Location

2006/08/25 00:44:43 -24.32 -66.89 157

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	USGS	HARVARD CMT
Mw=6.7 2006/08/25 00:44:43 EVID: LAT: 24.32S, LON: 66.89W, DEPTH: 190 Mw: 6.7, mb: 0.0, Ms: 0.0 Mo= 0.108E+27 (dyne-cm) No. of Stations: 43, GAP: 128 Error (clvd/dc)*100= 30.85 Bandpass: 20 - 100 sec Nodal plane parameters strike dip rake NP1: 321 77 -136 NP2: 219 47 -18 --------------- --------------------- ##---------------########## #######--------################ ##########---#################### ############-###################### ###########-----##################### ###########--------#################### ##########-----------############# ## #########-------------############ T ## ########----------------########## ## #######------------------############## #######-------------------############# ######---------------------############ #####----------------------########## ####---------- ----------######## ###---------- P -----------###### ##---------- ------------#### #-------------------------# --------------------- --------------- Stat Dist Az Misfit Stat Dist Az Misfit ACSO 65 346 0.65 AHID 78 328 0.35 BINY 66 352 0.43 BLA 62 347 ***** BMN 79 323 0.35 BMO 82 326 0.42 BOZ 80 329 0.36 BW06 77 329 0.35 CART 87 46 0.27 CBN 62 350 0.43 CMB 79 319 0.37 DUG 77 325 0.37 EGMT 81 332 0.31 ELK 78 324 0.38 ERPA 67 349 0.33 EYMN 75 343 0.31 HAWA 84 326 32.94 HLID 80 327 0.63 HNH 67 355 1.77 HOPS 82 319 0.40 HRV 66 356 0.21 HWUT 77 327 0.64 IMW 78 329 0.50 ISCO 73 329 0.65 JCT 62 328 0.33 LOHW 78 329 0.45 MOOW 78 329 0.67 MTE 84 41 0.29 PFO 74 318 0.40 QSPA 65 180 20.90 REDW 78 328 0.55 RRI2 78 328 0.50 RWWY 75 329 0.52 SBA 73 190 0.27 SCHQ 78 0 0.49 SFS 83 45 0.44 SNOW 78 329 0.52 SUR 75 119 0.59 TPAW 78 328 0.52 TPH 77 321 0.31 ULM 78 341 0.60 WES 66 356 1.04 YBH 83 321 0.34 Misfit > 1 heavily downweighted	SALTA, ARGENTINA Epicenter: -24.323 -66.887 MW 6.6 USGS MOMENT TENSOR SOLUTION Depth 186 No. of sta: 71 Moment Tensor; Scale 10**18 Nm Mrr=-5.87 Mtt=-2.16 Mpp= 8.03 Mrt= 3.57 Mrp=-3.87 Mtp= 0.14 Principal axes: T Val= 9.09 Plg=15 Azm= 86 N -0.35 26 348 P -8.74 59 203 Best Double Couple:Mo=8.9*10**18 NP1:Strike=208 Dip=37 Slip= -44 NP2: 335 65 -119 ------- ##-----------#### #######---########### #########--############## #########-----############### ########---------############## #######-----------############# #######-------------######### # #######--------------######## T # ######----------------####### # ######----------------########### #####-------- -------########## ####-------- P -------######### #####------- --------######## ####------------------####### ###-----------------##### #-----------------### ----------------# -------	August 25, 2006, SALTA, ARGENTINA, MW=6.6 Goran Ekstrom CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME C082506A DATA USED: GSN L.P. BODY WAVES: 55S,129C, T= 50 MANTLE WAVES: 30S, 47C, T=125 CENTROID LOCATION: ORIGIN TIME 00:44:50.3 0.2 LAT 24.27S 0.02;LON 67.05W 0.02 DEP 183.0 0.9;HALF-DURATION 4.7 MOMENT TENSOR; SCALE 10**26 D-CM MRR=-0.58 0.01; MTT=-0.22 0.02 MPP= 0.80 0.02; MRT= 0.40 0.01 MRP=-0.39 0.01; MTP=-0.16 0.02 PRINCIPAL AXES: 1.(T) VAL= 0.96;PLG=17;AZM= 76 2.(N) -0.08; 25; 338 3.(P) -0.88; 59; 197 BEST DOUBLE COUPLE:M0=9.2*10**25 NP1:STRIKE=199;DIP=35;SLIP= -44 NP2:STRIKE=327;DIP=66;SLIP=-117 ----------# #-------########### ######-################ #######----################ #######-------############### #######----------############## ######------------######### # ######--------------######## T ## ######----------------###### ## #####------------------########## #####------------------########## ####-------- --------######## #####------- P ---------####### ####------- ---------###### ####-------------------#### ###------------------## ##----------------- -----------

Deviatoric Moment Tensor Solution

The following broadband stations were used for the source inversion: ACSO AHID BINY BLA BMN BMO BOZ BW06 CART CBN CMB DUG EGMT ELK ERPA EYMN HAWA HLID HNH HOPS HRV HWUT IMW ISCO JCT LOHW MOOW MTE PFO QSPA REDW RRI2 RWWY SBA SCHQ SFS SNOW SUR TPAW TPH ULM WES YBH

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.)]

All observed and Greens function waveforms are corrected to instrument response to ground velocity in meters/sec for the passband of 0.01 - 5 Hz. Next tre traces were bandpass filtered by the application of the following high- and low-pass stages:

hp c 0.0100 2
lp c 0.0500 2
int

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  190.0  321.   77. -136.   6.65     0.317 0.101E-05     0.532     0.563 0.563E-06  30.8

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.

Detailed Waveform Comparison

Comparison of the observed traces (red) and solution predicted traces (blue) ordered in terms of increasing epicentral distance. Each pair of traces is annotated with the station name, epicentral distance in degrees, source to station azimuth in degrees. Each pair of traces is plotted with the same scale and the peak amplitudes are indicated at the lect of each trace. Finally the time shift between the P-wave first arrival picked and the the theoretical P-wave first arrival in the predicted trace is indicated, with a positive sign indicating that the predicted trace has been shifted to the right by the given number of seconds. 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