2007/10/31 03:04:54 37.43 -121.77 9.0 5.6 California
USGS Felt map for this earthquake
SLU Moment Tensor Solution
2007/10/31 03:04:54 37.43 -121.77 9.0 5.6 California
Best Fitting Double Couple
Mo = 2.09e+24 dyne-cm
Mw = 5.48
Z = 12 km
Plane Strike Dip Rake
NP1 235 85 -15
NP2 326 75 -175
Principal Axes:
Axis Value Plunge Azimuth
T 2.09e+24 7 282
N 0.00e+00 74 37
P -2.09e+24 14 190
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.83e+24
Mxy -7.32e+23
Mxz 5.37e+23
Myy 1.92e+24
Myz -1.61e+23
Mzz -9.39e+22
--------------
----------------------
#####-----------------------
########----------------------
############----------------------
###############-----------------####
##################-----------#########
####################-------#############
###################----###############
T ####################-##################
#################-----#################
#################---------################
###############------------###############
############---------------#############
#########-------------------############
######----------------------##########
###-------------------------########
---------------------------#######
--------------------------####
--------- -------------###
------ P -------------
-- ---------
Harvard Convention
Moment Tensor:
R T F
-9.39e+22 5.37e+23 1.61e+23
5.37e+23 -1.83e+24 7.32e+23
1.61e+23 7.32e+23 1.92e+24
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20071031030454/index.html
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STK = 235
DIP = 85
RAKE = -15
MW = 5.48
HS = 12
The surface-wave is preferred. Rake is least well determined.
The following compares this source inversion to others
SLU Moment Tensor Solution
2007/10/31 03:04:54 37.43 -121.77 9.0 5.6 California
Best Fitting Double Couple
Mo = 2.09e+24 dyne-cm
Mw = 5.48
Z = 12 km
Plane Strike Dip Rake
NP1 235 85 -15
NP2 326 75 -175
Principal Axes:
Axis Value Plunge Azimuth
T 2.09e+24 7 282
N 0.00e+00 74 37
P -2.09e+24 14 190
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.83e+24
Mxy -7.32e+23
Mxz 5.37e+23
Myy 1.92e+24
Myz -1.61e+23
Mzz -9.39e+22
--------------
----------------------
#####-----------------------
########----------------------
############----------------------
###############-----------------####
##################-----------#########
####################-------#############
###################----###############
T ####################-##################
#################-----#################
#################---------################
###############------------###############
############---------------#############
#########-------------------############
######----------------------##########
###-------------------------########
---------------------------#######
--------------------------####
--------- -------------###
------ P -------------
-- ---------
Harvard Convention
Moment Tensor:
R T F
-9.39e+22 5.37e+23 1.61e+23
5.37e+23 -1.83e+24 7.32e+23
1.61e+23 7.32e+23 1.92e+24
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20071031030454/index.html
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October 31, 2007, SAN FRANCISCO BAY AREA, CAL, MW=5.6
Goran Ekstrom
Meredith Nettles
CENTROID-MOMENT-TENSOR SOLUTION
GCMT EVENT: C200710310304A
DATA: IU II CU IC GE
L.P.BODY WAVES: 49S, 85C, T= 40
MANTLE WAVES: 15S, 15C, T=125
SURFACE WAVES: 50S, 104C, T= 50
TIMESTAMP: Q-20071031072823
CENTROID LOCATION:
ORIGIN TIME: 03:04:59.7 0.2
LAT:37.44N 0.02;LON:121.78W 0.02
DEP: 15.2 1.0;TRIANG HDUR: 1.5
MOMENT TENSOR: SCALE 10**24 D-CM
RR=-0.330 0.054; TT=-2.270 0.053
PP= 2.600 0.059; RT= 0.553 0.183
RP= 0.496 0.160; TP= 0.947 0.050
PRINCIPAL AXES:
1.(T) VAL= 2.887;PLG=11;AZM=282
2.(N) -0.344; 74; 52
3.(P) -2.543; 12; 189
BEST DBLE.COUPLE:M0= 2.71*10**24
NP1: STRIKE=326;DIP=74;SLIP=-179
NP2: STRIKE=235;DIP=89;SLIP= -16
-----------
-------------------
#####------------------
#########------------------
############--------------###
###############----------######
##############------#########
T ################-#############
##############---#############
###############------############
############----------###########
#########-------------#########
######-----------------########
##---------------------######
----------------------#####
-------- ----------##
------ P ----------
-- ------
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UCB Seismological Laboratory
Inversion method: complete waveform
Stations used: CMB MCCM ORV PKD RO4C SO5C
Berkeley Moment Tensor Solution
Best Fitting Double-Couple:
Mo = 2.05E+24 Dyne-cm
Mw = 5.48
Z = 14
Plane Strike Rake Dip
NP1 146 -178 89
NP2 56 -1 88
Principal Axes:
Axis Value Plunge Azimuth
T 2.049 1 281
N 0.000 88 173
