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Using a Consistent Travel-time Framework to Compare Three-dimensional Seismic Velocity Models for Location Accuracy

Description: 

Location algorithms have relied on one-dimensional (1D) velocity models for fast, seismic event locations. The fast computational speed of these models made them the preferred type of velocity model for operational needs. 3D seismic velocity models are becoming readily available and usually provide more accurate event locations over 1D models. The computational requirements of 3D models tend to make their operational use prohibitive. Comparing location accuracy for 3D seismic velocity models tends to be problematic as each model is determined using different ray-tracing algorithms. Attempting to use a different algorithm than used to develop a model usually results in poor travel-time prediction. We have previously demonstrated and validated the ability to quickly create 3D travel-time correction surfaces using an open-source framework (PCalc+GeoTess, www.sandia.gov/salsa3d, www.sandia.gov/geotess) that stores spatially-varying data, including 3D travel-time data. This framework overcomes the ray-tracing algorithm hurdle because the lookup tables can be generated using the preferred ray-tracing algorithm. We have created first-P 3D travel-time correction surfaces for several publicly available 3D models (e.g., RSTT, SALSA3D, G3D, DETOX-P2, etc.). We demonstrate using these correction surfaces to compare models fairly and consistently for seismic location accuracy via a set of validation events and International Monitoring System (IMS) stations.

Session: Emerging Developments in Operational Monitoring Systems and Products

Type: Oral

Date: 4/18/2023

Presentation Time: 05:15 PM (local time)

Presenting Author: Michael Begnaud

Student Presenter: No

Invited Presentation: 

Authors