Location

2008/03/25 11:59:38 44.697 -110.049 0.2 4.1 Wyoming

Arrival Times (from USGS)

Arrival time list

Felt Map

USGS Felt map for this earthquake

USGS Felt reports page for

Focal Mechanism

 SLU Moment Tensor Solution
 2008/03/25 11:59:38 44.697 -110.049 0.2 4.1 Wyoming
 
 Best Fitting Double Couple
    Mo = 2.60e+22 dyne-cm
    Mw = 4.21 
    Z  = 12 km
     Plane   Strike  Dip  Rake
      NP1      111    64   -146
      NP2        5    60   -30
 Principal Axes:
   Axis    Value   Plunge  Azimuth
     T   2.60e+22      3     237
     N   0.00e+00     49     144
     P  -2.60e+22     41     330



 Moment Tensor: (dyne-cm)
    Component  Value
       Mxx    -3.30e+21
       Mxy     1.82e+22
       Mxz    -1.18e+22
       Myy     1.46e+22
       Myz     5.49e+21
       Mzz    -1.13e+22
                                                     
                                                     
                                                     
                                                     
                     ----------####                  
                 ---------------#######              
              -------------------#########           
             ---------------------#########          
           ---------   ------------##########        
          ---------- P ------------###########       
         -----------   ------------############      
        #---------------------------############     
        ##--------------------------############     
       #####------------------------#############    
       #######----------------------#############    
       #########--------------------#############    
       ############----------------##############    
        ##############-------------#############     
        ###################--------#############     
            #################################--      
          T #####################-------------       
            #####################------------        
             ###################-----------          
              #################-----------           
                 ############----------              
                     #######-------                  
                                                     
                                                     
                                                     

 Harvard Convention
 Moment Tensor:
      R          T          F
 -1.13e+22  -1.18e+22  -5.49e+21 
 -1.18e+22  -3.30e+21  -1.82e+22 
 -5.49e+21  -1.82e+22   1.46e+22 


Details of the solution is found at

http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20080325115938/index.html
        

Preferred Solution

The preferred solution from an analysis of the surface-wave spectral amplitude radiation pattern, waveform inversion and first motion observations is

      STK = 5
      DIP = 60
     RAKE = -30
       MW = 4.21
       HS = 12.0

The depth resolution is not great. However both techniques provide the same solution. I did not use LKWY.

Moment Tensor Comparison

The following compares this source inversion to others
SLU
 SLU Moment Tensor Solution
 2008/03/25 11:59:38 44.697 -110.049 0.2 4.1 Wyoming
 
 Best Fitting Double Couple
    Mo = 2.60e+22 dyne-cm
    Mw = 4.21 
    Z  = 12 km
     Plane   Strike  Dip  Rake
      NP1      111    64   -146
      NP2        5    60   -30
 Principal Axes:
   Axis    Value   Plunge  Azimuth
     T   2.60e+22      3     237
     N   0.00e+00     49     144
     P  -2.60e+22     41     330



 Moment Tensor: (dyne-cm)
    Component  Value
       Mxx    -3.30e+21
       Mxy     1.82e+22
       Mxz    -1.18e+22
       Myy     1.46e+22
       Myz     5.49e+21
       Mzz    -1.13e+22
                                                     
                                                     
                                                     
                                                     
                     ----------####                  
                 ---------------#######              
              -------------------#########           
             ---------------------#########          
           ---------   ------------##########        
          ---------- P ------------###########       
         -----------   ------------############      
        #---------------------------############     
        ##--------------------------############     
       #####------------------------#############    
       #######----------------------#############    
       #########--------------------#############    
       ############----------------##############    
        ##############-------------#############     
        ###################--------#############     
            #################################--      
          T #####################-------------       
            #####################------------        
             ###################-----------          
              #################-----------           
                 ############----------              
                     #######-------                  
                                                     
                                                     
                                                     

 Harvard Convention
 Moment Tensor:
      R          T          F
 -1.13e+22  -1.18e+22  -5.49e+21 
 -1.18e+22  -3.30e+21  -1.82e+22 
 -5.49e+21  -1.82e+22   1.46e+22 


Details of the solution is found at

http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20080325115938/index.html
	

Waveform Inversion

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.
Location of broadband stations used for waveform inversion

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 0.02 n 3
lp c 0.07 n 3
The results of this grid search from 0.5 to 19 km depth are as follow:

