2010/06/23 17:41:42 45.904 -75.497 16.4 5.00 Quebec - NRCAN
2010/06/23 17:41:42 45.862 -75.457 18.0 5.00 Quebec - USGS
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2010/06/23 17:41:42:0 45.86 -75.46 18.0 5.0 Quebec Stations used: CN.A11 CN.A16 CN.A54 CN.A61 CN.A64 CN.GGN CN.KAPO CN.KGNO CN.LMQ CN.SADO CN.VLDQ IU.HRV LD.ACCN LD.BRNJ LD.CPNY LD.PTN NE.BRYW NE.FFD NE.HNH NE.PQI NE.QUA2 NE.TRY NE.WVL NE.YLE US.LONY US.NCB Filtering commands used: hp c 0.02 n 3 lp c 0.10 n 3 Best Fitting Double Couple Mo = 4.57e+23 dyne-cm Mw = 5.04 Z = 22 km Plane Strike Dip Rake NP1 145 60 80 NP2 344 31 107 Principal Axes: Axis Value Plunge Azimuth T 4.57e+23 73 30 N 0.00e+00 9 150 P -4.57e+23 14 242 Moment Tensor: (dyne-cm) Component Value Mxx -6.37e+22 Mxy -1.60e+23 Mxz 1.62e+23 Myy -3.26e+23 Myz 1.62e+23 Mzz 3.90e+23 ######-------- ##############-------- --##################-------- ---####################------- -----######################------- ------#######################------- -------########################------- ---------############ #########------- ---------############ T ##########------ -----------########### ##########------- ------------#######################------- -------------#######################------ --------------######################------ --------------#####################----- --- ---------###################------ -- P -----------#################----- - -------------##############----- ------------------############---- ------------------#########--- ---------------------###---- --------------------## -------------# Global CMT Convention Moment Tensor: R T P 3.90e+23 1.62e+23 -1.62e+23 1.62e+23 -6.37e+22 1.60e+23 -1.62e+23 1.60e+23 -3.26e+23 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20100623174142/index.html |
STK = 145 DIP = 60 RAKE = 80 MW = 5.04 HS = 22.0
There are great higher modes observable at NM stations on the Z. The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2010/06/23 17:41:42:0 45.86 -75.46 18.0 5.0 Quebec Stations used: CN.A11 CN.A16 CN.A54 CN.A61 CN.A64 CN.GGN CN.KAPO CN.KGNO CN.LMQ CN.SADO CN.VLDQ IU.HRV LD.ACCN LD.BRNJ LD.CPNY LD.PTN NE.BRYW NE.FFD NE.HNH NE.PQI NE.QUA2 NE.TRY NE.WVL NE.YLE US.LONY US.NCB Filtering commands used: hp c 0.02 n 3 lp c 0.10 n 3 Best Fitting Double Couple Mo = 4.57e+23 dyne-cm Mw = 5.04 Z = 22 km Plane Strike Dip Rake NP1 145 60 80 NP2 344 31 107 Principal Axes: Axis Value Plunge Azimuth T 4.57e+23 73 30 N 0.00e+00 9 150 P -4.57e+23 14 242 Moment Tensor: (dyne-cm) Component Value Mxx -6.37e+22 Mxy -1.60e+23 Mxz 1.62e+23 Myy -3.26e+23 Myz 1.62e+23 Mzz 3.90e+23 ######-------- ##############-------- --##################-------- ---####################------- -----######################------- ------#######################------- -------########################------- ---------############ #########------- ---------############ T ##########------ -----------########### ##########------- ------------#######################------- -------------#######################------ --------------######################------ --------------#####################----- --- ---------###################------ -- P -----------#################----- - -------------##############----- ------------------############---- ------------------#########--- ---------------------###---- --------------------## -------------# Global CMT Convention Moment Tensor: R T P 3.90e+23 1.62e+23 -1.62e+23 1.62e+23 -6.37e+22 1.60e+23 -1.62e+23 1.60e+23 -3.26e+23 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20100623174142/index.html USGS/SLU Moment Tensor Solution ENS 2010/06/23 17:41:43:0 45.96 -75.55 19.0 5.5 Quebec Stations used: IU.HRV LD.ACCN LD.BRNJ LD.CPNY LD.PTN NE.BRYW NE.FFD NE.HNH NE.PQI NE.QUA2 NE.TRY NE.WVL NE.YLE US.LONY US.NCB Filtering commands used: hp c 0.02 n 3 lp c 0.10 n 3 Best Fitting Double Couple Mo = 3.72e+23 dyne-cm Mw = 4.98 Z = 18 km Plane Strike Dip Rake NP1 305 65 50 NP2 188 46 144 Principal Axes: Axis Value Plunge Azimuth T 3.72e+23 52 167 N 0.00e+00 36 325 P -3.72e+23 11 63 Moment Tensor: (dyne-cm) Component Value Mxx 5.71e+22 Mxy -1.76e+23 Mxz -2.08e+23 Myy -2.75e+23 Myz -2.23e+22 Mzz 2.18e+23 #######------- #########------------- ##########------------------ #########--------------------- #--#######------------------------ ----------##--------------------- ----------########---------------- P - ----------############------------- -- ----------##############---------------- ----------##################-------------- ----------####################------------ ----------######################---------- ----------#######################--------- ---------#########################------ ---------##########################----- --------############ ############--- --------########### T #############- --------########## ############# ------######################## ------###################### -----################# ---########### Global CMT Convention Moment Tensor: R T P 2.18e+23 -2.08e+23 2.23e+22 -2.08e+23 5.71e+22 1.76e+23 2.23e+22 1.76e+23 -2.75e+23 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20100623174143/index.html |
