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Using Mapped Tectonic Faults as a Record of Past Earthquakes to Predict Future Surface Rupture Location

Description: 

In surface-rupturing earthquakes, fault displacement can damage infrastructure that crosses fault zones. Geologists often predict future fault rupture locations from faults mapped based on landforms interpreted from remote sensing datasets like lidar topography and imagery. The effective use of fault maps for this purpose requires the following: Past earthquakes must create a persistent record in the landscape’s geology and/or geomorphology. For example, earthquakes may create landforms such as fault scarps and triangular facets that are not significantly obscured by erosion. Geologists must accurately identify surface features, understand how tectonic and surface processes modify the landscape, and integrate these interpretations into the fault map. The record of past earthquakes must serve as a dependable predictor of future earthquakes, requiring that earthquakes largely rupture pre-existing faults.

We evaluated the accuracy of regional-scale fault maps in predicting the location of surface ruptures during the subsequent earthquake. Based on seven earthquakes with varying slip sense and in different climates, we found that the mapped faults predicted 12%- 68% of the principal ruptures with 15-30 m median separation distances between the predicted ruptures and well-mapped faults. We also investigated how tectonic landform type and surficial lithologic age influence fault location uncertainty. Certain tectonic landforms such as fault scarps and range fronts mapped prior to the earthquakes showed lower location error, while faults cutting Holocene units exhibited larger errors. Our work to quantify uncertainty in fault location mapping will improve engineering assessments, risk management and the definition of fault study and exclusion zones.

Session: The Landscape Record of Earthquakes and Faulting - I

Type: Oral

Date: 4/16/2025

Presentation Time: 08:30 AM (local time)

Presenting Author: Chelsea

Student Presenter: No

Invited Presentation: Yes

Poster Number:

Authors