(a) mLg computed using the IASPEI formula; (b) mLg residuals ; the values used for the trimmed mean are indicated.
USGS/SLU Moment Tensor Solution
ENS 2021/08/13 11:57:35:0 35.88 -84.90 0.0 3.0 Tennessee
Stations used:
CO.CASEE CO.HODGE CO.PAULI ET.CPCT IM.TKL IU.WCI IU.WVT
N4.R49A N4.R50A N4.S51A N4.T47A N4.T50A N4.U49A N4.V48A
N4.V53A N4.V55A N4.W50A N4.W52A N4.X48A N4.X51A N4.Y52A
NM.BLO NM.USIN US.GOGA US.LRAL US.TZTN
Filtering commands used:
cut o DIST/3.3 -20 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.03 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 8.04e+21 dyne-cm
Mw = 3.87
Z = 4 km
Plane Strike Dip Rake
NP1 245 80 93
NP2 50 10 75
Principal Axes:
Axis Value Plunge Azimuth
T 8.04e+21 55 158
N 0.00e+00 3 65
P -8.04e+21 35 333
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.91e+21
Mxy 1.24e+21
Mxz -6.90e+21
Myy -7.41e+20
Myz 3.12e+21
Mzz 2.65e+21
--------------
----------------------
----------------------------
------- --------------------
--------- P ----------------------
---------- -----------------------
-----------------------------------##-
------------------------------#########-
------------------------###############-
---------------------####################-
-----------------########################-
--------------##########################--
----------##############################--
------#################################-
----################## #############--
-#################### T ############--
#################### ###########--
################################--
############################--
-#######################----
-#################----
--------------
Global CMT Convention Moment Tensor:
R T P
2.65e+21 -6.90e+21 -3.12e+21
-6.90e+21 -1.91e+21 -1.24e+21
-3.12e+21 -1.24e+21 -7.41e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20210813115735/index.html
|
STK = 50
DIP = 10
RAKE = 75
MW = 3.87
HS = 4.0
The NDK file is 20210813115735.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2021/08/13 11:57:35:0 35.88 -84.90 0.0 3.0 Tennessee
Stations used:
CO.CASEE CO.HODGE CO.PAULI ET.CPCT IM.TKL IU.WCI IU.WVT
N4.R49A N4.R50A N4.S51A N4.T47A N4.T50A N4.U49A N4.V48A
N4.V53A N4.V55A N4.W50A N4.W52A N4.X48A N4.X51A N4.Y52A
NM.BLO NM.USIN US.GOGA US.LRAL US.TZTN
Filtering commands used:
cut o DIST/3.3 -20 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.03 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 8.04e+21 dyne-cm
Mw = 3.87
Z = 4 km
Plane Strike Dip Rake
NP1 245 80 93
NP2 50 10 75
Principal Axes:
Axis Value Plunge Azimuth
T 8.04e+21 55 158
N 0.00e+00 3 65
P -8.04e+21 35 333
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.91e+21
Mxy 1.24e+21
Mxz -6.90e+21
Myy -7.41e+20
Myz 3.12e+21
Mzz 2.65e+21
--------------
----------------------
----------------------------
------- --------------------
--------- P ----------------------
---------- -----------------------
-----------------------------------##-
------------------------------#########-
------------------------###############-
---------------------####################-
-----------------########################-
--------------##########################--
----------##############################--
------#################################-
----################## #############--
-#################### T ############--
#################### ###########--
################################--
############################--
-#######################----
-#################----
--------------
Global CMT Convention Moment Tensor:
R T P
2.65e+21 -6.90e+21 -3.12e+21
-6.90e+21 -1.91e+21 -1.24e+21
-3.12e+21 -1.24e+21 -7.41e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20210813115735/index.html
|
Moment (dyne-cm) 8.03E+21 dyne-cm
Magnitude (Mw) 3.87
Principal Axes:
Axis Value Plunge Azimuth
T 8.03E+21 55. 158.
N -1.64E+18 3. 65.
P -8.03E+21 35. 333.