P -2.049 2 11
Event Date/Time: October 31, 2007, 03:04:54.82 UTC
Event ID: nc40204628
Moment Tensor: Scale = 10**24 Dyne-cm
Component Value
Mxx -1.898
Mxy -0.766
Mxz -0.070
Myy 1.900
Myz -0.039
Mzz -0.002
------ P
------------ ----
#------------------------
####-------------------------
########-------------------------
##########------------------------#
############--------------------#####
##############-----------------########
###############------------###########
T ################---------##############
#################-----#################
####################-####################
###################--####################
################-------##################
############-----------################
#########---------------###############
#####--------------------############
#------------------------##########
-------------------------########
------------------------#####
------------------------#
-------------------
-------
Lower Hemisphere Equiangle Projection
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The focal mechanism was determined using broadband seismic waveforms. The location of the event and the and stations used for the waveform inversion are shown in the next figure.
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The program wvfgrd96 was used with good traces observed at short distance to determine the focal mechanism, depth and seismic moment. This technique requires a high quality signal and well determined velocity model for the Green functions. To the extent that these are the quality data, this type of mechanism should be preferred over the radiation pattern technique which requires the separate step of defining the pressure and tension quadrants and the correct strike.
The observed and predicted traces are filtered using the following gsac commands:
hp c 0.01 n 3 lp c 0.05 n 3 br c 0.12 0.25 n 4 p 2The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 55 80 25 5.25 0.3269
WVFGRD96 1.0 55 80 15 5.26 0.3448
WVFGRD96 2.0 235 70 15 5.33 0.4115
WVFGRD96 3.0 235 60 10 5.38 0.4403
WVFGRD96 4.0 235 90 -25 5.38 0.4609
WVFGRD96 5.0 235 85 -20 5.39 0.4760
WVFGRD96 6.0 235 85 -20 5.41 0.4873
WVFGRD96 7.0 235 80 -20 5.42 0.4974
WVFGRD96 8.0 230 75 -25 5.45 0.5044
WVFGRD96 9.0 235 80 -20 5.45 0.5115
WVFGRD96 10.0 235 80 -20 5.46 0.5152
WVFGRD96 11.0 235 80 -20 5.47 0.5162
WVFGRD96 12.0 235 85 -15 5.48 0.5162
WVFGRD96 13.0 235 85 -15 5.49 0.5147
WVFGRD96 14.0 235 80 -15 5.50 0.5117
WVFGRD96 15.0 235 80 -15 5.50 0.5079
WVFGRD96 16.0 235 80 -15 5.51 0.5038
WVFGRD96 17.0 235 80 -15 5.52 0.4986
WVFGRD96 18.0 235 80 -15 5.53 0.4931
WVFGRD96 19.0 235 80 -15 5.53 0.4866
WVFGRD96 20.0 235 80 -15 5.54 0.4799
WVFGRD96 21.0 235 80 -15 5.55 0.4724
WVFGRD96 22.0 235 80 -15 5.56 0.4642
WVFGRD96 23.0 235 80 -15 5.56 0.4559
WVFGRD96 24.0 235 80 -15 5.57 0.4473
WVFGRD96 25.0 235 80 -15 5.57 0.4388
WVFGRD96 26.0 235 80 -15 5.58 0.4305
WVFGRD96 27.0 235 80 -15 5.59 0.4222
WVFGRD96 28.0 235 80 -15 5.59 0.4138
WVFGRD96 29.0 235 80 -15 5.60 0.4057
The best solution is
WVFGRD96 12.0 235 85 -15 5.48 0.5162
The mechanism correspond to the best fit is
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The best fit as a function of depth is given in the following figure:
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The comparison of the observed and predicted waveforms is given in the next figure. The red traces are the observed and the blue are the predicted. Each observed-predicted componnet is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. The number in black at the rightr of each predicted traces it the time shift required for maximum correlation between the observed and predicted traces. This time shift is required because the synthetics are not computed at exactly the same distance as the observed and because the velocity model used in the predictions may not be perfect. A positive time shift indicates that the prediction is too fast and should be delayed to match the observed trace (shift to the right in this figure). A negative value indicates that the prediction is too slow. The bandpass filter used in the processing and for the display was
hp c 0.01 n 3 lp c 0.05 n 3 br c 0.12 0.25 n 4 p 2
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| Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to thewavefroms. Each solution is plotted as a vector at a given value of strike and dip with the angle of the vector representing the rake angle, measured, with respect to the upward vertical (N) in the figure. |
The following figure shows the stations used in the grid search for the best focal mechanism to fit the surface-wave spectral amplitudes of the Love and Rayleigh waves.
