Description of output from a search of the ISC Database

Contents

• IMS 1.0 ( abridged )
• Bulletin
  • Bulletin Title
  • Event Title
  • Origin Block
  • Magnitude Sub-block
  • Comment Sub-block
  • Phase Block
  • Station Block
• Arrival
• Extended Formats
  • Bibliographic Citations
  • Moment Tensor Origin Comments
  • Fault Plane Solution Origin Comments
  • Principal Axes Origin Comments
  • Additional Parameter Origin Comments
• Links to other Relevant Information
  • BATS Broadband Array in Taiwan for Seismology
  • GFZ GeoForschungsZentrum Potsdam
  • IRIS Incorporated Research Institutions for Seismology
  • IRIS Incorporated Research Institutions for Seismology, Wilber II
  • MedNet MedNet Data Centre
  • ORFEUS ORFEUS Data Centre
  • Tokyo Earthquake Research Institute
  • Michigan University of Michigan
  • Harvard Harvard University
  • Xerox PARC Xerox Palo Alto Research Center (Map)
  • COSMOS Virtual Data Center

IMS 1.0, Format of Returned Data

The format of the return is International Monitoring System 1.0 (IMS1.0), a standard that was developed for exchanging data used to monitor the Comprehensive Test Ban Treaty. A 2.8 MB PDF document that includes a description of the format can be downloaded from the Prototype International Data Centre. IMS1.0 is very similar to GSE2.1. Documentation for GSE2.1 is available in a variety of formats from the Swiss Seismological Service's AutoDRM documentation page.

The format used for moment tensors is part of the draft IASPEI Seismic Format (ISF). ISF is an extension of IMS1.0 being developed by the IASPEI Commission on Practice. This document is in PDF form and can be downloaded from the ISC.

A brief description of the format of the relevant data returned by the ISC search, as extracted from the IMS1.0 documentation is given in the following sections:

• Bulletin Title
• Event Title
• Origin Block
• Magnitude Sub-block
• Comment Sub-block
• Phase Block
• Bibliographic Citations
• Moment Tensor Origin Comments
• Fault Plane Solution Origin Comments
• Principal Axes Origin Comments
• Additional Parameter Origin Comments

Bulletin

Bulletins are composed of origin and arrival information. The information is pro-vided in a series of data blocks as shown in Table 38: bulletin title block (Table 39), event title block (Table 40), origin block (Table 41), phase block (Table 42), phase correction block (under development), event screening block (Table 43), and event characterization arrival block (Table 44). The verbosity of a bulletin can be controlled by specifying the subformat, which can be short or long. The default is short. The BULL_TYPE environment and the subformat control the blocks of information that appear in a bulletin. Table 38 lists the blocks that are included for each BULL_TYPE and subformat. A BULLETIN data message contains one bulletin title block and one set of the other block types for each event. The blocks in a BULLETIN data message appear in the order given in Table 38. Examples of the short and long subformats for bulletins are provided in Bulletin (IMS1.0:short Format) on page A16 and Bul-letin (IMS1.0:long Format) on page A16.

TABLE 39: BULLETIN TITLE BLOCK FORMAT

TABLE 40: EVENT TITLE BLOCK FORMAT

TABLE 41: ORIGIN BLOCK FORMAT

TABLE 42: PHASE BLOCK FORMAT

TABLE 11: STATION BLOCK FORMAT

TABLE 36: GROUPED ARRIVAL FORMAT

The grouped subtype is used for arrivals that have phase names and have been grouped together, with the implication that they were generated by the same seismic event. Table 36 gives the format for the grouped data subtype.

Bibliographic Citations

Prior to 1996 the ISC bibliography provided a link between events and research papers associated with them. This data block reproduces the ISC bibliography, though please note that the format has not been finalised.

Table: Bibliographic Citations

Moment Tensor Origin Comments

Each moment tensor report is comprised of two header lines and a variable number of pairs of data lines. All of the moment tensors in one report are for the same origin, which precedes the report. Several items are omitted: "Centroid, since it is presumed to precede in an origin line. "The best fitting double-couple, since it could follow as a FAULT_PLANE comment. "Principal axes, since they could follow as a PRINAX comment. "MW, since it could be included in the magnitude sub-block associated with the event. Several redundant items are included: "All three diagonal elements of the moment tensor are included since non-isotropic moment tensors may be reported occasionally "Scalar moment, fraction CLVD and their uncertainties are included since these may be the most frequently used moment tensor parameters.

Table: Formatted Moment Tensor Comment

Fault Plane Solution Origin Comments

Either one plane or two may be given.

