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Timescales of Surface Faulting Preservation in Stable Continental Regions From Landscape Evolution Modeling and the Geomorphic and Historical Record

Description: 

Large surface-rupturing intraplate earthquakes in stable continental regions are infrequent, with recurrence intervals of thousands to hundreds of thousands of years. The landscape preservation of surface ruptures is controlled by many factors, including earthquake depth, magnitude, and recurrence interval, climate, anthropogenic modification, and pre-existing topography or geomorphology. As such, recurrence intervals – and therefore seismic hazard – may be biased or inaccurate from the landscape record alone. In this study, we take a two-pronged approach to better understand how surface ruptures of primarily dip-slip events may be preserved in the landscape. First, we use a 2D scarp diffusion model to explore how different parameters influence the creation and erosion of fault scarps. These parameters include the magnitude of surface rupture vertical offset (likely related to depth and magnitude of faulting), climate (using diffusion rate as a proxy for precipitation), erodibility (related to underlying surface material), and recurrence interval of similar magnitude events. Second, we compile information on historical surface ruptures in intraplate settings in a variety of climates, including the central and eastern North America, Australia, Europe, Mongolia, India, and West Africa. We then use data from the compilation to assign parameter value ranges for the models. We use vertical offsets of 30 to 300 cm, recurrence intervals of 500 yr to 20 kyr, diffusion rates of 0.001 to 0.01 m²/yr, and erodibility values from 0.001 to 0.006 yr^-1 on both flat and sloping surfaces with cm- and m-scale roughness. We find that recurrence interval and erodibility strongly influence the timescales of scarp preservation in the landscape, whereas vertical offset and climate have less influence. We compare the timescales of scarp preservation in the landscape evolution modeling results with observations from the historical and paleoseismic record. This study highlights the factors influencing scarp preservation in intraplate settings and implications for calculating the seismic hazard of a region based on the landscape record.

Session: Cryptic Faults: Advances in Characterizing Low Strain Rate and Environmentally Obscured Faults - I

Type: Oral

Date: 5/1/2024

Presentation Time: 08:15 AM (local time)

Presenting Author: Jessica

Student Presenter: No

Invited Presentation: 

Authors