2008/02/21 14:16:05 41.076 -114.771 10.0 6.3 Nevada
USGS Felt map for this earthquake
SLU Moment Tensor Solution
2008/02/21 14:16:05 41.076 -114.771 10.0 6.3 Nevada
Best Fitting Double Couple
Mo = 8.32e+24 dyne-cm
Mw = 5.88
Z = 11 km
Plane Strike Dip Rake
NP1 205 50 -90
NP2 25 40 -90
Principal Axes:
Axis Value Plunge Azimuth
T 8.32e+24 5 295
N 0.00e+00 -0 205
P -8.32e+24 85 115
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.46e+24
Mxy -3.14e+24
Mxz 6.10e+23
Myy 6.73e+24
Myz -1.31e+24
Mzz -8.19e+24
##############
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#############--------------###
#############-----------------####
###########------------------#####
T #########--------------------######
# ########----------------------######
###########-----------------------######
###########------------------------#######
###########---------- ----------########
##########----------- P ----------########
##########----------- ---------#########
########------------------------########
########-----------------------#########
#######----------------------#########
######--------------------##########
#####-------------------##########
####----------------##########
####------------############
#---------############
##############
Harvard Convention
Moment Tensor:
R T F
-8.19e+24 6.10e+23 1.31e+24
6.10e+23 1.46e+24 3.14e+24
1.31e+24 3.14e+24 6.73e+24
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20080221141605/index.html
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STK = 25
DIP = 40
RAKE = -90
MW = 5.88
HS = 11
The waveform inversion is preferred. The surface-wave solution is consistent.
The following compares this source inversion to others
SLU Moment Tensor Solution
2008/02/21 14:16:05 41.076 -114.771 10.0 6.3 Nevada
Best Fitting Double Couple
Mo = 8.32e+24 dyne-cm
Mw = 5.88
Z = 11 km
Plane Strike Dip Rake
NP1 205 50 -90
NP2 25 40 -90
Principal Axes:
Axis Value Plunge Azimuth
T 8.32e+24 5 295
N 0.00e+00 -0 205
P -8.32e+24 85 115
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.46e+24
Mxy -3.14e+24
Mxz 6.10e+23
Myy 6.73e+24
Myz -1.31e+24
Mzz -8.19e+24
##############
###############------#
##############-----------###
#############--------------###
#############-----------------####
###########------------------#####
T #########--------------------######
# ########----------------------######
###########-----------------------######
###########------------------------#######
###########---------- ----------########
##########----------- P ----------########
##########----------- ---------#########
########------------------------########
########-----------------------#########
#######----------------------#########
######--------------------##########
#####-------------------##########
####----------------##########
####------------############
#---------############
##############
Harvard Convention
Moment Tensor:
R T F
-8.19e+24 6.10e+23 1.31e+24
6.10e+23 1.46e+24 3.14e+24
1.31e+24 3.14e+24 6.73e+24
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20080221141605/index.html
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USGS Body-Wave Moment Tensor Solution
08/02/21 14:16:03.82
NEVADA
Epicenter: 41.083 -114.730
MW 5.8
USGS MOMENT TENSOR SOLUTION
Depth 7 No. of sta: 91
Moment Tensor; Scale 10**17 Nm
Mrr=-6.82 Mtt= 2.12
Mpp= 4.70 Mrt= 1.59
Mrp= 2.38 Mtp= 1.19
Principal axes:
T Val= 5.79 Plg=12 Azm=293
N 1.69 3 23
P -7.48 76 128
Best Double Couple:Mo=6.8*10**17
NP1:Strike=206 Dip=58 Slip= -86
NP2: 19 33 -96
#######
#################
##############-----##
#############---------###
#############------------####
# #########-------------#####
# T ########---------------####
## #######----------------#####
###########-----------------#####
##########------- --------#####
#########-------- P -------######
#########-------- -------######
#######------------------######
