Error Analysis in the Joint Event Location/Seismic Calibration Inverse Problem
Abstract
The goal of this project was to develop new mathematical and computational techniques for quantifying the errors in seismic event locations, focusing on the effects of errors in travel-time predictions from a velocity model. Our approach associates these model errors with the uncertainty in path travel-time corrections inferred from a calibration analysis. The main accomplishment of the project was a general formulation of location uncertainty in terms of the joint inverse problem that combines event location and seismic calibration. The formulation accommodates travel-time nonlinearity, Gaussian and non-Gaussian observational error, and a broad class of parameterizations of path travel-time corrections. We implemented the formulation for the simple correction parameterization as station time terms, applying it to data from the Nevada Test Site (NTS) as a proof of concept of the joint inversion approach. To address the computational intensity of the approach, we re-formulated it as an approximate, two-stage process - calibration followed by location - which we also implemented for the time-term case using newly designed algorithms for each stage. Application of the two-stage approach to NTS data demonstrated its much greater efficiency and suggest it as a feasible uncertainty paradigm for more complex problems in which travel-time corrections are parameterized with 3-D Earth models.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 15, 2008
- Accession Number
- ADA480194
Entities
People
- William L. Rodi
Organizations
- Massachusetts Institute of Technology