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The 2023 Alaska National Seismic Hazard Model: Inputs and Implications

Description: 

The National Seismic Hazard Model (NSHM) Project of the U.S. Geological Survey is tasked with modeling the seismic hazard from potentially damaging earthquakes for the 50 U.S. states and its territories. The last comprehensive assessment for Alaska was published in 2007, and a significant update was released in late 2023. The 2023 Alaska NSHM considers two main input components: an earthquake rupture forecast (ERF) and ground motion model. The 2023 ERF includes over 80 new faults and a refined treatment of the subduction zone, an updated earthquake catalog and new declustering and smoothing algorithms for background seismicity, new geodetic deformation models, and improved modeling of subduction zone interface and intraslab geometries using the SLAB2 model. Relative to the previous model of seismic hazard for Alaska, the new model results (ERF and ground motion) in an overall increase in hazard across the state. We present the ERF model components in a geospatial format and provide assessments of where damaging shaking is likely to occur. The extent of damaging shaking is represented in terms of Modified Mercalli Intensity (MMI), a measure of earthquake effects that describes the strength of earthquake shaking inferred from intensity observations. Test sites (Anchorage, Fairbanks, Juneau, Nome, Prudhoe Bay, and Seward) were reviewed to identify sources of change in hazard, and we describe and represent those locations with their contributing factors in this presentation. Relative change from the 2007 model is presented to highlight where the hazard (or damaging shaking) has increased or decreased.

Session: The 2023 USGS National Seismic Hazard Model and Beyond [Poster Session]

Type: Poster

Date: 5/1/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Julie

Student Presenter: No

Invited Presentation: 

Authors