#######-----------------#######
######----------------#######
####--------------#######
##------------#######
#-------#########
#######
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USGS Centroid Moment Tensor Solution
08/02/21 14:16:03.82
NEVADA
Epicenter: 41.083 -114.730
MW 6.0
USGS CENTROID MOMENT TENSOR
08/02/21 14:16:41.29
Centroid: 42.125 -113.949
Depth 10 No. of sta: 60
Moment Tensor; Scale 10**18 Nm
Mrr=-1.12 Mtt= 0.26
Mpp= 0.85 Mrt= 0.29
Mrp=-0.60 Mtp= 0.53
Principal axes:
T Val= 1.23 Plg= 9 Azm=116
N 0.16 20 22
P -1.40 66 229
Best Double Couple:Mo=1.3*10**18
NP1:Strike= 9 Dip=58 Slip=-114
NP2: 230 40 -55
######-
############-----
###############------
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###########---------#########
##########------------#########
########--------------#########
#######----------------##########
######-----------------##########
#####------------------##########
####-------- -------###########
####-------- P -------###########
##--------- ------########
##------------------######## T
#-----------------#########
---------------##########
------------#########
--------#########
-######
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February 21, 2008, NEVADA, MW=6.0
Goran Ekstrom
CENTROID-MOMENT-TENSOR SOLUTION
GCMT EVENT: C200802211416A
DATA: II IU CU IC G GE
L.P.BODY WAVES: 92S, 209C, T= 40
MANTLE WAVES: 83S, 120C, T=125
SURFACE WAVES: 99S, 252C, T= 50
TIMESTAMP: Q-20080221151936
CENTROID LOCATION:
ORIGIN TIME: 14:16:10.1 0.1
LAT:41.23N 0.01;LON:114.86W 0.01
DEP: 14.1 0.2;TRIANG HDUR: 2.5
MOMENT TENSOR: SCALE 10**25 D-CM
RR=-1.230 0.010; TT= 0.245 0.008
PP= 0.990 0.009; RT=-0.078 0.018
RP= 0.125 0.018; TP= 0.628 0.007
PRINCIPAL AXES:
1.(T) VAL= 1.350;PLG= 2;AZM=300
2.(N) -0.098; 7; 209
3.(P) -1.247; 83; 43
BEST DBLE.COUPLE:M0= 1.30*10**25
NP1: STRIKE= 36;DIP=44;SLIP= -81
NP2: STRIKE=203;DIP=47;SLIP= -99
###########
###########--------
##########------------#
#########--------------###
T #######-----------------###
######------------------####
########-------------------####
########-------- ---------#####
########-------- P --------######
#######--------- -------#######
#######-------------------#######
######-----------------########
######----------------#########
#####--------------##########
####------------###########
###--------############
--#################
###########
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UCB Seismological Laboratory
Inversion method: complete waveform
Stations used: CMB KCC ORV
Berkeley Moment Tensor Solution
Best Fitting Double-Couple:
Mo = 1.04E+25 Dyne-cm
Mw = 5.95
Z = 11
Plane Strike Rake Dip
NP1 228 -71 65
NP2 10 -124 31
Principal Axes:
Axis Value Plunge Azimuth
T 10.400 18 305
N 0.000 17 40
P -10.400 65 171
Event Date/Time: February 21, 2008 at 14:16:05 UTC
Event ID: usus2008nsa9
Moment Tensor: Scale = 10**24 Dyne-cm
Component Value
Mxx 1.254
Mxy -4.116
Mxz 5.612
Myy 6.359
Myz -3.121
Mzz -7.613
#######
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## ###################-----######
### T ###############----------######
#### ############-------------#######
#################----------------######
################------------------#######
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############----------------------#######
###########-----------------------#######
##########---------- -----------#######
#######------------ P ----------#######
######------------- ---------########
#####------------------------########
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#------------------------########
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Lower Hemisphere Equiangle Projection
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USGS research CMT: maintained and developed by Jascha Polet at Cal Poly Pomona.
This is a research system and solutions are *not* official USGS earthquake magnitudes.
