Location

2006/04/16 11:48:57 30.23 138.51 437

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=5.8 2006/04/16 11:48:57 EVID: LAT: 30.23N, LON: 138.51E, DEPTH: 430 Mw: 5.8, mb: 0.0, Ms: 0.0 Mo= 0.534E+25 (dyne-cm) No. of Stations: 21, GAP: 196 Error (clvd/dc)*100= 84.15 Bandpass: 12 - 60 sec Nodal plane parameters strike dip rake NP1: 0 80 -69 NP2: 115 24 -154 --------####### ------------######### ---------------############ -----------------############## ------------------############### --------------------############### ---------------------################ #-------- ----------######### ##### #-------- P ----------######### T ##### #-------- ----------######### ##### ##--------------------################# ##--------------------################# ###-------------------################# ####------------------################# ####-----------------################ ####----------------############### #####-------------##############- #######----------###########--- #########------########---- ###########---------- ########------- Stat Dist Az Misfit Stat Dist Az Misfit AML 52 301 0.31 ARU 59 320 0.23 BILL 41 15 0.90 BRVK 53 315 0.24 BTDF 43 235 0.45 COLA 56 29 0.59 EKS2 52 302 0.31 GNI 73 307 0.35 KBK 51 302 0.36 KKM 31 225 0.34 KUM 43 242 0.48 KURK 48 312 0.31 KWP 82 323 0.70 LSA 40 281 0.50 MA2 30 12 0.67 PALK 58 259 0.49 TKM2 51 302 0.27 TLY 33 319 0.91 UCH 51 301 0.33 ULHL 50 301 0.26 YAK 32 352 1.71 Misfit > 1 heavily downweighted

2006/04/16 11:48:56.39 IZU ISLANDS, JAPAN REGION Epicenter: 30.216 138.544 MW 5.7 USGS MOMENT TENSOR SOLUTION Depth 424 No. of sta: 12 Moment Tensor; Scale 10**17 Nm Mrr=-1.07 Mtt= 2.23 Mff=-1.16 Mrt= 1.56 Mrf=-3.96 Mtf=-1.96 Principal axes: T Val= 5.05 Plg=31 Azm= 39 N 0.04 30 150 P -5.09 44 274 Best Double Couple:Mo=5.1*10**17 NP1:Strike= 76 Dip=31 Slip=-166 NP2: 334 83 -60 ####### -################ -----################ --------########## #### -----------######### T ###### -------------######## ####### --------------################# ----------------################# ------ --------###############- ------ P ---------##############- ------ ----------############-- --------------------##########--- -------------------########---- ##------------------#####------ ####----------------#-------- #######-------#####------ #################---- ################- #######

April 16, 2006, IZU ISLANDS, JAPAN REGION, MW=5.7 Goran Ekstrom CENTROID, MOMENT TENSOR SOLUTION HARVARD EVENT-FILE NAME B041606B DATA USED: GSN L.P. BODY WAVES: 73S,136C, T= 40 CENTROID LOCATION: ORIGIN TIME 11:48:58.8 0.2 LAT 30.26N 0.02;LON 138.58E 0.02 DEP 427.1 1.4;HALF-DURATION 1.8 MOMENT TENSOR; SCALE 10**24 D-CM MRR=-1.27 0.06; MTT= 2.42 0.08 MPP=-1.15 0.10; MRT= 1.14 0.10 MRP=-3.90 0.09; MTP=-2.11 0.08 PRINCIPAL AXES: 1.(T) VAL= 4.88;PLG=28;AZM= 38 2.(N) 0.29; 33; 149 3.(P) -5.17; 44; 278 BEST DOUBLE COUPLE:M0=5.0*10**24 NP1:STRIKE= 78;DIP=35;SLIP=-165 NP2:STRIKE=335;DIP=81;SLIP= -56 ########### ----############### -------########## ### ----------######### T ##### ------------######## ###### --------------################# ---------------################ ------ --------################ ------ P ---------##############- ------ ----------############-- --------------------##########--- -------------------#########--- ##------------------######----- ###-----------------###------ ######------------#-------- ##################----- ################--- ###########

Deviatoric Moment Tensor Solution

The following broadband stations were used for the source inversion: AML ARU BILL BRVK BTDF COLA EKS2 GNI KBK KKM KUM KURK KWP LSA MA2 PALK TKM2 TLY UCH ULHL 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  430.0    0.   80.  -69.   5.78     0.431 0.833E-07     0.561     0.657 0.477E-07  84.2

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