Deep long period volcanic earthquakes generated by degassing of volatile-rich basaltic magmas

• Published in: Nature Communications
• Main Authors: Melnik, Oleg, Lyakhovsky, Vladimir, SHAPIRO, Nikolaï, Galina, Natalia, Bergal-Kuvikas, Olga
• Other Authors: Lomonosov Moscow State University (MSU), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement IRD : UR219-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Institute of Volcanology and Seismology of the RAS, Far Eastern Branch of the Russian Academy of Sciences (FEB RAS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology; Kamchatka
• Online Access: https://hal.archives-ouvertes.fr/hal-02914641; https://hal.archives-ouvertes.fr/hal-02914641/document; https://hal.archives-ouvertes.fr/hal-02914641/file/Melnik_etal_NatComm2020.pdf; https://doi.org/10.1038/s41467-020-17759-4

International audience Deep long-period (DLP) earthquakes observed beneath active volcanoes are sometimes considered as precursors to eruptions. Their origin remains, however, unclear. Here, we present a possible DLP generating mechanism related to the rapid growth of gas bubbles in response to the slow decompression of over-saturated magma. For certain values of the gas and bubble content, the elastic deformation of surrounding rocks forced by the expanding bubbly magma can be fast enough to generate seismic waves. We show that amplitudes and frequencies of DLP earthquakes observed beneath the Klyuchevskoy volcano (Kamchatka, Russia) can be predicted by our model when considering pressure changes of~10 7 Pa in a volume of~10 3-10 4 m 3 and realistic magma compositions. Our results show importance of the deep degassing in the generation of volcanic seismicity and suggest that the DLP swarms beneath active volcanoes might be related to the pulses of volatile-rich basaltic magmas rising from the mantle.