           DEPTH  STK   DIP  RAKE   MW    FIT
WVFGRD96    0.5   225    50    70   3.90 0.2560
WVFGRD96    1.0    15    80    15   3.85 0.2603
WVFGRD96    2.0   215    50    55   4.03 0.3183
WVFGRD96    3.0    25    60    40   4.05 0.3270
WVFGRD96    4.0   200    50    25   4.07 0.3268
WVFGRD96    5.0    10    55   -15   4.07 0.3345
WVFGRD96    6.0    10    55   -15   4.09 0.3485
WVFGRD96    7.0     5    60   -25   4.12 0.3611
WVFGRD96    8.0     5    55   -25   4.16 0.3656
WVFGRD96    9.0     5    60   -30   4.18 0.3758
WVFGRD96   10.0     5    60   -30   4.19 0.3834
WVFGRD96   11.0     5    60   -30   4.20 0.3870
WVFGRD96   12.0     5    60   -30   4.21 0.3877
WVFGRD96   13.0     5    60   -30   4.22 0.3859
WVFGRD96   14.0    10    65   -30   4.23 0.3828
WVFGRD96   15.0    10    65   -30   4.24 0.3783
WVFGRD96   16.0    10    65   -30   4.24 0.3727
WVFGRD96   17.0    10    70   -30   4.25 0.3662
WVFGRD96   18.0    10    70   -30   4.26 0.3594
WVFGRD96   19.0    10    70   -30   4.27 0.3519
WVFGRD96   20.0    10    70   -30   4.27 0.3440
WVFGRD96   21.0    10    70   -30   4.28 0.3351
WVFGRD96   22.0    10    70   -30   4.29 0.3267
WVFGRD96   23.0    10    70   -30   4.29 0.3180
WVFGRD96   24.0    10    70   -30   4.30 0.3092
WVFGRD96   25.0    10    70   -30   4.30 0.3007
WVFGRD96   26.0    10    75   -35   4.31 0.2927
WVFGRD96   27.0    10    75   -35   4.32 0.2846
WVFGRD96   28.0   190    60   -25   4.31 0.2776
WVFGRD96   29.0   190    60   -25   4.31 0.2727

The best solution is

WVFGRD96   12.0     5    60   -30   4.21 0.3877

The mechanism correspond to the best fit is
Figure 1. Waveform inversion focal mechanism

The best fit as a function of depth is given in the following figure:

Figure 2. Depth sensitivity for waveform mechanism

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 0.02 n 3
lp c 0.07 n 3
Figure 3. Waveform comparison for depth of 8 km
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.

Surface-Wave Focal Mechanism

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.
Location of broadband stations used to obtain focal mechanism from surface-wave spectral amplitudes

The surface-wave determined focal mechanism is shown here.


  NODAL PLANES 

  
  STK=     114.99
  DIP=      55.00
 RAKE=    -130.00
  
             OR
  
  STK=     350.62
  DIP=      51.13
 RAKE=     -47.46
 
 
DEPTH = 15.0 km
 
Mw = 4.37
Best Fit 0.8261 - P-T axis plot gives solutions with FIT greater than FIT90

First motion data

The P-wave first motion data for focal mechanism studies are as follow:

