Quality Control of the Alaska Earthquake Center's ShakeMap Product

Session: Regional Earthquake Centers: Highlights and Challenges [Poster]
Type: Poster
Date: 4/28/2020
Time: 08:00 AM
Room: Ballroom
Description: 

The United States Geological Survey’s ShakeMap tool employed by the Alaska Earthquake Center is capable of providing near real-time ground-motion estimates over a continuous geographical region by combining observations, ground-motion prediction equations and site conditions and interpolating the results onto a dense grid. For significant earthquakes, these estimates are used to communicate earthquake severity and to prioritize response activities. Alaska ShakeMaps are provided to the USGS where they are used as input for downstream products such as PAGER and ground failure models. Ground-motion estimates are also highly-useful for public outreach, as they provide an indication of how widely an event was felt and provide valuable situational awareness while interacting with the public. The Alaska Earthquake Center produces ground motion maps for all events in mainland Alaska with magnitude above 3.5 that include peak horizontal velocity, peak ground acceleration and a suite of spectral accelerations. With hundreds of such earthquakes occurring in Alaska every year, we have a large dataset with which to evaluate ShakeMap performance. We chose hundreds of events from a range of tectonic and geographic environments to compile a dataset consisting of thousands of observations and model estimates and performed a rigorous error analysis by comparing model estimates to observations at strong-motion and broadband stations. We considered the error results both spatially and with respect to model inputs, allowing us to identify geographic trends as well as evaluate ground-motion prediction equations and the efficacy of the topographic approximation of Vs30. The diversity of Alaska’s tectonic and geographic setting along with heterogeneous station distribution pose challenges for ground-motion modeling. However, the state’s high-seismicity rate provides a rich dataset for error analysis and will allow us to tune model parameters in order to enhance our ground-motion modeling product.

Presenting Author: Kenneth A. Macpherson

Authors