TY - JOUR
T1 - Impact of sedimentary basins on Green's functions for static slip inversion
AU - Langer, Leah
AU - Beller, Stephen
AU - Hirakawa, Evan
AU - Tromp, Jeroen
N1 - Publisher Copyright:
© 2022 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society.
PY - 2023/1/1
Y1 - 2023/1/1
N2 - Earthquakes often occur in regions with complex material structure, such as sedimentary basins or mantle wedges. However, the majority of co-seismic modelling studies assume a simplified, often homogeneous elastic structure in order to expedite the process of model construction and speed up calculations. These co-seismic forward models are used to produce Green's functions for finite-fault inversions, so any assumptions made in the forward model may introduce bias into estimated slip models. In this study, we use a synthetic model of a sedimentary basin to investigate the impact of 3-D elastic structure on forward models of co-seismic surface deformation. We find that 3-D elastic structure can cause changes in the shape of surface deformation patterns. The magnitude of this effect appears to be primarily controlled by the magnitude of contrast in material properties, rather than the sharpness of contrast, the fault orientation, the location of the fault, or the slip orientation. As examples of real-world cases, we explore the impact of 3-D elastic structure with a model of the Taipei basin in Taiwan and a simulated earthquake on the Sanchaio fault, and with a 3-D geologic model of the San Francisco Bay Area and a slip model of the 1984 Morgan Hill earthquake on the Calaveras fault. Once again, we find that the presence of the basin leads to differences in the shape and amplitude of the surface deformation pattern, but we observe that the primary differences are in the magnitude of surface deformation and can be accounted for with a layered elastic structure. Our results imply that the use of homogeneous Green's functions may lead to bias in inferred slip models in regions with sedimentary basins, so, at a minimum, a layered velocity structure should be used.
AB - Earthquakes often occur in regions with complex material structure, such as sedimentary basins or mantle wedges. However, the majority of co-seismic modelling studies assume a simplified, often homogeneous elastic structure in order to expedite the process of model construction and speed up calculations. These co-seismic forward models are used to produce Green's functions for finite-fault inversions, so any assumptions made in the forward model may introduce bias into estimated slip models. In this study, we use a synthetic model of a sedimentary basin to investigate the impact of 3-D elastic structure on forward models of co-seismic surface deformation. We find that 3-D elastic structure can cause changes in the shape of surface deformation patterns. The magnitude of this effect appears to be primarily controlled by the magnitude of contrast in material properties, rather than the sharpness of contrast, the fault orientation, the location of the fault, or the slip orientation. As examples of real-world cases, we explore the impact of 3-D elastic structure with a model of the Taipei basin in Taiwan and a simulated earthquake on the Sanchaio fault, and with a 3-D geologic model of the San Francisco Bay Area and a slip model of the 1984 Morgan Hill earthquake on the Calaveras fault. Once again, we find that the presence of the basin leads to differences in the shape and amplitude of the surface deformation pattern, but we observe that the primary differences are in the magnitude of surface deformation and can be accounted for with a layered elastic structure. Our results imply that the use of homogeneous Green's functions may lead to bias in inferred slip models in regions with sedimentary basins, so, at a minimum, a layered velocity structure should be used.
KW - Fractures, faults, and high strain deformation zones
KW - Mechanics, theory, and modelling
KW - Numerical modelling
KW - Sedimentary basin processes
UR - http://www.scopus.com/inward/record.url?scp=85144606695&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85144606695&partnerID=8YFLogxK
U2 - 10.1093/gji/ggac344
DO - 10.1093/gji/ggac344
M3 - Article
AN - SCOPUS:85144606695
SN - 0956-540X
VL - 232
SP - 569
EP - 580
JO - Geophysical Journal International
JF - Geophysical Journal International
IS - 1
ER -