AUTOMATIC solution, not reviewed by a seismologist
--------------------------------------------------
General region : 2008nsa9 NEVADA
surface waves (3.0,3.5,7,7.5 mHz)
Stations used : NNA OTAV PET RPN SDV SFJD SJG TIXI WCI YAK
Origin time: 2008 52 14 16 5
Original location (lat,lon,depth) : 41.1000 -114.800 10
Moment tensor (x1.e26 dyncm) :
Mrr : -0.150983 Mtt : 0.023564
Mff : 0.127420 Mrt : 0.022792
Mrf : -0.075421 Mtf : 0.023294
T-axis: moment= 0.149 plunge= 13.405 azimuth= 98.088
N-axis: moment= 0.025 plunge= 9.737 azimuth= 5.744
P-axis: moment= -0.174 plunge= 73.324 azimuth= 240.795
best double couple: Mo= 0.161(x1.e26 dyncm) Mw=6.1 tau= 3.0
nodal planes (strike/dip/slip): 359.85/ 59.11/-101.37 201.23/ 32.72/-71.77
Centroid location : 41.464 -114.263 16.475
Centroid time : 16.680
Variance reduction (%) : 27
***********
****----ooooooo****
***-----oooo --oo-----***
**-----ooo oo-------**
**---- oo o--------**
*---- ooo oo---------*
*---- oo o----------*
**--- oo oo---------**
*--- o o----------*
**-- oo o----------**
**-- o + o----------**
**-- o P o--------T-**
*-- o o----------*
**- o oo---------**
*- oo o ---------*
* o oo---------*
** oo o -------**
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***oo oo-----***
**** ooo--****
***********
0- 30- 60- 90- 120- 150- 180- 210- 240- 270- 300- 330-
z-comp: 1 1 2 1 1 0 2 1 0 0 0 0
r-comp: 1 2 0 0 0 0 0 1 0 0 0 0
t-comp: 1 2 0 1 1 0 0 0 0 0 0 0
Total number of traces used = 18
number of runs = 6
starttime = Thu Feb 21 07:38:44 MST 2008
endtime = Thu Feb 21 07:58:07 MST 2008
inversion time = Thu Feb 21 07:57:44 MST 2008 - Thu Feb 21 07:58:06 MST 2008
Solution produced by inversion of channels with var red > 2%
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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 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 75 90 5 5.46 0.3454
WVFGRD96 1.0 75 85 0 5.49 0.3638
WVFGRD96 2.0 75 85 0 5.57 0.4303
WVFGRD96 3.0 70 60 -15 5.64 0.4563
WVFGRD96 4.0 70 45 -15 5.71 0.4951
WVFGRD96 5.0 70 45 -15 5.73 0.5349
WVFGRD96 6.0 65 45 -25 5.75 0.5711
WVFGRD96 7.0 50 40 -55 5.81 0.6126
WVFGRD96 8.0 45 35 -65 5.87 0.6594
WVFGRD96 9.0 205 50 -95 5.90 0.7102
WVFGRD96 10.0 35 40 -80 5.90 0.7386
WVFGRD96 11.0 30 40 -90 5.91 0.7403
WVFGRD96 12.0 35 40 -80 5.90 0.7245
WVFGRD96 13.0 35 40 -80 5.89 0.6981
WVFGRD96 14.0 50 45 -60 5.87 0.6699
WVFGRD96 15.0 65 55 -30 5.84 0.6500
WVFGRD96 16.0 70 60 -20 5.84 0.6350
WVFGRD96 17.0 70 65 -20 5.84 0.6216
WVFGRD96 18.0 70 65 -15 5.85 0.6096
WVFGRD96 19.0 70 65 -15 5.85 0.5972