USGS Body-Wave Moment Tensor Solution 10/06/23 17:41:42.05 ONTARIO-QUEBEC BORD REG., CANADA Epicenter: 45.945 -75.560 MW 5.0 USGS MOMENT TENSOR SOLUTION Depth 15 No. of sta: 23 Moment Tensor; Scale 10**16 Nm Mrr= 4.08 Mtt= 0.43 Mpp=-4.51 Mrt= 0.21 Mrp=-0.44 Mtp= 1.62 Principal axes: T Val= 4.11 Plg=86 Azm= 47 N 0.91 1 163 P -5.02 3 253 Best Double Couple:Mo=4.6*10**16 NP1:Strike=345 Dip=42 Slip= 92 NP2: 162 48 88 ------- --######--------- ---##########-------- -----############-------- ------##############--------- -------###############--------- -------################-------- --------#################-------- --------####### #######-------- --------####### T ########------- ---------###### ########------- -------#################------- P --------################------ ---------###############------ ----------#############------ ----------##########----- ----------########--- -----------###--- ------- |
June 23, 2010, ONTARIO-QUEBEC BORD REG., MW=5.2 Goran Ekstrom CENTROID-MOMENT-TENSOR SOLUTION GCMT EVENT: C201006231741A DATA: II IU CU IC G GE L.P.BODY WAVES: 73S, 112C, T= 40 MANTLE WAVES: 9S, 9C, T=125 SURFACE WAVES: 88S, 139C, T= 50 TIMESTAMP: Q-20100623191315 CENTROID LOCATION: ORIGIN TIME: 17:41:46.0 0.2 LAT:45.97N 0.02;LON: 75.61W 0.02 DEP: 22.7 0.4;TRIANG HDUR: 0.9 MOMENT TENSOR: SCALE 10**23 D-CM RR= 6.890 0.182; TT=-1.120 0.122 PP=-5.770 0.144; RT= 1.060 0.199 RP=-0.196 0.216; TP= 2.450 0.101 PRINCIPAL AXES: 1.(T) VAL= 7.029;PLG=82;AZM=356 2.(N) -0.180; 7; 156 3.(P) -6.849; 3; 246 BEST DBLE.COUPLE:M0= 6.94*10**23 NP1: STRIKE=344;DIP=43;SLIP= 101 NP2: STRIKE=150;DIP=48;SLIP= 80 ##--------- -#########--------- --#############-------- ----###############-------- ----#################-------- -----##################-------- -----###################------- -------######## #######-------- -------######## T ########------- --------####### ########------- --------##################------- ------#################------ P --------###############------ ---------##############----- -----------###########----- ------------#######---- --------------##--- ----------# |
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 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 0.5 120 75 -10 4.64 0.4688 WVFGRD96 1.0 90 40 -90 4.69 0.4879 WVFGRD96 2.0 285 65 -45 4.78 0.5021 WVFGRD96 3.0 285 70 -45 4.81 0.4701 WVFGRD96 4.0 295 90 50 4.77 0.4351 WVFGRD96 5.0 300 85 55 4.77 0.4576 WVFGRD96 6.0 300 85 55 4.77 0.4833 WVFGRD96 7.0 295 90 55 4.77 0.5070 WVFGRD96 8.0 295 90 55 4.78 0.5293 WVFGRD96 9.0 295 90 55 4.79 0.5478 WVFGRD96 10.0 295 90 55 4.83 0.5618 WVFGRD96 11.0 295 90 60 4.83 0.5771 WVFGRD96 12.0 295 90 60 4.84 0.5901 WVFGRD96 13.0 295 90 60 4.85 0.6001 WVFGRD96 14.0 295 90 60 4.86 0.6075 WVFGRD96 15.0 5 30 -30 4.89 0.6143 WVFGRD96 16.0 5 30 -30 4.90 0.6235 WVFGRD96 17.0 145 60 75 4.95 0.6342 WVFGRD96 18.0 145 60 75 4.97 0.6439 WVFGRD96 19.0 145 60 75 4.98 0.6516 WVFGRD96 20.0 145 60 75 5.02 0.6537 WVFGRD96 21.0 145 60 75 5.03 0.6578 WVFGRD96 22.0 145 60 80 5.04 0.6593 WVFGRD96 23.0 145 55 75 5.05 0.6588 WVFGRD96 24.0 145 55 75 5.06 0.6560 WVFGRD96 25.0 145 55 80 5.07 0.6512 WVFGRD96 26.0 145 55 80 5.07 0.6446 WVFGRD96 27.0 145 55 80 5.08 0.6364 WVFGRD96 28.0 145 55 80 5.09 0.6266 WVFGRD96 29.0 145 55 80 5.09 0.6150
The best solution is
WVFGRD96 22.0 145 60 80 5.04 0.6593
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
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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= 134.99 DIP= 55.00 RAKE= 65.00 OR STK= 354.10 DIP= 42.07 RAKE= 121.11 DEPTH = 18.0 km Mw = 5.14 Best Fit 0.8826 - P-T axis plot gives solutions with FIT greater than FIT90
The P-wave first motion data for focal mechanism studies are as follow:
Sta Az Dist First motion
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. |
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
Listing of broadband stations used
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 0.10 n 3
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=Fri Jun 25 10:28:16 CDT 2010