Moment Tensor: (dyne-cm) Aki-Richards
Component Value
Mxx -1.91E+21
Mxy 1.24E+21
Mxz -6.90E+21
Myy -7.40E+20
Myz 3.12E+21
Mzz 2.65E+21
Global CMT Convention Moment Tensor: (dyne-cm)
R T F
R 2.65E+21 -6.90E+21 -3.12E+21
T -6.90E+21 -1.91E+21 -1.24E+21
F -3.12E+21 -1.24E+21 -7.40E+20
Moment (dyne-cm) 8.03E+21 dyne-cm
Magnitude (Mw) 3.87
Principal Axes:
Axis Value Plunge Azimuth
T 8.03E+21 55. 158.
N -1.64E+18 3. 65.
P -8.03E+21 35. 333.
Moment Tensor: (dyne-cm) Aki-Richards Lune parameters
Component Value
Mxx -1.91E+21 beta: 90.00
Mxy 1.24E+21 gamma: -0.01
Mxy 1.24E+21
Mxz -6.90E+21
Myy -7.40E+20
Myz 3.12E+21
Mzz 2.65E+21
-------------- :
---------------------- :---:
---------------------------- ::. ..::
------- -------------------- :--------:
--------- P ---------------------- :: . . . :
---------- ----------------------- : . . . :
-----------------------------------##- :------------::
------------------------------#########- :: . . . :
-------------------------##############- : . . . :
---------------------####################- :---------------:
-----------------########################- : . . . :
--------------##########################-- :=======#=======:
----------##############################-- : . . . :
------#################################- : . . . :
----################## #############-- :---------------:
-#################### T ############-- : . . . :
#################### ###########-- :: . . . :
################################-- :------------::
############################-- : . . . :
-#######################---- :: . . . :
-#################---- :--------:
-------------- ::. ..::
:---:
:
|
Moment (dyne-cm) 1.05E+22 dyne-cm
Magnitude (Mw) 3.95
Principal Axes:
Axis Value Plunge Azimuth
T 6.79E+21 3. 229.
N 5.31E+21 10. 139.
P -1.21E+22 79. 335.
Moment Tensor: (dyne-cm) Aki-Richards
Component Value
Mxx 5.47E+21
Mxy 9.56E+20
Mxz -2.87E+21
Myy 6.05E+21
Myz 1.27E+21
Mzz -1.15E+22
Global CMT Convention Moment Tensor: (dyne-cm)
R T F
R -1.15E+22 -2.87E+21 -1.27E+21
T -2.87E+21 5.47E+21 -9.56E+20
F -1.27E+21 -9.56E+20 6.05E+21
Moment (dyne-cm) 1.05E+22 dyne-cm
Magnitude (Mw) 3.95
Principal Axes:
Axis Value Plunge Azimuth
T 6.79E+21 3. 229.
N 5.31E+21 10. 139.
P -1.21E+22 79. 335.
Moment Tensor: (dyne-cm) Aki-Richards Lune parameters
Component Value
Mxx 5.47E+21 beta: 89.96
Mxy 9.56E+20 gamma: 25.94
Mxy 9.56E+20
Mxz -2.87E+21
Myy 6.05E+21
Myz 1.27E+21
Mzz -1.15E+22
############## :
###################### :---:
############################ ::. ..::
#######-------------########## :--------:
######-------------------######### :: . . . :
######---------------------######### : . . . :
######------------------------######## :------------::
######--------------------------######## :: . . . :
######----------- ------------######## : . . . :
######------------ P ------------######### :---------------:
#######----------- ------------######### : . . . :
#######--------------------------######### :==============#:
########-------------------------######### : . . . :
########-----------------------######### : . . . :
#########---------------------########## :---------------:
##########-----------------########### : . . . :
############-----------############# :: . . . :
# ############################## :------------::
T ############################ : . . . :
########################### :: . . . :
###################### :--------:
############## ::. ..::
:---:
:
|
Moment (dyne-cm) 1.46E+22 dyne-cm
Magnitude (Mw) 4.04
Principal Axes:
Axis Value Plunge Azimuth
T -3.73E+21 10. 123.
N -5.65E+21 8. 214.
P -1.95E+22 77. 344.
