Magnitude 7.1 – ARAUCANIA, CHILE

A major 7.1 Magnitude earthquake struck this evening off the west coast of Chile along the subduction zone between the Nazca and South American plates.  This earthquake was south and west of the Argentina earthquake reported yesterday.  It is much closer to the surface than yesterday’s event but similar in magnitude so it is interesting to compare the seismograms.  The main difference being the prominence of the surface phases.  The Chilean earthquake today is considered to be an aftershock from the 8.8 Magnitude earthquake that occurred back in February.

Results from the USGS Arrival Time calculator are shown below:

DATE-(UTC)-TIME    LAT    LON     DEPTH MAG   Q   COMMENTS
2011/01/02 20:20:18  38.35S  73.28W  25.1 7.1      US: ARAUCANIA, CHILE
Expected 20s period surface wave amplitude [  8.95E+01 µm]  [  2.81E+01 µm/s]
Expected 1s period body wave amplitude     [  2.00E+00 µm]  [  1.25E+01 µm/s]

delta   azimuth (degrees clockwise from north)
(deg)      eq-to-station     station-to-eq
78.92          353.3             173.1

travel   arrival time
#  code      time(s)  dy hr mn sec
1  P          721.33   0 20 32 19
2  pP         729.42   0 20 32 27
3  PcP        729.65   0 20 32 27
4  sP         732.58   0 20 32 30
5  PP         899.87   0 20 35 17
6  PKiKP     1055.38   0 20 37 53
7  pPKiKP    1063.82   0 20 38  1
8  sPKiKP    1066.91   0 20 38  4
9  SKiKP     1267.45   0 20 41 25
10  S         1318.76   0 20 42 16
11  pS        1329.14   0 20 42 27
12  sS        1332.57   0 20 42 30
13  SKSac     1334.11   0 20 42 32
14  SKKSac    1336.07   0 20 42 34
15  ScS       1341.31   0 20 42 39
16  pSKSac    1345.16   0 20 42 43
17  sSKSac    1348.38   0 20 42 46
18  SPn       1359.70   0 20 42 57
19  PnS       1363.31   0 20 43  1
20  SS        1624.98   0 20 47 22
21  PKKPdf    1843.89   0 20 51  1
22  PKKPbc    1854.29   0 20 51 12
23  SKKPdf    2056.16   0 20 54 34
24  PKKSdf    2059.25   0 20 54 37
25  SKKPbc    2069.39   0 20 54 47
26  PKKSbc    2072.48   0 20 54 50
27  SKKSdf    2271.29   0 20 58  9
28  P'P'df    2338.91   0 20 59 16
29  S'S'df    3199.67   0 21 13 37
30  S'S'ac    3209.54   0 21 13 47
31  LQ        2003.17   0 20 53 41
32  LR        2223.23   0 20 57 21
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