28 June 2021 to 2 July 2021
Europe/Vienna timezone

Comparing three-dimensional velocity models for seismic location accuracy using a consistent travel time framework

30 Jun 2021, 12:25
Location 2 (Online)

Location 2


Oral T3.5 - Data Analysis Algorithms T3.5 - Data Analysis Algorithms


Mr Michael L. Begnaud (Los Alamos National Laboratory (LANL), Los Alamos, NM, USA)


Location algorithms have relied on simple, 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. Higher-dimensional (2D-3D) seismic velocity models are becoming readily available and provide more accurate event locations over 1D models. The computational requirements of these 2D-3D models tend to make their operational use prohibitive. 1D are generally used as travel-time lookup tables, one for each seismic phase, with travel-times pre-calculated for event distance and depth, that are extr fast to use. Comparing location accuracy for 2D-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 will demonstrate the current/updated ability to quickly create travel-time correction surfaces using an open-source framework (PCalc+GeoTess, www.sandia.gov/geotess) that easily stores 3D travel-time data. This framework overcomes the ray-tracing algorithm hurdle because the lookup tables can be generated using the exact ray-tracing algorithm that is preferred for the model. Having a common travel-time framework for a location algorithm allows individual velocity models to be compared in a fair, consistent manner.

Promotional text

Allowing for direct comparison and/or use of 3D velocity models pertains to Goal 1 for identifying opportunities/methods for improving nuclear test monitoring. Goals 4-5 are also relevant for supporting the exchange of knowledge and promoting wider application of techniques.

Primary author

Mr Michael L. Begnaud (Los Alamos National Laboratory (LANL), Los Alamos, NM, USA)


Mr Sanford Ballard (Sandia National Laboratories (SNL), Albuquerque, NM, USA) Mr Christopher Young (Sandia National Laboratories (SNL), Albuquerque, NM, USA) Ms Andrea Conley (Sandia National Laboratories (SNL), Albuquerque, NM, USA) Mr Patrick Hammond (Sandia National Laboratories (SNL), Albuquerque, NM, USA)

Presentation materials