2003/06/13 11:34:40 47.70 -70.09 11 4.10 Quebec, Canada
USGS Felt map for this earthquake
USGS Felt reports page for Eastern Canada
SLU Moment Tensor Solution
2003/06/13 11:34:40 47.70 -70.09 11 4.10 Quebec, Canada
Best Fitting Double Couple
Mo = 1.29e+21 dyne-cm
Mw = 3.34
Z = 9 km
Plane Strike Dip Rake
NP1 80 70 60
NP2 319 36 144
Principal Axes:
Axis Value Plunge Azimuth
T 1.29e+21 55 312
N 0.00e+00 28 91
P -1.29e+21 19 192
Moment Tensor: (dyne-cm)
Component Value
Mxx -9.03e+20
Mxy -4.46e+20
Mxz 8.03e+20
Myy 1.85e+20
Myz -3.65e+20
Mzz 7.17e+20
--------------
----------------------
##############--------------
###################-----------
########################----------
###########################---------
########### ################--------
############ T #################--------
############ ##################-------
###################################------#
####################################--####
###################################-######
###############################------#####
--#####################-------------####
------------------------------------####
-----------------------------------###
----------------------------------##
--------------------------------##
---------- ----------------#
--------- P ----------------
------ -------------
--------------
Harvard Convention
Moment Tensor:
R T F
7.17e+20 8.03e+20 3.65e+20
8.03e+20 -9.03e+20 4.46e+20
3.65e+20 4.46e+20 1.85e+20
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20030613113440/index.html
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STK = 80
DIP = 70
RAKE = 60
MW = 3.34
HS = 9.0
The waveform inversion is preferred.
The following compares this source inversion to others
SLU Moment Tensor Solution
2003/06/13 11:34:40 47.70 -70.09 11 4.10 Quebec, Canada
Best Fitting Double Couple
Mo = 1.29e+21 dyne-cm
Mw = 3.34
Z = 9 km
Plane Strike Dip Rake
NP1 80 70 60
NP2 319 36 144
Principal Axes:
Axis Value Plunge Azimuth
T 1.29e+21 55 312
N 0.00e+00 28 91
P -1.29e+21 19 192
Moment Tensor: (dyne-cm)
Component Value
Mxx -9.03e+20
Mxy -4.46e+20
Mxz 8.03e+20
Myy 1.85e+20
Myz -3.65e+20
Mzz 7.17e+20
--------------
----------------------
##############--------------
###################-----------
########################----------
###########################---------
########### ################--------
############ T #################--------
############ ##################-------
###################################------#
####################################--####
###################################-######
###############################------#####
--#####################-------------####
------------------------------------####
-----------------------------------###
----------------------------------##
--------------------------------##
---------- ----------------#
--------- P ----------------
------ -------------
--------------
Harvard Convention
Moment Tensor:
R T F
7.17e+20 8.03e+20 3.65e+20
8.03e+20 -9.03e+20 4.46e+20
3.65e+20 4.46e+20 1.85e+20
Details of the solution is found at
http://www.eas.slu.edu/Earthquake_Center/MECH.NA/20030613113440/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 0.20 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 50 45 -95 3.21 0.3565
WVFGRD96 1.0 235 40 -90 3.29 0.3715
WVFGRD96 2.0 250 85 -50 3.21 0.3294
WVFGRD96 3.0 75 85 50 3.22 0.3738
WVFGRD96 4.0 75 85 50 3.23 0.4132
WVFGRD96 5.0 250 90 -50 3.25 0.4416
WVFGRD96 6.0 75 80 55 3.27 0.4737
WVFGRD96 7.0 75 80 55 3.29 0.4913
WVFGRD96 8.0 80 70 60 3.32 0.5056
WVFGRD96 9.0 80 70 60 3.34 0.5113
WVFGRD96 10.0 80 70 60 3.37 0.5094
WVFGRD96 11.0 85 65 65 3.39 0.4957
WVFGRD96 12.0 85 65 65 3.39 0.4776
WVFGRD96 13.0 85 65 65 3.40 0.4495
WVFGRD96 14.0 85 70 60 3.39 0.4175
WVFGRD96 15.0 250 85 -70 3.41 0.3997
WVFGRD96 16.0 75 90 70 3.40 0.3855
WVFGRD96 17.0 75 90 70 3.41 0.3701
WVFGRD96 18.0 255 90 -70 3.41 0.3582
WVFGRD96 19.0 235 60 -85 3.49 0.3486
WVFGRD96 20.0 235 60 -80 3.51 0.3480
WVFGRD96 21.0 235 60 -80 3.51 0.3504
WVFGRD96 22.0 235 60 -80 3.52 0.3506
WVFGRD96 23.0 235 60 -80 3.52 0.3478
WVFGRD96 24.0 235 60 -80 3.52 0.3471
WVFGRD96 25.0 235 60 -80 3.52 0.3428
WVFGRD96 26.0 240 65 -80 3.52 0.3420
WVFGRD96 27.0 230 60 -85 3.52 0.3376
WVFGRD96 28.0 240 65 -75 3.53 0.3326
WVFGRD96 29.0 230 35 25 3.53 0.3297
The best solution is
WVFGRD96 9.0 80 70 60 3.34 0.5113
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 0.20 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. |
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=Sun Nov 23 18:20:46 CST 2008