2008/11/15 10:52:54 47.740 -69.719 15.0 3.80 Quebec, Canada
SLU Location
STA COMP DIS(K) AZM AIN ARR TIME RES(SEC) WT QFM PHASE WGT A21 Z 5.25 155. 160. 20081115105256.649 0.07 0 iC P 0.87 A21 Z 5.25 155. 160. 20081115105258.369 -0.09 0 iX S 0.84 A64 Z 15.73 304. 131. 20081115105257.690 0.15 0 iC P 0.75 A64 Z 15.73 304. 131. 20081115105300.092 -0.03 0 iX S 0.94 A16 Z 37.52 215. 107. 20081115105300.731 0.16 0 iC P 0.74 A16 Z 37.52 215. 107. 20081115105305.343 -0.03 0 iX S 0.94 A54 Z 61.30 239. 98. 20081115105311.540 -0.13 2 eX S 0.32 A54 Z 61.30 239. 98. 20081115105304.127 -0.08 0 iD P 0.70 ICQ Z 267.37 42. 51. 20081115105332.759 -0.06 2 e- P 0.08 ICQ Z 267.37 42. 51. 20081115105400.895 -0.37 2 eX S 0.05 ICQ Z 267.37 42. 94. 20081115105406.585 -2.85 2 eX Lg 0.01 PKME Z 277.85 173. 51. 20081115105334.710 0.60 2 e+ P 0.04 GGN Z 367.38 142. 51. 20081115105344.376 -0.72 2 eX P 0.02 GGN Z 367.38 142. 51. 20081115105422.860 0.32 2 eX S 0.04 MNT Z 389.31 232. 51. 20081115105347.335 -0.45 2 e+ P 0.03 LBNH Z 425.54 204. 51. 20081115105353.038 0.81 2 eX P 0.02 LMN Z 430.02 118. 51. 20081115105351.996 -0.78 2 e- P 0.02 FRNY Z 439.92 224. 51. 20081115105353.552 -0.44 2 e+ P 0.03 LONY Z 511.49 229. 51. 20081115105402.491 -0.28 2 e+ P 0.03 LONY Z 511.49 229. 51. 20081115105456.299 3.10 2 eX S 0.00 LONY Z 511.49 229. 92. 20081115105512.999 -5.15 2 eX Lg 0.00 ACCN Z 574.35 214. 51. 20081115105411.383 0.90 2 eX P 0.01Error Ellipse X= 0.4714 km Y= 0.5693 km Theta = 172.7037 deg RMS Error : 0.055 sec Travel_Time_Table: CUS Latitude : 47.7464 +- 0.0042 N 0.4731 km Longitude : -69.7190 +- 0.0076 E 0.5678 km Depth : 14.78 +- 0.57 km Epoch Time : 1226746374.007 +- 0.10 sec Event Time : 20081115105254.007 +- 0.10 sec HYPO71 Quality : BB Gap : 97 deg
USGS Felt map for this earthquake
SLU Moment Tensor Solution
2008/11/15 10:52:54 47.740 -69.719 15.0 3.80 Quebec, Canada
Best Fitting Double Couple
Mo = 2.85e+21 dyne-cm
Mw = 3.57
Z = 14 km
Plane Strike Dip Rake
NP1 175 55 70
NP2 27 40 116
Principal Axes:
Axis Value Plunge Azimuth
T 2.85e+21 72 34
N 0.00e+00 16 187
P -2.85e+21 8 279
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.20e+20
Mxy 5.68e+20
Mxz 6.37e+20
Myy -2.64e+21
Myz 8.64e+20
Mzz 2.52e+21
----##########
------###############-
--------#################---
--------###################---
----------####################----
----------#####################-----
-----------######################-----
-----------########### #########------
---------########### T #########------
P ---------########### #########-------
---------######################--------
------------######################--------
------------#####################---------
------------####################--------
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-----------###############----------
-----------#############----------
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----------------------
#######-------
Harvard Convention
Moment Tensor:
R T F
2.52e+21 6.37e+20 -8.64e+20
6.37e+20 1.20e+20 -5.68e+20
-8.64e+20 -5.68e+20 -2.64e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20081115105250/index.html
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STK = 175
DIP = 55
RAKE = 70
MW = 3.57
HS = 14.0
The waveform inversion is preferred. The location was obtained using elocate and picks made here. The GSC location is about 0.15 degree east, which introduces large time delays.
