Seismic Time Series Data

Seismic time series data is seismogram waveforms recorded at seismic stations. We mostly use digital data, which is a time series of velocity of the ground shaking.

Besides the waveform itself, metadata describes critical information of the waveform data. Metadata can include station information, earthquake information, instrument response, etc.

Resources

Nowadays, there are terabytes/petabytes of seismic data collected every years. Most oil & gas companies have their own data centers to store this data. In academia, some institutions also have their own exclusive data centers. However, most seismic data in the United States is archived at the IRIS DMC.

Incorporated Research Institutions for Seismology (IRIS)

IRIS is a consortium of over 120 US universities, including MSU, dedicated to the operation of science facilities for the acquisition, management, and distribution of seismological data.

IRIS Data Management Center (DMC) is located near the University of Washington in Seattle. Most data at the IRIS DMC is open to public immediately or after an embargo of a period of time (e.g. 2 years).

There are many ways to download data from the IRIS DMC: https://ds.iris.edu/ds/nodes/dmc/data/. IRIS has developed several tools to download data: https://ds.iris.edu/ds/nodes/dmc/tools/. However, SOD is still one of the most popular tools we use.

Formats

There are many different seismic data formats in seismology community. The most commonly used formats are SAC, miniSEED and SEED.

• SAC is a good format for data analysis, though difficult for storing. This format is defined by the software SAC (Seismic Analysis Codes), although it is supported by many other tools
• SEED (Standard for the Exchange of Earthquake Data) is a data format intended primarily for the archival and exchange of seismological time series data and related metadata.
• miniSEED is the subset of the SEED standard that is used for time series data. Very limited metadata for the time series is included in miniSEED beyond time series identification and simple state-of-health flags. In particular, geographic coordinates, response/scaling information and other information needed to interpret the data values are not included.