NASA Home Page Goddard Space Flight Center Home Page
NASA Logo - Goddard Space Flight Center   + Visit NASA.gov
a directory of Earth science data and services Global Change Master Directory Web site
header 2 bullet Links bullet FAQ bullet Contact Us bullet Site Map
Home Data Sets Data Services Learn about GCMD_legacy's portal collaborations. Add new dataset or dataservice records to GCMD_legacy What's New Participate Calendar About GCMD_legacy
 
Record Search Query: ServiceParameters>MODELS>GEOLOGIC/TECTONIC/PALEOCLIMATE MODELS

Earthquake Directivity Model
Entry ID: USGS_isodirect
[ Get Service ]
[ Update this Record ]


Summary
Abstract: Isodirect1 is a MATLAB-language function for modeling seismic directivity at user-selected sites around a user-defined fault. Isodirect1.m implements the Spudich and Chiou (Earthquake Spectra, 2008) directivity model. The results of isodirect1.m should be combined with the ground motion predictions of a non-directive predictive model like any of the four NGA models. Input to isodirect1.m consists of the coordinates of a set of sites where directivity predictions are desired, the coordinates of the corners of one or more fault segments, hypocenter location, earthquake magnitude and slip rake, desired periods for output. Output consists of directivity amplifications for all input sites, plus many intermediate results, such as the points on the fault closest to the input sites, rupture distances, etc.

[Summary provided by the USGS.]

Related URL
Link: GET SERVICE > GET SOFTWARE PACKAGE
Description: This package contains MATLAB-language 'main program' isodirect.m, two scripts that call isodirect1.m to calculate predicted directivity for five test cases, and numeric and plotted output from those test cases.

Link: VIEW RELATED INFORMATION
Description: Directivity in NGA Earthquake Ground Motions: Analysis Using Isochrone Theory:

We present correction factors that may be applied to the ground motion prediction relations of Abrahamson and Silva, Boore and Atkinson, Campbell and Bozorgnia, and Chiou and Youngs (all in this volume) to model the azimuthally varying distribution of the GMRotI50 component of ground motion (commonly called “directivity”) around earthquakes. Our correction factors may be used for planar or nonplanar faults having any dip or slip rake (faulting mechanism). Our correction factors predict directivity-induced variations of spectral acceleration that are roughly half of the strike-slip variations predicted by Somerville et al. (1997), and use of our factors reduces record-to-record sigma by about 2–20% at 5 sec or greater period.
Service Citation
Title: Earthquake Directivity Model
Provider: U.S. Geological Survey
URL: http://earthquake.usgs.gov/research/software/isodirect/
ISO Topic Category
GEOSCIENTIFIC INFORMATION
Access Constraints
None
Service Provider
Earthquake Hazards Program, Geological Division, U.S. Geological Survey, U.S. Department of the Interior

Service Provider Personnel
Name: EARTHQUAKE HAZARDS PROGRAM OFFICE
Contact Address:
12201 Sunrise Valley Drive, MS 905
City: Reston
Province or State: VA
Postal Code: 20192
Country: USA
Distribution Media
Distribution_Media: Online
Distribution_Size: 15 MB
Fees: No fees
Personnel
EARTHQUAKE HAZARDS PROGRAM OFFICE
Role: TECHNICAL CONTACT
Contact Address:
12201 Sunrise Valley Drive, MS 905
City: Reston
Province or State: VA
Postal Code: 20192
Country: USA

TYLER B. STEVENS
Role: SERF AUTHOR
Phone: (301) 614-6898
Fax: 301-614-5268
Email: Tyler.B.Stevens at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City: Greenbelt
Province or State: MD
Postal Code: 20771
Country: USA
Creation and Review Dates
SERF Creation Date: 2012-02-06
SERF Last Revision Date: 2012-02-07
[ Update this Record ]
USA dot gov - The U.S. Government's Official Web Portal NASA
Webmaster:  Monica Lyles
Responsible NASA Official:  Dr. Stephen Wharton
Last Updated:  June 2015