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wphase:tutorial [2015/01/23 19:41]
wphase [W-phase tutorial]
wphase:tutorial [2018/03/04 13:48] (current)
wphase
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 ======= W-phase tutorial ======= ======= W-phase tutorial =======
  
-You may also refer to [[wphase:​documentation|the W-phase documentation page]]:  +You may also refer to [[wphase:​documentation|the W-phase documentation page]], where scripts ​and executables are described in [[wphase:​documentation#​How to run W-phase|this section]], input and output file-formats are described ​[[wphase:​documentation#​Data formats|here]].
-   * Scripts ​and executables are described in [[wphase:​documentation#​How to run W-phase|this section]] +
-   * File-formats are detailed ​[[wphase:​documentation#​Data formats|here]].+
  
-===== Example of run ===== 
  
-This section provide ​a typical example of W phase inversion run. +This tutorial page only provides ​a typical example of W phase inversion run.
  
-The first thing to do is to create i_master and CMTSOLUTION files. Let’s consider the Mw8.8 2010 Maule earthquake. We can use as input the following CMTSOLUTION file+===== Example of run for the 2010 Maule earthquake===== 
 + 
 +We consider here an example of run for the Mw8.8 2010 Maule earthquake.  
 + 
 +==== Input files ==== 
 +The first thing to do is to create i_master and CMTSOLUTION files. We can use as input the following CMTSOLUTION file
 <​code>​ <​code>​
  ​PDEW2010 ​ 2 27  6 34 15.60 -35.8500 ​ -72.7100 ​ 44.8 8.9 8.9 NEAR COAST OF CENTRAL CH                ​  ​PDEW2010 ​ 2 27  6 34 15.60 -35.8500 ​ -72.7100 ​ 44.8 8.9 8.9 NEAR COAST OF CENTRAL CH                ​
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 </​code>​ </​code>​
  
-For more detailed information about file formats, please refer to [[wphase:​documentation#​Data formats|the "File formats"​ section of the W-phase documentation page]].  +This file correspond to the Global CMT solution except that we fixed the centroid latitute, longitude and depth to the PDE preliminary hypocenter values and that the time-shift and half duration have been fixed a priori using some initial magnitude estimate ​(for more detailed information about file formats, please refer to [[wphase:​documentation#​Data formats|the "File formats"​ section of the W-phase documentation page]]).
- +
-This file correspond to the Global CMT solution except that we fixed the centroid latitute, longitude and depth to the PDE preliminary hypocenter values and that the time-shift and half duration have been fixed a priori using some initial magnitude estimate.+
  
 The i_master file is the following : The i_master file is the following :
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 According to the i_master file above, data is included in the seed file ../​SEEDS/​201002270634A_eqdat.seed (in this case the seed volume was obtained using the request tools of the IRIS DMC). It contains a large dataset of LH channels from 0 to 180 degrees of epicentral distances for a distribution of stations corresponding to FDSN, GSN_BROADBAND and STS1 virtual networks. For the purpose of this example, we decided to restrict the our dataset to the stations having epicentral distances within 5.0 to 55.0 degrees. Of course it is possible to consider more stations by increasing DMAX since the green function database allow us to perform the W phase inversion for stations within 90 degrees of epicentral distances. The filter pass band is 1mHz-5mHz and the time window extent is from the P wave until $15\times\Delta$. According to the i_master file above, data is included in the seed file ../​SEEDS/​201002270634A_eqdat.seed (in this case the seed volume was obtained using the request tools of the IRIS DMC). It contains a large dataset of LH channels from 0 to 180 degrees of epicentral distances for a distribution of stations corresponding to FDSN, GSN_BROADBAND and STS1 virtual networks. For the purpose of this example, we decided to restrict the our dataset to the stations having epicentral distances within 5.0 to 55.0 degrees. Of course it is possible to consider more stations by increasing DMAX since the green function database allow us to perform the W phase inversion for stations within 90 degrees of epicentral distances. The filter pass band is 1mHz-5mHz and the time window extent is from the P wave until $15\times\Delta$.
  
 +==== Preliminary inversion with a fixed centroid location ====
 Once these files are ready, we can proceed with a moment tensor inversion at the centroid location specified in CMTSOLUTION (i.e. the PDE location in this example): Once these files are ready, we can proceed with a moment tensor inversion at the centroid location specified in CMTSOLUTION (i.e. the PDE location in this example):
 <​code>​${WPHASE_HOME}/​bin/​RUNA3.csh </​code>​ <​code>​${WPHASE_HOME}/​bin/​RUNA3.csh </​code>​
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 </​code>​ </​code>​
  
-This solution ​is computed with a fixed location (PDE). It is also possible to determine an optimum centroid position and timing by running the  wp_grid_search.py script:+==== Final inversion after centroid grid-search ==== 
 + 
 +The previous ​solution ​was computed with a fixed location (PDE). It is also possible to determine an optimum centroid position and timing by running the  wp_grid_search.py script:
 <​code>​ <​code>​
 ${WPHASE_HOME}/​bin/​wp_grid_search.py –z ${WPHASE_HOME}/​bin/​wp_grid_search.py –z
 </​code>​ </​code>​
-Without the '​-z'​ flag, this command performs a 2D grid search with a fixed depth. If the option –z is given ,   the depth is also explored. This command will perform the time-shift grid-search as well as the centroid position grid-search. The grid-search is first performed with a large sampling interval and refined around the parameters corresponding to minimal rms misfits. The solution after time-shift grid-search is given in ts_WCMTSOLUTION and the final optimum solution after centroid position grid-search is given in xy_WCMTSOLUTION:​+Without the '​-z'​ flag, this command performs a 2D grid search with a fixed depth. If the option –z is given, depth is also explored. This command will perform the time-shift grid-search as well as the centroid position grid-search. ​ 
 + 
 +The grid-search is first performed with a large sampling interval and refined around the parameters corresponding to minimal rms misfits. The solution after time-shift grid-search is given in ts_WCMTSOLUTION and the final optimum solution after centroid position grid-search is given in xy_WCMTSOLUTION:​
  
 <​code>​ <​code>​
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 Each spatial and temporal location explored during the grid-search is detailed in grid_search_ts_out (time-shift grid search) grid_search_xyz_out (lat, lon, dep grid-search) and grid_search_xy_out (finer lat, lon grid-search which is performed at the optimum depth found during the lat, lon, dep global exploration). Each spatial and temporal location explored during the grid-search is detailed in grid_search_ts_out (time-shift grid search) grid_search_xyz_out (lat, lon, dep grid-search) and grid_search_xy_out (finer lat, lon grid-search which is performed at the optimum depth found during the lat, lon, dep global exploration).
  
 +==== Plotting the results ==== 
 The grid-search exploration result can be displayed using the python script make_grids.py : The grid-search exploration result can be displayed using the python script make_grids.py :
 <​code>​ <​code>​
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 The second script plot the waveform fit: The second script plot the waveform fit:
 <​code>​ <​code>​
-${WPHASE_HOME}/​bin/​traces_global.py+${WPHASE_HOME}/​bin/​traces.py
 </​code>​ </​code>​
  
 The resulting figure is given in file wp_pages.pdf which is shown here in Fig. 4. If the basemap python module is available, a map is drawn showing the station location with respect to the centroid location. Otherwise, a simple polar representation is used to display the station location. The resulting figure is given in file wp_pages.pdf which is shown here in Fig. 4. If the basemap python module is available, a map is drawn showing the station location with respect to the centroid location. Otherwise, a simple polar representation is used to display the station location.
  
wphase/tutorial.1422038502.txt.gz · Last modified: 2015/01/23 19:41 by wphase