← Back to Sessions

Optimizing Grids for National Earthquake Hazard Mapping Projects

Session: Probabilistic Seismic Hazard Assessment: Where Do We Go from Here? [Poster]

Type: Poster

Date: 4/20/2021

Presentation Time: 11:30 AM Pacific

Description: 

Traditionally, seismic hazard maps are generated by gridding and then contouring seismic hazard values which are calculated on a semi-fixed regular grid (e.g., 0.1⁰, or 10 km, or 1 per 100 km2). The regular grid used for the Canadian seismic hazard maps prior to 2020 was composed of a 10 km equally spaced grid of roughly 206,000 points. In addition to being used to generate the hazard maps, this grid was also used to deliver online seismic hazard values for the National Building Code of Canada (NBCC) through the use of inverse distance weighted interpolation. For the 6th Generation model (CanadaSHM6, as proposed for NBCC 2020) the number of unique products has increased by more than an order of magnitude due to the move from a single reference site condition to a wide range of reference conditions based on V_S30 and Site Class. As a result of the increased computational load, the fact that hazard values are generally spatially smooth, and that for large regions within Canada the gradient of hazard is low, it is not efficient or computationally-practical to use a dense fixed grid. This presentation will discuss a new strategy adopted for CanadaSHM6 which through adaptive sampling uses a variable grid of roughly 30,000 points (i.e., 1/7th the number of points) which results in interpolated hazard values in excellent agreement with those of the regular grid.

Presenting Author: Michal Kolaj

Student Presenter: No

Authors