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Information message about the strong earthquake in the northern part of Honshu Island, Japan on June 13, 2008

The strong earthquake with М=7.2 has happened on June 13, 2008 at 23:43 GMT (June 14 at 3:43 Moscow time) in the northern part 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 48 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).

Preliminary processing has been done with data from 39 stations, accurate processing - with data 69 stations.

Fig. 1 presents fragments of records obtained from digital stations Matsushiro (∆ 3.3º), Erimo (∆ 3.4º), Petropavlovsk (∆ 18.6º), Yakutsk (∆ 23.9º), Seimchan (∆ 24.8º). Fig. 2 presents fragments of records obtained from digital stations Bilibino (∆ 32.3º), Tiksi (∆ 33.1º), Kurchatov (∆ 44.2º), Borovoe (∆ 48.8º), Obninsk (∆ 66.1º).

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	23-43-44.5	39.13	140.72	10	69	7.2/16	6.6/24	10-10.5	51	IPC GS RAS (Accurate)
2	23-43-48.1	39.17	140.78	33	39	7.2/15	6.6/14	8-8.5	97	IPC GS RAS (Preliminary)
3	23-43-49.7	39.12	140.64	33	523	7.0Mw			32	CSEM
4	23-43-58.1	39.14	140.58	105	206	7.2Mw	6.2/194			NEIC (Preliminary)
5	23-43-46.1	39.1	140.67	10	291	6.8Mw	6.4/227		18	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

Fig.3 downloaded from Geological Service USA NEIC depicts epicenter of this earthquake, which was located in the northern part of Honshu Island, Japan, at 80 km to the south-west from Morioka, at 390 km to the north-north-east from Tokyo.

Figure 3

Aftershock

Within the day GS RAS has registered 25 aftershocks of this earthquake including 11 with M>5:

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
20082035	2008-06-13 23:56:50.0	39.34	140.83	33	13	-	5.3/ 6	4-4.5	Eastern Honshu, Japan
20082036	2008-06-14 00:00:38.0	39.05	140.74	33	9	-	5.1/ 7	3.5-4	Eastern Honshu, Japan
20082037	2008-06-14 00:07:26.0	39.29	140.62	33	19	-	5.4/ 11	4.5	Eastern Honshu, Japan
20082038	2008-06-14 00:20:14.0	38.91	140.48	33	21	-	6.0/ 10	6	Eastern Honshu, Japan
20082039	2008-06-14 00:52:45.0	39.17	140.78	33	19	-	5.2/ 9	4-4.5	Eastern Honshu, Japan
20082041	2008-06-14 01:39:50.0	39.03	140.79	33	16	-	5.1/ 8	3.5-4	Eastern Honshu, Japan
20082044	2008-06-14 03:10:34.0	39.11	140.77	33	17	-	5.4/ 9	4.5	Eastern Honshu, Japan
20082046	2008-06-14 03:27:35.0	39.2	140.77	33	23	-	5.6/ 11	5	Eastern Honshu, Japan
20082049	2008-06-14 05:39:09.0	39.28	140.71	33	17	-	5.1/ 10	3.5-4	Eastern Honshu, Japan
20082054	2008-06-14 12:48:32.0	39.31	140.53	33	21	-	5.2/ 9	4-4.5	Eastern Honshu, Japan
20082059	2008-06-14 14:42:34.0	39.06	140.73	33	28	-	5.5/ 11	4.5-5	Eastern Honshu, Japan

Macroseismic manifestations

ITAR TASS reports that as a result of this earthquake at the north of Honshu Island 9 people were killed and 250 injured, while the destiny of 13 people is unknown. Ground shocks were felt in 20 from 47 Japanese prefectures including capital. The main shock influenced less populated agricultural regions of five prefectures: Akita, Ivate, Miyagi, Fukusima and Yamagata. Fig.4 shared from Geological Service USA NEIC presents the map with intensities. Leakage of radioactive water was noticed at the Nuclear Power Plant in Fukusima Prefecture, however this incident was not dangerous for the environment. Also it was noticed water leakage in the dam near Kurihari town /Miyagi Prefecture/. Experts analyze this case trying to find the probability of dam’s crash. This earthquake caused a few landslides, it destroyed the bridge in Kurihara town of Miyagi Prefecture, it damaged the road in Ivate Prefecture. Railroad traffic was temporarily terminated, 2 thousand people were locked inside the coach cars. More than 30 thousand of families were left without electricity after power supply breaks, more that 100 breaks of telephone lines were reported too.

Figure 4

Focal mechanism and seismic moment of the earthquake

Focal mechanism solutions of the earthquake 13.06.2008 were obtained by various seismological centers, they are presented on fig. 5, shared from EMSC-CSEM. Here: HRVD – Harvard Center, USA; USGS – NEIC USGS USA. Elements of focal mechanism were calculated with TMC technique in Garcvard Center (HARVARD), USA, and in NEIC, USA, they are presented in table 2. These solutions are almost similar. The earthquake has happened under the action of compression forces oriented to the south-east in accordance with NEIC and to the north-west in accordance with Harvard. Both nodal planes are rather steeply falling with north-eastern direction of propagation. The motion along both planes is characterized by uplift with slip components (left sided for NP1, right sided for NP2). Averaged value of seismic moment Мо of the earthquake 13.06.2008 calculated by IPC GS RAS from Р-wave spectra at three stations: Talaya (∆28.5º), Obninsk (∆66.1º), Kislovodsk (∆69.1º) makes Мо=2.3* 10** 19 n*m, the value of moment magnitude determined from Kanamori formula Mw = 6.9. The value of seismic moment Мо in accordance with NEIC makes Мо =2.3* 10** 19 n*m, in accordance with Harvard Мо =2.74* 10** 19 n*m, the values of moment magnitude Мw=6.8 by NEIC and Мw=6.9 by Harvard.

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
79	237	6	114	9	22	15	52	78	214	40	105	NEIC
83	163	4	289	6	20	13	41	81	205	50	98	HARVARD

NEIC - National Earthquakes Information Center of US Geological Service

HARVARD - Harvard Geophysical Center (USA)

Figure 5