Moment Tensor: (dyne-cm) Aki-Richards
Component Value
Mxx -5.71E+21
Mxy -6.84E+20
Mxz -3.01E+21
Myy -4.38E+21
Myz 1.06E+21
Mzz -1.88E+22
Global CMT Convention Moment Tensor: (dyne-cm)
R T F
R -1.88E+22 -3.01E+21 -1.06E+21
T -3.01E+21 -5.71E+21 6.84E+20
F -1.06E+21 6.84E+20 -4.38E+21
Moment (dyne-cm) 1.46E+22 dyne-cm
Magnitude (Mw) 4.04
Principal Axes:
Axis Value Plunge Azimuth
T -3.73E+21 10. 123.
N -5.65E+21 8. 214.
P -1.95E+22 77. 344.
Moment Tensor: (dyne-cm) Aki-Richards Lune parameters
Component Value
Mxx -5.71E+21 beta: 143.86
Mxy -6.84E+20 gamma: 23.57
Mxy -6.84E+20
Mxz -3.01E+21
Myy -4.38E+21
Myz 1.06E+21
Mzz -1.88E+22
-------------- :
---------------------- :---:
---------------------------- ::. ..::
------------------------------ :--------:
---------------------------------- :: . . . :
------------------------------------ : . . . :
-------------------------------------- :------------::
---------------------------------------- :: . . . :
------------------ ------------------- : . . . :
------------------- P -------------------- :---------------:
------------------- -------------------- : . . . :
------------------------------------------ :===============:
------------------------------------------ : . . . :
---------------------------------------- : . . . :
---------------------------------------- :---------------:
--------------------------------- -- : . . . :
-------------------------------- T - :: . . . :
------------------------------- :------------::
------------------------------ : . . . :
---------------------------- :: . . . #:
---------------------- :--------:
-------------- ::. ..::
:---:
:
|
Moment (dyne-cm) 1.30E+22 dyne-cm
Magnitude (Mw) 4.01
Principal Axes:
Axis Value Plunge Azimuth
T 1.44E+22 53. 22.
N -3.49E+21 1. 113.
P -1.09E+22 37. 204.
Moment Tensor: (dyne-cm) Aki-Richards
Component Value
Mxx -1.93E+21
Mxy 5.33E+20
Mxz 1.12E+22
Myy -3.32E+21
Myz 4.72E+21
Mzz 5.24E+21
Global CMT Convention Moment Tensor: (dyne-cm)
R T F
R 5.24E+21 1.12E+22 -4.72E+21
T 1.12E+22 -1.93E+21 -5.33E+20
F -4.72E+21 -5.33E+20 -3.32E+21
Moment (dyne-cm) 1.30E+22 dyne-cm
Magnitude (Mw) 4.01
Principal Axes:
Axis Value Plunge Azimuth
T 1.44E+22 53. 22.
N -3.49E+21 1. 113.
P -1.09E+22 37. 204.
Moment Tensor: (dyne-cm) Aki-Richards Lune parameters
Component Value
Mxx -1.93E+21 beta: 90.00
Mxy 5.33E+20 gamma: -13.43
Mxy 5.33E+20
Mxz 1.12E+22
Myy -3.32E+21
Myz 4.72E+21
Mzz 5.24E+21
----########-- :
---##################- :---:
----######################-- ::. ..::
---##########################- :--------:
----#############################- :: . . . :
-----############### ############- : . . . :
------############### T ############-- :------------::
--------############## #############-- :: . . . :
---------#############################-- : . . . :
-----------############################--- :---------------:
-------------##########################--- : . . . :
----------------######################---- :===#===========:
--------------------#################----- : . . . :
------------------------#########------- : . . . :
---------------------------------------- :---------------:
-------------------------------------- : . . . :
----------- ---------------------- :: . . . :
---------- P --------------------- :------------::
-------- ------------------- : . . . :
---------------------------- :: . . . :
---------------------- :--------:
-------------- ::. ..::
:---:
:
|
Moment (dyne-cm) 1.20E+22 dyne-cm
Magnitude (Mw) 3.99
Principal Axes:
Axis Value Plunge Azimuth
T -4.43E+21 23. 28.
N -5.08E+21 0. 118.
P -1.55E+22 67. 208.
