Information message about the strong earthquake off the east coast of Honshu, Japan, October 25, 2013. |
| The strong earthquake with M=7.3 has occurred off the east coast of Honshu, Japan, on October 25, 2013 at 17:10 GMT (21:10 Moscow time). |
| 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 18 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 59 stations, accurate processing - with data 72 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Erimo (∆ 4.9º), Matsushiro (∆ 5.3º), Kurilsk (∆ 8.3º), Yuzhno-Sakhalinsk (∆ 9.8º), Mys Shultsa (∆ 11.7º). Fig. 2 presents fragments of records obtained from digital stations Yakutsk (∆ 26.5º), Ulaanbaatar (∆ 29.4º), Bilibino (∆ 33.1º), Makanchi Array (∆ 46.2º), College (∆ 47.5º). |
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 |
17-10-15.0 |
37.27 |
144.73 |
10 |
72 |
7.3/29 | 7.2/37 | 10-10.5 | 61 | IPC GS RAS (Accurate) | | 2 |
17-10-15.4 |
37.3 |
144.71 |
10 |
59 |
7.3/26 | 7.2/33 | 10-10.5 | 86 | IPC GS RAS (Preliminary) | | 3 |
17-10-17.3 |
37.22 |
144.69 |
10 |
852 |
Mw 7.1 | | | 18 | CSEM | | 4 |
17-10-18.5 |
37.149 |
144.679 |
26.05 |
907 |
Mw 7.1 | 6.9 | | 10 | NEIC (Accurate) | | 5 |
17-10-16.0 |
37.194 |
144.663 |
10 |
47 |
Mw 7.3 | | | 76 | NEIC (Preliminary) | |
| 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 |
| Fig. 3 presents with red star epicenter of this earthquake which origin was located off the east coast of Honshu, Japan, at the depth of 10 km, 355 km E-S-E of Sendai and 476 km N-E of Tokyo - the Capital of Japan. |
Figure 3 |
|
| Aftershock |
| GSRAS registered 9 aftershocks M>=4.6 within 2 days after the main shock. |
| 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 |
| 20133752 | 2013-10-25 17:57:35.0 | 37.39 | 144.76 | 10 | 19 | - | 5.0/ 11 | 5-5.5 | Off east coast of Honshu, Japan | | 20133753 | 2013-10-25 19:02:56.0 | 37.3 | 144.66 | 10 | 27 | - | 5.0/ 12 | 5-5.5 | Off east coast of Honshu, Japan | | 20133754 | 2013-10-25 21:27:33.0 | 37.23 | 144.56 | 10 | 37 | - | 5.5/ 10 | 6.5-7 | Off east coast of Honshu, Japan | | 20133758 | 2013-10-26 01:06:45.0 | 37.12 | 144.65 | 10 | 24 | - | 5.0/ 10 | 5-5.5 | Off east coast of Honshu, Japan | | 20133759 | 2013-10-26 02:08:01.0 | 37.13 | 144.65 | 10 | 25 | - | 4.9/ 15 | 5-5.5 | Off east coast of Honshu, Japan | | 20133760 | 2013-10-26 05:18:38.0 | 37.2 | 144.85 | 10 | 24 | - | 4.9/ 11 | 5-5.5 | Off east coast of Honshu, Japan | | 20133762 | 2013-10-26 14:36:14.0 | 38.15 | 141.73 | 60 | 16 | - | 4.6/ 6 | - | Near east coast of Honshu, Japan | | 20133769 | 2013-10-27 18:13:03.0 | 37.27 | 144.62 | 10 | 62 | - | 5.8/ 25 | 7-7.5 | Off east coast of Honshu, Japan | | 20133770 | 2013-10-27 23:01:44.0 | 37.32 | 144.73 | 10 | 35 | - | 5.1/ 17 | 5.5-6 | Off east coast of Honshu, Japan | |
| Macroseismic manifestations |
| According to RIA-Novosti the waves of tsunami with height up to 30 cm were observed in some parts of Miyagi Prefecture. Personnel of "Fukushima" NPP has obtained the command of evacuation from the territory of the station. There is no information about victims or destructions.
Fig. 4 presents USGS Community Internet Intensity Map USGS NEIC based on 100 responses in 38 cities.
At the territory of Russia this earthquake was felt in Yuzhno-Kurilsk with intensity 2 MSK. |
Figure 4 |
|
| Historical records |
| This earthquake has occurred 213 km S-E of destructive earthquake March 11, 2011, М=8.8 |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of the origin was obtained in IPC GSRAS with signs of initial arrivals of P waves at 84 stations, including 12 stations which registered compression waves (plus signs) and 72 stations which registered expansion waves (minus signs). All these stations are located in the interval of epicentral distances of 5–98º and are evenly dispersed along the azimuths. Focal mechanism solution of the origin in stereographic projection at the lower hemisphere is presented at fig. 5, elements of mechanism are presented in table.2. Fig. 6, 7 present focal mechanism solutions obtained in USGS NEIC with W-phase Moment Tensor technique and in Quick CMT Catalog, USA obtained with CMT technique. All solutions are close. The earthquake has occurred under the action of expansion stresses oriented to the west (IPC GSRAS and USGS) and to the east (CMT). Both nodal planes in all solutions decline to the horizon under nearly the same angles (DP=35-59º), they strike to the north (STK=7-14º) and to the south (STK=162-180º). The type of motion along both planes – normal fault with slip components (right lateral slip for NP1, left lateral slip for NP2).
Averaged value of seismic moment was obtained in IPC GSRAS with Р-waves spectra registered at «Talaya» station (∆32.15º) and «Obninsk» station (∆69.44º) Мо=1.0*10**20 N*m, average value of moment magnitude - Mw=7.3. According to USGS NEIC – Mo=5.48*10**19 N*m, Mw=7.1, according to Quick CMT – Mo=6.39*10**19 N*m, Mw=7.1. |
| 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 |
| 12 | 264 | 34 | 71 |
14 | 171 | 162 | 59 | -106 | 12 |
35 | -65 | IPC GS RAS | | 1 | 277 | 14 | 82 |
7 | 187 | 180 | 46 | -100 | 15 |
45 | -79 | NEIC | | 7 | 92 | 81 | 311 |
6 | 183 | 176 | 38 | -99 | 7 |
52 | -83 | Quick CMT | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Quick CMT - Quick CMT catalog |
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