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The surface-wave determined focal mechanism is shown here.
NODAL PLANES
STK= 59.99
DIP= 80.00
RAKE= 29.99
OR
STK= 324.26
DIP= 60.51
RAKE= 168.49
DEPTH = 12.0 km
Mw = 5.55
Best Fit 0.8661 - P-T axis plot gives solutions with FIT greater than FIT90
 |
The P-wave first motion data for focal mechanism studies are as follow:
Sta Az(deg) Dist(km) First motion WENL 3 21 -12345 JRSC 266 42 -12345 BDM 352 59 -12345 PACP 137 63 -12345 SAO 159 79 -12345 FARB 286 113 -12345 CVS 329 118 -12345 R04C 38 118 -12345 MCCM 309 126 -12345 S05C 94 128 -12345 Q03C 351 135 -12345 CMB 61 139 -12345 U04C 143 148 -12345 V03C 163 163 -12345 MNRC 340 171 -12345 LAVA 31 173 -12345 T06C 104 189 -12345 U05C 129 191 -12345 PKD 146 198 -12345 HOPS 327 208 -12345 KCC 92 217 -12345 ORV 6 237 -12345 R06C 59 237 -12345 V05C 136 241 -12345 PHL 154 250 -12345 RCT 118 258 -12345 GASB 342 260 -12345 MLAC 84 260 -12345 WCN 40 272 -12345 SMM 145 284 -12345 O05C 15 291 -12345 BEK 24 297 -12345 P06A 33 298 -12345 VES 125 298 -12345 Q07A 56 309 -12345 TIN 96 317 -12345 O04C 10 326 -12345 MPP 147 332 -12345 R08A 71 338 -12345 P07A 46 344 -12345 CWC 107 347 -12345 O06A 28 347 -12345 O01C 330 350 -12345 ISA 123 354 -12345 WDC 349 356 -12345 ARV 133 367 -12345 Q08A 64 372 -12345 SBC 150 380 -12345 GRA 96 394 -12345 O07A 39 394 -12345 N02C 341 399 -12345 S09A 84 403 -12345 N06A 24 405 -12345 TPH 78 407 -12345 P08A 51 408 -12345 MPM 110 411 -12345 R09A 76 423 -12345 JCC 333 424 -12345 LRL 119 426 -12345 SCZ2 152 427 -12345 M03C 356 428 -12345 Q09A 67 431 -12345 SLA 112 436 -12345 EDW2 129 442 -12345 LGU 146 442 -12345 N07B 32 444 -12345 O08A 44 446 -12345 FUR 102 450 -12345 M02C 348 450 -12345 S10A 82 460 -12345 VCS 134 464 -12345 P09A 58 468 -12345 DEC 138 470 -12345 DJJ 140 475 -12345 CHF 134 482 -12345 YBH 351 484 -12345 PASC 137 485 -12345 PASC 137 485 -12345 N08A 39 487 -12345 MWC 136 489 -12345 R10A 77 490 -12345 TPNV 95 493 -12345 Q10A 70 496 -12345 U10A 101 497 -12345
Surface wave analysis was performed using codes from Computer Programs in Seismology, specifically the multiple filter analysis program do_mft and the surface-wave radiation pattern search program srfgrd96.
