2009/10/19 10:08:50 44.76 9.735 25.8 3.9 Italy
STA COMP DIS(K) AZM AIN ARR TIME RES(SEC) WT QFM PHASE WGT BOB Z 28.47 269. 132. 20091019100856.047 0.02 0 iC P 0.95 BOB Z 28.47 269. 132. 20091019100901.261 -0.16 2 eX S 0.37 PRMA Z 40.05 91. 122. 20091019100857.746 0.14 2 e- P 0.38 SC2M Z 46.46 208. 118. 20091019100858.609 0.06 0 iD P 0.89 MSSA Z 55.86 204. 114. 20091019100859.957 -0.04 0 iD P 0.83 VLC Z 82.41 146. 55. 20091019100903.653 -0.24 0 iD P 0.40 BDI Z 101.04 141. 55. 20091019100906.516 0.00 0 iD P 0.49 PCP Z 103.40 256. 55. 20091019100907.216 0.37 2 e- P 0.13 ZCCA Z 104.11 116. 55. 20091019100909.205 2.26 2 eX P 0.02 ROVR Z 138.84 45. 55. 20091019100911.502 -0.33 0 iC P 0.20 MABI Z 152.71 21. 55. 20091019100913.313 -0.47 2 e- P 0.08 RORO Z 156.91 243. 55. 20091019100914.106 -0.27 2 e- P 0.10 TUE Z 192.11 349. 48. 20091019100919.073 0.22 0 iD P 0.18 BRMO Z 194.23 13. 48. 20091019100919.322 0.20 2 eX P 0.09 BLB Z 201.38 273. 48. 20091019100920.001 -0.03 2 eX P 0.12 DOI Z 205.36 263. 48. 20091019100921.562 1.03 2 e- P 0.03 RETURN FOR NEXT SCREEN Error Ellipse X= 0.7484 km Y= 0.8221 km Theta = 127.2335 deg RMS Error : 0.067 sec Travel_Time_Table: nnCIA Latitude : 44.7741 +- 0.0071 N 0.7959 km Longitude : 9.8073 +- 0.0099 E 0.7762 km Depth : 27.77 +- 0.81 km Epoch Time : 1255946928.866 +- 0.08 sec Event Time : 20091019100848.866 +- 0.08 sec Event (OCAL) : 2009 10 19 10 08 48 866 HYPO71 Quality : BB Gap : 76 deg
USGS/SLU Moment Tensor Solution
ENS 2009/10/19 10:08:50:0 44.76 9.73 25.8 3.9 Italy
Stations used:
IG.PCP IG.SC2M IV.BDI IV.BOB IV.MAGA IV.MSSA IV.PRMA
IV.ROVR IV.ZCCA MN.VLC
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 5.50e+21 dyne-cm
Mw = 3.76
Z = 23 km
Plane Strike Dip Rake
NP1 255 60 125
NP2 20 45 45
Principal Axes:
Axis Value Plunge Azimuth
T 5.50e+21 59 216
N 0.00e+00 30 55
P -5.50e+21 8 320
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.22e+21
Mxy 3.35e+21
Mxz -2.58e+21
Myy -1.67e+21
Myz -9.40e+20
Mzz 3.89e+21
--------------
--------------------##
---------------------####
- P ----------------------####
--- ----------------------######
------------------------------######
----------------------################
---------------#################------##
-----------#####################--------
---------########################---------
------###########################---------
----############################----------
---#############################----------
############## #############----------
############## T ############-----------
############# ###########-----------
#########################-----------
#######################-----------
###################-----------
################------------
##########------------
#-------------
Global CMT Convention Moment Tensor:
R T P
3.89e+21 -2.58e+21 9.40e+20
-2.58e+21 -2.22e+21 -3.35e+21
9.40e+20 -3.35e+21 -1.67e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20091019100850/index.html
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STK = 20
DIP = 45
RAKE = 45
MW = 3.76
HS = 23.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/10/19 10:08:50:0 44.76 9.73 25.8 3.9 Italy
Stations used:
IG.PCP IG.SC2M IV.BDI IV.BOB IV.MAGA IV.MSSA IV.PRMA
IV.ROVR IV.ZCCA MN.VLC
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 5.50e+21 dyne-cm
Mw = 3.76
Z = 23 km
Plane Strike Dip Rake
