Information message about the destructive earthquake in Kyushu, Japan, April 15, 2016 |
| The destructive earthquake M=7.4 has occurred on April 15, 2016 at 16:25 GMT (19:25 Moscow time) in Kyushu, 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 11 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 32 stations, accurate processing - with data 69 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Taejon (∆ 4.7º), Matsushiro (∆ 7.4º), Mys Shultsa (∆ 10º), Erimo (∆ 13.7º), Yuzhno-Sakhalinsk (∆ 17.1º). Fig. 2 presents fragments of records obtained from digital stations Severo-Kurilsk (∆ 26º), Petropavlovsk (∆ 18.6º), Magadan (∆ 30.1º), Zalesovo Array (∆ 38.7º), Tiksi (∆ 39.1º). |
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 |
16-25-02.9 |
32.6 |
130.68 |
10 |
69 |
7.4/31 | 6.7/43 | 10.5-11 | 101 | IPC GS RAS (Accurate) | | 2 |
16-25-04.5 |
32.62 |
130.74 |
10 |
32 |
| 6.6/23 | 9-9.5 | 101 | IPC GS RAS (Preliminary) | | 3 |
16-25-07.3 |
32.85 |
130.57 |
10 |
162 |
Mw 7 | | | 20 | CSEM | | 4 |
16-25-06.3 |
32.78 |
130.73 |
10 |
85 |
Mw 7 | | | 39 | NEIC | |
| 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 the epicenter of this earthquake, its origin was located on the island of Kyushu, Japan, at a depth of 10 km, 78 km E of Nagasaki, 113 km S of Fukuoka, 240 km S-W of Matsuyama. |
Figure 3 |
|
| Aftershock |
| GS RAS registered 15 aftershocks М>=4.6 within 16 hours 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 |
| 20161349 | 2016-04-15 16:44:04.0 | 32.57 | 130.63 | 10 | 36 | - | 5.5/ 22 | 6.5-7 | Kyushu, Japan | | 20161350 | 2016-04-15 16:45:53.0 | 32.77 | 130.87 | 10 | 51 | - | 6.1/ 32 | 8 | Kyushu, Japan | | 20161351 | 2016-04-15 17:04:10.0 | 32.78 | 130.88 | 10 | 23 | - | 5.0/ 13 | 5-5.5 | Kyushu, Japan | | 20161352 | 2016-04-15 18:03:10.0 | 32.88 | 131.02 | 10 | 44 | - | 5.5/ 30 | 6.5-7 | Kyushu, Japan | | 20161354 | 2016-04-15 18:55:51.0 | 32.87 | 131.13 | 10 | 55 | - | 5.7/ 27 | 7-7.5 | Kyushu, Japan | | 20161355 | 2016-04-15 22:11:38.0 | 33.22 | 131.37 | 10 | 46 | - | 5.1/ 25 | 5.5-6 | Kyushu, Japan | | 20161356 | 2016-04-15 22:23:52.0 | 32.6 | 130.7 | 10 | 41 | - | 5.0/ 18 | 5-5.5 | Kyushu, Japan | | 20161357 | 2016-04-15 23:20:38.0 | 32.55 | 130.63 | 10 | 26 | - | 4.9/ 15 | 5-5.5 | Kyushu, Japan | | 20161359 | 2016-04-16 00:48:30.0 | 32.8 | 130.86 | 10 | 48 | - | 5.6/ 31 | 6.5-7 | Kyushu, Japan | | 20161360 | 2016-04-16 02:02:48.0 | 32.61 | 130.76 | 10 | 34 | - | 5.0/ 18 | 5-5.5 | Kyushu, Japan | | 20161365 | 2016-04-16 05:03:58.0 | 32.99 | 131.1 | 10 | 23 | - | 4.6/ 15 | 4.5 | Kyushu, Japan | | 20161366 | 2016-04-16 05:27:05.0 | 32.64 | 130.81 | 10 | 19 | - | 4.6/ 14 | 4.5 | Kyushu, Japan | | 20161367 | 2016-04-16 07:01:59.0 | 32.68 | 130.72 | 10 | 61 | - | 5.4/ 33 | 6-6.5 | Kyushu, Japan | | 20161370 | 2016-04-16 08:40:19.0 | 32.77 | 130.63 | 10 | 23 | - | 4.6/ 18 | 4.5 | Kyushu, Japan | |
| Macroseismic manifestations |
| According to ITAR-TASS 42 people were killed and 1094 injured in a series of shocks in the region of Kumamoto Prefecture on the southwestern Japanese island of Kyushu. More than 150 thousand local residents were forced to leave their homes and are in temporary shelters.
At least 1262 buildings were damaged. More than 400 homes in the most affected Kumamoto Prefecture were completely destroyed, the walls of local sightseeing - Kumamoto ancient feudal castle collapsed. The destruction was not so significant in neighboring Oita and Miyazaki prefectures, there are only three homes affected (fig. 4).
Fig. 5 was obtained from USGS NEIC , it presents USGS Community Internet Intensity Map based on 57 responses in 33 cities. |
Figure 4 | 
Figure 5 |
|
| Historical records |
| The epicenter of earthquake was located 25 km S-E of strong earthquake epicenter of April 14, 2016 М=6.3. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of the origin was obtained in IPC GS RAS with signs of initial arrivals of P waves at 77 stations, including 18 of them which registered compression waves (plus) and 59 stations which registered tensile waves (minus). These stations are located in the interval of epicentral distances 0.5–99.3º and in azimuth sector Az=0-360º. Focal mechanism solution of the origin in stereographic projection at the lower hemisphere according to GS RAS data is given at fig. 6, elements of mechanism are presented in table 2. Fig. 7,8 present focal mechanism solutions of the origin obtained in USGS NEIC with W-phase Moment Tensor (Mwс) technique and in Quick CMT Catalog Center, USA with CMT technique.
All solutions obtained in different centers are close, solutions obtained in USGS NEIC and Quick CMT are nearly the same. According to USGS NEIC and Quick CMT this earthquake has occurred under prevailing action of tensile stresses oriented to the north (AZ=355º) and compression stresses oriented south-east (AZ=85º). Nodal planes NP1 and NP2 are steeply dipping under nearly the same angles (DP=74º-77º), NP1 plane strikes southо-west (STK=222º), NP2 plane strikes south-east (STK=128º). The type of motion in the origin – slip with fault component (right lateral for NP1 and left lateral for NP2).
According to IPC GS RAS this earthquake has occurred under prevailing action of compression stresses oriented north-east and tensile stresses oriented south-east. Both nodal planes decline to the horizon under rather big angles (DP=76-81º), NP1 plane strikes to the west (STK=284º), NP2 plane strikes to the south (STK=191º). The type of motion – left lateral slip with reverse fault component for NP1 and right lateral slip with reverse fault component for NP2.
Seismic moment of the earthquake was obtained in IPC GS RAS with spectra of P waves registered at the station "Obninsk" (∆66.16º), Mo=2.1*10**19 N*m, Mw=6.8. According to USGS NEIC – Mo=4.63*10**19 N*m, Mw=7.0; according to СМТ – Mo=4.46*10**19 N*m, Mw=7.0. |
| 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 |
| 16 | 148 | 3 | 57 |
73 | 316 | 284 | 81 | 14 | 192 |
76 | 171 | IPC GS RAS | | 2 | 355 | 21 | 86 |
69 | 258 | 222 | 77 | -163 | 128 |
73 | -14 | NEIC | | 2 | 355 | 21 | 85 |
69 | 260 | 222 | 77 | -163 | 128 |
74 | -14 | 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 |
|
