Location

2006/04/17 23:50:06 -12.63 165.96 71

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=6.0 2006/04/17 23:50:06 EVID: LAT: 12.63S, LON: 165.96E, DEPTH: 25 Mw: 6.0, mb: 0.0, Ms: 0.0 Mo= 0.111E+26 (dyne-cm) No. of Stations: 68, GAP: 109 Error (clvd/dc)*100= 32.48 Bandpass: 12 - 60 sec Nodal plane parameters strike dip rake NP1: 141 49 97 NP2: 310 42 82 --------------- --------------------- #-------------------------- #-##############--------------- ---##################------------ ----####################----------- -----######################---------- ------########################--------- -------########################-------- -------############# ##########------ --------############ T ###########----- ---------########### ###########----- ----------#########################---- -----------########################---- ------------######################--- -------------####################-- - ----------##################- P -------------############### -----------------######### --------------------- --------------- Stat Dist Az Misfit Stat Dist Az Misfit 115A 89 56 0.25 A05A 87 38 0.22 AHID 93 47 0.55 B04A 86 39 0.21 B05A 87 39 0.26 BBOO 33 228 0.48 BESE 85 26 0.25 BILL 80 0 0.31 BLDU 48 240 0.56 BMN 88 48 0.65 BMR 83 21 0.27 BNLO 83 49 0.28 BPAW 83 17 0.35 COLA 84 18 0.33 COLD 85 15 0.35 DAV 44 293 0.81 DIV 82 21 0.29 DOT 85 20 0.70 DUG 91 49 0.27 E03A 86 40 0.28 E05A 87 41 0.20 F04A 86 41 0.23 FARB 83 49 0.59 FITZ 39 256 0.59 FUR 87 51 0.29 GSC 87 53 0.27 GUMO 33 320 0.61 HATC 85 46 0.35 HLID 91 45 0.29 IRM 88 54 0.18 J06A 87 44 0.17 K06A 86 45 0.19 LAVA 85 48 0.25 LKWY 94 45 0.95 LSA 83 302 0.37 MCK 83 18 0.34 MOD 86 45 0.27 MSO 92 42 0.44 N02C 84 46 0.76 O04C 85 47 0.26 O05C 85 47 0.21 P08A 87 48 0.27 PAX 84 20 0.71 PFO 86 54 0.25 PKD 84 51 0.38 PPLA 81 17 0.26 R06C 86 49 0.26 R07C 86 49 0.29 RPV 85 54 0.43 S09A 87 50 0.24 SNZO 29 166 0.38 STKA 29 225 0.42 SWD 80 20 0.30 TNA 80 10 0.29 TRF 82 18 0.30 TUC 91 57 0.23 TUQ 87 53 0.60 ULN 79 324 0.36 W12A 88 53 0.33 WRAB 31 252 0.49 WVOR 87 45 0.25 X14A 89 54 0.23 Y12C 88 55 0.23 Y13A 88 55 0.30 Y14A 89 55 0.22 YAK 79 343 0.29 YNG 26 213 0.64 Z14A 89 55 0.25 Misfit > 1 heavily downweighted	SANTA CRUZ ISLANDS 2006/04/17 23:50: 6.58 EVID: LQBV LAT: 12.63S, LON: 165.97E, DEPTH: 20 Mw: 5.9, mb: 6.0, Ms: 6.0 Mo= 0.782E+25 (dyne-cm) No. of Stations: 7, GAP: 144 Error (clvd/dc)*100= 1.12 Nodal plane parameters strike dip rake NP1: 150 52 83 NP2: 342 39 99 ---------- ##########---------- --##############---------- ----################---------- ----###################--------- -----#####################-------- ------######################-------- -------#######################-------- -------#######################-------- ---------#######################-------- ---------#######################-------- ----------#######################------- -----------######################------- -----------#####################------ ------------####################------ ------------##################------ -------------################----- --------------#############----- ---------------##########----- -----------------#####---- ------------------## ---------- Stat Dist Az Misfit Stat Dist Az Misfit CMB 85 49 0.48 INCN 62 325 0.39 MAJO 55 332 0.33 TIXI 87 348 0.37 TLY 83 326 0.45 VNDA 64 180 0.44 YSS 62 342 0.60 Median of misfit: 0.44 Average misfit: 0.44	April 17, 2006, SANTA CRUZ ISLANDS, MW=6.1 Natasha Maternovskaya CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME C041706A DATA USED: GSN L.P. BODY WAVES: 78S,180C, T= 40 MANTLE WAVES: 66S,103C, T=125 CENTROID LOCATION: ORIGIN TIME 23:50: 4.9 0.1 LAT 12.58S 0.01;LON 166.23E 0.01 DEP 31.7 0.8;HALF-DURATION 2.7 MOMENT TENSOR; SCALE 10**25 D-CM MRR= 1.49 0.01; MTT=-0.13 0.02 MPP=-1.36 0.02; MRT= 0.42 0.04 MRP=-0.71 0.04; MTP= 0.54 0.02 PRINCIPAL AXES: 1.(T) VAL= 1.70;PLG=75;AZM= 50 2.(N) 0.06; 4; 157 3.(P) -1.76; 14; 248 BEST DOUBLE COUPLE:M0=1.7*10**25 NP1:STRIKE=345;DIP=31;SLIP= 99 NP2:STRIKE=155;DIP=59;SLIP= 85 ####------- --###########------ ---##############------ -----################------ ------#################------ -------##################------ --------######## #######----- ---------######## T ########----- ---------######## ########----- ----------##################----- -- ------#################----- - P -------################---- - --------###############---- ------------#############---- -------------##########---- -------------#######--- --------------###-- ----------#

Deviatoric Moment Tensor Solution

The following broadband stations were used for the source inversion: 115A A05A AHID B04A B05A BBOO BESE BILL BLDU BMN BMR BNLO BPAW COLA COLD DAV DIV DOT DUG E03A E05A F04A FARB FITZ FUR GSC GUMO HATC HLID IRM J06A K06A LAVA LKWY LSA MCK MOD MSO N02C O04C O05C P08A PAX PFO PKD PPLA R06C R07C RPV S09A SNZO STKA SWD TNA TRF TUC TUQ ULN W12A WRAB WVOR X14A Y12C Y13A Y14A YAK YNG Z14A

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   25.0  141.   49.   97.   6.00     0.526 0.312E-06     0.546     0.735 0.257E-06  32.5

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