WVFGRD96 20.0 75 70 -10 5.86 0.5847
WVFGRD96 21.0 75 70 -10 5.86 0.5730
WVFGRD96 22.0 75 70 -5 5.86 0.5602
WVFGRD96 23.0 75 75 5 5.87 0.5488
WVFGRD96 24.0 75 75 5 5.87 0.5372
WVFGRD96 25.0 75 75 5 5.88 0.5253
WVFGRD96 26.0 75 75 5 5.88 0.5132
WVFGRD96 27.0 75 75 5 5.89 0.5012
WVFGRD96 28.0 75 75 5 5.89 0.4894
WVFGRD96 29.0 75 80 5 5.90 0.4782
The best solution is
WVFGRD96 11.0 30 40 -90 5.91 0.7403
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
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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= 194.99
DIP= 55.00
RAKE= -104.99
OR
STK= 40.01
DIP= 37.70
RAKE= -69.72
DEPTH = 10.0 km
Mw = 5.97
Best Fit 0.8931 - P-T axis plot gives solutions with FIT greater than FIT90
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The P-wave first motion data for focal mechanism studies are as follow:
Sta Az(deg) Dist(km) First motion N12A 222 34 -12345 ELK 227 54 -12345 N13A 117 54 -12345 M13A 58 60 -12345 N11A 251 86 -12345 O12A 179 90 -12345 M11A 295 94 -12345 L12A 350 121 -12345 O13A 147 124 -12345 M14A 68 128 -12345 O11A 216 129 -12345 L13A 31 132 -12345 N14A 100 136 -12345 L11A 326 146 -12345 N10A 255 152 -12345 M10A 289 156 -12345 L14A 50 166 -12345 O10A 240 170 -12345 K12A 356 174 -12345 P12A 184 178 -12345 L10A 309 180 -12345 K13A 18 184 -12345 P11A 207 189 -12345 N15A 95 191 -12345 DUG 120 192 -12345 M15A 77 199 -12345 K14A 39 210 -12345 O15A 114 214 -12345 P10A 222 216 -12345 P14A 138 219 -12345 L15A 62 224 -12345 Q12A 181 226 -12345 M09A 281 228 -12345 O09A 245 228 -12345 N09A 265 233 -12345 J12A 354 243 -12345 Q13A 165 244 -12345 K10A 318 257 -12345 K15A 45 258 -12345 Q11A 197 259 -12345 J13A 11 263 -12345 L09A 294 263 -12345 P09A 231 263 -12345 M16A 83 265 -12345 Q14A 151 265 -12345 J14A 22 270 -12345 P15A 127 270 -12345 J11A 342 274 -12345 HLID 6 278 -12345 N16A 93 281 -12345 N08A 265 285 -12345 Q10A 210 286 -12345 L16A 68 297 -12345 O08A 254 299 -12345 I12A 354 303 -12345 K09A 307 304 -12345 R12A 177 305 -12345 Q15A 138 308 -12345 J10A 328 309 -12345 P16A 121 310 -12345 R11A 193 311 -12345 I13A 9 320 -12345 P08A 242 320 -12345 J15A 36 322 -12345 L08A 294 322 -12345 Q09A 220 323 -12345 K16A 52 328 -12345 R13A 168 329 -12345 I11A 343 330 -12345 N17A 91 332 -12345 I14A 18 335 -12345 R10A 203 336 -12345 R14A 153 343 -12345 L17A 69 344 -12345 M17A 81 347 -12345 N07B 266 355 -12345 O17A 105 355 -12345 WVOR 296 355 -12345 J16A 46 357 -12345 AHID 57 358 -12345 K08A 302 359 -12345 O07A 255 362 -12345 Q08A 229 365 -12345 K17A 59 370 -12345 M07A 277 370 -12345 R09A 213 372 -12345 I15A 29 375 -12345 RRI2 47 381 -12345 R15A 145 383 -12345 S10A 205 384 -12345 S12A 181 385 -12345 H12A 359 386 -12345 P17A 116 386 -12345 P07A 245 389 -12345 H13A 6 390 -12345 Q16A 127 390 -12345 S11A 193 390 -12345 S14A 159 393 -12345 L07A 287 395 -12345 M18A 83 396 -12345 S13A 168 396 -12345 J08A 311 397 -12345 I09A 324 404 -12345 L18A 75 406 -12345 DCID1 45 407 -12345 REDW 51 411 -12345 I16A 40 412 -12345 K07A 297 412 -12345 O18A 101 413 -12345 TPAW 48 414 -12345 H11A 346 416 -12345 R08A 224 416 -12345 P18A 111 417 -12345 Q07A 237 418 -12345 R16A 137 419 -12345 J17A 51 420 -12345 H10A 338 422 -12345 SRU 120 423 -12345 SNOW 50 424 -12345 N06A 267 428 -12345 S09A 210 428 -12345 T11A 185 428 -12345 K18A 65 429 -12345 H15A 23 430 -12345 S15A 150 431 -12345 O06A 258 440 -12345 I08A 317 443 -12345 IMW 44 444 -12345 LOHW 49 444 -12345 MOOW 47 445 -12345 G13A 5 448 -12345 J07A 306 453 -12345 R17A 129 456 -12345 T13A 170 456 -12345 J18A 57 459 -12345 P06A 252 462 -12345 H09A 330 463 -12345 L19A 74 465 -12345 BMO 335 468 -12345 I17A 46 468 -12345 WCN 247 468 -12345 T14A 161 469 -12345 BW06 65 471 -12345 M19A 82 473 -12345 G14A 13 475 -12345 T12A 179 483 -12345 O19A 98 485 -12345 G15A 21 491 -12345 R06C 236 491 -12345 BEK 256 492 -12345 H16A 34 495 -12345 T15A 155 496 -12345 H08A 321 498 -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) N13A 117 54 M13A 58 60 N11A 251 86 O12A 179 90 L12A 350 121 O13A 147 124 M14A 68 128 O11A 216 129 L13A 31 132 N14A 100 136 L11A 326 146 N10A 255 152 M10A 289 156 L14A 50 166 O10A 240 170 K12A 356 174 P12A 184 178 L10A 309 180 K13A 18 184 P11A 207 189 N15A 96 191 M15A 77 199 K14A 39 210 O15A 114 214 P10A 222 216 P14A 138 219 L15A 62 224 Q12A 181 226 M09A 281 228 O09A 245 228 N09A 265 233 J12A 354 243 Q13A 164 244 K10A 318 257 K15A 45 258 Q11A 197 259 J13A 11 263 L09A 294 263 P09A 231 263 M16A 83 265 Q14A 151 265 J14A 22 270 P15A 128 270 J11A 342 274 HLID 6 278 N16A 93 281 N08A 264 285 Q10A 210 286 L16A 68 297 O08A 254 299 I12A 354 303 K09A 307 304 R12A 177 305 Q15A 138 308 J10A 328 309 P16A 121 310 R11A 193 311 I13A 10 320 P08A 242 320 J15A 36 322 L08A 294 322 Q09A 220 323 K16A 52 328 R13A 168 329 I11A 343 330 N17A 91 332 I14A 18 335 R10A 204 336 R14A 154 343 L17A 69 344 M17A 81 347 N07B 266 355 O17A 105 355 J16A 46 357 AHID 57 358 K08A 302 359 O07A 255 362 Q08A 229 365 K17A 58 370 M07A 277 370 R09A 213 372 I10A 334 374 I15A 29 375 RRI2 47 381 R15A 145 383 S10A 205 384 S12A 181 385 H12A 359 386 P17A 116 386 P07A 245 389 H13A 6 390 Q16A 127 390 S11A 