UC Berkeley

This dissertation investigates multi-scale surface deformation across Northern California using advanced InSAR techniques, focusing on ALOS-2 ScanSAR data to constrain regional-scale velocity fields, characterize surface creep rates along the Maacama and Rodgers Creek faults, and examine triggered accelerations of slow-moving landslides. In Chapter 2, we utilize L-band InSAR data from the ALOS-2 satellite to capture surface deformation across Northern California from 2015 to 2024. Our analysis spans spatial scales, from slow-moving landslides to tectonic processes around the Mendocino Triple Junction. By validating InSAR observations with GNSS velocities and time series, we establish robust regional velocity fields and address the challenges associated with detecting long-wavelength deformation. Our new vertical velocity field encompasses the region north of San Francisco to the Oregon border, nearly spanning the width of the state. Our observations reveal significant aquifer subsidence in 2022 during the last year of record drought, subsidence at the summit of Medicine Lake Volcano, and seasonal landslide acceleration. This chapter highlights the ability of L-band InSAR to maintain coherence in vegetated regions and detect subtle seasonal deformation, laying the groundwork for future observations with the upcoming NISAR mission. Chapter 3 aims to resolve creep variability along the Maacama and Rodgers Creek Faults. Understanding where creep occurs and how creep rates change through time is integral to determining seismic potential and constraining future earthquake scenarios. We utilize an updated repeating micro-earthquake catalog and surface creep rates from radar satellite-based and terrestrial measurements to identify decadal-scale changes in fault behavior on the Rodgers Creek and Maacama faults. We examine the distribution of creep within the seismogenic zone, as inferred by the presence of CREs, and surface creep, measured by InSAR and alignment arrays. We analyzed 20 years of alignment array measurements to examine temporal changes in creep rates along the northern Maacama Fault. The time series reveal a notable creep event in 2002, followed by a multi-year suppression in surface creep that is mirrored by a reduction in CRE productivity. We find seasonally modulated surface creep in both the alignment array and InSAR time series. This work contributes to refining seismic hazard assessments by characterizing decadal-scale changes in fault dynamics. Chapter 4 documents the kinematic evolution of slow-moving landslides in Northern California, influenced by precipitation and earthquake shaking, between July 2021 and March 2024. During our study period, slow-moving landslides in Northern California experienced increased precipitation and earthquake shaking (Mw 6.2, December 20, 2021; Mw 6.4, December 20, 2022). The seasonal accelerations of slow-moving landslides induced by precipitation are well established; however, the combined effect with earthquake shaking is less well understood. We apply a systematic approach to extracting and cleaning InSAR displacement time series for over 400 slow-moving landslides. By grouping landslides with similar acceleration responses following the 2022 earthquake, we find that spatial clustering correlated with the region of highest shaking in the larger 2022 earthquake. These landslides cluster in the direction of rupture propagation of the 2022 earthquake, exhibiting an immediate onset of sliding and subsequent decay. The kinematic response of these slides is well-fitted with a piecewise model (linear + exponential), indicating that landslides return to within 90\% of their pre-event rates in approximately 16 months. We suggest that the directivity of the 2022 earthquake contributed to the spatial clustering of the triggered landslides, while the shaking preconditioned further-field slides, and decreased the delay time between the onset of precipitation and seasonal sliding. Drawing on a nine-year ALOS-2 ScanSAR record and supporting observations, this dissertation shows that L-band InSAR—integrated with GNSS, alignment arrays, and repeating-earthquake catalogs—can coherently resolve deformation from hillslope to plate-boundary scales. At a broader level, the work illustrates why space geodetic observations using InSAR of actively deforming systems matter: We link the slow, regional accumulation of tectonic strain to week-to-month-long accelerations on faults and slopes, providing a continuous view across spatial and temporal scales that seismology or field measurements alone rarely capture. By making dense, repeatable measurements of the real world, future modeling efforts can test frictional and hydrologic models, evaluate when stable sliding persists, and identify conditions that tip systems toward shear failure. These capabilities address enduring questions—Which faults host shallow creep, and how stable are they over time? Where are landslides slipping slowly, and what processes drive some into catastrophic motion? They also serve practical goals: earlier detection of transient deformation, better constraints on time-varying hazard, and more targeted monitoring where risk is highest. Ultimately, this work serves as a demonstration of L-band InSAR capabilities at the dawn of the NISAR (NASA-ISRO Synthetic Aperture Radar) era. L-band data preserves long-wavelength deformation, while also providing high temporal and spatial resolution of localized features. Integrating detailed observations enhances our scientific understanding of the mechanisms and systems driving the evolution of the Earth's surface, and consequently improves our ability to prepare communities for fault and slope hazards.