Seismology seminars

Abyssal marine turbidites provide some of the longest and most spatially extensive records of subduction zone earthquake recurrence globally; however, correlation of these deposits over long distances and interpretation of synchronous emplacement requires both an understanding of the turbidite generating systems and precise dating. Here, we present an integrated suite of high-resolution bathymetry, subbottom profiles, and sediment cores from combined autonomous underwater vehicle, remotely operated vehicle, and ship-based studies at a key paleoseismic site in the southern Cascadia subduction zone. We demonstrate how widespread, earthquake-triggered landslides on the lower slope deposit discrete, proximal mass transport deposits (MTDs) that grade offshore into complex, interfingered abyssal turbidites, which correspond to records of megathrust earthquake history. We propose accretion and oversteepening of thrust folds on the lower slope both preconditions the slope to fail and provides a perpetual source of unstable material to fail during every earthquake cycle. Furthermore, we suggest the periodic and pervasive landsliding indicates coseismic deformation of the outer accretionary wedge during megathrust rupture.

We quantify slow-moving landslide kinematics across northern California using a 14-day L-band ALOS-2 ScanSAR InSAR time series. After systematically extracting and cleaning the displacement time series, we analyze deformation of 437 landslides across a ∼300 x 400 km area and group time series by relative velocity changes to identify anomalously fast motions. We test associations with external drivers (PGA, precipitation) and landslide attributes (slope, aspect ratio, area). Shaking from the 2022 event shows the strongest association with faster sliding rates. For slides that experienced higher PGA and increased velocities, a piecewise model yields recovery to within ~10% of pre-event rates in ~1.3 years. Using two earthquakes of similar magnitude and location, we demonstrate that rupture dynamics shape the spatial distribution of triggering and supply rare regional constraints on onset and recovery.

The 2025 Matai’an landslide in eastern Taiwan represents the largest landslide event ever recorded in the region and initiated a cascading hazard sequence involving landslide-dam formation and repeated dam-breach floods. In this talk, I will demonstrate how seismic observations and remote sensing can be integrated to track landslide processes from pre-failure deformation to post-failure hazard evolution. I will also present a seismic-based monitoring framework capable of detecting landslides in near real time, estimating their size, and identifying landslide-dam formation, providing a practical approach for early warning of downstream flood hazards.

On February 6, 2023, a Mw 7.8 and Mw 7.5 earthquake doublet struck along the East Anatolian Fault Zone in Türkiye, triggering over 3,600 coseismic landslides. Roughly a month later, a rare atmospheric river event delivered up to 183 mm of rainfall in just 20 hours to the earthquake impacted region. This extreme precipitation induced additional landslides, debris flows, and flooding. In our research, we conduct a probabilistic landslide hazard assessment using the open-source Landlab earth surface modeling library, integrating both seismic and climatic drivers. The model incorporates earthquake legacy effects, representing post-seismic slope weakening, and simulates shallow landslide susceptibility using a Monte Carlo implementation of the infinite slope stability theorem informed by remote sensing datasets. I will present three key analyses: (1) modeling hydrologic response to the AR event and mapping landslide probability with and without earthquake legacy effects; (2) examining how the sequence and combination of extreme events alter landslide hazard; and (3) demonstrating how using historic climate data can effectively replicate post-seismic landslide hazard maps that use real-time data, offering an approach for seasonal hazard forecasting in tectonically active and climate-sensitive regions.