Moment Tensor: (dyne-cm) Aki-Richards
Component Value
Mxx -5.91E+21
Mxy -4.52E+20
Mxz 3.54E+21
Myy -5.33E+21
Myz 1.92E+21
Mzz -1.38E+22
Global CMT Convention Moment Tensor: (dyne-cm)
R T F
R -1.38E+22 3.54E+21 -1.92E+21
T 3.54E+21 -5.91E+21 4.52E+20
F -1.92E+21 4.52E+20 -5.33E+21
Moment (dyne-cm) 1.20E+22 dyne-cm
Magnitude (Mw) 3.99
Principal Axes:
Axis Value Plunge Azimuth
T -4.43E+21 23. 28.
N -5.08E+21 0. 118.
P -1.55E+22 67. 208.
Moment Tensor: (dyne-cm) Aki-Richards Lune parameters
Component Value
Mxx -5.91E+21 beta: 148.63
Mxy -4.52E+20 gamma: 27.00
Mxy -4.52E+20
Mxz 3.54E+21
Myy -5.33E+21
Myz 1.92E+21
Mzz -1.38E+22
-------------- :
---------------------- :---:
-------------------- ----- ::. ..::
--------------------- T ------ :--------:
----------------------- -------- :: . . . :
------------------------------------ : . . . :
-------------------------------------- :------------::
---------------------------------------- :: . . . :
---------------------------------------- : . . . :
------------------------------------------ :---------------:
------------------------------------------ : . . . :
------------------------------------------ :===============:
----------------- ---------------------- : . . . :
---------------- P --------------------- : . . . :
---------------- --------------------- :---------------:
-------------------------------------- : . . . :
------------------------------------ :: . . . :
---------------------------------- :------------::
------------------------------ : . . . :
---------------------------- :: . . . #:
---------------------- :--------:
-------------- ::. ..::
:---:
:
|
(a) mLg computed using the IASPEI formula; (b) mLg residuals ; the values used for the trimmed mean are indicated.
(a) ML computed using the IASPEI formula for Horizontal components; (b) ML residuals computed using a modified IASPEI formula that accounts for path specific attenuation; the values used for the trimmed mean are indicated. The ML relation used for each figure is given at the bottom of each plot.
(a) ML computed using the IASPEI formula for Vertical components (research); (b) ML residuals computed using a modified IASPEI formula that accounts for path specific attenuation; the values used for the trimmed mean are indicated. The ML relation used for each figure is given at the bottom of each plot.
 |
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.
|
|
|
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:
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 1.0 240 85 90 4.10 0.3487
WVFGRD96 2.0 30 5 55 3.96 0.4096
WVFGRD96 3.0 40 10 65 3.90 0.4386
WVFGRD96 4.0 50 10 75 3.87 0.4468
WVFGRD96 5.0 50 10 75 3.85 0.4414
WVFGRD96 6.0 65 10 85 3.84 0.4292
WVFGRD96 7.0 240 15 -100 3.85 0.4207
WVFGRD96 8.0 50 60 -80 3.89 0.4185
WVFGRD96 9.0 45 55 -80 3.91 0.4152
WVFGRD96 10.0 50 60 -80 3.91 0.3944
WVFGRD96 11.0 40 55 -85 3.92 0.3844
WVFGRD96 12.0 40 55 -85 3.92 0.3702
WVFGRD96 13.0 40 55 -85 3.91 0.3537
WVFGRD96 14.0 215 35 -90 3.91 0.3361
WVFGRD96 15.0 215 35 -90 3.91 0.3181
WVFGRD96 16.0 220 40 -80 3.92 0.3013
WVFGRD96 17.0 225 45 -75 3.92 0.2852
WVFGRD96 18.0 225 45 -75 3.92 0.2719
WVFGRD96 19.0 225 45 -75 3.93 0.2588
WVFGRD96 20.0 225 50 -75 3.94 0.2412
WVFGRD96 21.0 225 50 -75 3.95 0.2312
WVFGRD96 22.0 35 65 -90 3.95 0.2230
WVFGRD96 23.0 215 30 -85 3.96 0.2168
WVFGRD96 24.0 35 60 -90 3.96 0.2101
WVFGRD96 25.0 35 60 -90 3.97 0.2029
WVFGRD96 26.0 215 30 -85 3.97 0.1957
WVFGRD96 27.0 215 30 -85 3.98 0.1879
WVFGRD96 28.0 295 20 -85 4.02 0.1879
WVFGRD96 29.0 300 20 -75 4.03 0.1885
The best solution is
WVFGRD96 4.0 50 10 75 3.87 0.4468
The mechanism correspond to the best fit is
|
|
|
The best fit as a function of depth is given in the following figure:
|
|
|
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 component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. A pair of numbers is given in black at the right of each predicted traces. The upper number 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 lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3
|
|
|
|
| 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. |
A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of the figure.
