Location

2006/04/16 17:46:16 4.58 125.42 185

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=5.7 2006/04/16 17:46:16 EVID: LAT: 4.58N, LON: 125.42E, DEPTH: 180 Mw: 5.7, mb: 0.0, Ms: 0.0 Mo= 0.376E+25 (dyne-cm) No. of Stations: 34, GAP: 115 Error (clvd/dc)*100= 36.13 Bandpass: 12 - 60 sec Nodal plane parameters strike dip rake NP1: 317 74 40 NP2: 215 52 160 ############### ##################### #################---------- ------##########--------------- ----------####------------------- ----------------------------------- -------------####-------------------- ------------########------------------- -----------##########-------------- - ----------#############------------ P - ---------################---------- - --------##################------------- --------###################------------ -------######################---------- ------#######################-------- -----########################------ ----########## ############---- ---########## T ############--- --######### ############# ##################### ############### Stat Dist Az Misfit Stat Dist Az Misfit ARU 73 327 0.36 BBOO 38 165 0.96 BJT 36 347 0.54 BPAW 83 26 0.59 BRVK 65 327 0.35 COLD 83 22 0.71 CSS 89 304 0.83 CTAO 31 140 0.74 EIDS 38 141 0.73 EKS2 59 317 0.51 FORT 35 176 15.30 GNI 79 309 0.62 HIA 44 354 0.23 ISP 91 307 0.66 KBK 58 318 0.65 KIV 81 313 0.39 KMBL 35 185 0.61 KURK 60 327 0.36 KZA 58 317 0.54 LSA 40 311 0.67 MAJO 33 18 0.29 MALT 84 307 0.88 MDJ 40 4 0.44 OBN 85 324 0.40 PALK 44 275 0.88 STKA 39 158 0.58 SUW 93 324 0.81 TIRR 91 314 0.60 TIXI 67 1 0.24 TLY 50 342 0.34 TOO 45 157 1.33 ULN 45 342 0.22 USP 59 318 0.37 YAK 57 2 0.24 Misfit > 1 heavily downweighted

06/04/16 17:46:16.40 KEPULAUAN SANGIHE, INDONESIA Epicenter: 4.575 125.416 MW 5.7 USGS MOMENT TENSOR SOLUTION Depth 183 No. of sta: 14 Moment Tensor; Scale 10**17 Nm Mrr= 0.88 Mtt= 2.94 Mff=-3.82 Mrt=-2.13 Mrf= 0.76 Mtf= 0.72 Principal axes: T Val= 4.29 Plg=32 Azm=178 N -0.17 55 332 P -4.11 12 80 Best Double Couple:Mo=4.2*10**17 NP1:Strike=215 Dip=58 Slip= 165 NP2: 313 77 33 ####### ################# #################---- -##############---------- ------#########-------------- ----------####----------------- ------------#------------------ ------------####------------- - -----------#######----------- P - ----------##########--------- - ---------#############----------- --------###############---------- ------##################------- ------###################------ -----######## ##########--- ---######## T ########### -######## ######### ################# #######

April 16, 2006, KEPULAUAN SANGIHE, INDONESIA, MW=5.7 Goran Ekstrom CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME C041606C DATA USED: GSN L.P. BODY WAVES: 65S,130C, T= 40 SURFACE WAVES: 73S,155C, T= 50 CENTROID LOCATION: ORIGIN TIME 17:46:19.0 0.1 LAT 4.55N 0.01;LON 125.71E 0.01 DEP 185.5 0.9;HALF-DURATION 1.7 MOMENT TENSOR; SCALE 10**24 D-CM MRR= 1.11 0.04; MTT= 2.58 0.05 MPP=-3.68 0.06; MRT=-2.55 0.04 MRP= 0.78 0.04; MTP=-1.07 0.05 PRINCIPAL AXES: 1.(T) VAL= 4.71;PLG=36;AZM=191 2.(N) -0.81; 53; 1 3.(P) -3.89; 5; 97 BEST DOUBLE COUPLE:M0=4.3*10**24 NP1:STRIKE=228;DIP=61;SLIP= 156 NP2:STRIKE=330;DIP=69;SLIP= 31 ########### --################# -------################ -----------########-------- --------------##------------- --------------##--------------- ------------######------------- -----------#########------------- ---------############------------ --------##############--------- -------################-------- P -----#################-------- ----###################-------- ---######## ########------- -######### T #########----- ######## #########--- ##################- ###########

Deviatoric Moment Tensor Solution

The following broadband stations were used for the source inversion: ARU BBOO BJT BPAW BRVK COLD CSS CTAO EIDS EKS2 FORT GNI HIA ISP KBK KIV KMBL KURK KZA LSA MAJO MALT MDJ OBN PALK STKA SUW TIRR TIXI TLY TOO ULN USP YAK

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  180.0  317.   74.   40.   5.68     0.263 0.838E-07     0.358     0.527 0.476E-07  36.1

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