Location

2006/04/07 08:30:43 -16.62 177.00 7

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=6.3 2006/04/07 08:30:43 EVID: LAT: 16.62S, LON: 177.00E, DEPTH: 15 Mw: 6.3, mb: 0.0, Ms: 0.0 Mo= 0.348E+26 (dyne-cm) No. of Stations: 42, GAP: 121 Error (clvd/dc)*100= 12.24 Bandpass: 12 - 60 sec Nodal plane parameters strike dip rake NP1: 274 80 -13 NP2: 6 77 -170 ##########----- #############-------- T ##############---------- ## ##############------------ ####################------------- #####################-------------- ######################--------------- #######################---------------- #######################---------------- ##---------------------##-------------- -----------------------############---- -----------------------################ ----------------------################# ----------------------################# ---------------------################ --- -------------################ -- P -------------############### - ------------############### --------------############# ----------########### ------######### Stat Dist Az Misfit Stat Dist Az Misfit A04A 84 35 1.01 BAK 79 48 0.96 BBOO 40 238 0.55 BESE 84 23 1.09 BLDU 56 244 0.69 CASY 65 204 1.03 COCO 77 260 1.08 COLA 85 14 1.04 DUG 86 46 1.06 E05A 83 37 1.09 EGMT 91 40 1.07 FARB 78 44 0.92 FITZ 48 260 0.98 FORT 46 243 32.11 HWUT 87 45 1.08 I05A 82 39 0.98 ISCO 91 48 1.04 KKM 64 285 0.79 KMBL 51 243 1.50 L02A 80 40 0.95 LAO 93 42 0.94 LKWY 89 43 0.95 LSA 94 299 0.67 LTX 89 59 0.97 MAJO 64 325 0.69 MDJ 74 326 0.67 MNTX 88 56 1.02 MPM 81 48 1.02 MUN 56 242 0.99 NEW 87 37 1.18 O07A 82 44 0.93 PHL 78 47 1.10 QSPA 73 180 1.46 SBA 61 182 1.54 SKAG 85 22 1.07 SNAA 91 180 1.32 STKA 35 238 0.59 WMOK 94 55 1.02 WRAB 40 258 0.91 X13A 83 50 0.96 YAQ 80 51 0.95 YNG 31 230 0.72 Misfit > 1 heavily downweighted

Mw=6.3 FIJI 2006/04/07 08:30:43.26 EVID: LFAL LAT: 16.62S, LON: 177.00E, DEPTH: 10 Mw: 6.3, mb: 6.3, Ms: 6.3 Mo= 0.373E+26 (dyne-cm) No. of Stations: 11, GAP: 272 Error (clvd/dc)*100= 13.92 Nodal plane parameters strike dip rake NP1: 84 84 12 NP2: 353 78 174 ###------- #########----------- ############-------------- ###############--------------- #################--------------- ##################---------------- ###################----------------- #####################----------------- #####################----------------- #######################----------------- #######################-------------#### #######################--############### -----------------------################# ----------------------################ ----------------------################ ---------------------############### ---------------------############# -------------------############# ------------------############ ----------------########## -------------####### --------## Stat Dist Az Misfit Stat Dist Az Misfit BW06 89 44 0.80 CMB 79 45 0.76 HLID 86 42 0.83 ISCO 91 48 0.82 MA2 78 346 0.67 MAJO 64 325 0.72 MOD 82 42 0.86 NEW 87 37 0.81 TPNV 82 47 0.81 TUC 84 54 0.83 WDC 79 42 0.79 Median of misfit: 0.81 Average misfit: 0.79

April 7, 2006, FIJI, MW=6.4 Natasha Maternovskaya CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME C040706A DATA USED: GSN L.P. BODY WAVES: 79S,188C, T= 40 MANTLE WAVES: 77S,159C, T=125 CENTROID LOCATION: ORIGIN TIME 08:30:50.9 0.1 LAT 16.51S 0.01;LON 177.08E 0.01 DEP 12.0 FIX;HALF-DURATION 4.1 MOMENT TENSOR; SCALE 10**25 D-CM MRR= 0.07 0.03; MTT=-0.25 0.04 MPP= 0.18 0.05; MRT= 0.34 0.10 MRP= 0.25 0.12; MTP= 5.77 0.03 PRINCIPAL AXES: 1.(T) VAL= 5.77;PLG= 4;AZM=314 2.(N) 0.04; 86; 124 3.(P) -5.81; 1; 224 BEST DOUBLE COUPLE:M0=5.8*10**25 NP1:STRIKE=359;DIP=87;SLIP= 178 NP2:STRIKE= 89;DIP=88;SLIP= 3 #####------ #########---------- T ##########----------- # ##########------------- ###############-------------- ################--------------- ################--------------- #################---------------- #################---------------- -----------------################ -----------------################ ----------------############### ----------------############### ---------------############## - ----------############# P ----------########### ----------######### ------#####

Deviatoric Moment Tensor Solution

The following broadband stations were used for the source inversion: A04A BAK BBOO BESE BLDU CASY COCO COLA DUG E05A EGMT FARB FITZ FORT HWUT I05A ISCO KKM KMBL L02A LAO LKWY LSA LTX MAJO MDJ MNTX MPM MUN NEW O07A PHL QSPA SBA SKAG SNAA STKA WMOK WRAB X13A YAQ YNG

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

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   15.0  274.   80.  -13.   6.33     0.016 0.438E-05     0.251     0.128 0.578E-06  12.2

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