Digital data were collected, instrument response removed and traces converted
to Z, R an T components. Multiple filter analysis was applied to the Z and T traces to obtain the Rayleigh- and Love-wave spectral amplitudes, respectively.
These were input to the search program which examined all depths between 1 and 25 km
and all possible mechanisms.
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| Pressure-tension axis trends. Since the surface-wave spectra search does not distinguish between P and T axes and since there is a 180 ambiguity in strike, all possible P and T axes are plotted. First motion data and waveforms will be used to select the preferred mechanism. The purpose of this plot is to provide an idea of the possible range of solutions. The P and T-axes for all mechanisms with goodness of fit greater than 0.9 FITMAX (above) are plotted here. |
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| Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to the Love and Rayleigh wave radiation patterns. Each solution is plotted as a vector at a given value of strike and dip with the angle of the vector representing the rake angle, measured, with respect to the upward vertical (N) in the figure. Because of the symmetry of the spectral amplitude rediation patterns, only strikes from 0-180 degrees are sampled. |
The distribution of broadband stations with azimuth and distance is
Sta Az(deg) Dist(km) CCM 309 126 MCCM 309 126 CMB 61 139 U04C 143 148 V03C 163 163 MNRC 340 171 LAVA 31 173 PKD 146 198 HOPS 327 208 KCC 92 217 ORV 6 237 R06C 58 237 V05C 136 241 PHL 154 250 RCT 118 258 GASB 342 260 MLAC 84 260 WCN 40 272 SMM 145 284 O05C 14 291 P06A 33 298 VES 126 298 Q07A 56 309 TIN 96 317 O04C 10 326 MPP 147 332 R08A 71 338 P07A 46 344 CWC 107 347 O06A 28 347 O01C 330 350 ISA 123 354 WDC 349 356 Q08A 64 372 SBC 150 380 GRA 96 394 O07A 39 394 N02C 341 399 S09A 84 403 N06A 24 405 TPH 78 407 P08A 51 408 MPM 110 411 R09A 76 423 LRL 119 426 SCZ2 152 427 M03C 356 428 Q09A 67 431 SLA 112 436 EDW2 129 442 LGU 146 442 N07B 32 444 O08A 44 446 FUR 102 450 M02C 348 450 S10A 82 460 VCS 134 464 P09A 58 468 DEC 138 470 DJJ 140 475 CHF 134 482 YBH 351 484 N08A 39 487 MWC 136 489 R10A 77 490 TPNV 95 493 Q10A 70 496 U10A 101 497 GSC 116 504 SNCC 156 507 RPV 142 510 VTV 127 511 MOD 14 512 BFS 132 513 RRX 122 515 BMN 48 516 FMP 142 519 SHO 107 520 P10A 61 523 N09A 43 528 M01C 338 530 M08A 32 533 S11A 86 533 L02A 344 548 L07A 22 550 R11A 78 553 O10A 54 557 Q11A 72 559 BBR 127 561 SVD 130 561 HEC 119 568 SDD 138 569 TUQ 111 569 SCI2 148 574 P11A 64 575 M09A 39 579 U11A 99 580 T11A 90 581 N10A 50 583 HUMO 350 584 K05A 7 593 MUR 134 594 V11A 105 594 DGR 133 602 L08A 28 604 SMER 135 607 K02A 347 610 K06A 12 610 O11A 59 610 S12A 86 612 RDM 132 614 KNW 130 616 WVOR 25 617 L09A 33 619 K07A 19 622 GMR 116 623 CRY 132 626 WMC 131 630 T12A 95 632 Q12A 72 633 PLM 134 635 SND 131 635 BZN 132 637 R12A 79 638 M10A 