3D architecture and complex behavior along the simple central San Andreas fault

The central San Andreas Fault (CSAF) exhibits a simple linear large-scale fault geometry, yet seismic and aseismic deformation features vary in a complex way along the fault. Here we investigate fault zone behaviors using geodetic observation, seismicity and microearthquake focal mechanisms. We empl...

Full description

Saved in:
Bibliographic Details
Published in:Nature communications 2024-06, Vol.15 (1), p.5390-12, Article 5390
Main Authors: Cheng, Yifang, Bürgmann, Roland, Allen, Richard M.
Format: Article
Language:English
Subjects:
704/2151/2809
704/2151/508
704/2151/562
704/4111
Creep rate
Earthquakes
Geological faults
Humanities and Social Sciences
Kinematics
Mechanical properties
multidisciplinary
Science
Science (multidisciplinary)
Seismic activity
Seismicity
Spatial variations
Stress distribution
Citations: Items that this one cites
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The central San Andreas Fault (CSAF) exhibits a simple linear large-scale fault geometry, yet seismic and aseismic deformation features vary in a complex way along the fault. Here we investigate fault zone behaviors using geodetic observation, seismicity and microearthquake focal mechanisms. We employ an improved focal-mechanism characterization method using relative earthquake radiation patterns on 75,164 M l  ≥ 1 earthquakes along a 2-km-wide, 190-km-long segment of the CSAF, from 1984 to 2015. The data reveal the 3D fine-scale structure and interseismic kinematics of the CSAF. Our findings indicate that the first-order spatial variations in interseismic fault creep rate, creep direction, and the fault zone stress field can be explained by a simple fault coupling model. The inferred 3D mechanical properties of a mechanically weak and poorly coupled fault zone provide a unified understanding of the complex fine-scale kinematics, indicating distributed slip deficits facilitating small-to-moderate earthquakes, localized stress heterogeneities, and complex multi-scale ruptures along the fault. Through this detailed mapping, we aim to relate the fine-scale fault architecture to potential future faulting behavior along the CSAF. This study on the central San Andreas Fault shows how its fine-scale structures and kinematics, resolved using high-quality focal mechanisms of small earthquakes, are influenced by a weak, poorly coupled fault zone.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-024-49454-z