Automatic approach for increasing the location accuracy of slow-moving landslide endogenous seismicity: the APOLoc method

Abstract

Seismological observations offer valuable insights on the stress-strain states, the physical mechanisms and the possible precursory signs of activation of various Earth surface processes (i.e. volcanoes, glaciers and landslides). Comprehensive catalogues of the endogenous landslide seismicity, that is corresponding to seismic sources generated by the unstable slope from either mechanical or hydrological origins, should include the typology and an estimate of the source parameters (location, magnitude) of the event. These advanced catalogues constitute a strong basis to better describe the slope deformation and its time evolution and better understand the controlling factors. Because the number of seismic events in landslide catalogues is generally large, automatic approaches must be considered for defining both the typology and the location of the sources. We propose here a new location approach called Automatic Picking Optimization and Location method-APOLoc for locating landslide endogenous seismic sources from seismological arrays located at close distance. The approach is based on the automatic picking of the P waves arrivals by optimizing the intertrace correlations. The method is tested on calibration shots realized at the Super-Sauze landslide (Southeast French Alps) and compared to other location approaches. By using a realistic velocity model obtained from a seismic tomography campaign, APOLoc reduces the epicentre errors to 23 m (on average) compared to ca. 40 m for the other approaches. APOLoc is then applied for documenting the endogenous seismicity (i.e. slopequakes and rockfalls) at the landslide.