NP1 255 60 125
NP2 20 45 45
Principal Axes:
Axis Value Plunge Azimuth
T 5.50e+21 59 216
N 0.00e+00 30 55
P -5.50e+21 8 320
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.22e+21
Mxy 3.35e+21
Mxz -2.58e+21
Myy -1.67e+21
Myz -9.40e+20
Mzz 3.89e+21
--------------
--------------------##
---------------------####
- P ----------------------####
--- ----------------------######
------------------------------######
----------------------################
---------------#################------##
-----------#####################--------
---------########################---------
------###########################---------
----############################----------
---#############################----------
############## #############----------
############## T ############-----------
############# ###########-----------
#########################-----------
#######################-----------
###################-----------
################------------
##########------------
#-------------
Global CMT Convention Moment Tensor:
R T P
3.89e+21 -2.58e+21 9.40e+20
-2.58e+21 -2.22e+21 -3.35e+21
9.40e+20 -3.35e+21 -1.67e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20091019100850/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 1.0 40 45 85 3.36 0.2830
WVFGRD96 2.0 225 45 95 3.45 0.3054
WVFGRD96 3.0 180 90 -30 3.39 0.2687
WVFGRD96 4.0 0 90 25 3.43 0.2759
WVFGRD96 5.0 350 70 -40 3.50 0.2853
WVFGRD96 6.0 350 70 -45 3.52 0.2921
WVFGRD96 7.0 355 60 -40 3.54 0.3052
WVFGRD96 8.0 -5 60 -40 3.54 0.3222
WVFGRD96 9.0 355 60 -40 3.55 0.3368
WVFGRD96 10.0 355 60 -40 3.57 0.3493
WVFGRD96 11.0 355 65 -35 3.58 0.3595
WVFGRD96 12.0 355 65 -35 3.59 0.3684
WVFGRD96 13.0 350 65 -35 3.61 0.3767
WVFGRD96 14.0 15 60 35 3.62 0.3842
WVFGRD96 15.0 20 55 45 3.66 0.4052
WVFGRD96 16.0 20 55 45 3.67 0.4229
WVFGRD96 17.0 20 55 45 3.69 0.4389
WVFGRD96 18.0 20 50 45 3.70 0.4532
WVFGRD96 19.0 20 50 45 3.71 0.4655
WVFGRD96 20.0 20 50 45 3.73 0.4747
WVFGRD96 21.0 20 50 45 3.74 0.4824
WVFGRD96 22.0 20 50 45 3.75 0.4858
WVFGRD96 23.0 20 45 45 3.76 0.4862
WVFGRD96 24.0 20 45 45 3.77 0.4842
WVFGRD96 25.0 15 45 40 3.78 0.4834
WVFGRD96 26.0 20 40 45 3.78 0.4787
WVFGRD96 27.0 15 40 40 3.79 0.4741
WVFGRD96 28.0 15 40 40 3.80 0.4680
WVFGRD96 29.0 15 40 40 3.81 0.4601
The best solution is
WVFGRD96 23.0 20 45 45 3.76 0.4862
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 component 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 nnCIA used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01
C.It. A. Di Luzio et al Earth Plan Lettrs 280 (2009) 1-12 Fig 5. 7-8 MODEL/SURF3
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
1.5000 3.7497 2.1436 2.2753 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
3.0000 4.9399 2.8210 2.4858 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
3.0000 6.0129 3.4336 2.7058 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
7.0000 5.5516 3.1475 2.6093 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
15.0000 5.8805 3.3583 2.6770 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
6.0000 7.1059 4.0081 3.0002 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
8.0000 7.1000 3.9864 3.0120 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
0.0000 7.9000 4.4036 3.2760 0.167E-02 0.333E-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 Oct 19 13:07:25 CDT 2009