34-2 Source Characterization in the Northernmost Andes Through Ground Motion Variability

Session: Advancing Earthquake Geology and Surficial Deformation from Geologic Provinces to Political Entities through Multidisciplinary High-Resolution Data (Posters)

Presenting Author:

Authors:

Abstract:

Shallow continental earthquakes cause significant numbers of fatalities worldwide. Studying seismic sources is a fundamental step in assessing seismic hazard.

The tectonic setting of the region is characterized by the subduction of the Nazca and Caribbean plates beneath the South American continental plate. The latter consists of an ensemble of tectonic blocks that interact with each other, producing crustal deformation and an active continental region under transpression regime. In this study, we analyze ground motion variability related to earthquakes along the main seismic sources of the Northernmost Andes, which define the boundaries of these tectonic blocks in the longest mountain range in the world.

We used a dataset of approximately 7,000 earthquakes with corresponding acceleration records. Ground Motion Models (GMMs) were applied to statistically fit the data and identify the model that best represents ground motion in the region. We then quantified ground motion variability—specifically between-event variability (delta Be) and between- tectonic locality variability (delta L2L)—to identify spatial patterns and delineate fault segments with similar behavior. This approach enables us to characterize the seismic behavior of faults along the Northern Andean Cordillera.

Furthermore, delta Be has been correlated with earthquake parameters such as stress drop, making it a potential indicator for distinguishing fault behavior, such as creeping versus locked segments along major faults. We also analyzed other source parameters and explored how these relate to structural complexity in the region.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9296

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