资源环境科技发展态势分析平台

We demonstrate the feasibility of detecting very weak deformation in the shallow crust with high temporal resolution by monitoring the relative changes in seismic wave velocity (dv/v) using dense arrays of seismometers. We show that the dv/v variations are consistent between independent measurements from two seismic arrays. Dominant peaks in the observed dv/v spectrum suggest that tides and temperature changes are the major causes of daily and subdaily velocity changes, in accordance with theoretical strain modeling. Our analysis illustrates that dv/v perturbations of the order of 10(-4), corresponding to crustal strain changes of the order of 10(-8), can be measured from ambient seismic noise with a temporal resolution of 1hr. This represents a low-cost technique for high precision and high time-resolution monitoring of crustal deformation that is complementary to existing geodetic measurements and is instrumental in both the detection and understanding of low-amplitude precursory processes of natural catastrophic events.

Plain Language Summary Theoretical and laboratory studies have shown that the onset of earthquakes, landslides, and volcanic eruptions is often preceded by a so-called initiation phase. Detecting such a precursory phenomenon will help in the prediction, early warning, or assessment of catastrophic geological events. The time scale and amplitude of these precursory evolutions are not well known, however, and their detection and characterization require monitoring techniques with both high precision and high temporal resolution. We present here an approach to monitor the elastic properties of crustal rocks using continuous recordings of ambient seismic noise by networks of dense autonomous sensors. We show that this technique allows the monitoring at a temporal resolution of 1hr for crustal strain variations of the order of 10(-8), namely, the deformation associated with tides. This technique can be used in concert with existing geodetic techniques for understanding and detecting transient crustal deformation.