Shallow Shear-Wave Velocity Structure beneath the West Lake Area in Hangzhou, China, from Ambient-Noise Tomography

Urban geophysical exploration plays an important role in the sustainable development of and mitigation geological hazards metropolitan areas. However, it is not suitable to implement active seismic methods densely populated urban The rapidly developing ambient-noise tomography (ANT) method a promising technique for imaging near-surface velocity structure. We selected West Lake area city Hangzhou as case study probe shallow subsurface shear-wave (Vs) structure using ANT. conducted interferometry on data recorded by 28 seismograph stations during time period 17 days. Fundamental-mode Rayleigh-wave group- phase-velocity dispersion were measured from cross-correlation functions then inverted 3D Vs model uppermost 1 km that covers about 7 × 8 km. tomographic results reveal two prominent anomalies, with high velocities southwest low northeast. fast anomaly corresponds presence limestone sandstone, whereas slow due relatively low-velocity rhyolite volcanic tuff area. boundary between anomalies lies NE NW–SE trending fault, indicating fault dips toward NE. In addition, pronounced appear under Baoshi mountain, likely thick beneath extinct volcano. Our correlate well regional features suggest ANT could be facilitating underground space.