PACKET RADIO: Siesmic Technospeak
Steve Wolf, W8IZ@W8IZ
(This text from the W8IZ packet radio bulletin
board. It's formatted to fit a 80 character screen.)
MSG # TR SIZE TO FROM @BBS DATE TITLE 42688 B$ 6016 ALL WB3CSY ALLUS 901123 Seismic Data Explained
EXPLANATION OF ABBREVIATIONS AND SYMBOLS APPEARING IN THIS LISTING
Abbreviations in Heading:
UTC TIME - Origin time in Coordinated Universal Time. HRMNSEC - Hour, minute, second. LAT - Geographic latitude in degrees. LONG - Geographic longitude in degrees. DEP - Depth in kilometers. GS MAGS - Magnitudes computed by USGS/NEIS. MB - Body wave magnitude. Msz - Vertical surface wave magnitude. SD - Standard Deviation from the arithmetic mean of residuals. STA USED - Number of stations reporting P or PKP phases used in computation.
Symbols Following Origin Time:
& Indicates that parameters of the hypocenter were supplied or determined by a computational procedure not normally used by NEIS. The source or nature of the determination is indicated by a 2 to 5 letter code enclosed by angle brackets and appearing in the first line of comments. A "-P" appended to the code indicates that the computation is preliminary. These codes are included in the list of abbreviations below.
% Indicates a single network solution. A non-furnished hypocenter has been computed using data reported by a single network of stations for which the date and/or origin time cannot be confirmed from seismograms available to a NEIS analyst. The geometric mean of the semi-major and semi-minor axes of the horizontal 90% confidence ellipse is less than or equal to 16.0 km.
* Indicates a less reliable solution. In general, the geometric mean of the semi-major and semi-minor axes of the horizontal 90% confidence ellipse is greater than 8.5 km and less than or equal to 16.0 km.
? Indiates a poor solution, published for completeness of the catalogue. In general, the geometric mean of the semi-major and semi-minor axes of the horizontal 90% confidence ellipse is greater than 16.0 km. This includes a poor solution computed using data reported by a single network.
Q Indicates a preliminary solution obtained from the NEIC Earthquake Early Alerting Service program "Quick-quake."
The lack of any symbol indicates that the geometric mean of the semi-major and semi-minor axes of the horizontal 90% confidence ellipse is less than or equal to 8.5 km.
Symbols Following Depth:
N Indicates depth was restrained at 33 km for earthquakes whose character on seismograms indicate a shallow focus but whose depth is not satisfactorily determined by the data.
D Indicates depth was restrained by the computer program based on 2 or more compatible pP phases and/or unidentified secondary arrivals used as pP.
G Indicates the depth was restrained by a geophysicist.
* Indicates a less well-constrained free depth. The 90% marginal confidence interval on depth is greater than 8.5 km and less than or equal to 16.0 km.
? Indicates a poorly-constrained free depth. The 90% marginal confidence interval on depth is greater than 16.0 km.
The lack of any symbol indicates that the 90% marginal confidence interval on depth is less than or equal to 8.5 km, or that a contributed hypocenter was computed with a free depth, regardless of the size of the confidence interval.
Symbols and Abbreviations Used in Comments:
BLA Virginia Polytechnic Institute and State University, Blacksburg. BRK University of California, Berkeley. CL Coda length magnitude. DOE U.S. Department of Energy. ERDA U.S. Energy Research and Development Administration. EXPLO Some or all parameters of explosion (controlled or accidental) supplied by any group or individual other than ERDA or its successor organizations. GLD U.S. Geological Survey, Golden, Colorado (other than NEIS). GS U.S. Geological Survey, Menlo Park, California HVO Hawaiian Volcano Observatory. JMA Japan Meteorological Agency (generally used to indicate 7-point Japanese Intensity Scale). LDG Laboratoire de Detection et de Geophysique, Montrouge, France. MACRO Hypocenter based upon macroseismic information. MD Duration magnitude. NEIS U.S. Geological Survey, National Earthquake Information Service, Golden, Colorado OTT Earth Physics Branch, Ottawa, Canada. PAL Columbia University, Lamont-Doherty Observatory, Palisades, New York. PAS California Institute of Technology, Pasadena. PGC Pacific Geoscience Centre, Sidney, British Columbia, Canada. PMR Alaska Tsunami Warning Center, Palmer, Alaska. RF Rossi-Forel Intensity Scale. SEA University of Washington, Seattle. SLC University of Utah, Salt Lake City. SLM St. Louis University, Missouri. TEIC Tennessee Earthquake Information Center, Memphis. TUL Oklahoma Geological Survey, Leonard. WES Weston Observatory, Massachusetts.
Roman Used to indicate intensity (when not followed by RF or JMA they refer Numerals c -P Supplied hypocenter is a preliminary computation.
Any additional 3 to 5 letter codes enclosed i
For an explanation of other topics such as magnitude formulas, travel time tables or intensity scales, please refer to the latest January or July issue of the publication "Preliminary Determination .
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