Location

2006/01/08 11:34:55 36.41 23.21 66

Moment Tensor Comparison

The following compares this source inversion to the USGS Rapid Moment Tensor Solution and to the Harvard CMT solutions, if they are available.

SLU Moment Tensor Solution 2006/01/08 11:34:55 Best Fitting Double Couple Mo = 1.26e+26 dyne-cm Mw = 6.70 Z = 70 km Plane Strike Dip Rake NP1 55 53 115 NP2 197 44 61 Principal Axes: Axis Value Plunge Azimuth T 1.26e+26 70 24 N 0.00e+00 20 219 P -1.26e+26 5 128 Moment Tensor: (dyne-cm) Component Value Mxx -3.37e+25 Mxy 6.61e+25 Mxz 4.41e+25 Myy -7.60e+25 Myz 8.19e+24 Mzz 1.10e+26 -----------### -----------########### -----------################# ----------#################### ----------######################## ----------#########################- ----------##########################-- ----------########### ############---- ---------############ T ############---- ----------############ ###########------ ---------##########################------- ---------########################--------- ---------#######################---------- --------#####################----------- --------###################------------- -------################--------------- ------#############------------- - ------#######------------------ P #####------------------------ #####----------------------- ###------------------- -------------- Harvard Convention Moment Tensor: R T F 1.10e+26 4.41e+25 -8.19e+24 4.41e+25 -3.37e+25 -6.61e+25 -8.19e+24 -6.61e+25 -7.60e+25

06/01/08 11:34:52.60 SOUTHERN GREECE Epicenter: 36.250 23.498 MW 6.7 USGS MOMENT TENSOR SOLUTION Depth 66 No. of sta: 67 Moment Tensor; Scale 10**19 Nm Mrr= 1.04 Mtt=-0.21 Mff=-0.83 Mrt= 0.44 Mrf= 0.02 Mtf=-0.71 Principal axes: T Val= 1.20 Plg=69 Azm= 18 N 0.12 20 217 P -1.33 6 125 Best Double Couple:Mo=1.3*10**19 NP1:Strike=193 Dip=43 Slip= 59 NP2: 52 54 115 ------- ---------######## --------############# --------################# ---------###################- ---------###################--- --------####### ##########--- --------######## T #########----- --------######## ########------ -------###################------- -------#################--------- -------###############----------- ------#############------------ -------#########----------- - ------######-------------- P #####------------------- ####----------------- ###-------------- -------

Deviatoric Moment Tensor Solution

The following broadband stations were used for the source inversion: BBSR BILL COLA COR DWPF INCN KBS KEV LSZ MAJO PET RCBR RSSD SDV SFJD SJG TATO TIXI TRIS ULN WCI WVT YAK YSS

Location of the earthquake (yellow star) and great circle path from the epicenter to each station (red) [created using GMT (Wessel, P., and W. H. F. Smith, New version of Generic Mapping Tools released, EOS Trans. AGU, 76 329, 1995.)]

The traces were next integrated to ground displacment in meters. Finally waveforms were cut from 30 seconds before to 140 seconds after the P arrival so that the direct P wave, pP and perhaps the sP are included.

The source inversion is a multipass operation since a lower frequency filter band is used for larger earthquakes and since a search is made over depth. Up to three passed of the outer loop are made, after which the moment magnitude is determined and filter settings readjusted. The inner loop over depth samples all depths from 0 to 800 km with 5 km increments in depth to 50 km, followed by 10 km depth sampling for the remaining range.

The following filter ranges are used according to the moment magnitude Mw:

   FILTER_BAND   FH(s)  FL(s)
       1           60     12      Mw < 6.4
       2          100     20      6.4 < Mw <= 6.9
       3          120     40      Mw > 6.9

For this data set the favored solution is

WVFMTD96   70.0   55.   53.  115.   6.70     0.741 0.105E-05     0.741     0.882 0.105E-05  16.6

The following figures show the sensitivity of the goodness of fit parameter so source depth, the waveform comparison as a function of epicentral distance in degrees and the source to station azimuth

Depth Sensitivity

Goodness of fit as a function of source depth. The measure is 1 - SUM (o -p)2 / SUM o2. A value of 1.0 is the best fit. The best double couple mechanism for the solution depth is plotted above goodness of fit value to indicate how the mefhanism may change with depth.

Fit with Distance

Fit with Azimuth

Comparison of the observed traces (red) and solution predicted traces (blue) as a function of source to station azimuth in degrees (D). The purpose of this display is to highlight the azimuthal dependence on the first motion. The traces are annotated with the station name at the top.

Inversion Details