Information message about the strong earthquake in Costa Rica on September 5, 2012 |
| The strong earthquake with M=7.9 has occurred in Costa Rica on September 5, 2012 at 14:42 GMT (18:42 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 34 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 41 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Hockley (∆ 22.1º), Albuquerque (∆ 31.4º), Falkland Islands (∆ 65.9º), Kipapa (∆ 70.4º), Kingsbay (∆ 81.5º). Fig. 2 presents fragments of records obtained from digital stations Pulkovo (∆ 93.7º), Tiksi (∆ 95.3º), Petropavlovsk (∆ 97.1º), Magadan (∆ 97.4º), Obninsk (∆ 99º). |
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 |
14-42-09.0 |
10.12 |
-85.33 |
33 |
41 |
7.9/20 | 6.6/14 | 9.5 | 127 | IPC GS RAS (Accurate) | | 2 |
14-42-09.9 |
10.1 |
-85.24 |
33 |
36 |
7.9/17 | 6.5/11 | 9.5 | 127 | IPC GS RAS (Preliminary) | | 3 |
14-42-10.5 |
10.16 |
-85.39 |
40 |
859 |
Mw 7.6 | | | 48 | CSEM | | 4 |
14-42-07.6 |
9.996 |
-85.318 |
40.2 |
713 |
Mw 7.6 | 6.7/550 | | 40 | 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 epicenter of this earthquake which origin was was locate on the territory of Costa Rica at the depth of 33 km, 57 km W-N-W of Puntarenas, 58 km S-S-E of Liberia and 139 km W-N-W of San Jose city the capital of Costa Rica. |
Figure 3 |
|
| Macroseismic manifestations |
| In accordance with RIA-Novosti two persons became the victims of this powerful earthquake. Immediately after the earthquake it was announced the alert warning about the risk of tsunami for some countries of the Central America, however later it was canceled.
Fig. 4 shared from USGS NEIC, presents the USGS Community Internet Intensity Map by 295 responses in 105 cities.
|
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution for this earthquake which happened on September 5, 2012 at 14:32 UTC is presented at figures 5, 6 in stereographic projection at lower hemisphere, elements of mechanism are presented in table 2. Focal mechanism was calculated with Centroid Moment Solution method in USGS NEIC and in GCMT with Global CMT Project Moment Tensor Solution.
Both solutions obtained in USGS NEIC and GCMT are identical.
One nodal plane NP1 is steeply dipping (DP=69-73º), it strikes S-E (stk=108-124º). Another nodal plane NP2 is low angle (DP=19-21º) and strikes N-W (stk=307-317º).
This earthquake has occurred under the action of prevailing stress of compression oriented S-W, extension stress is oriented N-E. The type of motion in origin for NP1 – reverse fault, for NP2 – thrust.
Seismic moment of this earthquake in accordance with USGS NEIC makes Мо=2.8*10**20 N*m, Mw=7.6, in accordance with Global CMT – Мо=3.12*10**20 N*m, Mw=7.6.
|
| 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 |
| 66 | 32 | 24 | 215 |
1 | 124 | 124 | 69 | 89 | 307 |
21 | 93 | NEIC | | 61 | 5 | 28 | 205 |
9 | 110 | 108 | 73 | 81 | 317 |
19 | 118 | Quick CMT | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Quick CMT - Quick CMT catalog |
Figure 5 | 
Figure 6 |
|
