Recent graduate of the Department, Chelsea Blanton, published her thesis work in Geomorphology. Look for her paper in the May 15th volume.
Refining the spatial and temporal signatures of creep and co-seismic slip along the southern San Andreas Fault using very high resolution UAS imagery and SfM-derived topography, Coachella Valley, California
Abstract
The current interseismic period for an event on the Coachella Valley segment of the San Andreas Fault (SAF) is ~300 years, much greater than the best-estimated average recurrence interval of ~180 years, prompting questions regarding earthquake recurrence and fault behavior. Digital Surface Models (DSMs) generated using Structure-from-Motion-Multiview Stereo (SfM-MVS) techniques on unmanned aerial systems (UAS) imagery and very-high resolution UAS orthomosaicswere used to identify and measure fault-related offsets of small geomorphic features and develop a model of late Holocene slip-per-event for the southern SAF (sSAF) in the Coachella Valley. We aim to better constrain slip estimates from recent earthquakes along the sSAF and combine new slip data with ages of past earthquakes from paleoseismic studies to understand earthquake recurrence. Slip-per-event for paleoearthquakes, which ruptured this segment of the sSAF, and the relationship between co-seismic slip events, creep or afterslip, and triggered slip were evaluated. Examination of offsets suggests that five (5) large, surface rupturing events produced average displacements of 2.6–3.1 m per event. Gaussian distribution analysis revealed small-scale offset clusters thatwe attribute to climate-modulated channel incision across the fault and subsequent creep. These offset clusters support a creep rate of ~3 mm/yr in the Mecca Hills averaged over the past ~160 years.