A systematic approach for identifying fault zones in Seismic reflection data
Abstract
Traditional structural interpretation methods applied to seismic reflection data are inherently non-unique and are subject to a priori geologic assumptions. Complex or poorly resolved reflection profiles can thus lead to multiple possible structural models, the relative accuracy of which are often difficult to discern between. Additionally, qualitative interpretations applied to individual profiles can make it difficult to identify how different deformation features are distributed throughout a fault zone or to efficiently communicate the holistic interpretation of a model geographically. Here, we present an approach to quantify structural characteristics used to denote faulting in seismic reflection data, and apply this approach to develop a new model for the Seattle fault zone (SFZ) in western Washington State.
In A.D. 900-930, a M 7.0-7.5 earthquake ruptured a blind, north-vergent thrust fault in the SFZ, resulting in up to 8 meters of vertical land level changes, a local tsunami, and probable concurrent surface rupture on north-dipping back-thrusts. Multiple studies have interpreted regional crustal-scale seismic reflection datasets, leading to a list of non-unique structural models that explain the SFZ geometry. The metrics that are used to denote tectonic deformation in these seismic interpretations include: 1) changes in bedding plane dip, 2) reflector truncations, and 3) zones of incoherence. Here we present an approach for quantifying these metrics via an objective coherence analysis in all existing regional seismic profiles. We extend this approach to a new, high-resolution marine seismic reflection dataset, illuminating additional near surface deformation. We evaluate these metrics in the marine setting around Seattle to objectively map the spatial connectivity of fault zone structures. This approach is presented as a quantitative complement to traditional seismic interpretation methods, making structural interpretations more accessible and unbiased.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T41H0361M
- Keywords:
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- 8036 Paleoseismology;
- STRUCTURAL GEOLOGY;
- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS;
- 8123 Dynamics: seismotectonics;
- TECTONOPHYSICS;
- 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS