Project Details

Description

Our aim is to develop a system of generating centimeter resolution, textured topographic maps along active faults using digital cameras mounted on Unmanned Aerial Vehicles (UAVs). The technique uses structure from motion (SFM) algorithms to calculate spot heights from pho- tographs captured sequentially along the UAV ight line, and will oer a range of benets over existing sub-meter resolution airborne Light Detection And Ranging (lidar) datasets: enhanced spatial resolution, enabling the identication of oset markers that are too small or subtle to be imaged with lidar; aordable enough for focused data to be collected along key faults in S California; a straightforward work ow will facilitate rapid data collection (with potential deployment within hours of an earthquake) and maximize the accessibility to geologists; used in repeat mode the system will generate detailed maps of near-fault earthquake deformation, which are crucial for the interpretation of paleoseismic data The new system will be trialled along the southern San Andreas, San Jacinto and Elsinore fault zones, at sites which contain displaced features that have been identied on the ground but which are imperceptible in existing lidar data. By revealing many new osets along key faults, the project answers SCEC's call for improved slip-per-event data and longer paleo- seismic histories (in line with the SoSAFE focus group) and will greatly increase the number of last-event slip inputs into the Uniform Californian Earthquake Rupture Forecast (UCERF 3). The proposal also addresses SCEC's objective to improve the Community Fault Model (CFM) though better dened fault traces, and in doing so could also help rene the Community Geode- tic Model (CGM) by resolving discrepancies between geodetic slip rates (which typically span the whole fault zone) and geological ones (normally measured across a discrete fault strand). The system could form a key component of an improved post-earthquake rapid response plan, widely discussed as a high priority at the 2011 SCEC meeting. Finally, the system should be cheap enough for eventual use in countries where lidar remains unfeasible.

Description

Project management: Our group has extensive experience with paleoseismic investigations in the Carrizo Plain and a seasoned awareness of access, working conditions, and contacts with excavation equipment rental companies. The trenches will all be 5 feet or less in depth so that no shoring is required. Each site will have a fault locator trench and two closely spaced fault parallel trenches on either side of the fault. Fault facing trench walls will be dug towards the fault and piercing lines will be surveyed and followed. Excavation and hand-digging will be used alternating to maximize efficiency without compromising the data collection quality. Shallow trenches are justified because the proposed study is mainly concerned with the effects of the most recent earthquake as preserved in the uppermost stratigraphic units. The distinct surface expression of fault trace and offset features indicate relatively low sedimentation rates so that all required information should be stored within the first meter or so of soil. Our group has a long and successful history of collaboration beginning with Grant -Ludwig and Arrowsmiths Ph.D. research along the San Andreas Fault in the Carrizo Plain in the early 1990s. We have worked with SCEC and USGS support along the Cholame segment together, with SCEC and USGS support at the Van Matre Ranch site in the Carrizo Plain (Figure 1; Noriega, et al, 2006). Most importantly, our proposed work builds directly from SCEC, USGS NEHRP, and National Science Foundation support for our research at Bidart Fan from 2005-2010 (Akciz, et al., 2009; Grant -Ludwig, et al., 2010; Zielke, et al., 2010; and Akciz et al., 2010; Akciz et al., in review). All investigators will work closely to make project decisions, though project scientist Akciz will take the lead role in taking care of field logistics, data collection and interpretation. A graduate student from ASU and at least one SCEC intern will be involved with all aspects of the trenching work during the summer.

Description

Stream channels offset by the San Andreas and San Jacinto Faults and imaged with airborne LiDAR topography have transformed our understanding of the seismogenic behavior of these faults (e.g. Zielke et al., 2010; Salisbury et al., 2012). Perhaps surprisingly, however, these meter-resolution topography data are too coarse to image the most subtle or smallest of offsets and, moreover, cannot constrain the ages of these features. This additional information is crucial if we are to fully characterize the recent earthquake history here. We propose to bring a new technology to this long-standing problem by mapping and analyzing offsets along key sections of the south central San Andreas and San Jacinto Faults using improved, decimeter-resolution topography and image texture maps generated with Structure from Motion (SfM) photogrammetry. Firstly, our measurements will provide additional slip data in areas where LiDAR has been unable to reveal offsets, potentially filling in gaps in the slip distributions of previous events including the 1857 and 1812 earthquakes. Secondly, the shapes of these channels will be interrogated with scarp degradation models to try to date channel abandonment (and constrain offset age) directly from the topography. The project builds on a previous SCEC award, described in Section 2, in which we explored SfM topographic mapping using remote controlled helicopters. A third goal of the project is to further improve this mapping system by testing a range of different unmanned platforms and developing improved means of stripping vegetation from and geo-referencing the resulting point clouds. Our proposed research targets several of SCEC4s research priorities, disciplinary activities and interdisciplinary focus areas. Improved slip-per-event data will provide better constraints on long-term behavior (2a), the new mapping tool will lead to improvements to the Community Fault Model (4c) and can make rapid gathering of high-resolution topographic data accessible to SCEC scientists. Further along the line, repeat surveying with SfM could also help improve the Community Geodetic Model (1a). Late Quaternary records of faulting and new tools for data gathering in response to major earthquakes are two high-priority objectives of the Earthquake Geology Disciplinary Committee, while improved paleo-earthquake chronologies and slip distributions are a key objective of the interdisciplinary SoSAFE group.
StatusFinished
Effective start/end date2/1/121/31/17

Funding

  • National Science Foundation (NSF): $165,374.00

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