Location

2006/04/15 22:40:54 22.74 121.30 18

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=5.6 2006/04/15 22:40:54 EVID: LAT: 22.74N, LON: 121.30E, DEPTH: 10 Mw: 5.6, mb: 0.0, Ms: 0.0 Mo= 0.331E+25 (dyne-cm) No. of Stations: 51, GAP: 84 Error (clvd/dc)*100= 20.91 Bandpass: 12 - 60 sec Nodal plane parameters strike dip rake NP1: 208 46 104 NP2: 8 46 76 ------------### --------------###---- -------------########------ -------------###########------- ------------##############------- -----------################-------- ----------##################-------- P ---------###################--------- --------####################--------- ---------#####################--------- --------######### ##########--------- --------######### T ##########--------- -------########## ##########--------- -------######################---------- ------#####################---------- -----#####################--------- -----###################--------- ----##################--------- ---###############--------- -############-------- ########------- Stat Dist Az Misfit Stat Dist Az Misfit ADK 55 41 0.62 ANTO 74 307 0.49 AQU 87 315 0.49 ARU 56 323 0.55 BILL 53 19 0.63 BNI 90 319 0.54 CEL 87 310 0.55 COEN 42 147 0.51 CSS 75 302 0.51 CUC 86 312 0.72 DPC 81 321 0.54 EIDS 55 147 0.37 EKS2 43 308 0.51 FORT 53 172 4.70 GAMB 59 28 0.83 GNI 65 305 0.55 GRFO 85 322 0.56 GVD 82 304 0.51 HLG 84 327 0.60 HNR 49 125 0.87 IBBN 85 325 0.58 ISP 77 305 0.48 KEV 70 338 0.53 KMBL 53 179 0.38 KSDI 74 299 0.70 KURK 43 321 0.57 KWP 78 318 0.53 KZA 42 307 0.63 LAST 81 304 0.54 MALT 70 304 0.55 MORC 81 320 0.57 MSEY 69 255 0.56 PALK 41 254 0.75 PET 41 33 0.63 PMG 40 138 0.60 PSZ 80 318 0.53 RUE 82 323 0.72 SSB 91 320 0.53 SUW 76 323 0.50 TIR 83 312 0.55 TIRR 76 312 0.52 TNA 61 26 0.52 TRF 69 28 0.49 TUE 87 320 0.50 USP 43 309 0.52 VLC 88 317 0.59 VSL 91 314 0.58 VSU 73 326 0.53 WDD 89 308 0.61 WRAB 44 162 0.64 YAK 39 6 0.49 Misfit > 1 heavily downweighted

TAIWAN REGION Epicenter: 22.742 121.301 MW 5.9 USGS MOMENT TENSOR SOLUTION Depth 8 No. of sta: 26 Moment Tensor; Scale 10**17 Nm Mrr= 8.54 Mtt= 1.34 Mff=-9.85 Mrt=-2.61 Mrf=-0.53 Mtf=-0.51 Principal axes: T Val= 9.39 Plg=72 Azm=177 N 0.51 18 4 P -9.90 2 273 Best Double Couple:Mo=9.7*10**17 NP1:Strike=346 Dip=46 Slip= 65 NP2: 200 50 114 ####### --------###------ -----------#--------- -----------#####--------- -----------########---------- -----------##########---------- ----------############--------- ----------##############--------- --------################-------- P --------################-------- -------####### #######-------- --------####### T #######-------- -------####### #######------- -------#################------- ------#################------ -----###############----- ---##############---- --############--- #######

April 15, 2006, TAIWAN REGION, MW=5.9 Goran Ekstrom CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME C041506B DATA USED: GSN L.P. BODY WAVES: 80S,165C, T= 40 SURFACE WAVES: 74S,164C, T= 50 CENTROID LOCATION: ORIGIN TIME 22:40:57.3 0.1 LAT 22.85N 0.01;LON 121.37E 0.01 DEP 24.9 0.3;HALF-DURATION 2.2 MOMENT TENSOR; SCALE 10**25 D-CM MRR= 0.73 0.01; MTT= 0.08 0.01 MPP=-0.81 0.01; MRT=-0.28 0.02 MRP= 0.06 0.02; MTP=-0.26 0.01 PRINCIPAL AXES: 1.(T) VAL= 0.85;PLG=68;AZM=194 2.(N) 0.03; 22; 15 3.(P) -0.88; 0; 285 BEST DOUBLE COUPLE:M0=8.7*10**24 NP1:STRIKE=354;DIP=49;SLIP= 60 NP2:STRIKE=216;DIP=50;SLIP= 120 -----###### ------------####### -------------##-------- ------------#######-------- -----------##########-------- ---------############--------- P --------##############-------- -------###############--------- --------#################-------- -------##################-------- ------######## ########-------- -----######## T ########------- -----######## #######-------- ----##################------- ---#################------- -################------ ##############----- ########---

Deviatoric Moment Tensor Solution

The following broadband stations were used for the source inversion: ADK ANTO AQU ARU BILL BNI CEL COEN CSS CUC DPC EIDS EKS2 FORT GAMB GNI GRFO GVD HLG HNR IBBN ISP KEV KMBL KSDI KURK KWP KZA LAST MALT MORC MSEY PALK PET PMG PSZ RUE SSB SUW TIR TIRR TNA TRF TUE USP VLC VSL VSU WDD WRAB 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

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   10.0  208.   46.  104.   5.65     0.385 0.182E-06     0.391     0.639 0.159E-06  20.9

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