Table: Fault Plane Solution Origin Comment

Principal Axes Origin Comments

Principal axes can be computed from either a moment tensor or a fault plane solution. A bulletin may include the principal axes alone, or as well as the moment tensor or fault plane solution from which they were computed. Principal values are optional since they may not be available if the principal axes are computed from a fault plane solution based on first motions. The error header and error lines are each optional. ISPF writers should write the error header if the error data line is written. ISPF parsers should be able to parse the error line regardless of whether or not the error header line is present.

Table: Formatted Principal Axes Origin Comment

Additional Parameter Origin Comments

After the keyword PARAM, each origin parameter comment consists of a set of names from the MSOP list of earthquake parameters followed by an equal sign and a value. Spaces are not allowed before or after the equal sign, but are instead reserved as a separator between measurements. Units are not given for the measurements, but specified for each standard measurement name (e.g., STRESS_DROP must be given in Pascals). Values must be stated as real numbers including a decimal point and may include an exponent, indicated by an upper-case E , e.g., 1.0E27.

Table: Formatted Additional Parameter Origin Comment

Table: Preliminary List of Additional Origin Parameters

Links to other Relevant Information

The icons included with each suitable event are links to other froms of data about the event, such as moment tensor solutions or waveform data. These links are not to data at the ISC but directly to the event information on the website of the agency or institution concerned. Where possible links have been included in the description to further details of the information displayed on following each link.

Broadband Array in Taiwan for Seismology

Broadband Array in Taiwan for Seismology (BATS) routinely estimates the source parameters of earthquakes occurring in the region. The link provided is to the image file posted on the BATS website.

GeoForschungsZentrum Potsdam (GFZ)

The GEOFON SPYDER node presently regularly retrieves the data from about 40 stations e.g. nearly all permanent GEOFON stations and a set of other stations in Central Europe for all global events larger mb 5.5. This system is a common effort with IRIS DMC, ORFEUS DC and several other SPYDER nodes worldwide triggered by NEIC alerts. From GFZ, the GEOFON SPYDER data are distributed to ORFEUS Data Center and IRIS DMC by Internet and their data are copied to Potsdam the same way. Therefore several hours after origin time the event data for up to over 100 stations become available at the GEOFON DC for all major global events.

A more detailed description of the data from the GFZ link and other sevices can be found on the GFZ website.

Incorporated Research Institutions for Seismology (IRIS)

The IRIS Fast Archive Recovery Method ( FARM ) provides a source of information about events of magnitude 5.7 or larger or deep events of magnitude 5.5 and larger. Each data set will include atleast:

• .contents file a summary of the seismograms.
• .gif file showing the long period vertical channels for all stations contained in the FARM product.
• .seed file.

More information on the FARM data can be found on the IRIS website.

Incorporated Research Institutions for Seismology (IRIS)

The IRIS Wilber II interface offers an improved service over the previous FARM system ( detailed above ). More details can be seen about Wilber II at the IRIS website. Data selection can also be made from the Wilber II interface.

MedNet Data Centre

Regional Centroid Moment Tensor solutions from the MedNet ( Very-broadband seismographic network in the Mediterranean )

ORFEUS Data Centre

Provides direct access to the waveform data at the Royal Netherlands Meteorological Institute as part of the ORFEUS Data Centre. The data is in the form of SUN binary files and contains:

• Broad-band (generally 3-comp) with time window 4-10 minutes
• Long Period (3-comp) with time window 4-93 minutes
• Very Long Period (3-comp) with time window of 5 hours

Earthquake Research Institute

This link is to the Centroid Moment Tensor (CMT) calculated by the Earthquake Research Institute (ERI) at the University of Tokyo. These CMT solutions are automatically calculated and posted on the internet by the ERI. A brief description of the data and a full listing of the available soltuions can be accessed on the ERI website.

University of Michigan

The Department of Geological Sciences at the University of Michigan provides access to summary information on Moment Tensor Rate Functions solutions and Source Time Function solutions (STF) as part of the Seismological Observatory.

The icon shown above provides a link to the STF solution.

Harvard University

The Harvard Seismology, Centroid-Moment Tensor Project routinely calculates Centroid Moment Tensor solutions for events with a moment magnitude (Mw) greater than 5.5. The link provided here is to the solution which matches certain parameters of the event in question. On occaisions more than one solution may be returned if a number of events occur in close proximity.

The icon shown above provides a link to the STF solution.

Xerox Palo Alto Research Center

The Xerox Palo Alto Research Center (Xerox PARC) provides a server that produces maps from http requests.

The link provides a simple map that shows the position of the station or of the epicentres for an event.

COSMOS Virtual Data Center

The Consortium of Organizations for Strong-Motion Observation Systems COSMOS provides access to a number of strong-motion data sources.