Hydroacoustic Blockage Calibration for Discrimination
The core focus of this hydroacoustic research is to develop a better understanding of hydroacoustic blockage to better predict those stations that can be used in discrimination analysis for any particular event. The research involves two approaches: (1) model-based assessment of blockage and (2) ground-truth data-based assessment of blockage. The goal is to reliably determine all hydroacoustic stations that can be brought to bear on a discrimination analysis from any event location in the world s oceans. An important aspect of this capability is to include reflected T-phases where they reliably occur since reflected T-phases can allow station utilization when the direct path is otherwise completely blocked. We have conceptually designed an approach to automate assessment procedures that will allow both model-based and data-based methodologies to be utilized and in the future, integrated. We have modified the HydroCAM model-based network assessment code to include variable density bathymetry grids. This will improve the reliability of model-based blockage assessment as dense bathymetry grids are added to the bathymetry database where available and needed. We are also running the HydroCAM code to produce blockage grids in the Indian Ocean for many different blockage criteria. We have been building the database necessary to begin the data driven assessment of blockage. At present, the database is accumulating earthquake events within the Indian Ocean basin as recorded at Diego Garcia and Cape Leeuwin. Over 130 events from 2001 and 2002 have been loaded. Now earthquake event data is automatically loaded into the Lawrence Livermore National Laboratory database at 1-hour record lengths to accommodate future reflection phase analysis. Future work will focus on the utilization of reflected T-phases, the automated use of model-based blockage grids, and the enhancement and use of the data-based method for blockage assessment in the Indian Ocean. The analysis methodology will then be applied to other ocean basins to eventually include all ocean basins for a full worldwide blockage assessment capability.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15004854
- Report Number(s):
- UCRL-JC-153967; TRN: US200321%%361
- Resource Relation:
- Conference: Seismic Research Review, Tucson, AZ (US), 09/23/2003--09/25/2003; Other Information: PBD: 11 Jul 2003
- Country of Publication:
- United States
- Language:
- English
Similar Records
Hydroacoustic Studies Using HydroCAM - Station-centric Integration of Models and Observations Quarterly Report No.4 July 2003 - September 2003
Hydroacoustic Studies Using HydroCAM - Station-centric Integration of Models and Observations Quarterly Report No. 2 January 2003 - March 2003