← Back to Sessions

WITHDRAWN When Ruptures Don’t Care: Hazard Implications of Modeling an Unsegmented Alaska-Aleutian Subduction Interface

Description: 

WITHDRAWN The Alaska-Aleutian Subduction Interface is considered a “Megathrust” fault for its ability to generate earthquakes of magnitudes larger than 9. In 1964, the Megathrust generated a Mw9.2 earthquake, the second-largest earthquake magnitude on record! In modeling interface sources, slab tears and various geological features (e.g., fracture zones, or discontinuities in rupture-governing parameters) are often thought of as boundaries to rupture propagation. The US Geological Survey’s (USGS’) National Seismic Hazard Model 2023 considers 14 segments with selected, prescribed multi-segment rupture possibilities. Another segmentation configuration was proposed by Porto and Fitzenz (2016), where they identified two robust segment boundaries along the interface based on zonal seismicity characteristics. As the USGS moves more toward relaxing segmentation in both their crustal fault (e.g., Uniform California Earthquake Rupture Forecast3) and subduction interface (e.g., upcoming Puerto Rico Virgin Islands update) models, we likewise take a step in this direction for the Alaska Interface. In this work, we propose modeling the Alaska-Aleutian interface without any segment boundaries to rupture propagation.

We investigate the effects of this model on hazard around Anchorage and other cities in Alaska. Since subduction interfaces are bustling with substantial fluid and heat flows and high strain rates and are constantly evolving in many degrees of freedom, we face the quandary of whether the lack of historical precedence of rupturing through a potential segment boundary implies future impossibility. The unsegmented modeling methodology attempts to better incorporate the effects of uncertainties around segment boundaries, including rupture extents of historical events, heterogeneities in material properties and occurrence rates, and accommodate the dynamic nature of this formidable geologic feature

Session: Compiling Active Faults for Improved Hazard Modeling from Cascadia to Alaska [Poster]

Type: Poster

Date: 4/17/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Noha

Student Presenter: No

Invited Presentation: 

Poster Number: 75

Authors