Information message about the strong earthquakes on the shore of Honshu Island on September 5, 2004. |
| On September 5, 2004 two strong earthquakes have happened near the Southern shore of Honshu Island, Japan. The first of them happened at 14:07 Moscow time (10:07 GMT) with magnitude 7.2, another one - at 18:57 (14:57 GMT) with magnitude 7.5. |
| 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 45 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 37 stations, accurate processing - with data 46 stations. |
| Fig. 1 presents fragments of records from digital stations Petropavlovsk-Kamchatsky (delta 2,8 degrees), Magadan (delta 6.4 degrees), Bilibino (delta 12,8 degrees), South-Ssahalinsk (delta 13,9 degrees), Yakutsk (delta 16.9 degrees), Tiksi (delta 28 degrees). Fig. 2 presents fragments of records from digital stations Borovoe (delta 49 degrees), Lovozero (delta 50 degrees), Arti (delta 52 degrees), Pulkovo (delta 58 degrees), Obninsk (delta 60 degrees), Kislovodsk (delta 68 degrees). These records demonstrate well extracted depth phases рР. |
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: |
| Note: [1]data on the first earthquake
[2]data on the second earthquake |
| 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 |
14-57-16.50 |
33.19 |
137.05 |
10 |
43 |
7.5/16 | 6.40/9 | 10-11 | 116 | IPC GS RAS (accurate [2]) | | 2 |
10-07-09.20 |
33.45 |
136.66 |
20 |
26 |
7.20/10 | 6.80/9 | 9-9.5 | 232 | IPC GS RAS (preliminary [1]) | | 3 |
14-57-20.20 |
33.62 |
137.12 |
20 |
19 |
7.6/7 | 6.2/7 | 9.5-10 | 228 | IPC GS RAS (preliminary [2]) | | 4 |
10-07-07.60 |
33.14 |
136.62 |
20 |
46 |
7.20/18 | 6.90/13 | 9-9.5 | 142 | IPC GS RAS (accurate [1]) | | 5 |
14-57-22.80 |
33.68 |
137.07 |
33 |
276 |
7.3 Mw | | | 157 | CSEM (accurate [2]) | | 6 |
10-07-05.80 |
32.63 |
137.36 |
33 |
256 |
7.2 Mw | | | 284 | CSEM (accurate [1]) | | 7 |
10-07-09.08 |
33.09 |
136.63 |
19.9 |
201 |
6.80/25 | 6.80/113 | | 54 | NEIC (preliminary [1]) | | 8 |
14-57-18.85 |
33.15 |
137.04 |
10 |
186 |
7.0/27 | 6.9/99 | | 58 | NEIC (accurate [2]) | | 9 |
14-57-18.84 |
33.15 |
137.04 |
10 |
186 |
7.0/15 | 6.1/99 | | 58 | NEIC (preliminary [2]) | | 10 |
10-07-09.08 |
33.09 |
136.63 |
19.8 |
201 |
6.9/73 | 6.80/113 | | 54 | NEIC (accurate [1]) | |
| 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 |
| Aftershock |
| 12 aftershocks have been registered near Pacific Ocean shore of Honshu Island within the period between September 5 and 7. |
| 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 |
| 20041530 | 2004-09-05 15:53:21.0 | 33.3 | 136.89 | 33 | 6 | - | 5.0/ 4 | 3.5-4 | Near s. coast of Western Honshu | | 20041531 | 2004-09-05 17:34:13.0 | 33.6 | 136.5 | 20 | 6 | - | 4.8/ 3 | 3.5-4 | Near s. coast of Western Honshu | | 20041532 | 2004-09-05 18:13:48.0 | 33.52 | 136.98 | 33 | 7 | - | 5.0/ 4 | 3.5-4 | Near s. coast of Western Honshu | | 20041533 | 2004-09-05 20:31:03.0 | 33.86 | 136.43 | 20 | 12 | 5.8/ 6 | 5.5/ 7 | 7-7.5 | Near s. coast of Western Honshu | | 20041534 | 2004-09-05 22:48:47.0 | 33.57 | 137.06 | 33 | 9 | 4.1/ 5 | 4.6/ 4 | 3.5-4 | Near s. coast of Honshu, Japan | | 20041536 | 2004-09-06 09:12:02.0 | 33.42 | 136.65 | 33 | 11 | - | 5.0/ 7 | 3.5-4 | Near s. coast of Western Honshu | | 20041537 | 2004-09-06 10:29:25.0 | 34.1 | 136.34 | 33 | 9 | - | 4.7/ 6 | 2.5-3 | Western Honshu, Japan | | 20041538 | 2004-09-06 10:39:47.0 | 33.11 | 137.37 | 33 | 8 | - | 4.5/ 7 | 2-2.5 | Near s. coast of Honshu, Japan | | 20041543 | 2004-09-06 16:45:32.0 | 33.65 | 136.5 | 33 | 7 | - | 4.6/ 6 | 2.5-3 | Near s. coast of Western Honshu | | 20041544 | 2004-09-06 23:29:36.0 | 33.39 | 137.29 | 20 | 26 | 6.5/ 17 | 6.4/ 13 | 8-8.5 | Near s. coast of Honshu, Japan | | 20041546 | 2004-09-07 06:10:05.0 | 33.69 | 137.04 | 20 | 18 | 4.7/ 4 | 5.2/ 8 | 5-5.5 | Near s. coast of Honshu, Japan | | 20041553 | 2004-09-07 18:36:22.0 | 33.62 | 136.99 | 20 | 14 | 5.3/ 6 | 5.6/ 8 | - | Near s. coast of Western Honshu | |
| Macroseismic manifestations |
| From ITAR-TASS information epicenter was located near Pacific Ocean peninsula Kii. Vibrations have been felt on a vast territory of 600-700 km away from the origin place. Underground strikes have been registered in ancient capital Nara with numerous temples. Local media said nothing about the damage to the cultural and historical places.
In both cases tsunami alert messages have been broadcasted. For the first case the height of tide wave was less than 60cm, for the other one - almost a meter. After the first earthquake temporary stoppage of high speed railroad traffic took place. A few people have been injured but not seriously. At this moment the number of injured is 14 and obviously it will increase.
Electric power supply interruption was registered in Vakayama prefecture in 600 houses. One fire took place in Osaka, it was quickly liquidated. 4 small ships have been turned over near the shore of Mie prefecture without victims.
Fig.3 shows the map with two origins of the earthquakes on September 5. This map shows populated sights, those points with known intensities are depicted in red. This map was built with LAT-2002 software, which was developed in CIEKS for calculation of potential damages from the earthquakes. This program is used by CEME GS RAS in test mode today.
|
Figure 3 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism parameters have been determined with TMC method in NEIC (USA) and in Harvard Center (USA), they are presented in table 2 and shown on fig. 4, 5.
As one can see the solutions obtained in different centers are close to each other. The motion in origin has happened under the action of prevailing strengths of expansion oriented in South-Eastern direction. The motion along NP1 plane has near meridian spread direction and flat nature, it is represented by trap down with presence of insignificant component of right sided drift. For NP2 plane it had steep fall and North-Eastern spread direction with almost “pure” trap down.
|
| 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 |
| 59 | 23 | 29 | 183 |
9 | 278 | 248 | 18 | 59 | 100 |
75 | 100 | NEIC | | 80 | 4 | 10 | 181 |
1 | 271 | 270 | 35 | 89 | 91 |
55 | 91 | NEIC | | 71 | 286 | 5 | 181 |
18 | 90 | 190 | 43 | 117 | 75 |
53 | 67 | HARVARD | | 79 | 337 | 10 | 181 |
5 | 90 | 277 | 35 | 98 | 87 |
55 | 84 | HARVARD | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| NEIC - National Earthquakes Information Center of US Geological Service |
| HARVARD - Harvard Geophysical Center (USA) |
| HARVARD - Harvard Geophysical Center (USA) |
Figure 4 | 
Figure 5 | | 
Figure 6 | 
Figure 7 |
|
