundreds of constructions were significantly damaged. The earthquake caused numerous fires. Huge cracks and breaks appeared on the main highways.
Figure 4 presents the map of macroseismic picture obtained from USGS NEIC
|
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solutions of the earthquake’s origin 25.03.2007 have been obtained with the tensor method in NEIC, USA and with tensor method of centroid in Harvard Center, USA. They are presented in table 2 and figures 5-6. Both solutions are close. The earthquake has occurred under the action of compression strengths oriented to the South-East in NEIC solution and to the north-west in HARVARD solution. Both nodal planes lay rather steep (DP=40-60°) and have north-eastern - south-western direction of propagation. In accordance with data of these two centers the type of motion in origin – uplift (with shift components – left sided along NP1 NEIC and NP2 HRVD, right sided along NP2 NEIC and NP1 HRVD).
The value of seismic moment Мо of the earthquake 25.03.2007 in accordance with NEIC made 9.1* 10** 18 n*m, the value of moment magnitude - Mw = 6.6. The value of seismic moment Мо in accordance with HARVARD made 1.38* 10** 19 n*m, the value of moment magnitude - Mw = 6.7.
|
| Table 2 |
| Axes of main strengths |
Nodal planes |
Center |
| T |
P |
N |
NP1 |
NP2 |
| Pl |
Azm |
Pl |
Azm |
Pl |
Azm |
Stk |
Dp |
Slip |
Stk |
Dp |
Slip |
| 64 | 16 | 11 | 129 |
23 | 223 | 193 | 40 | 52 | 58 |
60 | 117 | NEIC | | 66 | 34 | 5 | 292 |
23 | 200 | 46 | 45 | 124 | 182 |
55 | 61 | HARVARD | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| HARVARD - Harvard Geophysical Center (USA) |
Figure 5 | 
Figure 6 |
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