Constraining the depth extent of low-velocity zone along the Chenghai Fault by dense array ambient noise interferometry and horizontal-to-vertical spectral ratio
Constraining the depth extent of low-velocity zone along the Chenghai Fault by dense array ambient noise interferometry and horizontal-to-vertical spectral ratio
The depth extent of low velocity fault zones is still a matter of debate due to the lack of vertical resolution for most seismic methods. Autocorrelations and cross-correlations of seismic ambient noise provide us new constraints on this issue by obtaining the shallow subsurface reflections without the need of active sources or earthquakes. The horizontal-to-vertical spectral ratio (HVSR) method can also give constraints on this interface and does not need any extra cost of data collection. In this study, we used one-month continuous seismic data from a dense linear array deployed crossing the Chenghai Fault (CHF) in Yunnan, southwest China. Single station autocorrelation and adjacent station pair cross-correlation methods were used to retrieve body wave reflections from the interface of the shallow crustal low-velocity zone (LVZ). The HVSR method was also performed to delineate the shape of the LVZ. Results show an inverted trapezoidal LVZ which extends to similar to 1.0 km depth across the fault zone with a lateral extent of similar to 3 km. Previous studies based on ambient noise surface-wave tomography and teleseismic travel time analysis in the same area show similar characteristics, consistent with the interpretation of our results.
NSTL
Elsevier