Rates and patterns of surface deformation from laser scanning following the South Napa earthquake, California
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- 3D point cloud data from laser scanning along the 2014 South Napa Earthquake surface rupture, California, USA
- USGS data release - 3D point cloud data from laser scanning along the 2014 South Napa Earthquake surface rupture (2016)
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Abstract
The A.D. 2014 M6.0 South Napa earthquake, despite its moderate magnitude, caused significant damage to the Napa Valley in northern California (USA). Surface rupture occurred along several mapped and unmapped faults. Field observations following the earthquake indicated that the magnitude of postseismic surface slip was likely to approach or exceed the maximum coseismic surface slip and as such presented ongoing hazard to infrastructure. Using a laser scanner, we monitored postseismic deformation in three dimensions through time along 0.5 km of the main surface rupture. A key component of this study is the demonstration of proper alignment of repeat surveys using point cloud–based methods that minimize error imposed by both local survey errors and global navigation satellite system georeferencing errors. Using solid modeling of natural and cultural features, we quantify dextral postseismic displacement at several hundred points near the main fault trace. We also quantify total dextral displacement of initially straight cultural features. Total dextral displacement from both coseismic displacement and the first 2.5 d of postseismic displacement ranges from 0.22 to 0.29 m. This range increased to 0.33–0.42 m at 59 d post-earthquake. Furthermore, we estimate up to 0.15 m of vertical deformation during the first 2.5 d post-earthquake, which then increased by ∼0.02 m at 59 d post-earthquake. This vertical deformation is not expressed as a distinct step or scarp at the fault trace but rather as a broad up-to-the-west zone of increasing elevation change spanning the fault trace over several tens of meters, challenging common notions about fault scarp development in strike-slip systems. Integrating these analyses provides three-dimensional mapping of surface deformation and identifies spatial variability in slip along the main fault trace that we attribute to distributed slip via subtle block rotation. These results indicate the benefits of laser scanner surveys along active faults and demonstrate that fine-scale variability in fault slip has been missed by traditional earthquake response methods.
Study Area
Publication type | Article |
---|---|
Publication Subtype | Journal Article |
Title | Rates and patterns of surface deformation from laser scanning following the South Napa earthquake, California |
Series title | Geosphere |
DOI | 10.1130/GES01189.1 |
Volume | 11 |
Issue | 6 |
Year Published | 2015 |
Language | English |
Publisher | Geological Society of America |
Publisher location | Boulder, CO |
Contributing office(s) | Earthquake Science Center |
Description | 16 p. |
First page | 2015 |
Last page | 2030 |
Country | United States |
State | California |
Other Geospatial | Napa Valley |
Online Only (Y/N) | N |
Additional Online Files (Y/N) | N |
Google Analytic Metrics | Metrics page |