Note
Click here to download the full example code
Catalogs operations¶
This example demonstrates how to perform standard operations on a catalog. This example requires an internet connection to access ComCat.
- Overview:
Load catalog from ComCat
Create filtering parameters in space, magnitude, and time
Filter catalog using desired filters
Write catalog to standard CSEP format
Load required libraries¶
Most of the core functionality can be imported from the top-level csep
package. Utilities are available from the
csep.utils
subpackage.
import csep
from csep.core import regions
from csep.utils import time_utils, comcat
Load catalog¶
PyCSEP provides access to the ComCat web API using csep.query_comcat()
. This function requires a
datetime.datetime
to specify the start and end dates.
start_time = csep.utils.time_utils.strptime_to_utc_datetime('2019-01-01 00:00:00.0')
end_time = csep.utils.time_utils.utc_now_datetime()
catalog = csep.query_comcat(start_time, end_time)
print(catalog)
Out:
Fetched ComCat catalog in 10.188417911529541 seconds.
Downloaded catalog from ComCat with following parameters
Start Date: 2019-01-01 12:01:46.950000+00:00
End Date: 2021-02-24 19:05:11.070000+00:00
Min Latitude: 31.5025 and Max Latitude: 42.8543333333333
Min Longitude: -125.3826667 and Max Longitude: -113.1295
Min Magnitude: 2.5
Found 6640 events in the ComCat catalog.
Name: None
Start Date: 2019-01-01 12:01:46.950000+00:00
End Date: 2021-02-24 19:05:11.070000+00:00
Latitude: (31.5025, 42.8543333333333)
Longitude: (-125.3826667, -113.1295)
Min Mw: 2.5
Max Mw: 7.1
Event Count: 6640
Filter to magnitude range¶
Use the csep.core.catalogs.AbstractBaseCatalog.filter()
to filter the catalog. The filter function uses the field
names stored in the numpy structured array. Standard fieldnames include ‘magnitude’, ‘origin_time’, ‘latitude’, ‘longitude’,
and ‘depth’.
catalog = catalog.filter('magnitude >= 3.5')
print(catalog)
Out:
Name: None
Start Date: 2019-01-13 09:35:49.870000+00:00
End Date: 2021-02-22 01:38:13.840000+00:00
Latitude: (31.5158, 42.7775)
Longitude: (-125.3826667, -113.4886667)
Min Mw: 3.5
Max Mw: 7.1
Event Count: 877
Filter to desired time interval¶
We need to define desired start and end times for the catalog using a time-string format. PyCSEP uses integer times for doing
time manipulations. Time strings can be converted into integer times using
csep.utils.time_utils.strptime_to_utc_epoch()
. The csep.core.catalog.AbstractBaseCatalog.filter()
also
accepts a list of strings to apply multiple filters.
# create epoch times from time-string formats
start_epoch = csep.utils.time_utils.strptime_to_utc_epoch('2019-07-06 03:19:54.040000')
end_epoch = csep.utils.time_utils.strptime_to_utc_epoch('2019-09-21 03:19:54.040000')
# filter catalog to magnitude ranges and times
filters = [f'origin_time >= {start_epoch}', f'origin_time < {end_epoch}']
catalog = catalog.filter(filters)
print(catalog)
Out:
Name: None
Start Date: 2019-07-06 03:20:36.080000+00:00
End Date: 2019-09-19 09:59:46.580000+00:00
Latitude: (32.2998352, 41.1244)
Longitude: (-125.0241667, -115.3243332)
Min Mw: 3.5
Max Mw: 5.5
Event Count: 358
Filter to desired spatial region¶
We use a circular spatial region with a radius of 3 average fault lengths as defined by the Wells and Coppersmith scaling
relationship. PyCSEP provides csep.utils.spatial.generate_aftershock_region()
to create an aftershock region
based on the magnitude and epicenter of an event.
We use csep.utils.comcat.get_event_by_id()
the ComCat API provided by the USGS to obtain the event information
from the M7.1 Ridgecrest mainshock.
m71_event_id = 'ci38457511'
event = comcat.get_event_by_id(m71_event_id)
m71_epoch = time_utils.datetime_to_utc_epoch(event.time)
# build aftershock region
aftershock_region = regions.generate_aftershock_region(event.magnitude, event.longitude, event.latitude)
# apply new aftershock region and magnitude of completeness
catalog = catalog.filter_spatial(aftershock_region).apply_mct(event.magnitude, m71_epoch)
print(catalog)
Out:
Name: None
Start Date: 2019-07-06 03:22:35.630000+00:00
End Date: 2019-09-08 14:07:23.350000+00:00
Latitude: (35.448, 36.1823333)
Longitude: (-117.8886667, -117.2796667)
Min Mw: 3.5
Max Mw: 5.5
Event Count: 235
Write catalog¶
Use csep.core.catalogs.AbstractBaseCatalog.write_ascii()
to write the catalog into the comma separated value format.
catalog.write_ascii('2019-11-11-comcat.csv')
Total running time of the script: ( 0 minutes 12.728 seconds)