Imaging glacier structures at high resolution using source localisation with a dense seismic array

Over the past two decades, the growing use of dense seismic arrays has often overcome limitations of traditional observations methods and yielded new insights on the physics of subsurface process and properties. Yet scientific and computational challenges remain to be addressed for using the appropriate array-processing approaches and automating the techniques on large volume of data and for complex wavefields. In this presentation I will present how we addressed such challenges in the particular case of monitoring glaciers, which host numerous and diverse sets of seismic sources that produce signals ranging from impulsive to tremor-like. We evaluate different levels of phase coherence using a gradient-descent optimization (matched field processing). We show that even a small coherence in the phase signal remains rich in statistical information on concomitant and/or low amplitudes micro-seismic sources. This allows us to localize seismic sources with a super-resolution (meter to decameter) and identify emerging patterns associated with a wide range of glacier features and their dynamics, ranging from active crevasses, debris in transverse passive crevasses and subglacial water flow. Such methodological and conceptual advance may enable a more efficient and complete imaging of geophysical objects.