obspy.core.inventory

Module for handling station metadata

This module provides a class hierarchy to consistently handle station metadata. This class hierarchy is closely modelled after the upcoming de-facto standard format FDSN StationXML which was developed as a human readable XML replacement for Dataless SEED.

Note

IRIS is maintaining a Java tool for converting dataless SEED into StationXML and vice versa at https://seiscode.iris.washington.edu/projects/stationxml-converter

copyright:: The ObsPy Development Team (devs@obspy.org) & Chad Trabant
license:: GNU Lesser General Public License, Version 3 (https://www.gnu.org/copyleft/lesser.html)

Reading

StationXML files can be read using the read_inventory() function that returns an Inventory object.

>>> from obspy import read_inventory
>>> inv = read_inventory("/path/to/BW_RJOB.xml")
>>> inv  
<obspy.core.inventory.inventory.Inventory object at 0x...>
>>> print(inv)  
Inventory created at 2013-12-07T18:00:42.878000Z
    Created by: fdsn-stationxml-converter/1.0.0
            http://www.iris.edu/fdsnstationconverter
    Sending institution: Erdbebendienst Bayern
    Contains:
        Networks (1):
            BW
        Stations (1):
            BW.RJOB (Jochberg, Bavaria, BW-Net)
        Channels (3):
            BW.RJOB..EHZ, BW.RJOB..EHN, BW.RJOB..EHE

The file format in principle is autodetected. However, the autodetection uses the official StationXML XSD schema and unfortunately many real world files currently show minor deviations from the official StationXML definition causing the autodetection to fail. Thus, manually specifying the format is a good idea:

>>> inv = read_inventory("/path/to/BW_RJOB.xml", format="STATIONXML")

Class hierarchy

The Inventory class has a hierarchical structure, starting with a list of Networks, each containing a list of Stations which again each contain a list of Channels. The Responses are attached to the channels as an attribute.

>>> net = inv[0]
>>> net  
<obspy.core.inventory.network.Network object at 0x...>
>>> print(net)  
Network BW (BayernNetz)
    Station Count: None/None (Selected/Total)
    -- - --
    Access: UNKNOWN
    Contains:
        Stations (1):
            BW.RJOB (Jochberg, Bavaria, BW-Net)
        Channels (3):
            BW.RJOB..EHZ, BW.RJOB..EHN, BW.RJOB..EHE

>>> sta = net[0]
>>> print(sta)  
Station RJOB (Jochberg, Bavaria, BW-Net)
    Station Code: RJOB
    Channel Count: None/None (Selected/Total)
    2007-12-17T00:00:00.000000Z -
    Access: None
    Latitude: 47.74, Longitude: 12.80, Elevation: 860.0 m
    Available Channels:
        RJOB..EHZ, RJOB..EHN, RJOB..EHE

>>> cha = sta[0]
>>> print(cha)  
Channel 'EHZ', Location ''
   Time range: 2007-12-17T00:00:00.000000Z - --
   Latitude: 47.74, Longitude: 12.80, Elevation: 860.0 m, Local Depth: 0.0 m
   Azimuth: 0.00 degrees from north, clockwise
   Dip: -90.00 degrees down from horizontal
   Channel types: TRIGGERED, GEOPHYSICAL
   Sampling Rate: 200.00 Hz
   Sensor (Description): Streckeisen STS-2/N seismometer (None)
   Response information available

>>> print(cha.response)  
Channel Response
   From M/S (Velocity in Meters Per Second) to COUNTS (Digital Counts)
   Overall Sensitivity: 2.5168e+09 defined at 0.020 Hz
   4 stages:
      Stage 1: PolesZerosResponseStage from M/S to V, gain: 1500
      Stage 2: CoefficientsTypeResponseStage from V to COUNTS, gain: 1.67...
      Stage 3: FIRResponseStage from COUNTS to COUNTS, gain: 1
      Stage 4: FIRResponseStage from COUNTS to COUNTS, gain: 1

Preview plots of station map and instrument response

For station metadata, preview plot routines for geographic location of stations as well as bode plots for channel instrument response information are available. The routines for station map plots are:

Inventory.plot()

Network.plot()

For example:

>>> from obspy import read_inventory
>>> inv = read_inventory()
>>> inv.plot()  

(Source code, png)

../../_images/obspy-core-inventory-1.png

The routines for bode plots of channel instrument response are:

Inventory.plot_response()

Network.plot_response()

Station.plot()

Channel.plot()

Response.plot()

For example:

>>> from obspy import read_inventory
>>> inv = read_inventory()
>>> resp = inv[0][0][0].response
>>> resp.plot(0.001, output="VEL")  

(Source code, png)

../../_images/obspy-core-inventory-2.png

When plotting stations with instrumentation changes, epoch times can be added to the legend labels:

>>> from obspy import read_inventory
>>> inv = read_inventory()
>>> inv = inv.select(station='RJOB', channel='EHZ')
>>> inv.plot_response(0.001, label_epoch_dates=True)  

(Source code, png)

../../_images/obspy-core-inventory-3.png

For more examples see the Obspy Gallery.

Dealing with the Response information

The get_evalresp_response() method will call some functions within evalresp to generate the response.

>>> response = cha.response
>>> response, freqs = response.get_evalresp_response(0.1, 16384, output="VEL")
>>> print(response)  
 [  0.00000000e+00 +0.00000000e+00j  -1.36383361e+07 +1.42086194e+06j
   -5.36470300e+07 +1.13620679e+07j ...,   2.48907496e+09 -3.94151237e+08j
    2.48906963e+09 -3.94200472e+08j   2.48906430e+09 -3.94249707e+08j]

Some convenience methods to perform an instrument correction on Stream (and Trace) objects are available and most users will want to use those. The remove_response() method deconvolves the instrument response in-place. As always see the corresponding docs pages for a full list of options and a more detailed explanation.

>>> from obspy import read
>>> st = read()
>>> inv = read_inventory("/path/to/BW_RJOB.xml")
>>> st.remove_response(
...     inventory=inv, output="VEL", water_level=20)  
<obspy.core.stream.Stream object at 0x...>

Writing

Inventory objects can be exported to StationXML files, e.g. after making modifications.

>>> inv.write('my_inventory.xml', format='STATIONXML')  