Introduction

We will shortly be shutting down Arclink at the GEOFON data centre. An Arclink server for archived seismic waveform data has been running at GEOFON for many years. However only a handful of users continue to use it today. The EIDA management board has decided to end synchonisation of inventory between EIDA nodes in December 2019. (See http://www.orfeus-eu.org/)

This guide will help you adapt to the newer FDSN web services.

Using fdsnws_fetch

fdsnws_fetch is a command-line FDSN Web Service client using EIDA routing and authentication. With it, you can request StationXML metadata, or waveform data as mini-SEED. You can access both open and restricted data. See Access to restricted data below for details.

sudo pip install fdsnwsscripts

$ wget https://raw.githubusercontent.com/SeisComP3/seiscomp3/master/src/trunk/apps/fdsnws/fdsnws_fetch.py
$ mv fdsnws_fetch.py fdsnws_fetch
$ chmod +x fdsnws_fetch

$ ./fdsnws_fetch -h
A command-line FDSN Web Service client using EIDA routing and authentication.

Usage: fdsnws_fetch [-h|--help] [OPTIONS] -o file

Options:
  --version             show program's version number and exit
  -h, --help            show help message and exit
  -l, --longhelp        show extended help message and exit
[etc]

$ cat >req.arclink
2010,02,18,12,00,00 2010,02,18,12,10,00 GE WLF BH*
2010,02,18,12,00,00 2010,02,18,12,10,00 GE VSU BH*
[Use Control+D to end the file]

$ fdsnws_fetch -f req.arclink -y station -q level=channel -v -o station.xml

Access to restricted data

The EIDA Authentication System (EAS) is a system designed to let users log in and request a "token", which can be used as credentials for many EIDA services. From its conception, the EAS was designed to make use of the discovery service provided by eduGAIN (GEANT initiative), so that a user could login at EIDA by authenticating at his/her home institution, not with EIDA.

You can request a token for the system from here: http://geofon.gfz-potsdam.de/eas/ There is some helpful documentation there too. [EIDA], [QH19]

After you have your token, fdsnws_fetch can use it. Specify the location of your token file with the -a option, or fdsnws_fetch will use the default ${HOME}/.eidatoken, if it exists:

$ cat >req.arclink
2010,05,05,00,00,00 2010,05,05,23,59,59 CX PB01 VH*

$ fdsnws_fetch -f req.arclink -a {myeidatoken} -v -o data.mseed

for VH data from IPOC Station Huatacondo (CX.PBO1), Chile on 2010-05-05. Note that this request will fail unless the PI of the CX network has given you access to the data.

Other ways to request data

1. With Direct HTTP requests to FDSN web services (wget, curl etc.)
2. Using WebDC. Behind the scenes, the WebDC web interface now uses FSDN web services to request inventory and waveform data. You may notice that the "Download data" status page shows the locations of FDSN web services endpoints instead of Arclink status details. See the online help for WebDC, located at http://eida.gfz-potsdam.de/webdc3/help.html
3. Using ObsPy (see following section)

Direct HTTP requests to FDSN web services

You can use any web browser or a tool such as wget or curl to make requests.

For example, suppose we would like to request one hour of BHZ data for GEOFON station APE on January 1 2010. This above example request could be made using wget as:

wget -v "http://geofon.gfz-potsdam.de/fdsnws/dataselect/1/query?net=GE&station=APE&channel=BHZ&start=2010-01-01T10:00:00&end=2010-01-01T11:00:00" \
    -O my-dataselect.seed

The data will be saved in the file my-dataselect.seed in your local directory. Remember to use quotation marks around the URL to protect the shell from the ampersand ("&") characters between parts of the query string. By replacing "dataselect" by "station" in the above request, and adding "&level=response", you may obtain metadata for this station as Station XML.

More examples are provided on our web page, Using the GEOFON/FDSN web services. The webservice URL builder tool might help you get started.

ObsPy is a convenient seismological toolbox which is a good alternative for Python users. Where you may have used obspy.clients.arclink in the past, you would instead use obspy.clients.fdsn.

Full (dataless) SEED for metadata

If you still require full SEED, you may try fdsnws2seed. This requires SeisComP be installed locally on your computer. It uses fdsnws-station to request Station XML, and converts the result to SEED for you. To install it:

$ curl -L https://github.com/andres-h/fdsnws_scripts/tarball/master \
    | tar xzf -
$ cd andres-h-fdsnws_scripts-*
$ for f in fdsnwsscripts/fdsn*.py; do chmod a+x $f; mv $f `basename $f .py`; done

Example usage of fdsnws2seed with BREQ_FAST input, for dataless SEED output:

$ cat >req.breq
.NAME Jana Seismologist
.END
APE GE 2000 01 01 12 00 00.0000 2020 01 01 12 10 00.0000 01 BH?

$ ./fdsnws2seed -v -r 1 --dataless -b req.breq -o req.seed
getting routes from http://geofon.gfz-potsdam.de/eidaws/routing/1/query
getting data from http://geofon.gfz-potsdam.de/fdsnws/station/1/query
got 82233 bytes (application/xml) from http://geofon.gfz-potsdam.de/fdsnws/station/1/query

In case of problems with your request, plese use the contact form at

    http://www.orfeus-eu.org/organization/contact/form/?recipient=EIDA

The .NAME line is not required for unrestricted metadata.

Contributors

This document was written by Peter Evans, Javier Quinteros, and others. Please contact us if you have comments, difficulties, or questions. Last update 2020-06-23.