Sta Az(deg)    Dist(km)   First motion
LKWY      242   31 -12345
H17A      231   54 -12345
RLMT       52   78 -12345
G18A       29   79 -12345
G17A      322   88 -12345
H16A      271   95 -12345
I18A      170  112 -12345
IMW       219  114 -12345
F18A       11  137 -12345
F17A      341  143 -12345
I16A      232  147 -12345
G16A      294  151 -12345
TPAW      209  152 -12345
DCID1     217  153 -12345
J17A      200  157 -12345
REDW      204  162 -12345
BOZ       311  163 -12345
J18A      179  165 -12345
F16A      315  173 -12345
G15A      286  200 -12345
E17A      342  206 -12345
H15A      268  206 -12345
E18A        3  208 -12345
I15A      249  209 -12345
DLMT      291  214 -12345
BW06      169  218 -12345
K17A      198  227 -12345
K18A      180  229 -12345
K19A      155  229 -12345
F15A      304  230 -12345
AHID      202  231 -12345
E16A      329  240 -12345
K16A      211  241 -12345
K20A      148  265 -12345
G14A      284  276 -12345
D17A      350  277 -12345
D18A        4  278 -12345
E15A      314  279 -12345
D16A      336  284 -12345
F14A      297  289 -12345
L19A      169  294 -12345
K15A      223  300 -12345
L16A      201  318 -12345
D15A      325  324 -12345
L20A      155  329 -12345
E14A      307  330 -12345
C17A      351  331 -12345
G13A      279  333 -12345
H13A      269  334 -12345
I13A      256  336 -12345
K14A      228  348 -12345
L15A      213  354 -12345
F13A      291  357 -12345
J13A      248  361 -12345
M17A      188  362 -12345
M18A      180  363 -12345
C16A      340  369 -12345
EGMT        3  371 -12345
HLID      252  371 -12345
LAO        52  371 -12345
L21A      143  373 -12345
D14A      316  377 -12345
E13A      302  377 -12345
H12A      269  382 -12345
MSO       309  384 -12345
M20A      156  387 -12345
L14A      222  393 -12345
C15A      331  395 -12345
K13A      236  397 -12345
M16A      199  397 -12345
B17A      352  404 -12345
M21A      147  407 -12345
M15A      209  409 -12345
B18A        3  412 -12345
I12A      258  418 -12345
N17A      189  422 -12345
SPU       208  424 -12345
B16A      343  432 -12345
D13A      309  434 -12345
J12A      250  436 -12345
N16A      195  438 -12345
C14A      321  445 -12345
M14A      218  445 -12345
B15A      335  446 -12345
K12A      241  453 -12345
N20A      161  453 -12345
M22A      141  461 -12345
N15A      206  469 -12345
H11A      272  473 -12345
A17A      354  475 -12345
I11A      262  479 -12345
C13A      315  481 -12345
BGU       211  485 -12345
A16A      347  487 -12345
D12A      304  488 -12345
O18A      180  492 -12345
G11A      281  496 -12345
F11A      288  497 -12345
N14A      212  498 -12345
M13A      224  500 -12345
O17A      187  503 -12345
O16A      194  513 -12345
E11A      293  515 -12345
A15A      338  518 -12345
N22A      145  523 -12345
C12B      311  536 -12345
M12A      229  538 -12345
A14A      333  540 -12345
N13A      220  546 -12345
D11A      300  553 -12345
J10A      258  556 -12345
G10A      279  561 -12345
P18A      182  563 -12345
F10A      287  580 -12345
P16A      194  581 -12345
E10A      292  585 -12345
N12A      225  591 -12345
B12A      317  596 -12345
P15A      199  598 -12345
O13A      214  601 -12345
H09A      272  604 -12345
G09A      279  613 -12345
I09A      265  618 -12345
D10A      298  619 -12345
O12A      220  625 -12345
F09A      283  627 -12345
N11A      229  634 -12345
A12A      320  636 -12345
B11A      313  638 -12345
C10A      304  658 -12345
E09A      291  663 -12345
P13A      211  668 -12345
A11A      317  675 -12345
B10A      309  681 -12345
H08A      271  684 -12345
I08A      266  685 -12345
F08A      283  696 -12345

Surface-wave analysis

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.

Data preparation

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.
Best mechanism fit as a function of depth. The preferred depth is given above. Lower hemisphere projection

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.


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.

