SKS splitting offline

Program sks_offline.py

Calculates single station SKS splitting results from data previously downloaded using the program SKS data preparation. Station selection is specified by a network and station code. The data base is provided in a pickled file as a StDb dictionary.

Usage

$ sks_offline.py -h
Usage: sks_offline.py [options] <station database>

Script to process and calculate the spliting parmaters for a dataset that has
already been downloaded by sks_prep.py.

Options:
  -h, --help            show this help message and exit
  --keys=STKEYS         Specify a comma separated list of station keys for
                        which to perform analysis. These must be contained
                        within the station database. Partial keys will be used
                        to match against those in the dictionary. For
                        instance, providing IU will match with all stations in
                        the IU network [Default processes all stations in the
                        database]

  Event Settings:
    Settings associated with refining the events to include in matching
    station pairs

    --start-time=STARTT
                        Specify a UTCDateTime compatible string representing
                        the start time for the event search. This will
                        override any station start times. [Default more recent
                        start date for each station pair]
    --end-time=ENDT     Specify a UTCDateTime compatible string representing
                        the start time for the event search. This will
                        override any station end times [Default older end date
                        for each the pair of stations]
    -R, --reverse-order
                        Reverse order of events. Default behaviour starts at
                        oldest event and works towards most recent. Specify
                        reverse order and instead the program will start with
                        the most recent events and work towards older
    --min-mag=MINMAG    Specify the minimum magnitude of event for which to
                        search. [Default 6.0]
    --max-mag=MAXMAG    Specify the maximum magnitude of event for which to
                        search. [Default None, ie no limit]

  Geometry Settings:
    Settings associatd with the event-station geometries

    --min-dist=MINDIST  Specify the minimum great circle distance (degrees)
                        between the station and event. [Default 85]
    --max-dist=MAXDIST  Specify the maximum great circle distance (degrees)
                        between the station and event. [Default 120]

  Parameter Settings:
    Miscellaneous default values and settings

    --Vp=VP             Specify default P velocity value. [Default 6.0 km/s]
    --SNR=MSNR          Specify the SNR threshold used to determine whether
                        events are processedc. [Default 7.5]
    --window=DTS        Specify time window length before and after the SKS
                        arrival. The total window length is 2*dst. [Default
                        120 s]
    --max-delay=MAXDT   Specify the maximum delay time. [Default 4 s]
    --time-increment=DDT
                        Specify the time increment. [Default 0.1 s]
    --angle-increment=DPHI
                        Specify the angle increment. [Default 1 d]
    --transverse-SNR=SNRTLIM
                        Specify the minimum SNR Threshold for the Transverse
                        component to be considered Non-Null. [Default 1.]

Example

Assume we have followed the steps in SKS data preparation and saved some data to disk in a folder called DATA_D85-120_M6.0+_S7.5+. Now we can simply run sks_offline.py by specifying the data folder containing the prepared waveforms, which execute the SKS splitting analysis and generate Figures and picking windows similar to SKS splitting on the fly (see the program for details).

$ sks_offline.py ./DATA_D85-120_M6.0+_S7.5+


|===============================================|
|===============================================|
|                    TA.EPYK                    |
|===============================================|
|===============================================|
|  Working on    13 saved events                |
|===============================================|

****************************************************
* #1 (2/13):  20130409_115250
*   Origin Time: 2013-04-09 11:52:50
*   Lat:  28.45; Lon:   51.63
*   Dep:  12.80; Mag: 6.3
*     EPYK  -> Ev: 9467.98 km;   85.15 deg; 352.65;   3.35
* SNR Passed: 20.13 >= 7.5
* --> Calculating Rotation-Correlation (RC) Splitting
* --> Calculating Silver-Chan (SC) Splitting

...

This uses all default settings for window lengths, magnitude criteria, etc. See the program SKS splitting on the fly for details on the interactions with the code to produce splitting results.