2013/06/30 18:18:52 44.178 10.207 9.5 3.6 Italy
USGS Felt map for this earthquake
SLU Moment Tensor Solution ENS 2013/06/30 18:18:52:0 44.18 10.21 9.5 3.6 Italy Stations used: GU.FINB GU.GORR GU.MAIM GU.PCP GU.POPM IV.ASQU IV.BDI IV.BOB IV.CAFI IV.CELB IV.CESX IV.CING IV.CRE IV.CRMI IV.CSNT IV.FDMO IV.FNVD IV.GROG IV.GUMA IV.MSSA IV.NRCA IV.PARC IV.PLMA IV.QLNO IV.ROVR IV.SACS IV.TERO IV.ZCCA MN.VLC Filtering commands used: cut a a 120 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 2.32e+21 dyne-cm Mw = 3.51 Z = 5 km Plane Strike Dip Rake NP1 242 61 -118 NP2 110 40 -50 Principal Axes: Axis Value Plunge Azimuth T 2.32e+21 11 352 N 0.00e+00 24 257 P -2.32e+21 63 105 Moment Tensor: (dyne-cm) Component Value Mxx 2.16e+21 Mxy -1.72e+20 Mxz 6.80e+20 Myy -4.11e+20 Myz -9.67e+20 Mzz -1.75e+21 ### ######## ####### T ############ ########## ############### ############################## ################################## ########################-----------# ###################------------------- -###############------------------------ -############--------------------------- --##########------------------------------ ---######----------------- ------------- ----####------------------ P ------------- -----#-------------------- ------------- ----#----------------------------------- ---####--------------------------------- -#######-----------------------------# ##########------------------------## ##############---------------##### ############################## ############################ ###################### ############## Global CMT Convention Moment Tensor: R T P -1.75e+21 6.80e+20 9.67e+20 6.80e+20 2.16e+21 1.72e+20 9.67e+20 1.72e+20 -4.11e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130630181852/index.html |
STK = 110 DIP = 40 RAKE = -50 MW = 3.51 HS = 5.0
The waveform inversion is preferred.
The following compares this source inversion to others
SLU Moment Tensor Solution ENS 2013/06/30 18:18:52:0 44.18 10.21 9.5 3.6 Italy Stations used: GU.FINB GU.GORR GU.MAIM GU.PCP GU.POPM IV.ASQU IV.BDI IV.BOB IV.CAFI IV.CELB IV.CESX IV.CING IV.CRE IV.CRMI IV.CSNT IV.FDMO IV.FNVD IV.GROG IV.GUMA IV.MSSA IV.NRCA IV.PARC IV.PLMA IV.QLNO IV.ROVR IV.SACS IV.TERO IV.ZCCA MN.VLC Filtering commands used: cut a a 120 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 2.32e+21 dyne-cm Mw = 3.51 Z = 5 km Plane Strike Dip Rake NP1 242 61 -118 NP2 110 40 -50 Principal Axes: Axis Value Plunge Azimuth T 2.32e+21 11 352 N 0.00e+00 24 257 P -2.32e+21 63 105 Moment Tensor: (dyne-cm) Component Value Mxx 2.16e+21 Mxy -1.72e+20 Mxz 6.80e+20 Myy -4.11e+20 Myz -9.67e+20 Mzz -1.75e+21 ### ######## ####### T ############ ########## ############### ############################## ################################## ########################-----------# ###################------------------- -###############------------------------ -############--------------------------- --##########------------------------------ ---######----------------- ------------- ----####------------------ P ------------- -----#-------------------- ------------- ----#----------------------------------- ---####--------------------------------- -#######-----------------------------# ##########------------------------## ##############---------------##### ############################## ############################ ###################### ############## Global CMT Convention Moment Tensor: R T P -1.75e+21 6.80e+20 9.67e+20 6.80e+20 2.16e+21 1.72e+20 9.67e+20 1.72e+20 -4.11e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130630181852/index.html |
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:
cut a a 120 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 1.0 115 40 -30 3.36 0.3771 WVFGRD96 2.0 115 35 -30 3.43 0.4188 WVFGRD96 3.0 110 40 -45 3.44 0.4552 WVFGRD96 4.0 110 45 -55 3.48 0.4753 WVFGRD96 5.0 110 40 -50 3.51 0.4818 WVFGRD96 6.0 105 40 -60 3.53 0.4735 WVFGRD96 7.0 110 45 -50 3.49 0.4511 WVFGRD96 8.0 115 50 -40 3.44 0.4179 WVFGRD96 9.0 130 65 -15 3.41 0.4067 WVFGRD96 10.0 130 65 -5 3.41 0.4035 WVFGRD96 11.0 135 65 15 3.42 0.4027 WVFGRD96 12.0 135 65 15 3.43 0.4032 WVFGRD96 13.0 130 70 15 3.43 0.4021 WVFGRD96 14.0 135 70 15 3.45 0.4007 WVFGRD96 15.0 135 65 20 3.47 0.3993 WVFGRD96 16.0 135 65 20 3.47 0.3975 WVFGRD96 17.0 130 65 20 3.47 0.3947 WVFGRD96 18.0 130 65 20 3.48 0.3919 WVFGRD96 19.0 130 70 20 3.49 0.3888 WVFGRD96 20.0 130 70 20 3.50 0.3857 WVFGRD96 21.0 130 70 20 3.51 0.3821 WVFGRD96 22.0 130 70 20 3.51 0.3785 WVFGRD96 23.0 130 70 20 3.52 0.3745 WVFGRD96 24.0 130 70 20 3.53 0.3702 WVFGRD96 25.0 130 70 20 3.54 0.3670 WVFGRD96 26.0 130 70 20 3.55 0.3641 WVFGRD96 27.0 130 70 20 3.56 0.3612 WVFGRD96 28.0 130 70 20 3.58 0.3585 WVFGRD96 29.0 130 70 20 3.59 0.3556
The best solution is
WVFGRD96 5.0 110 40 -50 3.51 0.4818
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. A pair of numbers is given in black at the right of each predicted traces. The upper number 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 lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
cut a a 120 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 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. |
A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of 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=Sun Jun 30 14:26:02 CDT 2013