5. Retrieving Data from Data Centers¶
This section is intended as a small guide to help you choose the best way to download data for a given purpose using ObsPy. Keep in mind that data centers and web services are constantly changing so this recommendation might not be valid anymore at the time you read this. For actual code examples, please see the documentation of the various modules.
Note
The most common use case is likely to download waveforms and event/station meta information. In almost all cases you will want to use the obspy.clients.fdsn module for this. It supports the largest number of data centers and uses the most modern data formats. There are still a number of reasons to choose a different module but please make sure you have one.
5.1. The FDSN Web Services¶
5.1.1. Basic FDSN Web Services¶
| Available Data Types | Format |
|---|---|
| Waveforms | MiniSEED and optionally others |
| Station Information | StationXML and Text |
| Event Information | QuakeML and Text |
Note
Not all data providers offer all three data types. Many offer only one or two.
If you want to requests waveforms, or station/event meta information you will most likely want to use the obspy.clients.fdsn module. It is able to request data from any data center implementing the FDSN web services. Example data centers include IRIS/ORFEUS/INGV/ETH/GFZ/RESIF/... - a curated list can be found here. As a further advantage it returns data in the most modern and future proof formats.
5.1.2. FDSN Routing Web Services¶
If you don’t know which data center has what data, use one of the routing services. ObsPy has support for two of them:
- The IRIS Federator.
- The EIDAWS Routing Service.
See the bottom part of the obspy.clients.fdsn module page for usage details.
5.1.3. FDSN Mass Downloader¶
If you want to download a lot of data across a number of data centers, ObsPy’s mass (or batch) downloader is for you. You can formulate your queries for example in terms of geographical domains and ObsPy will download waveforms and corresponding station meta information to produce complete data sets, ready for research, including some basic quality control.
See the obspy.clients.fdsn.mass_downloader page for more details.
5.2. ArcLink¶
| Available Data Types | Format |
|---|---|
| Waveforms | MiniSEED, SEED |
| Station Information | dataless SEED, SEED |
ArcLink is a distributed data request protocol usable to access archived waveform data in the MiniSEED or SEED format and associated meta information as Dataless SEED files. You can use the obspy.clients.arclink module to request data from the EIDA initiative but most (or all) of that data can also be requested using the obspy.clients.fdsn module.
5.3. IRIS Web Services¶
Available Data Types and Formats: Various
IRIS (in addition to FDSN web services) offers a variety of special-purpose web services, for some of which ObsPy has interfaces in the obspy.clients.iris module. Use this if you require response information in the SAC poles & zeros or in the RESP format. If you just care about the instrument response, please use the obspy.clients.fdsn module to request StationXML data which contains the same information.
The interfaces for the calculation tools are kept around for legacy reasons; internal ObsPy functionality should be considered as an alternative when working within ObsPy:
| IRIS Web Service | Equivalent ObsPy Function/Module |
|---|---|
| obspy.clients.iris.client.Client.traveltime() | obspy.taup |
| obspy.clients.iris.client.Client.distaz() | obspy.geodetics |
| obspy.clients.iris.client.Client.flinnengdahl() | obspy.geodetics.flinnengdahl.FlinnEngdahl |
5.4. Earthworm Wave Server¶
| Available Data Types | Format |
|---|---|
| Waveforms | Custom Format |
Use the obspy.clients.earthworm module to request data from the Earthworm data acquisition system.
5.5. NERIES Web Services¶
This service is largely deprecated as the data can just as well be requested via the obspy.clients.fdsn module.
5.6. NEIC¶
| Available Data Types | Format |
|---|---|
| Waveforms | MiniSEED |
The Continuous Waveform Buffer (CWB) is a repository for seismic waveform data that passes through the NEIC “Edge” processing system. Use the obspy.clients.neic module to request data from it.
5.7. SeedLink¶
| Available Data Types | Format |
|---|---|
| Waveforms | MiniSEED |
To connect to a real time SeedLink server, use the obspy.clients.seedlink module. Also see the ObsPy Tutorial for a more detailed introduction.
5.8. Syngine Service¶
| Available Data Types | Format |
|---|---|
| Waveforms | MiniSEED and zipped SAC files |
Use the obspy.clients.syngine module to download high-frequency global synthetic seismograms for any source receiver combination from the IRIS syngine service.