ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS; REPORTING PERIOD NOVEMBER 1, 2006 - JANUARY 31, 2007

PDF Version Also Available for Download.

Description

The amplitude fluctuations of seismic waves from point source radiation patterns are among the direct results of rupture propagation. However, these amplitude signals are seldom used for small earthquakes due to the large uncertainties in the focal mechanisms of the events or the empirical Green’s functions (EGFs). Moreover, it has been controversial if radiation patterns still exist at high frequencies, e.g., 10 Hz. We present an evidence for high frequency radiation patterns by showing that with accurately determined focal mechanism solutions, the broadband P wave records from a thrust event (M 3.0) can be turned into those from a distinctly ... continued below

Creation Information

Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J. January 31, 2007.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Sponsor

Publisher

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

The amplitude fluctuations of seismic waves from point source radiation patterns are among the direct results of rupture propagation. However, these amplitude signals are seldom used for small earthquakes due to the large uncertainties in the focal mechanisms of the events or the empirical Green’s functions (EGFs). Moreover, it has been controversial if radiation patterns still exist at high frequencies, e.g., 10 Hz. We present an evidence for high frequency radiation patterns by showing that with accurately determined focal mechanism solutions, the broadband P wave records from a thrust event (M 3.0) can be turned into those from a distinctly different strike slip event of similar magnitude with simple radiation pattern corrections. Moreover, we observe systematic azimuthal variations in the P and S wave amplitude ratios between the records from unilateral magnitude 4 events and the EGF events, which suggest that these simple amplitude ratios can provide fast and useful indications of the rupture directivity. For further estimates of the fault dimension and rupture speed, we developed a forward modeling approach to retrieve apparent source time functions (ASTFs) of small earthquakes, where we assume simple Haskell model and take a grid search approach to find the ASTFs for each recording station. Compared to the usually used deconvolution approach, this method fully utilizes the information of both duration as well as amplitude. We applied this approach to the 2003 Big Bear sequence, and successfully obtained the complex rupture propagation patterns of the few large events (3.5 < M < 4.25), where both uni-lateral and bi-lateral events, fast and slow rupture speeds are observed.

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Report No.: DOE/DE-FC52-06NA27319
  • Grant Number: FC52-06NA27319
  • DOI: 10.2172/898293 | External Link
  • Office of Scientific & Technical Information Report Number: 898293
  • Archival Resource Key: ark:/67531/metadc888155

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • January 31, 2007

Added to The UNT Digital Library

  • Sept. 22, 2016, 2:13 a.m.

Description Last Updated

  • Oct. 31, 2016, 7:45 p.m.

Usage Statistics

When was this report last used?

Congratulations! It looks like you are the first person to view this item online.

Interact With This Report

Here are some suggestions for what to do next.

Enlarge

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Helmberger, Donald V.; Tromp, Jeroen & Rodgers, Arthur J. ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS; REPORTING PERIOD NOVEMBER 1, 2006 - JANUARY 31, 2007, report, January 31, 2007; United States. (digital.library.unt.edu/ark:/67531/metadc888155/: accessed December 12, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.