193 390 S14A 159 393 L07A 287 395 M18A 83 396 S13A 168 396 J08A 311 397 I09A 324 404 L18A 75 406 DCID1 45 407 REDW 51 411 I16A 40 412 K07A 297 412 O18A 101 413 TPAW 48 414 H11A 346 416 R08A 224 416 P18A 111 417 Q07A 237 418 R16A 137 419 J17A 52 420 H10A 338 422 SRU 120 423 SNOW 50 424 N06A 267 428 S09A 210 428 T11A 185 428 K18A 65 429 H15A 23 430 S15A 150 431 O06A 258 440 I08A 316 443 IMW 44 444 LOHW 49 444 MOOW 47 445 G13A 5 448 J07A 306 453 R17A 129 456 T13A 170 456 J18A 57 459 P06A 252 462 H09A 330 463 L19A 74 465 I17A 46 468 WCN 247 468 T14A 161 469 BW06 65 471 M19A 82 473 G14A 12 475 T12A 179 483 O19A 98 485 G15A 22 491 R06C 236 491 BEK 256 492 H16A 34 495 T15A 155 496 H08A 322 498 I18A 53 501 H17A 42 504 G10A 339 506 GRA 207 506 J06A 300 506 DLMT 20 508 I07A 312 512 S17A 137 513 R18A 124 514 U12A 178 516 P19A 106 517 MLAC 224 519 U11A 186 519 F12A 356 521 G16A 27 521 U13A 172 522 F13A 4 525 Q19A 115 526 G09A 333 527 LKWY 41 527 K19A 66 528 U10A 195 534 T16A 147 535 U14A 164 535 TIN 215 537 F14A 12 538 K05A 292 540 FUR 200 543 L20A 77 546 N20A 91 548 I06A 307 549 M20A 83 553 S18A 131 557 F15A 18 561 K20A 70 562 O20A 99 562 R19A 121 565 BOZ 26 568 T17A 142 568 P20A 106 570 G17A 33 574 F10A 341 579 G08A 325 579 F16A 25 582 V11A 186 584 V13A 173 584 SHO 193 589 V12A 181 594 E11A 349 598 E13A 4 598 Q20A 111 601 E14A 9 602 MPM 204 605 H06A 314 609 T18A 134 609 S19A 126 610 G07A 321 612 N21A 91 612 U17A 143 612 F08A 330 616 SLA 202 616 E15A 15 618 V14A 166 621 M21A 82 623 L21A 78 625 O21A 96 625 V15A 158 626 E10A 343 630 F17A 30 631 G18A 40 633 U16A 149 633 RLMT 43 634 TUQ 190 634 RWWY 81 636 W12A 181 641 MSO 6 643 E16A 21 655 RCT 218 657 WDC 268 658 LDF 183 661 E09A 337 662 G06A 316 664 GSC 196 665 W14A 167 667 W13A 173 668 D13A 2 669 U18A 139 670 LRL 203 671 F18A 36 674 D11A 350 675 D14A 8 675 E17A 26 676 F07A 324 678 ISA 210 682 T19A 132 685 WUAZ 153 685 M22A 84 686 D15A 14 687 W15A 161 690 MVCO 126 691 E08A 332 693 D10A 344 694 HUMO 287 700 NEE2 179 700 N22A 90 701 GMR 187 703 HAWA 329 704 G05A 313 705 HEC 192 707 D16A 20 710 F06A 319 713 Q22A 108 715 RRX 197 715 DAN 184 717 W16A 156 722 D09A 338 723 E18A 31 724 X13A 173 724 H04A 306 726 V18A 143 730 HOOD 312 731 E07A 328 733 C13A 1 734 C12B 356 739 D08A 335 743 EDW2 203 743 D17A 24 750 SAO 232 751 X14A 167 752 PDM 176 754 W17A 151 755 R22A 112 757 C15A 12 764 X15A 162 765 MCCM 248 768 IRM 183 769 C10A 346 776 G04A 309 776 V19A 138 777 BBR 195 780 PHWY 85 781 C16A 17 785 E06A 323 786 D18A 29 787 ISCO 97 789 VCS 203 789 X16A 157 795 C09A 341 797 D07A 330 