Event 20020420
 
         
 
EVENT ON
Apr 20 2002
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Instrumental
Intensity
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Peak Ground
Acceleration
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Peak Ground
Velocity
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Focal
Mechanism
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Format Information
Maps:
JPEG JPEG (which stands for Joint Photographic Experts Group, the standards body that created it) is a 24-bit, platform-independent image and graphics format. This format can be viewed in any web browser, and can be manipulated by most image-production applications. The compression scheme is "lossy" though, so multiple generations of editing and saving will degrade the image.
Postscript A language to describe graphics independently of the resolution of the output device. Printers with Postscript drivers will rasterize these printer files to high-quality map plots.
8-1/2 x 11 Postscript file with map sized to print on 8.5" x 11" paper.
Poster Postscript file with map sized to print on a poster printer (approximately 32" x 28"). This file is only available for larger earthquakes.
PDF Portable Document Format. Can be viewed and printed with the free Adobe Acrobat Reader. More information about Acrobat and a software download site are available http://www.adobe.com/products/acrobat/readstep.html. This file is only available for larger earthquakes.
Files:
Raw Grids
Text X, Y, Z Values

Values of the peak amplitudes at the ShakeMap map grid nodes. File is ASCII text in the following format:

First line is a header with:
<name/CUSPID of event> <mag> <epicentral lat> <epicentral lon> <MMM DD YYYY> <HH:MM:SS timezone> <W bound> <S bound> <E bound> <N bound> (Process time: <time>) <Location String>

The first 'time' field is the time of the event.
'Process time' is the time this file was last updated.

ex:
Northridge 6.7 34.213 -118.5357 JAN 17 1994 04:30:55 PST -119.1857 33.7775 -117.857 34.6485 (Process Time: Wed Nov 4 17:25:18 1998) Northridge Earthquake

For large or historic earthquakes the "Location String" will usually be the name of the earthquake, otherwise it will be something of the form "12.1 mi. SSW of Carpinteria, CA"

The remaining lines are of the form:
<lon> <lat> <pga> <pgv> <mmi> <psa03> <psa10> <psa30>

psa03 = spectral acceleration at 0.3 s period, 5% damping.
psa10 = spectral acceleration at 1.0 s period, 5% damping.
psa30 = spectral acceleration at 3.0 s period, 5% damping.

For pga value == (%g)
For pgv and psa?? value == (cm/s)
For mmi value == Intensity
For psa value == (%g)

GIS Files:
HAZUS ZIP File

Contour polygons of the peak ground motion amplitudes in ArcView shape files. This is an archive of files (three files for each of the mapped parameters) compressed in zip format.

The three files are:
.dbf = A DBase file with layer attributes
.shp = The file with geographic coordinates
.shx = An index file

These shape files are designed with intervals that are appropriate for use with the HAZUS software, though they may be imported into any GIS package that can read ArcView shapefiles. Because HAZUS expects PGV in inches/sec, this file may not be suitable for all applications; see "Shape Files" below for another set of shapefiles with more generally useful units.

The contour intervals are 0.04g for PGA and the three spectral acceleration parameters (only two of which are used by HAZUS), and 4 inches/second for PGV. The file also includes MMI contour polygons in intervals of 0.2 intensity units.

The HAZUS GIS files are only generated for events that are larger than (approx.) M5.0.

If you are unfamiliar with using shape files to run HAZUS, see the tutorial.

Shape Files

High-resolution contour polygons of the peak ground motion parameters in ArcView shape files. This is an archive of files (three files for each of the mapped parameters) compressed in zip format.

The three files are:
.dbf = A DBase file with layer attributes
.shp = The file with geographic coordinates
.shx = An index file

These shape files are intended for use with any GIS software that can read ArcView shape files. Note, however, that the PGV contours are in cm/s, and are therefore NOT suitable for HAZUS input.

The contour intervals are 0.04g for PGA and the three spectral acceleration parameters (only two of which are used by HAZUS), and 2 cm/sec for PGV. The file also includes MMI contour polygons in intervals of 0.2 intensity units.

shape.zip is available for all events, but the spectral values are only included for earthquakes of magnitude 5.0 and larger.

Station Lists:
Text

A table of earthquake and station parameters, formatted to be read easily by humans. An XML formatted file is also available, and is the best option for parsing the information by computer.

The earthquake information includes: CUSP ID, magnitude, date, time, epicenter coordinates and depth.

The station information includes name and/or code, location coordinates, and peak velocity and acceleration values.

Stations may be flagged to indicate they were not used in the ShakeMap processing. The types of flags are indicated at the bottom of the list.

XML

A table of earthquake and station parameters, tagged in XML format for parsing by computer. The DTD defining the structure of the XML flags is incorporated in the file.

The earthquake information includes: CUSP ID, magnitude, date, time, epicenter coordinates and depth.

The station information includes name and/or code, location coordinates, and peak velocity and acceleration values.

Stations may be flagged to indicate they were not used in the ShakeMap processing. The types of flags are indicated at the bottom of the text version of the station list.

For more information on XML and XML parsers, see the XML page of the World Wide Web Consortium.

Media Maps:
General The Media Maps are simplified versions of the Instrumental Intensity maps (PostScript and JPEG format, see above). While the intensity information they contain is exactly the same as that in the other maps, they are packaged in a way that makes them more suitable for broadcast to low-resolution devices, such as TV monitors: roads and borders are thicker, fonts are larger, and the title and intensity scale are simplified.
Decorated Shows state borders, map title, simplified intensity scale, and the intensity overlay. Includes some city names, major freeways and a distance scale.
Bare Shows only state borders, latitude, longitude, and the shaking intensity.
Info Sheet Intended to supplement the Media Maps, the Info Sheet is a text file that provides basic event information, organizational credits, contact information, and information about earthquake intensities and ShakeMap.