V040-0002
Automatic detection of the seismicity associated to the Mayotte volcanic crisis
Wednesday, 16 December 2020
Poster
Lise Retailleau1, Jean-Marie Saurel2, Simon Issartel3, Weiqiang Zhu4, Gregory C Beroza4, Claudio Satriano5, Valerie Ferrazzini1 and Jean-Christophe Komorowski6, (1)Institut de Physique du Globe de Paris, Paris, France, (2)Université de Paris, Institut de Physique du Globe de Paris, Paris, France, (3)EOST École et Observatoire des Sciences de la Terre, Strasbourg Cedex, France, (4)Stanford University, Department of Geophysics, Stanford, CA, United States, (5)Institut de Physique du Globe, Paris, France, (6)Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, Paris, France
Abstract:
Seismology is one of the main monitoring techniques for volcanoes, and has been used for Mayotte volcanic crisis since its beginning in 2018. While classic detection algorithms are used, the seismicity has been mostly identified manually and current catalogs are limited by the capacity of skilled analysts to process the data using classical methods. We implemented the deep neural network based method Phasenet to identify seismic P and S waves in continuous data for 2019 and 2020, and use those measurements to locate events with the NonLinLoc software. We also built an interface to process the picks with earthworm, followed by the location, to implement the process in real time at the REVOSIMA/OVPF (REseau de surveillance VOlcanologique et SIsmologique de MAyotte, Observatoire Volcanologique du Piton de la Fournaise).
The crisis has been mostly tracked using the numerous volcano-tectonic (VT) earthquakes (2-40 Hz frequency band). Volcanoes, however, can show a great variety of signals, including long period (LP) earthquakes often associated with fluid movements. LP events have also been recorded (0.5-5 Hz frequency band) but had not been systematically identified on Mayotte. We now show that these events occur mostly in swarms and are located in the area of the main volcano-tectonic earthquakes cluster close to Mayotte island. We compare the LP seismicity evolution in 2019 and 2020 to the VT and VLP seismicity (Very Long Period between 5 and 100 sec) and provide new insights about the origin of LP seismicity and what they might tell us about the ongoing volcanic activity.