797 OSI 207 797 COR 302 799 BFS 200 800 SVD 196 800 CHF 202 801 PHL 221 807 Y14A 168 807 Y13A 174 810 B13A 2 811 W19A 143 813 Y12C 178 813 MWC 202 814 T22A 121 816 C08A 337 819 Y15A 164 819 DEC 204 820 F04A 314 820 NEW 348 820 TAKO 294 821 B15A 12 823 PASC 202 823 B12A 356 824 X17A 154 825 B10A 347 826 BC3 184 826 B11A 352 828 LTY 328 832 D06A 326 835 KNW 192 835 DJJ 204 839 X18A 148 841 PFO 191 842 USC 203 842 TOLO 301 845 C07A 332 847 RDM 193 847 DGR 194 848 B16A 16 850 WMC 192 850 Y16A 159 850 SND 192 851 CRY 192 852 SBC 212 855 FRD 192 857 MUR 195 857 B09A 343 859 W20A 138 859 B17A 20 861 LGU 208 861 HEBO 305 863 EGMT 26 868 Z14A 169 871 LVA2 191 872 SMER 195 872 SDD 198 873 FMP 202 875 RPV 203 875 A12A 356 876 PLM 193 877 SDCO 112 879 A14A 6 884 A11A 352 885 B08A 338 886 WALA 4 890 Y17A 156 890 D05A 322 891 F03A 310 891 GLA 180 891 A15A 10 893 SCZ2 210 895 Z15A 164 895 C06A 330 903 B18A 24 904 A10A 347 905 SWS 186 907 Z16A 160 908 W21A 134 909 A16A 15 910 HWB 193 914 C05A 326 918 MONP2 190 920 B07A 335 923 113A 174 926 LAO 45 927 A09A 342 928 D04A 319 928 Y19A 147 928 A17A 19 931 109C 194 932 E03A 314 932 114A 169 939 SOL 194 940 DVT 188 942 RSSD 65 943 A08A 340 944 Z17A 155 944 BAR 191 947 112A 179 948 A18A 22 954 SCI2 202 959 W22A 131 961 SNCC 207 965 Z18A 153 981 B06A 330 982 116A 163 983 WISH 316 984 A07A 335 989 PNT 339 991 Z19A 149 992 ANMO 130 997 X22A 134 999 NLWA 317 1009 117A 158 1010 SQM 323 1017 214A 170 1027 118A 154 1029 A06A 332 1035 TUC 159 1036 OPC 322 1038 Y22D 136 1040 119A 150 1042 216A 163 1049 A05A 329 1051 VGZ 323 1059 HOPB 333 1060 OGNE 87 1071 OFR 318 1078 SNB 325 1081 PGC 324 1084 217A 160 1091 120A 148 1093 218A 156 1095 HNB 329 1097 PFB 321 1129 SLEB 348 1151 318A 157 1152 122A 141 1158 NLLB 324 1158 DGMT 42 1171 MGB 322 1176 SHB 326 1184 WSLR 330 1188 LLLB 335 1194 CBB 324 1292 CBKS 96 1307 AMTX 117 1338 EDM 4 1354 EDB 320 1371 PHC 322 1449 CMB 237 1474 MCMB1 335 1474 ECSD 73 1520 BCBC 328 1550 KSU1 92 1561 WMOK 112 1569 BBB 325 1598 BMBC 345 1749 ULM 49 1783 JCT 126 1788 CIA 202 1798 SCIA 80 1798 MOBC 322 1862 RUBB 327 1868 DIB 321 1893 EPLO 53 1896 EYMN 60 1992 MIAR 104 1996 ATKO 57 2010 JFWS 76 2035 CCM 248 2043 FNBB 346 2064 NATX 114 2071 UALR 102 2085 CRAG 326 2088 HKT 120 2106 SLM 89 2110 FVM 91 2114 WRAK 329 2127 HDIL 83 2143 KVTX 129 2153 BMO 335 2156 PBMO 95 2156 PKLO 50 2194 DLBC 336 2210 SIUC 91 2224 PVMO 95 2232 MUMO 47 2241 MPH 99 2268 OLIL 88 2286 UTMT 95 2304 SIT 327 2308 OXF 100 2340 USIN 90 2346 VBMS 107 2371 NANO 55 2379 PNPO 60 2386 KASO 46 2391 WVT 94 