How Do Slow-moving Landslides Maintain Steady Motion?
Description:
Slow-moving landslides predominantly manifest steady motion, in striking contrast to rapid runaway landslides that accelerate and fail catastrophically. However, we do not fully understand how slow-moving landslides arrest and stabilize their motion. Better understanding of the underlying mechanisms potentially holds the key to illuminate their slow-to-fast motion transition and also offers insights on frictional faulting processes. To approach this problem, we deployed dense instrumentation on the slow-moving (~1.5 cm/d) Slumgullion landside in Colorado from 2022 to 2023. The sensors encompass four surface creepmeters along its southern edge, four embedded strainmeters on the slide, and six GPS receivers and 150 nodal seismometers covering the middle section. These sensors record data at one-minute or higher rates. We complemented the field measurements with high-resolution TerraSAR-X and PAZ SAR repeat acquisitions.
From the 2.5-μm-precision creepmeter and strainmeter data, we observed coupled slip and strain events that migrate along the slide on a ten-day timescale, appearing as accelerations or decelerations in slip rate and axial strain with wavelengths of ~100 m. From creepmeters along the southern edge, we have also observed slip signatures of episodic acceleration-deceleration in duration of minutes and magnitude of sub-millimeters. These distinct slip patterns seemingly resemble fault creep that consists of a relatively sharp acceleration followed by gradual slowdown. The observed motion propagation and high-rate creep signals suggest possible changes in landslide shear strength, which may be related to pore-pressure feedback and/or rate-dependent material strength. We are actively processing the collected GPS, SAR, and nodal seismic data to extend our observations form the marginal transform to interior parts of the slide. These additional data may allow distinguishing the frictional properties and strength of the basal and lateral landslide boundaries. Findings from this work are anticipated to shed light on the mechanism of slow-to-fast slip in landslides and tectonic faults.
Session: Detecting, Characterizing and Monitoring Mass Movements - III
Type: Oral
Date: 5/2/2024
Presentation Time: 02:45 PM (local time)
Presenting Author: Yuankun
Student Presenter: No
Invited Presentation:
Authors
Yuankun Xu Presenting Author Corresponding Author yuankunx@berkeley.edu University of California, Berkeley |
Roland Bürgmann burgmann@berkeley.edu University of California, Berkeley |
Roger Bilham Roger.Bilham@colorado.edu University of Colorado Boulder |
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How Do Slow-moving Landslides Maintain Steady Motion?
Category
Detecting, Characterizing and Monitoring Mass Movements