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.
|
|
|
The program wvfmtd96 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:
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3The results of this grid search over depth are as follow:
MT Program H(km) Mxx(dyne-cm) Myy Mxy Mxz Myz Mzz Mw Fit WVFMT96 0.5 113. 77. 89. 3.99 0.428 0.171E-06 0.442 0.655 0.125E-06 58.8 -0.2980918E+22 -0.3882107E+22 0.2982569E+21 0.9632894E+22 0.3907966E+22 0.6863025E+22 WVFMT96 1.0 110. 76. 89. 4.00 0.408 0.174E-06 0.422 0.639 0.127E-06 65.1 -0.3402779E+22 -0.4586292E+22 0.3235546E+21 0.9962901E+22 0.3507894E+22 0.7989070E+22 WVFMT96 2.0 102. 73. 93. 3.96 0.322 0.187E-06 0.330 0.568 0.138E-06 77.1 -0.3552998E+22 -0.4683210E+22 0.6233890E+21 0.8181899E+22 0.2190273E+22 0.8236208E+22 WVFMT96 3.0 111. 75. 94. 3.94 0.310 0.189E-06 0.325 0.557 0.135E-06 66.6 -0.3174843E+22 -0.3323615E+22 0.7088393E+21 0.7573593E+22 0.3413733E+22 0.6498457E+22 WVFMT96 4.0 304. 73. -96. 3.86 0.235 0.199E-06 0.247 0.485 0.146E-06 53.0 0.2183667E+22 0.3068718E+22 0.6005593E+21 0.5455640E+22 0.2938517E+22 -0.5252385E+22 WVFMT96 5.0 325. 59. -100. 3.93 0.308 0.189E-06 0.324 0.555 0.138E-06 84.4 0.4252532E+22 0.5838505E+22 0.1670062E+21 0.3947046E+22 0.2470017E+22 -0.1009104E+23 WVFMT96 6.0 349. 54. -102. 3.95 0.377 0.179E-06 0.397 0.614 0.130E-06 88.4 0.4771483E+22 0.6402436E+22 -0.3566412E+21 0.3037754E+22 0.2408470E+22 -0.1117392E+23 WVFMT96 7.0 357. 52. -103. 3.94 0.411 0.174E-06 0.431 0.641 0.127E-06 87.2 0.4663736E+22 0.6338698E+22 -0.5404676E+21 0.2811287E+22 0.2261645E+22 -0.1100243E+23 WVFMT96 8.0 360. 51. -105. 3.93 0.420 0.173E-06 0.438 0.648 0.126E-06 86.5 0.4454107E+22 0.6175325E+22 -0.6258397E+21 0.2850330E+22 0.2102078E+22 -0.1062943E+23 WVFMT96 9.0 4. 51. -106. 3.93 0.419 0.173E-06 0.436 0.648 0.126E-06 84.1 0.4292159E+22 0.6129663E+22 -0.8083560E+21 0.2836526E+22 0.2094064E+22 -0.1042182E+23 WVFMT96 10.0 11. 49. -107. 3.95 0.408 0.174E-06 0.424 0.639 0.127E-06 86.4 0.4952394E+22 0.6474266E+22 -0.9658130E+21 0.3095382E+22 0.2093309E+22 -0.1142666E+23
The best solution is
WVFMT96 4.0 304. 73. -96. 3.86 0.235 0.199E-06 0.247 0.485 0.146E-06 53.0 0.2183667E+22 0.3068718E+22 0.6005593E+21 0.5455640E+22 0.2938517E+22 -0.5252385E+22
The complete moment tensor decomposition using the program mtdinfo is given in the text file MTDinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.
The P-wave first motion mechanism corresponding to the best fit is
|
|
|
The best fit as a function of depth is given in the following figure:
|
|
|
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 component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. A pair of numbers is given in black at the right of each predicted traces. The upper number 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 lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3
|
|
|
A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of the figure.
