Leveraging high temporal and spatial resolution geodetic data through the earthquake cycle

Earthquake Science Center Seminars

Cassie Hanagan, USGS

Advancing our understanding of earthquake processes inevitably pushes the bounds of data resolution in the spatial and temporal domains. This talk will step through a series of examples leveraging two relatively niche geodetic datasets for understanding portions of the earthquake cycle: (1) temporally dense and sensitive borehole strainmeter (BSM) data, and (2) spatially dense sub-pixel image correlation displacement data. More specifically, I will detail gap-filling benefits of these two datasets for different earthquakes.

BSMs respond to a frequency of deformation that bridges the capabilities of more common GNSS stations and seismometers. As such, they are typically installed to capture deformation signals such as slow slip or transient creep. In practice they are also useful for measuring dynamic and static coseismic strains. This portion of the talk will focus on enhanced network capabilities for detecting both coseismic and postseismic deformation with a relatively new BSM array in the extensional Apennines of Italy, with events spanning tens to thousands of kms away. Then, we will transition toward how these instruments can constrain spatiotemporally variable afterslip following the 2019 Mw7.1 Ridgecrest, California earthquake.

High spatial resolution displacements from sub-pixel image correlation serve as gap-filling datasets in another way – providing higher spatial resolution (~0.5 m) maps of the displacement fields than any other method to date, and patching areas where other methods fail to capture the full deformation magnitude or extent, such as where InSAR decorrelates. This portion of the talk will focus on new results that define expected displacement detection thresholds from high-resolution satellite optical imagery and, alternatively, from repeat lidar data. Examples will include synthetic and real case studies of discrete and diffuse deformation from earthquakes and fault creep.