Quasi-Block Modeling of Walker Lane Tectonic Deformation, Using Geodetic and Geologic Data to Constrain System Complexity and Time-Variable Behavior

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

Deformation within the Walker Lane and Eastern California shear zone in Nevada and California (western Basin and Range) accommodates a portion of the relative motion between the Pacific and North American plates. The system-wide geodetically (GPS) inferred crustal deformation rate in the northern Walker Lane is 2 to 3 times greater than the rate inferred from geologic data such as fault slip rates. Understanding the reasons behind this discrepancy is central to fully integrating these complementary constraints on continental deformation, and to rigorously identifying time-variable behavior over geologic time. In order to understand this discrepancy, this research team is developing a quantitative methodology that rigorously integrates the geodetic and geologic constraints on tectonic deformation. New GPS data are being collected in areas that lack coverage. The new and existing geodetic data will be combined with geologic constraints on fault geometry, slip rates, and paleomagnetic rotations using a block modeling quantitative framework. When geodetic and geologic data are in significant conflict - when slip rates for a single fault have different geologic and geodetic estimates - the kinematic self-consistency of the block modeling quantitative framework will be used to place constraints on how deformation patterns have changed over time. Slow tectonic deformation of continental interiors results in sudden slip of faults (i.e. earthquakes) after long periods of interseismic strain accumulation. Precise measurement of these motions, before, during, and after earthquakes is essential for understanding the causes and controls of earthquake occurrence. By combining measurements of the location, rate, and direction of the change in shape of the land's surface between earthquakes with computer modeling that rigorously integrates geologic and geodetic data, understanding of which faults are the most likely to slip in sudden potentially damaging earthquakes in the growing Reno/Carson/Tahoe metropolitan areas can be improved.