43 639 K01A 340 640 FRD 131 641 PFO 130 641 N11A 52 643 DBO 349 644 BEL 124 646 J05A 4 652 K08A 24 652 DAN 116 654 U12A 98 654 LVA2 132 655 SOL 140 655 HWB 137 656 109C 138 659 J06A 12 661 W12A 109 663 J03A 352 668 BVDA2 131 669 ELK 55 674 J02A 348 677 K09A 29 679 M11A 47 680 O12A 60 686 L10A 40 687 J07A 17 692 R13A 81 692 N12A 55 695 Q13A 74 699 S13A 86 699 T13A 91 699 IRM 119 700 MONP2 134 700 NEE2 112 708 BC3 124 709 I04A 356 709 P13A 69 713 PIN 6 713 J08A 22 715 K10A 34 726 TAKO 345 728 I06A 10 735 L11A 42 736 WIFE 360 736 M12A 51 737 SWS 131 737 I03A 350 738 DVT 134 740 J09A 26 740 O13A 64 740 EUO 352 741 I05A 3 749 I02A 347 750 W13A 108 754 N13A 58 756 S14A 85 760 I07A 14 763 Q14A 74 763 K11A 38 768 I08A 20 769 PDM 114 771 T14A 90 771 U14A 96 773 Y12C 120 773 R14A 80 776 L12A 46 780 J10A 31 789 P14A 70 796 GLA 126 797 V14A 102 801 I09A 24 802 H05A 3 803 COR 351 805 H04A 358 806 H03A 352 815 H07A 12 817 W14A 105 818 TOLO 348 819 H06A 8 820 K12A 43 823 Y13A 117 823 H02A 348 826 H08A 17 829 S15A 85 831 N14A 60 833 J11A 35 834 T15A 90 834 DUG 66 836 Q15A 75 840 R15A 81 840 L13A 50 846 I10A 28 849 112A 128 851 U15A 95 851 M14A 55 854 J12A 39 859 X14A 110 865 G04A 356 866 O15A 66 867 G05A 2 868 I11A 32 871 G06A 6 872 H09A 22 874 K13A 46 875 HOOD 1 876 V15A 99 876 Y14A 113 882 G03A 352 885 N15A 62 886 G07A 11 888 W15A 104 889 L14A 52 892 113A 123 894 S16A 85 899 H10A 26 900 I12A 36 902 G08A 14 904 BMO 23 905 R16A 81 910 T16A 90 912 P16A 72 914 M15A 58 918 X15A 108 919 Z14A 117 919 HLID 40 923 J13A 42 924 K14A 50 927 F06A 5 930 G09A 20 933 Y15A 112 937 F05A 2 939 H11A 29 941 O16A 68 943 Q16A 77 943 F04A 357 946 L15A 55 951 F07A 9 953 W16A 103 955 WUAZ 100 955 F03A 352 956 G10A 22 956 J14A 44 958 U16A 95 960 F08A 14 962 I13A 40 967 S17A 85 969 N16A 64 971 F09A 18 974 M16A 61 974 T17A 90 974 R17A 80 978 K15A 51 980 H12A 34 981 Z15A 115 986 P17A 73 988 X16A 107 990 HWUT 59 992 U17A 92 992 G11A 26 997 SRU 76 1001 O17A 69 1005 I14A 42 1007 HAWA 10 1013 E05A 0 1014 E06A 3 1014 115A 118 1015 214A 124 1020 E04A 356 1021 F10A 20 1021 L16A 57 1021 N17A 64 1021 E07A 8 1026 W17A 101 1027 E08A 12 1031 J15A 47 1032 P18A 73 1033 Q18A 76 1034 S18A 85 1040 Z16A 113 1043 X17A 106 1047 F11A 25 1049 R18A 81 1049 K16A 52 1054 T18A 88 1055 G13A 34 1059 116A 118 1065 H14A 39 1065 U18A 92 1066 O18A 69 1068 I15A 44 1070 F12A 28 1072 Y17A 110 1073 V18A 97 1076 E10A 20 1077 J16A 50 1078 D04A 356 1079 AHID 54 1084 D05A 359 1084 D06A 4 1087 D03A 352 1088 E11A 23 1093 D07A 7 1095 D08A 12 1095 R19A 81 1104 H15A 41 1106 D09A 14 1107 Q19A 77 1108 W18A 100 1110 G14A 36 1111 X18A 103 1113 F13A 31 1115 N18A 66 1115 S19A 84 1116 216A 120 1119 E12A 25 1122 Z17A 111 1123 I16A 47 1125 D10A 18 1131 T19A 90 1134 Y18A 107 1137 C05A 0 1140 P19A 74 1140 117A 115 1141 W19A 99 1141 O19A 70 1142 J17A 52 1145 C04A 356 1147 N19A 67 1153 TUC 116 1153 V19A 96 1154 G15A 39 1157 D11A 21 1158 F14A 34 1163 C06A 3 1168 Z18A 111 1170 C08A 