Date Time(UT) Lat Long Depth Mag Region and Comment
---- -------- --- ---- ----- --- ------------------
2009/05/28 13:57:32 66.30 -135.11 20.0g 4.3ML 130 km SSW of Fort McPherson
http://earthquakescanada.nrcan.gc.ca/stnsdata/nedb/bull_e.php?solid=20090528.1357001
This supercedes the AIEC location given next. The NEIC location is similar to the SLU Elocate solution. The SLU Elocate solution is used for this event.
4.0 2009/05/28 13:57:30 66.250 -135.050 10.0 NORTHERN YUKON TERRITORY, CANADA
2009 05 28 13 57 23 66.33 -135.55 16.2 4.3 Yukon 2009/05/28 13:57:30 66.32 -135.16 10.0 4.30 Yukon, Canada
This was located using the following arrival time picks:
STA IWT ARRIVAL TIME PhIDQL PHASE FM CHAN COLA 2 20090528135851.852 1 0 e P X Z DAWY 2 20090528135816.470 1 0 e P + Z EGAK 0 20090528135816.867 1 0 i P C Z EGAK 2 20090528135851.225 2 0 e S X Z EGAK 2 20090528135906.237 3 0 e Lg X Z INK 2 20090528135806.514 1 0 e P + Z INK 2 20090528135837.233 3 0 e Lg X Z WHY 2 20090528135854.807 1 0 e P X Z
Error Ellipse X= 2.1578 km Y= 4.4881 km Theta = 29.2849 deg RMS Error : 0.346 sec Travel_Time_Table: CUS Latitude : 66.3176 +- 0.0259 N 2.8916 km Longitude : -135.1603 +- 0.0923 E 4.0543 km Depth : 10.00 +- 5.78 km Epoch Time : 1243519050.815 +- 0.59 sec Event Time : 20090528135730.815 +- 0.59 sec HYPO71 Quality : DD Gap : 161 deg
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/05/28 13:57:30:0 66.32 -135.16 10.0 4.3 Yukon, Canada
Stations used:
CN.DAWY CN.INK CN.WHY IU.COLA US.EGAK
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 8.04e+21 dyne-cm
Mw = 3.87
Z = 12 km
Plane Strike Dip Rake
NP1 226 62 112
NP2 5 35 55
Principal Axes:
Axis Value Plunge Azimuth
T 8.04e+21 66 175
N 0.00e+00 19 35
P -8.04e+21 14 300
Moment Tensor: (dyne-cm)
Component Value
Mxx -5.06e+20
Mxy 3.14e+21
Mxz -3.96e+21
Myy -5.68e+21
Myz 1.91e+21
Mzz 6.19e+21
-----------###
------------------####
----------------------######
------------------------#-----
----------------------######------
- ---------------###########------
-- P -------------#############-------
--- -----------################-------
---------------##################-------
--------------#####################-------
------------#######################-------
-----------########################-------
----------########################--------
--------########### ###########-------
-------############ T ##########--------
-----############# ##########-------
----#########################-------
--#########################-------
########################------
#####################-------
################------
#########-----
Global CMT Convention Moment Tensor:
R T P
6.19e+21 -3.96e+21 -1.91e+21
-3.96e+21 -5.06e+20 -3.14e+21
-1.91e+21 -3.14e+21 -5.68e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20090528135730/index.html
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STK = 5
DIP = 35
RAKE = 55
MW = 3.87
HS = 12.0
The waveform inversion is preferred. The depth and moment magnitude are constrained. I am note sure about the mechanism. The time shifts required to fit the synthetics indicates that the event should be west of its location, e.g., to make it close to INK, EGAK and COLA without changing the distance to DAWY. In addition having a NNE striking normal fault differs from previous solutions. So beware
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/05/28 13:57:30:0 66.32 -135.16 10.0 4.3 Yukon, Canada
Stations used:
CN.DAWY CN.INK CN.WHY IU.COLA US.EGAK
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 8.04e+21 dyne-cm
Mw = 3.87
Z = 12 km
Plane Strike Dip Rake
NP1 226 62 112
NP2 5 35 55
Principal Axes:
Axis Value Plunge Azimuth
T 8.04e+21 66 175
N 0.00e+00 19 35
P -8.04e+21 14 300
Moment Tensor: (dyne-cm)
Component Value
Mxx -5.06e+20
Mxy 3.14e+21
Mxz -3.96e+21
Myy -5.68e+21
Myz 1.91e+21
Mzz 6.19e+21
-----------###
------------------####
----------------------######
------------------------#-----
----------------------######------
- ---------------###########------
-- P -------------#############-------
--- -----------################-------
---------------##################-------
--------------#####################-------
------------#######################-------
-----------########################-------
----------########################--------
--------########### ###########-------
-------############ T ##########--------
-----############# ##########-------
----#########################-------
--#########################-------
########################------
#####################-------
################------
#########-----
Global CMT Convention Moment Tensor:
R T P
6.19e+21 -3.96e+21 -1.91e+21
-3.96e+21 -5.06e+20 -3.14e+21
-1.91e+21 -3.14e+21 -5.68e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20090528135730/index.html
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20090528135733/index.html
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20090528135733/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 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 145 55 -50 3.59 0.4853
WVFGRD96 1.0 140 50 -55 3.63 0.5019
WVFGRD96 2.0 135 45 -60 3.74 0.4848
WVFGRD96 3.0 325 75 -55 3.73 0.4400
WVFGRD96 4.0 235 40 -5 3.70 0.4541
WVFGRD96 5.0 0 20 45 3.85 0.4846
WVFGRD96 6.0 5 25 55 3.85 0.5156
WVFGRD96 7.0 5 25 55 3.85 0.5413
WVFGRD96 8.0 5 30 50 3.83 0.5584
WVFGRD96 9.0 10 30 60 3.84 0.5715
WVFGRD96 10.0 10 30 60 3.87 0.5735
WVFGRD96 11.0 5 30 55 3.88 0.5791
WVFGRD96 12.0 5 35 55 3.87 0.5800
WVFGRD96 13.0 5 35 55 3.88 0.5772
WVFGRD96 14.0 5 35 55 3.88 0.5708
WVFGRD96 15.0 315 60 -60 3.80 0.5639
WVFGRD96 16.0 315 60 -60 3.81 0.5551
WVFGRD96 17.0 85 30 60 3.79 0.5427
WVFGRD96 18.0 85 30 60 3.80 0.5331
WVFGRD96 19.0 85 30 60 3.81 0.5221
WVFGRD96 20.0 85 30 60 3.84 0.5124
WVFGRD96 21.0 80 30 55 3.85 0.4990
WVFGRD96 22.0 80 30 55 3.85 0.4840
WVFGRD96 23.0 80 30 50 3.86 0.4680
WVFGRD96 24.0 85 30 60 3.87 0.4521
WVFGRD96 25.0 85 30 60 3.87 0.4355
WVFGRD96 26.0 80 35 45 3.88 0.4183
WVFGRD96 27.0 85 35 50 3.88 0.4018
WVFGRD96 28.0 85 35 50 3.89 0.3853
WVFGRD96 29.0 85 35 50 3.89 0.3693
The best solution is
WVFGRD96 12.0 5 35 55 3.87 0.5800
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. |
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=Mon Jun 1 19:00:40 CDT 2009