The following compares this source inversion to others
SLU Moment Tensor Solution
2008/11/15 10:52:54 47.740 -69.719 15.0 3.80 Quebec, Canada
Best Fitting Double Couple
Mo = 2.85e+21 dyne-cm
Mw = 3.57
Z = 14 km
Plane Strike Dip Rake
NP1 175 55 70
NP2 27 40 116
Principal Axes:
Axis Value Plunge Azimuth
T 2.85e+21 72 34
N 0.00e+00 16 187
P -2.85e+21 8 279
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.20e+20
Mxy 5.68e+20
Mxz 6.37e+20
Myy -2.64e+21
Myz 8.64e+20
Mzz 2.52e+21
----##########
------###############-
--------#################---
--------###################---
----------####################----
----------#####################-----
-----------######################-----
-----------########### #########------
---------########### T #########------
P ---------########### #########-------
---------######################--------
------------######################--------
------------#####################---------
------------####################--------
------------###################---------
------------#################---------
-----------###############----------
-----------#############----------
----------#########-----------
----------######------------
----------------------
#######-------
Harvard Convention
Moment Tensor:
R T F
2.52e+21 6.37e+20 -8.64e+20
6.37e+20 1.20e+20 -5.68e+20
-8.64e+20 -5.68e+20 -2.64e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20081115105250/index.html
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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 0.02 n 3 lp c 0.10 n 3 br c 0.12 0.25 n 4 p 2The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 170 55 -85 3.43 0.4086
WVFGRD96 1.0 185 65 -85 3.55 0.4097
WVFGRD96 2.0 115 30 -70 3.51 0.4127
WVFGRD96 3.0 160 35 -20 3.48 0.3994
WVFGRD96 4.0 170 30 -10 3.46 0.4137
WVFGRD96 5.0 155 70 60 3.51 0.4455
WVFGRD96 6.0 165 65 70 3.53 0.4765
WVFGRD96 7.0 165 65 70 3.52 0.4966
WVFGRD96 8.0 175 60 70 3.53 0.5112
WVFGRD96 9.0 175 60 70 3.53 0.5208
WVFGRD96 10.0 175 60 75 3.56 0.5243
WVFGRD96 11.0 170 60 70 3.55 0.5292
WVFGRD96 12.0 180 55 75 3.57 0.5322
WVFGRD96 13.0 175 55 70 3.57 0.5341
WVFGRD96 14.0 175 55 70 3.57 0.5345
WVFGRD96 15.0 175 55 70 3.58 0.5318
WVFGRD96 16.0 175 55 70 3.59 0.5287
WVFGRD96 17.0 175 55 70 3.59 0.5233
WVFGRD96 18.0 175 50 70 3.60 0.5179
WVFGRD96 19.0 175 50 70 3.61 0.5119
WVFGRD96 20.0 175 50 70 3.64 0.5024
WVFGRD96 21.0 175 50 70 3.65 0.4945
WVFGRD96 22.0 175 50 70 3.65 0.4875
WVFGRD96 23.0 175 50 70 3.66 0.4800
WVFGRD96 24.0 175 50 70 3.66 0.4713
WVFGRD96 25.0 170 50 65 3.67 0.4631
WVFGRD96 26.0 180 45 70 3.68 0.4553
WVFGRD96 27.0 175 45 70 3.69 0.4470
WVFGRD96 28.0 175 45 70 3.69 0.4399
WVFGRD96 29.0 175 45 70 3.70 0.4322
The best solution is
WVFGRD96 14.0 175 55 70 3.57 0.5345
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 0.02 n 3 lp c 0.10 n 3 br c 0.12 0.25 n 4 p 2
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| Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to thewavefroms. Each solution is plotted as a vector at a given value of strike and dip with the angle of the vector representing the rake angle, measured, with respect to the upward vertical (N) in the figure. |
The P-wave first motion data for focal mechanism studies are as follow:
Sta Az Dist First motion A21 151 5 iP_C A64 307 16 iP_C ICQ 41 268 eP_- PKME 173 277 eP_+ GGN 142 367 eP_X MNT 232 389 eP_+ LBNH 205 425 eP_X FRNY 224 439 eP_+ LONY 229 511 eP_+ ACCN 214 574 eP_X VLDQ 278 602 iP_D
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 CUS 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
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Sat Nov 15 09:15:33 CST 2008