Location

2006/04/09 20:50:46 -20.39 -70.20 34

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.

Mw=5.9 2006/04/09 20:50:46 EVID: LAT: 20.39S, LON: 70.20W, DEPTH: 35 Mw: 5.9, mb: 0.0, Ms: 0.0 Mo= 0.731E+25 (dyne-cm) No. of Stations: 23, GAP: 203 Error (clvd/dc)*100= 82.39 Bandpass: 12 - 60 sec Nodal plane parameters strike dip rake NP1: 250 74 155 NP2: 348 66 18 ----########### ---------############ --------------############# -----------------############## -----------------############## P ------------------############## - ------------------############### --------------------------------------- ------------------#######-------------- --------------###########-------------- ----------################------------- -------###################------------- ----######################------------- --########################------------- #########################------------ ########################----------- ######### ###########---------- ######## T ###########--------- ###### ###########------- ################----- ############--- Stat Dist Az Misfit Stat Dist Az Misfit C04A 82 327 0.43 CIA 70 318 0.92 DBIC 69 74 0.16 FRNY 64 357 0.49 FVM 61 341 0.59 HEBO 81 324 0.96 HWUT 72 328 0.23 I03A 80 324 0.33 I05A 79 325 0.24 JTS 33 333 0.57 LBTB 86 115 0.25 LSZ 92 107 0.19 M05C 77 323 0.31 MLAC 73 321 0.95 MNTX 61 326 0.26 N02C 78 321 1.59 NATX 56 335 0.31 P05C 75 321 0.36 P08A 74 323 0.31 PLAL 57 342 0.71 RCBR 36 71 0.36 TEIG 44 335 0.55 W14A 68 323 0.30 Misfit > 1 heavily downweighted

06/04/09 20:50:46.27 OFFSHORE TARAPACA, CHILE Epicenter: -20.389 -70.198 MW 5.8 USGS MOMENT TENSOR SOLUTION Depth 36 No. of sta: 11 Moment Tensor; Scale 10**17 Nm Mrr= 5.04 Mtt=-3.66 Mff=-1.38 Mrt=-1.64 Mrf=-1.48 Mtf=-2.27 Principal axes: T Val= 5.52 Plg=78 Azm=129 N -0.01 4 237 P -5.50 12 327 Best Double Couple:Mo=5.5*10**17 NP1:Strike= 63 Dip=34 Slip= 97 NP2: 234 57 85 ------- --------------- - P ----------------- --- ------------------- -------------------########## ----------------############### -------------################## -----------####################-- ---------######################-- -------########## ##########--- ------########### T #########---- -----############ ########----- ---#######################----- --######################------- ####################--------- ----#########------------ --------------------- ----------------- -------

April 9, 2006, OFFSHORE TARAPACA, CHILE, MW=5.7 Natasha Maternovskaya CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME C040906A DATA USED: GSN L.P. BODY WAVES: 73S,152C, T= 40 SURFACE WAVES: 75S,158C, T= 50 CENTROID LOCATION: ORIGIN TIME 20:50:51.1 0.2 LAT 20.48S 0.01;LON 70.78W 0.02 DEP 38.7 0.6;HALF-DURATION 1.8 MOMENT TENSOR; SCALE 10**24 D-CM MRR= 3.86 0.09; MTT=-1.50 0.07 MPP=-2.37 0.09; MRT=-0.98 0.08 MRP=-2.36 0.11; MTP=-2.11 0.06 PRINCIPAL AXES: 1.(T) VAL= 4.66;PLG=72;AZM= 99 2.(N) 0.12; 8; 214 3.(P) -4.79; 16; 307 BEST DOUBLE COUPLE:M0=4.7*10**24 NP1:STRIKE= 49;DIP=30;SLIP= 106 NP2:STRIKE=210;DIP=61;SLIP= 81 ----------- ----------------### ---------------######## - ----------############- -- P --------###############- --- -------################-- ------------#################-- -----------###################--- ----------######### ########--- ----------######### T #######---- ---------########## #######---- -------####################---- -------##################------ ------#################------ -----###############------- #--###########--------- #------------------ -----------

Deviatoric Moment Tensor Solution

The following broadband stations were used for the source inversion: C04A CIA DBIC FRNY FVM HEBO HWUT I03A I05A JTS LBTB LSZ M05C MLAC MNTX N02C NATX P05C P08A PLAL RCBR TEIG W14A

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 0.0167 2
lp c 0.0833 2
br c 0.12 0.25 n 4 p 2

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   35.0  250.   74.  155.   5.88     0.125 0.263E-06     0.337     0.353 0.881E-07  82.4

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