Subjects: Geophysics and Space Physics >> Applied Geophysics >> Survey Geophysics submitted time 2026-04-06
Abstract： With the continuous advancement of urbanization, utilizing urban ambient noise to perform passive source seismic imaging has emerged as a vital pathway for addressing challenges in underground space exploration. This technology is rooted in seismic interferometry theory, which extracts underground structural information by recovering the empirical Green’s function through cross-correlation processing of noise signals. However, the prominently inhomogeneous noise field in urban environments often leads to the generation of spurious phases, which challenges the reliability of automatic dispersion curve extraction. To address this scientific problem, Distributed Acoustic Sensing (DAS) technology utilizes existing "dark fiber" infrastructure to achieve ultra-high-density observations, effectively mitigating the interference caused by inhomogeneous sources and enhancing spatial resolution. Furthermore, machine learning methods integrated with physical constraints—such as the DispFormer model—significantly improve the automation and precision of processing complex seismic data. The deep integration of these advanced technologies is driving the transformative shift of urban random noise from "interference" into a high-value resource for geophysical exploration.
Peer Review Status:
Awaiting Review
Subjects: Geophysics and Space Physics >> Geodesy >> Physical Geodesy Subjects: Geophysics and Space Physics >> Seismology submitted time 2025-12-10
Abstract： It is believed that the accumulation of small fractures (small earthquakes) in the crust is one of many ways for the formation of large fractures (large earthquakes). In such cases, the temporal variations in the accumulation number of small earthquakes can be used to predict future seismic activity in the region. To do so, a structural system of the crust is constructed using the logarithmic linear relationship between earthquake frequency and magnitude, and a relationship between earthquake accumulation and time is derived by assuming that the rate of earthquake accumulation is proportional to the q-th power of the existing number of earthquakes. Earthquake record from selected regions of China and Italy are fitted by the theory and the obtained fitting parameters are used to evaluate the future seismic activity. It is found that the extent of deviation of earthquake accumulation from the theoretical expectation can be a reasonable judgement of the local seismic dangerous level and q ≥ 1 can be considered a marker of local crust entering an accelerated fracturing phase. The proposed method made the physical evaluation of local seismic activity possible by simplifying the 3D (space-time-magnitude) problem into 2D (time-magnitude) problem in earthquake prediction.
Peer Review Status:Awaiting Review
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