Waveform Data

The IRIS DMC archives waveform (time-series) data from stations around the world. The following information highlights passive and active source data available through the DMC.

Time-series data is collected for many types of data, identified using a system of channel codes.

Passive Source

Example waveform data showing an event arrival

Most of the data archived at the DMC is from broad-band stations recording passive (or natural) source events. Some stations record continuously, some have triggered channels. Most of the passive source data are from permanent station installations and are archived in SEED format, but some data come to us from temporary installations and in formats other than SEED.

Active Source

Active source refers to the creation of seismic events using explosives or mechanical devices like air guns, from either experiments on land or while underway on properly equipped research ships.

Much of the active source data at the DMC is recorded using temporary deployments of instruments provided by the PASSCAL program, but we do have some active source data from other sources. Active source data can come in a variety of formats.

Waveform Request Tools

IRIS provides a variety of Web Tools for requesting waveform data.

Request Waveform Data Using BREQ_FAST

Batch access to the IRIS DMC archive can be obtained by electronically mailing a specially formatted file to the IRIS DMC in Seattle. These are BREQ_FAST files and provide a base level access to the DMC needed by any user. Learn how to submit a BREQ_FAST Request »

WebRequest – An easy way to submit a request for data

WebRequest is a data request form that allows users to submit BREQ_FAST-formatted data requests to the DMC. Submit a WebRequest »

SOD – Standing Order for Data

SOD is a program that automates tedious data selection, downloading, and routine processing tasks in seismology. It allows you to define your desired data based on earthquakes, recording stations, and the resulting combination of information. SOD then retrieves the data that matches the criteria. Learn more about SOD »

JWEED

Using JWEED a person can obtain waveforms from any institution which has implemented DHI servers. JWEED now utilizes Web Mapping Services (WMS) for displaying maps. Learn more about JWEED »

Waveform Data Formats

SEED (Standard for the Exchange of Earthquake Data) format

SEED is an international standard format for the exchange of digital seismological data. SEED was designed for use by the earthquake research community, primarily for the exchange between institutions of unprocessed earth motion data. It is a format for digital data measured at one point in space and at equal intervals of time.

SEED helps seismologists who record, share, and use seismological data. By providing a standard, SEED makes transmitting, receiving, and processing earthquake data easier and more accurate. Before the introduction of SEED, ease and accuracy had been goals, but not really attained.

Simple ASCII format

Simple ASCII is a text column representation timeseries data that IRIS DMC now provides. This representation makes it very simple to import into other utilities such as spreadsheets and mathematical analysis programs. More information on the Simple ASCII format »

SAC (Seismic Analysis Code) format

The SAC format comes in fixed binary and ASCII forms and is read by the SAC analysis utility: A general purpose interactive program designed for the study of sequential signals, especially time series data. More information on SAC »

Assembled Data

The IRIS DMC distributes several pre-assembled data sets. Most of these data sets are from temporary deployments and in formats other than SEED. An assembled set is accompanied by a data report. We have assembled data from various sources including IRIS PASSCAL (mostly active source), the USGS, and others.