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U.S. Geological Survey’s Hazard and Impact Assessment of the 2023 Türkiye Earthquake Sequence

Description: 

The 2023 Türkiye earthquake sequence caused devastating losses throughout the region. The U.S. Geological Survey pursued rapid characterization of all aspects of the largest earthquakes, including their complex fault geometries, critical to estimating the shaking and impact. ShakeMap shaking constraints—and thus PAGER loss estimates—naturally evolved with time as we obtained more stations, macroseismic intensities, and better resolution of the fault rupture complexity. Complicating single-event impact assessments was the substantial contribution of aftershocks to losses. This led to reexamining Composite ShakeMap—depicting the maximum shaking at each location for the entire sequence—to estimate the total losses better. Though this approach does not accommodate complexities of population migration (displaced, sheltered, or relocated persons), weakened structures, or reduced building exposure due to prior collapses, loss estimates are improved by considering the maximum shaking integrated across the sequence. Composite ShakeMap also depicts the shaking history at each location, allowing modelers to estimate the number of times a structure’s design level was exceeded. We also introduce a new framework for more rapidly ascertaining the fault dimensions necessary for accurate shaking estimates. Our proposed framework involves enhanced multidisciplinary, near-real-time collaboration among seismologists, engineers, geologists, and geodesists—harmonizing disparate seismological, faulting, imagery, and impact observations needed to constrain rupture complexity controlling the shaking distribution. Lastly, we report on detailed building damage and ground failure estimates, combining prior models and updated with satellite imagery. Such rapid updating is part of an evolving USGS strategy to improve our impact assessments with ground-truth observations rapidly.

Session: February 2023 Mw 7.8 Earthquake Sequence in Turkey

Type: Oral

Date: 4/19/2023

Presentation Time: 02:00 PM (local time)

Presenting Author: David J. Wald

Student Presenter: No

Invited Presentation: 

Authors