Quantifying relationships between fault parameters and surface deformation associated with thrust and reverse fault earthquakes: A distinct element approach
Kristen Chiama, William Bednarz,
Robb Moss,
Andreas Plesch, &
John H. Shaw
Published September 8, 2024, SCEC Contribution #13505,
2024 SCEC Annual Meeting Poster
#089 (PDF)
We evaluate the influence of geological site characteristics and earthquake source parameters on fault scarp morphologies for thrust and reverse fault earthquakes using geomechanical models. Based on the distinct element method (DEM), we performed 3,434 2D numerical experiments to investigate the impact of the sediment depth, density, strength, and fault dip on the resultant ground surface deformation expected in thrust or reverse fault earthquakes. We applied a machine learning model based on computer vision to obtain measurements (scarp height, uplift, deformation zone width, and scarp dip) from 346,834 model stages corresponding to M 5.5 to 7.7 events. The DEM dataset exhibits a broad range of scarp behaviors, including monoclinal, pressure ridge, and simple scarps – each of which can be modified by hanging wall collapse. The fault displacement (i.e., anticipated earthquake magnitude), fault dip, sediment depth, and sediment strength have the most influence on resultant surface rupture patterns. The DEM results comprehensively describe the range of historic surface rupture observations in the Fault Displacement Hazards Initiative (FDHI) dataset. We develop relationships of observed (FDHI) and anticipated (DEM model) surface ruptures by incorporating additional information about the earthquake size, fault geometry, and surface deformation style. Furthermore, we extend these 2D DEM models into 3D to evaluate the influence of model parameters on along-strike variability, including changing the fault dip along strike and adding obliquity. We suggest that this DEM dataset can be used to supplement field data and help forecast patterns of ground surface deformation in future earthquakes given specific anticipated source and site characteristics.
Key Words
distinct element method, ground surface deformation, surface ruptures, fault scarps, tectonic geomorphology, thrust fault, reverse fault
Citation
Chiama, K., Bednarz, W., Moss, R., Plesch, A., & Shaw, J. H. (2024, 09). Quantifying relationships between fault parameters and surface deformation associated with thrust and reverse fault earthquakes: A distinct element approach. Poster Presentation at 2024 SCEC Annual Meeting.
Related Projects & Working Groups
Earthquake Geology
