Page History

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1. Seed Waveform: The User selects a Seed file from the Episode database, or after applying the ‘Signal Download Tool’ (see “Data Handling Applications” chapter).
2. Catalog: The User selects a Seismic Catalog from the Episode database (See "AH Episodes" chapter)
3. Seismic Event: The User selects a seismic event which has been downloaded after applying the ‘Signal Download Tool’ (see “Data Handling Applications” chapter).
4. Seismogram picks: P-wave first arrival phase picks, selected by the User from the waveforms (described below)
5. Ray Tracing Angles: Ray tracing angles table uploaded from the selected Episode database (see "AH Episodes" chapter).

Figure 1. Inputs for the application

Figure 2. Selection of the waveform data from a catalog uploaded in the workspace

The FOCI application can be selected from the seed file as shown in Figure 2b:

Figure 2b. Selection of the application from the data uploaded in the workspace

Once all these files are selected, a map appears on the screen showing the epicenter of the selected event (red circle) and the locations of the seismic stations comprising the regional network (green triangles), as demonstrated in Figure 3. Information on the event and the stations appears on the screen, after clicking on the circle or the triangles, respectively. Moreover, the waveforms are also shown in the screen and are available for elaboration (see also "Waveform viewer guide" in "Visualization" chapter). As depicted in Figure 3, only the vertical channels are shown by default, since the methodology applied in this application uses only P-waves. Nevertheless, the User can make all the channels appear on the window, by ticking the "E" and "N" components, next to the 'Show channels' field (1), just below the map in Figure 3. 

Figure 3. Description of waveform processing

Waveform Processing

The options provided by the waveform viewer are described in Figure 3: When clicking on one waveform, a detailed waveform window extends.

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NOTE: Although it is not necessary to pick P-wave arrivals in all of the waveforms to run the application, a minimum of 8 picks is required for the application to proceed to the calculations (stated also at the bottom of Figure 4). The number of the seismograms and P-wave phases picked, are updated, each time the User selects makes a new picking.

Figure 4. Demonstration of waveform picking

Parameters selected for the waveform inversion:

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Advanced Options: (NOT IMPLEMENTED YET)

Figure 5. Additional input parameters selection

When the picking and the parameter selection is over, the User shall click on 'RUN' (green button, bottom of Figure 5) to initiate the Moment Tensor Inversion.

The results obtained after the process terminates include the values of the parameters and also focal mechanism types, as requested in the previous step (Figure 5). An example is shown in Figure 6. The scheme of the focal mechanisms (.png files, red frame of Figure 6) can be demonstrated and downloaded by the User. Tables with numerical values (.asc files, red frame of Figure 6) can also be displayed on the screen.

Figure 6. Outputs of the application