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.
|
|
|
The program wvfmt96 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:
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3The results of this grid search over depth are as follow:
MT Program H(km) Mxx(dyne-cm) Myy Mxy Mxz Myz Mzz Mw Fit WVFMT96 0.5 112. 87. 89. 3.99 0.431 0.171E-06 0.446 0.657 0.124E-06 24.8 -0.5651100E+22 -0.6550450E+22 0.2939653E+21 0.9604919E+22 0.3880261E+22 -0.3554232E+22 WVFMT96 1.0 292. 83. -89. 4.07 0.431 0.171E-06 0.448 0.657 0.124E-06 14.3 -0.8573793E+22 -0.9611517E+22 0.2913409E+21 0.8952540E+22 0.3732950E+22 -0.1302787E+23 WVFMT96 2.0 289. 73. -90. 4.08 0.440 0.170E-06 0.456 0.663 0.123E-06 48.6 -0.9120139E+22 -0.9971795E+22 0.2926164E+21 0.5531422E+22 0.1967272E+22 -0.1697616E+23 WVFMT96 3.0 294. 68. -89. 4.08 0.448 0.168E-06 0.466 0.669 0.122E-06 69.3 -0.8539645E+22 -0.9043900E+22 0.1315286E+21 0.4438938E+22 0.2077270E+22 -0.1829677E+23 WVFMT96 4.0 292. 65. -87. 4.06 0.455 0.167E-06 0.474 0.674 0.121E-06 86.6 -0.7620610E+22 -0.7658268E+22 -0.2660424E+21 0.3811035E+22 0.2008392E+22 -0.1834035E+23 WVFMT96 5.0 348. 57. -110. 4.04 0.458 0.167E-06 0.476 0.677 0.122E-06 96.8 -0.6718315E+22 -0.5774986E+22 -0.6828674E+21 0.3565491E+22 0.2263350E+22 -0.1732724E+23 WVFMT96 6.0 1. 53. -112. 4.01 0.457 0.167E-06 0.476 0.676 0.122E-06 91.9 -0.5355998E+22 -0.4188419E+22 -0.8072977E+21 0.3346521E+22 0.2219578E+22 -0.1643328E+23 WVFMT96 7.0 6. 51. -112. 3.99 0.452 0.168E-06 0.470 0.673 0.122E-06 87.9 -0.3942296E+22 -0.2647008E+22 -0.9362626E+21 0.3173859E+22 0.2187076E+22 -0.1542404E+23 WVFMT96 8.0 8. 50. -111. 3.96 0.444 0.169E-06 0.461 0.666 0.123E-06 85.6 -0.2539388E+22 -0.1174210E+22 -0.9884313E+21 0.3030280E+22 0.2122756E+22 -0.1445834E+23 WVFMT96 9.0 11. 49. -110. 3.94 0.433 0.171E-06 0.449 0.658 0.125E-06 83.5 -0.1255312E+22 0.1879463E+21 -0.1036037E+22 0.2914626E+22 0.1901911E+22 -0.1369065E+23 WVFMT96 10.0 11. 49. -109. 3.97 0.419 0.173E-06 0.434 0.647 0.126E-06 85.9 -0.7330636E+21 0.6982674E+21 -0.1040060E+22 0.3208249E+22 0.2156021E+22 -0.1492567E+23
The best solution is
WVFMT96 10.0 11. 49. -109. 3.97 0.419 0.173E-06 0.434 0.647 0.126E-06 85.9 -0.7330636E+21 0.6982674E+21 -0.1040060E+22 0.3208249E+22 0.2156021E+22 -0.1492567E+23
The complete moment tensor decomposition using the program mtinfo is given in the text file MTinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.
The P-wave first motion mechanism corresponding 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 component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. A pair of numbers is given in black at the right of each predicted traces. The upper number 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 lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3
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A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of the figure.