10 1172 X19A 103 1173 M19A 64 1174 MVCO 87 1176 E13A 30 1181 L19A 60 1182 217A 119 1183 C09A 13 1187 I17A 49 1188 B04A 354 1189 C03A 350 1190 D12A 24 1192 OPC 354 1193 BW06 56 1196 H16A 44 1196 118A 113 1200 G16A 41 1201 B05A 359 1204 C10A 16 1210 E14A 32 1210 F15A 37 1211 H17A 47 1218 Z19A 108 1224 I18A 52 1227 MSO 29 1227 VGZ 355 1227 B08A 8 1230 D13A 27 1230 218A 116 1232 B06A 1 1232 B07A 6 1233 BOZ 40 1243 119A 111 1248 C12B 22 1252 F16A 39 1253 PGC 354 1254 A04A 357 1256 B09A 12 1256 PFB 351 1257 NEW 16 1261 B10A 16 1263 SNB 355 1266 318A 118 1269 D14A 30 1269 G17A 43 1270 C13A 25 1281 A05A 359 1285 YOUB 352 1290 219A 114 1293 A06A 1 1296 A07A 4 1296 A08A 8 1296 B11A 18 1299 MGB 350 1307 A09A 10 1308 D15A 32 1310 E16A 36 1310 OZB 348 1316 F17A 41 1318 HNB 357 1318 NLLB 353 1323 B12A 20 1325 A10A 14 1328 319A 117 1329 HOPB 1 1329 PNT 7 1332 G18A 46 1343 E17A 38 1348 RLMT 47 1349 A11 17 1353 A11A 17 1353 B13A 24 1353 D16A 35 1357 SHB 354 1362 A12A 19 1370 BTB 348 1371 C15A 30 1371 F18A 43 1373 Y22D 101 1392 B14A 27 1397 ANMO 97 1403 E18A 40 1409 D17A 37 1412 C16A 32 1413 B15A 29 1422 CBB 350 1429 ISCO 74 1429 SDCO 84 1436 WALA 24 1439 C17A 35 1447 EDB 344 1447 A14A 25 1449 D18A 38 1463 LLLB 360 1464 B16A 31 1468 A15A 27 1476 A16 30 1521 A16A 30 1521 EGMT 36 1530 PHC 345 1542 SLEB 10 1553 FLLB 357 1594 TALB 354 1632 LAO 46 1642 RSSD 58 1666 THMB 354 1690 ALRB 352 1696 CLSB 358 1705 BBB 345 1713 UBRB 355 1728 OGNE 71 1745 SULB 354 1773 AMTX 93 1826 EDM 18 1872 DGMT 44 1879 MOBC 339 1917 CBKS 79 1933 DIB 338 1939 VIB 338 1946 RUBB 344 1987 BMBC 359 2070 JCT 104 2166 KSU1 77 2203 ECSD 64 2232 FNBB 358 2388 DLBC 348 2412 AGMN 52 2420 KVTX 109 2488 SCIA 70 2488 ULM 47 2502 HKT 102 2534 MIAR 89 2553 NATX 96 2555 EPLO 50 2620 UALR 87 2655 PLBC 342 2663 EYMN 55 2719 JFWS 67 2736 ATKO 53 2737 FVM 79 2751 SLM 78 2758 HDIL 73 2819 PVMO 82 2846 COWI 60 2855 MPH 85 2858 SIUC 79 2861 LDIO 53 2889 VBMS 92 2903 PKLO 48 2915 UTMT 82 2921 OXF 86 2922 MUMO 45 2957 USIN 78 2991 ROMN 4 3001 WVT 82 3017 CTLN 5 3028 BLO 75 3070 FCC 31 3098 NSKO 47 3098 WCI 77 3105 COWN 9 3174 DAWY 344 3188 GLMI 63 3196 JERN 9 3250 BRAL 92 3258 ARV 133 3264 ARVN 27 3264 AAM 68 3278 ACSO 72 3356 KAPO 54 3400 BRCO 64 3448 ELFO 66 3463 OTRO 53 3474 TRO 130 3474 GOGA 86 3483 COLA 339 3500 INK 352 3512 JOSN 26 3514 SEDN 26 3533 CLWO 64 3538 KLBO 62 3543 ACTO 66 3562 ALLY 69 3574 ERPA 68 3581 KILO 56 3591 MALO 54 3604 BUKO 62 3607 ADO 128 3629 SADO 63 3629 BLA 78 3635 MEDO 66 3695 BULN 21 3705 ALGO 61 3711 BANO 63 3724 VLDQ 57 3735 DELO 64 3751 SSPA 71 3777 SNQN 42 3781 STLN 20 3783 NHSC 85 3784 WAGN 23 3787 PECO 65 3806 KGNO 64 3843 MPPO 63 3856 CBN 75 3872 DWPF 93 3886 SDMD 73 3889 OTT 62 3895 INUQ 39 3905 BINY 68 3908 CNNC 80 3911 MVL 72 3918 QILN 23 3948 ALFO 62 3958 PTN 63 3960 AKVQ 35 3987 LONY 63 3991 MRHQ 61 4008 NCB 64 4026 BRNJ 70 4053 MNT 62 4057 IVKQ 33 4066 FRNY 63 4067 ACCN 65 4079 CPNY 70 4101 PAL 69 4101 FOR 69 4106 CUNY 70 4114 SRLN 22 4178 LBNH 64 4206 LAIN 21 4208 HRV 66 4264 ILON 21 4280 LMQ 58 4292 A61 58 4309 GIFN 21 4326 RES 11 4382 PKME 62 4397 ICQ 55 4502 FRB 33 4561 GGN 61 4592 LMN 60 4734 GBN 60 4995 DRLN 54 5208 SJNN 55 5598