Love-wave radiation patterns

Rayleigh-wave radiation patterns

Broadband station distribution

The distribution of broadband stations with azimuth and distance is

Sta Az(deg)    Dist(km)   
SNOW	  203	  148
E17A	  342	  206
H15A	  268	  206
E18A	    3	  208
DLMT	  291	  214
BW06	  169	  218
K19A	  155	  229
F15A	  304	  230
AHID	  202	  231
E16A	  329	  240
K20A	  148	  265
G14A	  284	  276
D17A	  350	  277
D18A	    4	  278
E15A	  314	  279
D16A	  336	  284
F14A	  297	  289
L19A	  169	  294
L17A	  193	  296
K15A	  223	  300
L18A	  180	  308
L16A	  201	  318
D15A	  324	  324
L20A	  154	  329
E14A	  307	  330
C17A	  351	  331
G13A	  279	  333
H13A	  269	  334
I13A	  256	  336
K14A	  228	  348
L15A	  213	  354
F13A	  291	  357
M17A	  188	  362
M19A	  168	  362
M18A	  180	  363
C16A	  340	  369
EGMT	    3	  371
HLID	  252	  371
LAO	   52	  371
L21A	  144	  373
D14A	  316	  377
E13A	  302	  377
H12A	  269	  382
MSO	  309	  384
M20A	  156	  387
HVU	  215	  392
L14A	  222	  393
C15A	  331	  395
K13A	  236	  397
M16A	  200	  397
B17A	  352	  404
M21A	  147	  407
M15A	  209	  409
B18A	    3	  412
N18A	  176	  414
I12A	  258	  418
N17A	  189	  422
SPU	  208	  424
L13A	  229	  428
N19A	  170	  428
B16A	  344	  432
D13A	  310	  434
J12A	  250	  436
C14A	  321	  445
M14A	  218	  445
B15A	  335	  446
K12A	  241	  453
N20A	  161	  453
M22A	  141	  461
N15A	  206	  469
H11A	  272	  473
A17A	  354	  475
I11A	  262	  479
NOQ	  201	  480
C13A	  315	  481
RSSD	   96	  483
J11A	  255	  484
N21A	  154	  484
BGU	  211	  485
A16A	  346	  487
L12A	  237	  492
O18A	  180	  492
O19A	  171	  495
G11A	  281	  496
F11A	  288	  497
N14A	  212	  498
M13A	  224	  500
O17A	  187	  503
O16A	  194	  513
E11A	  293	  515
A15A	  338	  518
N22A	  144	  523
O20A	  163	  528
O15A	  203	  529
PHWY	  134	  531
C12B	  311	  536
M12A	  229	  538
A14A	  333	  540
O21A	  156	  541
I10A	  265	  542
N13A	  220	  546
DUG	  205	  549
D11A	  300	  553
J10A	  258	  556
G10A	  279	  561
P18A	  182	  563
F10A	  287	  580
P16A	  194	  581
P17A	  186	  583
E10A	  292	  585
N12A	  225	  591
M11A	  234	  592
P20A	  166	  593
B12A	  317	  596
L10A	  243	  596
P15A	  199	  598
O13A	  214	  601
H09A	  272	  604
TMU	  190	  607
ELK	  226	  611
G09A	  279	  613
P21A	  159	  613
DGMT	   45	  614
I09A	  265	  618
P14A	  205	  620
Q18A	  181	  621
SRU	  184	  622
O12A	  220	  625
F09A	  283	  627
N11A	  229	  634
J09A	  259	  635
M10A	  238	  635
A12A	  320	  636
B11A	  313	  638
Q16A	  189	  649
Q20A	  166	  654
ISCO	  145	  655
K09A	  253	  657
C10A	  304	  658
Q15A	  198	  662
E09A	  291	  663
P13A	  211	  668
NEW	  309	  672
A11A	  317	  675
B10A	  309	  681
H08A	  271	  684
I08A	  266	  685
L09A	  247	  685
O11A	  224	  685
Q14A	  204	  688
N10A	  232	  689
J08A	  260	  691
D09A	  295	  693
F08A	  283	  696
Q22A	  157	  698
R17A	  185	  699
R18A	  179	  701
M09A	  242	  704
G08A	  278	  705
P12A	  216	  706
K08A	  255	  714
Q13A	  209	  718
C09A	  302	  721
O10A	  230	  721
R16A	  190	  722
L08A	  250	  727
R21A	  163	  733
R20A	  168	  736
D08A	  294	  737
WVOR	  253	  738
P11A	  222	  741
Q12A	  214	  743
A10A	  312	  744
R15A	  195	  744
B09A	  307	  746
R14A	  200	  753
H07A	  272	  755
I07A	  268	  756
J07A	  262	  756
LTH	  288	  757
G07A	  278	  761
HAWA	  288	  764
R22A	  158	  769
C08A	  300	  773
P10A	  225	  773
K07A	  256	  774
OGNE	  120	  776