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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|
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The program wvfmtgrd96 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:
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3The results of this grid search over depth are as follow:
MT Program H(km) Mxx(dyne-cm) Myy Mxy Mxz Myz Mzz Mw Fit WVFMTGRD96 1.0 -0.107E+23 -0.115E+23 -0.541E+21 -0.105E+22 0.129E+22 -0.192E+23 4.0977 0.4731 WVFMTGRD96 2.0 -0.100E+23 -0.105E+23 -0.821E+21 -0.240E+22 0.371E+22 -0.199E+23 4.1038 0.4895 WVFMTGRD96 3.0 -0.743E+22 -0.832E+22 -0.771E+21 -0.448E+22 0.258E+22 -0.193E+23 4.0803 0.5066 WVFMTGRD96 4.0 -0.716E+22 -0.759E+22 -0.797E+21 -0.368E+22 0.944E+21 -0.195E+23 4.0713 0.5162 WVFMTGRD96 5.0 -0.571E+22 -0.438E+22 -0.684E+21 -0.301E+22 0.106E+22 -0.188E+23 4.0431 0.5194 WVFMTGRD96 6.0 -0.352E+22 -0.259E+22 -0.698E+21 -0.282E+22 0.140E+22 -0.172E+23 4.0081 0.5174 WVFMTGRD96 7.0 -0.194E+22 -0.101E+22 -0.703E+21 -0.284E+22 0.141E+22 -0.157E+23 3.9778 0.5098 WVFMTGRD96 8.0 -0.799E+21 0.728E+21 -0.875E+21 -0.291E+22 0.207E+21 -0.148E+23 3.9588 0.4987 WVFMTGRD96 9.0 0.492E+21 0.204E+22 -0.890E+21 -0.296E+22 0.210E+21 -0.137E+23 3.9420 0.4837 WVFMTGRD96 10.0 0.541E+21 0.225E+22 -0.978E+21 -0.325E+22 0.231E+21 -0.151E+23 3.9695 0.4634
The best solution is
WVFMTGRD96 5.0 -0.571E+22 -0.438E+22 -0.684E+21 -0.301E+22 0.106E+22 -0.188E+23 4.0431 0.5194
The complete moment tensor decomposition using the program mtinfo is given in the text file MTGRDinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.
The P-wave first motion mechanism corresponding to the best fit is
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The best fit as a function of depth is given in the following figure:
|
|
|
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 component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. A pair of numbers is given in black at the right of each predicted traces. The upper number 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 lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3
|
|
|
A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of the figure.
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.
|
|
|
The program wvfmtgrd96 -DC 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:
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3The results of this grid search over depth are as follow:
MT Program H(km) Mxx(dyne-cm) Myy Mxy Mxz Myz Mzz Mw Fit WVFMTGRD96 1.0 -0.235E+22 -0.783E+21 0.136E+22 -0.154E+23 0.888E+22 0.313E+22 4.1039 0.3487 WVFMTGRD96 2.0 -0.869E+21 -0.698E+21 0.954E+21 -0.989E+22 0.455E+22 0.157E+22 3.9613 0.4096 WVFMTGRD96 3.0 -0.179E+22 -0.981E+21 0.148E+22 -0.775E+22 0.344E+22 0.277E+22 3.9011 0.4386 WVFMTGRD96 4.0 -0.191E+22 -0.740E+21 0.124E+22 -0.690E+22 0.312E+22 0.265E+22 3.8697 0.4468 WVFMTGRD96 5.0 -0.178E+22 -0.689E+21 0.116E+22 -0.642E+22 0.290E+22 0.247E+22 3.8489 0.4414 WVFMTGRD96 6.0 -0.209E+22 -0.354E+21 0.868E+21 -0.635E+22 0.228E+22 0.245E+22 3.8376 0.4292 WVFMTGRD96 7.0 0.326E+22 0.432E+21 -0.119E+22 -0.601E+22 0.219E+22 -0.369E+22 3.8457 0.4205 WVFMTGRD96 8.0 0.304E+22 0.432E+22 -0.385E+22 -0.373E+22 0.216E+22 -0.736E+22 3.8905 0.4185 WVFMTGRD96 9.0 0.292E+22 0.551E+22 -0.421E+22 -0.281E+22 0.153E+22 -0.842E+22 3.9061 0.4152 WVFMTGRD96 10.0 0.327E+22 0.465E+22 -0.414E+22 -0.402E+22 0.232E+22 -0.792E+22 3.9121 0.3944
The best solution is
WVFMTGRD96 4.0 -0.191E+22 -0.740E+21 0.124E+22 -0.690E+22 0.312E+22 0.265E+22 3.8697 0.4468
The complete moment tensor decomposition using the program mtinfo is given in the text file MTGRDDCinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.