2400 BESE 331 2404 BLO 86 2407 PLAL 98 2429 FCC 29 2443 WCI 88 2453 GLMI 70 2481 SKAG 332 2493 PLBC 331 2535 WHY 334 2575 AAM 77 2580 CTLN 359 2600 ARVN 25 2632 SILO 46 2657 VIMO 50 2669 KAPO 59 2673 ACSO 82 2675 PNL 329 2678 COWN 4 2702 BRAL 105 2712 BASO 72 2720 TOBO 69 2724 BRCO 71 2736 SUNO 66 2736 TZTN 90 2743 OTRO 57 2748 TRO 190 2748 TIMO 61 2749 BMRO 71 2751 BWLO 72 2761 JERN 3 2784 CLWO 71 2825 KLBO 69 2826 ACTO 73 2853 YBKN 19 2855 RSPO 67 2858 HSMO 64 2865 KILO 61 2865 TYNO 74 2875 MALO 58 2877 ALLY 77 2878 GOGA 97 2887 BUKO 68 2889 SEDN 24 2910 TORO 73 2911 ADO 199 2914 SADO 70 2914 PKRO 72 2928 STCO 73 2930 BEL 188 2938 BELQ 64 2938 DRWO 72 2956 DREO 72 2958 BLA 87 2981 WLVO 72 2982 MEDO 73 2988 MID 324 2988 ALGO 67 2991 BANO 69 3007 VLDQ 62 3010 DAWY 336 3012 EYAK 326 3022 MATQ 59 3027 DELO 70 3037 WEMQ 52 3052 PEMO 68 3055 SNQN 44 3073 PLVO 69 3074 NUNN 21 3077 SSPA 79 3086 PECO 71 3094 BULN 18 3122 EGAK 336 3128 KGNO 71 3130 MPPO 70 3141 PRNY 74 3156 PAX 331 3160 NHSC 95 3177 OTT 68 3177 SWD 324 3178 GAC 67 3192 CBN 83 3201 BINY 75 3206 SDMD 81 3207 INUQ 40 3208 SAW 327 3214 MVL 79 3231 INK 346 3232 ALFO 68 3239 PMR 326 3239 RC01 325 3241 CHGQ 59 3262 OHAK 316 3269 CNNC 89 3271 LON 21 3275 LONY 70 3275 MRHQ 67 3288 AKVQ 36 3306 HCNY 73 3324 MNT 68 3338 QILN 22 3341 FRNY 69 3350 MCK 330 3351 DWPF 105 3352 BRNJ 77 3358 ACCN 72 3368 COLA 333 3379 LATQ 64 3384 TRF 329 3393 IVKQ 33 3398 PAL 76 3404 CPNY 77 3405 TEIG 125 3408 FOR 77 3409 KTH 329 3426 PPLA 327 3447 BPAW 330 3459 UCCT 74 3520 A54 63 3562 LMQ 63 3567 A11 352 3580 A16 15 3592 A21 63 3613 LAIN 20 3616 COLD 335 3618 ILON 21 3686 ICQ 59 3775 SCHQ 50 3802 FALS 310 3847 RES 9 3878 FRB 34 3891 AKUT 309 3998 LMN 65 4011 UNV 308 4046 TNA 328 4264 GBN 65 4273 SPIA 314 4280 GAMB 324 4407 DRLN 58 4481 BBSR 86 4513 POHA 251 4515 ATKA 306 4576 SJNN 60 4871 PAYG 146 5244 SJG 104 5266 BILL 331 5392
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
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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.
Thanks also to the many seismic network operators whose dedication make this effort possible: University of Alaska, University of Washington, Oregon State University, University of Utah, Montana Bureas of Mines, UC Berkely, Caltech, UC San Diego, Saint L ouis University, Universityof Memphis, Lamont Doehrty Earth Observatory, Boston College, the Iris stations and the Transportable Array of EarthScope.
The WUS.REG 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=Sat Feb 23 17:42:37 CST 2008