S18A	  180	  778
S17A	  185	  787
E07A	  289	  792
R13A	  206	  794
Q11A	  218	  799
R12A	  210	  803
S15A	  195	  803
S21A	  166	  804
A09A	  309	  806
L07A	  252	  809
S14A	  200	  813
H06A	  274	  814
D07A	  293	  817
B08A	  303	  820
J06A	  262	  826
M07A	  247	  829
G06A	  278	  837
Q10A	  221	  839
T18A	  179	  840
C07A	  297	  841
R11A	  215	  843
A08A	  307	  847
F06A	  282	  850
S13A	  203	  852
T17A	  184	  857
SDCO	  152	  861
T16A	  189	  865
T15A	  194	  875
E06A	  287	  876
B07A	  302	  877
D06A	  292	  881
R10A	  218	  882
S12A	  209	  884
T14A	  198	  886
G05A	  278	  890
T22A	  162	  893
K05A	  260	  900
U17A	  184	  901
C06A	  297	  908
T13A	  202	  912
N06A	  245	  913
S11A	  213	  917
U18A	  179	  919
S10A	  218	  930
U20A	  172	  933
T11A	  210	  935
U19A	  175	  936
U15A	  192	  938
U16A	  186	  954
U14A	  197	  957
H04A	  274	  961
D05A	  291	  965
T12A	  206	  969
B06A	  300	  972
U13A	  201	  977
F04A	  282	  979
G04A	  278	  982
U12A	  204	  993
V20A	  172	  997
V18A	  179	  998
V15A	  191	 1002
V21A	  168	 1008
V17A	  184	 1010
U11A	  208	 1023
D04A	  290	 1024
WUAZ	  187	 1026
A05A	  302	 1033
V13A	  200	 1037
V14A	  196	 1039
COR	  274	 1050
U10A	  212	 1061
W18A	  178	 1064
HUMO	  262	 1066
W19A	  177	 1066
F03A	  282	 1067
W17A	  183	 1069
W20A	  172	 1071
E03A	  286	 1072
W15A	  191	 1074
W16A	  187	 1074
CBKS	  124	 1077
ECSD	   91	 1078
W21A	  168	 1083
V11A	  207	 1084
W14A	  195	 1084
NLWA	  290	 1109
W13A	  198	 1115
W12A	  203	 1121
ANMO	  163	 1125
X20A	  173	 1135
X19A	  176	 1142
X16A	  186	 1147
LDF	  204	 1149
X15A	  190	 1149
X17A	  184	 1152
X14A	  193	 1161
X22A	  166	 1161
X13A	  197	 1167
GSC	  211	 1191
Y21A	  169	 1204
Y17A	  184	 1223
ISA	  218	 1232
Y13A	  196	 1251
Z17A	  182	 1266
KSU1	  114	 1274
Z18A	  180	 1289
AMTX	  144	 1303
SAO	  231	 1303
OSI	  216	 1343
117A	  183	 1347
MWC	  213	 1350
120A	  174	 1354
GLA	  199	 1357
TUC	  183	 1377
SCIA	   97	 1398
112A	  198	 1406
BAR	  206	 1452
WMOK	  135	 1466
EYMN	   69	 1470
MNTX	  163	 1499
SNCC	  216	 1511
JFWS	   90	 1602
SLM	  105	 1776
FVM	  108	 1798
MIAR	  123	 1803
JCT	  147	 1816
BMO	  111	 1869
PBMO	  111	 1869
UALR	  120	 1869
SIUC	  107	 1904
OLIL	  102	 1936
PVMO	  111	 1946
NATX	  132	 1962
GLMI	   81	 2005
USIN	  104	 2009
UTMT	  110	 2012
MPH	  115	 2014
BLO	   99	 2037
HKT	  138	 2058
OXF	  116	 2093
WCI	  102	 2101
WVT	  109	 2103
PLAL	  112	 2158
VBMS	  123	 2186
ACSO	   93	 2269
LTL	  126	 2306
LRAL	  115	 2370
TZTN	  103	 2405
ALLY	   87	 2441
BRAL	  119	 2504
MCWV	   92	 2542
GOGA	  110	 2603
BINY	   84	 2751
SDMD	   90	 2791
CBN	   93	 2803
MVL	   89	 2804
NHSC	  106	 2871
CNNC	  100	 2918
EGAK	  330	 2942
PAL	   85	 2958

Waveform comparison for this mechanism

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:

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 0.02 n 3
lp c 0.07 n 3

Discussion

The Future

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.

Acknowledgements

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.

Appendix A


Spectra fit plots to each station

Velocity Model

The VMODEL 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    

Quality Control

Here we tabulate the reasons for not using certain digital data sets

The following stations did not have a valid response files:

DATE=Tue Mar 25 16:24:06 CDT 2008

Last Changed 2008/03/25