The P-wave first motion mechanism corresponding to the best fit is
|
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|
The best fit as a function of depth is given in the following figure:
|
|
|
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 component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. A pair of numbers is given in black at the right of each predicted traces. The upper number 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 lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3
|
|
|
A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of the figure.
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.
|
|
|
The program wvfmtgrd96 -DEV 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:
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3The results of this grid search over depth are as follow:
MT Program H(km) Mxx(dyne-cm) Myy Mxy Mxz Myz Mzz Mw Fit WVFMTGRD96 1.0 -0.385E+22 -0.468E+22 -0.591E+21 0.429E+22 -0.674E+22 0.854E+22 3.9587 0.4381 WVFMTGRD96 2.0 -0.218E+22 -0.362E+22 -0.859E+21 -0.942E+22 0.439E+22 0.579E+22 3.9763 0.4356 WVFMTGRD96 3.0 -0.177E+22 -0.304E+22 -0.701E+21 -0.809E+22 0.307E+22 0.481E+22 3.9230 0.4542 WVFMTGRD96 4.0 -0.343E+22 -0.456E+22 -0.362E+21 -0.611E+22 0.346E+22 0.799E+22 3.9299 0.4639 WVFMTGRD96 5.0 -0.465E+22 -0.485E+22 -0.109E+22 -0.429E+22 0.391E+22 0.950E+22 3.9372 0.4665 WVFMTGRD96 6.0 0.457E+22 0.621E+22 0.710E+21 -0.409E+22 0.199E+22 -0.108E+23 3.9458 0.4540 WVFMTGRD96 7.0 0.488E+22 0.686E+22 0.116E+21 -0.307E+22 0.118E+22 -0.117E+23 3.9537 0.4775 WVFMTGRD96 8.0 0.547E+22 0.605E+22 0.956E+21 -0.287E+22 0.127E+22 -0.115E+23 3.9476 0.4829 WVFMTGRD96 9.0 0.526E+22 0.624E+22 -0.109E+22 -0.254E+22 0.288E+21 -0.115E+23 3.9435 0.4766 WVFMTGRD96 10.0 0.548E+22 0.666E+22 -0.765E+21 -0.363E+22 -0.148E+21 -0.121E+23 3.9652 0.4577
The best solution is
WVFMTGRD96 8.0 0.547E+22 0.605E+22 0.956E+21 -0.287E+22 0.127E+22 -0.115E+23 3.9476 0.4829
The complete moment tensor decomposition using the program mtinfo is given in the text file MTGRDDEVinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.
The P-wave first motion mechanism corresponding to the best fit is
|
|
|
The best fit as a function of depth is given in the following figure:
|
|
|
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 component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. A pair of numbers is given in black at the right of each predicted traces. The upper number 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 lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
cut o DIST/3.3 -20 o DIST/3.3 +50 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3
|
|
|
A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of the figure.
Thanks also to the many seismic network operators whose dedication make this effort possible: University of Nevada Reno, University of Alaska, University of Washington, Oregon State University, University of Utah, Montana Bureau of Mines, UC Berkely, Caltech, UC San Diego, Saint Louis University, University of Memphis, Lamont Doherty Earth Observatory, the Oklahoma Geological Survey, TexNet, the Iris stations, the Transportable Array of EarthScope and other networks.
The CUS model used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01 CUS Model with Q from simple gamma values 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 1.0000 5.0000 2.8900 2.5000 0.172E-02 0.387E-02 0.00 0.00 1.00 1.00 9.0000 6.1000 3.5200 2.7300 0.160E-02 0.363E-02 0.00 0.00 1.00 1.00 10.0000 6.4000 3.7000 2.8200 0.149E-02 0.336E-02 0.00 0.00 1.00 1.00 20.0000 6.7000 3.8700 2.9020 0.000E-04 0.000E-04 0.00 0.00 1.00 1.00 0.0000 8.1500 4.7000 3.3640 0.194E-02 0.431E-02 0.00 0.00 1.00 1.00