The seismic noise at Las Caٌadas volcanic caldera, Tenerife, Spain: Persistence characterization, and possible relationship with regional tectonic events

The origin of the continuous seismic noise recorded during the last few years in the volcanic island of Tenerife (Canary Islands, Spain) is under debate, due to the important implications in terms of hazard. The seismic noise is strongly affected by anthropogenic contamination but previous work has shown that nevertheless a significant fraction of this noise has a natural origin, an origin that appears to be related to the generation of local tectonic events within or close to the island. In this paper, the variogram tool is used to characterize the so called “persistence” of the seismic noise. This analysis can quantify how much memory the seismic noise has of its recent past. This has important implications in terms of how informative the recorded noise can be about its future evolution, and this in turn puts important constraints on how likely it is for the seismic noise to be the source of potential precursors highlighting variations in the volcanic activity that is supposed to generate (part of) this seismic noise. In particular, the memory characterization can help to distinguish the naturally generated seismic noise from the anthropogenic contamination. Although only a few clear examples have been observed until now, the possibility that this memory can be affected by the occurrence of local tectonic events is also discussed.