Ambient Noise Surface Wave Reverse Time Migration for Fault Imaging

Abstract

Faults are basic components of subsurface structures that represent discontinuities in physical properties. In addition to being the controlling factor of major tectonic earthquakes (e.g., Angelier, 1990; Martin et al., 2016; Sibson, 1983), subsurface faults also play an essential role in natural resources, including hydrocarbon accumulation and formation of oil and gas reservoirs (Aydin, 2000), aggregation of metallic ore deposits (e.g., Goldfarb et al., 2005; Spencer & Welty, 1986), and generation of geothermal reservoirs (Chen & Huang, 2015). Therefore, detailed characterization of subsurface faults is crucial for understanding tectonic activities and for exploring natural resources. Many geophysical approaches for fault delineation have been proposed in the past decades, such as gravity, magnetic, electromagnetic, and seismic methods (e.g.,

Continent‐Continent Collision Between the South and North China Plates Revealed by Seismic Refraction and Reflection at the Southern Segment of the Tanlu Fault Zone

“…The role of the extensional structures in melting, assimilation, storage, and homogenization of magma intrusion and mineralization of the MLYMB, in which deep faults could serve as the conduits of upwelling magmas has also been emphasized (Lü et al., 2013, 2015; Shi et al., 2013). The ZBLU in the upper crust is characterized as a HVZ bounded by sedimentary basins with low velocities on both sides (Figure 10a), which is also consistent with most local and regional high‐resolution tomographic studies of the TFZ in the adjacent regions (e.g., Gu et al., 2019; Li, Li, et al., 2020; Luo et al., 2021; Xu et al., 2021). This HVZ is defined by a P‐wave velocity from around 6.0 km/s to 6.7 km/s as outlined by the dashed line in Figure 10a, which is quite high for rock formations within the shallow crust.…”

“…Near the Chao Lake, the S‐wave velocity models of the upper crust derived from ambient noise tomography suggest that there are high‐velocity anomalies beneath the ZBLU, which are interpreted as magma intrusions through the TFZ (Gu et al., 2019; Luo & Yao, 2021; Luo et al., 2019; Xu et al., 2021). The active‐source seismic traveltime tomography also reveals similar high‐velocity structures along the TFZ (Qin et al., 2018, 2020; Xu et al., 2014), and the migrated images using transmitted surface waves indicate that the shallow fault planes of the TFZ down to 5 km in depth are rather steep (Li, Li, et al., 2020).…”

Reverse Time Migration Based on the Pseudo-Space-Domain First-Order Velocity-Stress Acoustic Wave Equation

“…Since the wave equation does not need to be decomposed, there is no strata dip angle limitation caused by the wave equation approximation. The RTM is recognized as an ideal imaging method for complex structures and has been a popular topic in the field of geophysics (Moradpouri et al, 2017;Li et al, 2018;Zhou et al, 2018;Li et al, 2020). Chang and McMechan (1987) generalized the two-dimensional RTM to the elastic wavefield and then extended it to three dimensions McMechan, 1990, 1994).…”