Earthquake having the characteritics of a subduction

interplaque (thrust)event (all source inversions coincide

in this). The epicenter (USGS) is located

inland, near the border between the Oaxaca and Guerrero

states. Focal depth given between 10 and 27 km.

Some destructions are already reported in the old part of

far distance Mexico city (site effect expected).

No tsunami alert (no tsunami expected after NOAA)

21h57 french hour: after the president of Mexico, there

would not be heavy damages in the country.

Location NEIC - USGS:

Location EMSC (CSEM):

EARTHQUAKE on 20/03/2012 at 18:02 (UTC)

GUERRERO, MEXICO 10 km NW Huanjintepec

MAGNITUDE: Mw 7.3

Data provided by: BGSG GFZ IMP INGV LED MAD NEIC PDA PPTm PTWC

SC3 ZAMG

Latitude = 16.69 N

Longitude = 98.23 W

Origin Time = 18:02:49.6 (UTC)

Depth = 20 Km

RMS = 1.28 sec

Gap = 80 degrees

95% confidence ellipse: - Semi major = 5.5 Km

- Semi minor = 3.3 Km

- Azimuth of major axis = 28 degrees

Number of data used = 467

Preliminary location computed on Tue Mar 20 19:54:06 2012 (UTC)

Done by J-P Santoire

First source inversions:

USGS WPhase Moment Solution

12/03/20 18:02:48

Epicenter: 16.662 -98.187

MW 7.3

USGS/WPHASE CENTROID MOMENT TENSOR

12/03/20 18:02:48.00

Centroid: 16.262 -97.665

Depth 11 No. of sta: 30

Moment Tensor; Scale 10**19 Nm

Mrr= 6.30 Mtt=-6.17

Mpp=-0.13 Mrt= 8.97

Mrp=-6.92 Mtp= 1.74

Principal axes:

T Val= 13.26 Plg=58 Azm= 47

N = -0.45 9 301

P =-12.81 30 206

Best Double Couple:Mo=1.3*10**20

NP1:Strike=268 Dip=17 Slip= 55

NP2: 124 76 100

Geoazur SCARDEC mechanism and source function

USGS Centroid Moment Solution

OAXACA, MEXICO

12/03/20 18:02:49.81

Epicenter: 16.665 -98.212

MW 7.3

USGS CENTROID MOMENT TENSOR

12/03/20 18:03:15.20

Centroid: 17.054 -98.118

Depth 10 No. of sta: 60

Moment Tensor; Scale 10**20 Nm

Mrr= 0.57 Mtt=-0.48

Mpp=-0.10 Mrt= 0.88

Mrp=-0.15 Mtp= 0.22

Principal axes:

T Val= 1.07 Plg=61 Azm= 2

N -0.02 7 104

P -1.05 29 198

Best Double Couple:Mo=1.1*10**20

NP1:Strike=102 Dip=74 Slip= 83

NP2: 306 17 113

Shake map (USGS)

Ground deformation simulated by Jean-Claude Ruegg:

See attached files below

Message from JC Ruegg: message_JC_Ruegg_simulation_ground_deformation.txt

deformation file 1:cmt_8m6h_Ruegg.pdf

deformation file 2:120320_180249_8m6hA.SP_ruegg.pdf

GPS time series in the frame of ongoing project in mexico:

Posted by Nathalie Cotte and the ISTerre group