Since the analysis of the surface-wave radiation patterns uses only spectral amplitudes and because the surfave-wave radiation patterns have a 180 degree symmetry, each surface-wave solution consists of four possible focal mechanisms corresponding to the interchange of the P- and T-axes and a roation of the mechanism by 180 degrees. To select one mechanism, P-wave first motion can be used. This was not possible in this case because all the P-wave first motions were emergent ( a feature of the P-wave wave takeoff angle, the station location and the mechanism). The other way to select among the mechanisms is to compute forward synthetics and compare the observed and predicted waveforms.
The fits to the waveforms with the given mechanism are show below:
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This figure shows the fit to the three components of motion (Z - vertical, R-radial and T - transverse). For each station and component, the observed traces is shown in red and the model predicted trace in blue. The traces represent filtered ground velocity in units of meters/sec (the peak value is printed adjacent to each trace; each pair of traces to plotted to the same scale to emphasize the difference in levels). Both synthetic and observed traces have been filtered using the SAC commands:
hp c 0.01 n 3 lp c 0.05 n 3 br c 0.12 0.25 n 4 p 2
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Should the national backbone of the USGS Advanced National Seismic System (ANSS) be implemented with an interstation separation of 300 km, it is very likely that an earthquake such as this would have been recorded at distances on the order of 100-200 km. This means that the closest station would have information on source depth and mechanism that was lacking here.
Dr. Harley Benz, USGS, provided the USGS USNSN digital data. The digital data used in this study were provided by Natural Resources Canada through their AUTODRM site http://www.seismo.nrcan.gc.ca/nwfa/autodrm/autodrm_req_e.php, and IRIS using their BUD interface
The WUS used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01
Model after 8 iterations
ISOTROPIC
KGS
FLAT EARTH
1-D
CONSTANT VELOCITY
LINE08
LINE09
LINE10
LINE11
H(KM) VP(KM/S) VS(KM/S) RHO(GM/CC) QP QS ETAP ETAS FREFP FREFS
1.9000 3.4065 2.0089 2.2150 0.302E-02 0.679E-02 0.00 0.00 1.00 1.00
6.1000 5.5445 3.2953 2.6089 0.349E-02 0.784E-02 0.00 0.00 1.00 1.00
13.0000 6.2708 3.7396 2.7812 0.212E-02 0.476E-02 0.00 0.00 1.00 1.00
19.0000 6.4075 3.7680 2.8223 0.111E-02 0.249E-02 0.00 0.00 1.00 1.00
0.0000 7.9000 4.6200 3.2760 0.164E-10 0.370E-10 0.00 0.00 1.00 1.00
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Thu Nov 1 21:59:42 CDT 2007