Informational message about the destructive earthquake in Northern California, August 24, 2014 |
| The destructive earthquake M=6.1 has occurred in Northern California on August 24, 2014 at 10:20 Greenwich time (14:20 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 15 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 14 stations, accurate processing - with data 39 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Albuquerque (∆ 13.1º), Hockley (∆ 23.4º), College (∆ 30.6º), Kipapa (∆ 35º), Juntas de Abangares (∆ 43.5º). Fig. 2 presents fragments of records obtained from digital stations Kuldur (∆ 71.1º), Lovozero (∆ 72.7º), Talaya (∆ 81.8º), Obninsk (∆ 85.2º), Arti (∆ 85.6º). |
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 |
10-20-46.2 |
38.32 |
-122.26 |
10 |
39 |
6.1/25 | 6/23 | 8.5-9 | 85 | IPC GS RAS (Accurate) | | 2 |
10-20-52.6 |
38.56 |
-122.06 |
33 |
14 |
| 6.1/14 | 6-6.5 | 99 | IPC GS RAS (Preliminary) | | 3 |
10-20-43.2 |
38.21 |
-122.32 |
11 |
174 |
Mw 6.1 | | | 35 | CSEM | | 4 |
10-20-44.0 |
38.22 |
-122.313 |
11.3 |
146 |
Mw 6.0 | | | 28.8 | 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 located in Northern California, USA, at a depth of 10 km, 55 km N of Auckland, 59 km N-N-E of San Francisco and 78 km W-S-W of Sacramento. |
Figure 3 |
|
| Macroseismic manifestations |
| According to ITAR-TASS, as a result of the earthquake about 120 buildings were critically injured and 500 buildings are in need of major repairs (Fig.4). It affected more than 170 people.
According to various estimates, the amount of damage caused by the disaster can range from $ 1.4 billion to $ 4 billion.
Fig. 5 was obtained from of USGS NEIC, it presents USGS Community Internet Intensity Map , based on 40834 responses in 610 ZIP codes. |
Figure 4 | 
Figure 5 |
|
| Historical records |
| This earthquake was the strongest in the last 25 years. The epicenter was located 145 km S-S-W of the destructive earthquake of October 18, 1989 M=6.9. Then, the death toll was 62 people. The state economy has been damaged in the amount of $ 10 billion. |
| Focal mechanism and seismic moment of the earthquake |
| The focal mechanism solution of this earthquake in stereographic projection is shown in Fig. 6, 7. It was obtained in USGS NEIC with W-phase Moment Tensor (Mw) technique and in Quick CMT data center with CMT technique. Elements of the mechanism are presented in Table 2. Both solutions obtained in these centers are close.
The earthquake has occurred under the action close to the value of the compression stresses oriented S-W–N-E, and tensile stresses oriented S-E–N-W.
Both nodal planes in solutions of all centers are almost vertical (DP=78-84º). NP1 plane strikes S-W (STK=246-247º), NP2 strikes S-E–N-W (155-338º).
The type of motion along both planes – slips (left lateral for NP1, right lateral for NP2) with components of fault-overthrust.
Seismic moment according to USGS NEIC – Mo=1.33*10**18 N*m, Mw=6.0, according to Quick CMT – Mo=1.7*10**18 N*m, Mw=6.1. |
| 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 |
| 11 | 111 | 0 | 201 |
79 | 293 | 247 | 82 | 8 | 155 |
82 | 172 | NEIC | | 5 | 293 | 12 | 202 |
77 | 43 | 247 | 84 | -12 | 338 |
78 | -174 | Quick CMT | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Quick CMT - Quick CMT catalog |
Figure 6 | 
Figure 7 |
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