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Analysis and modeling of Deep Long Period volcanic earthquakes to illuminate the roots of magmatic-plumbing systems beneath the active volcanoes

Nikolai M. Shapiro1 , Nataliya A. Galina2, Cyril Journeau3, Andrés Barajas1, Jean Soubestre1, Oleg Melnik4, Vladimir Lyakhovsky5

  • Affiliations: 1ISTerre, Université Grenoble Alpes, CNRS, Université Savoie Mont Blanc, IRD, Université Gustave Eiffel, Grenoble, France; 2Earthquake Research Institute,The University of Tokyo, Tokyo, Japan; 3Department of Earth Sciences, University of Oregon, Eugene, United States; 4Department of Earth Sciences, University of Oxford,  Oxford, UK; 5Geological Survey of Israel, Jerusalem, Israel

  • Presentation type: Talk

  • Presentation time: Friday 14:45 - 15:00, Room S160

  • Programme No: 2.1.10

  • Theme 2 > Session 1

Abstract

Long-period earthquakes and tremors form one of two main classes of volcano-seismic activity. Deep long-period (DLP) earthquakes are particularly interesting because usually they are attributed to the processes occurring in the deep roots of the magma plumbing systems in the vicinity the crust-mantle boundary. The DLPs are often considered as manifestations of deep magmatic reactivation and possible early precursors to eruptions. The physical mechanism of generation of the DLP earthquakes remains, however, not fully understood. To advance toward more quantitative interpretation of the DLP seismicity in terms of underlying magmatic processes, a systematic analysis of their observations needs to be combined with physical modeling of their sources. In this presentation, we compare observations of DLP seismicity in several volcanic regions with different data analysis approaches. We then discuss how these observation can be interpreted in the framework of the models implying the supply of fresh magma from the mantle to the crust. One considered DLP generating mechanism consists of the rapid growth of gas bubbles in response to the slow decompression of H2O--CO2 over‐saturated basaltic magma. The nucleation and rapid growth of gas bubbles lead to rapid pressure change in the magma and elastic rebound of the host rocks, radiating seismic waves recorded as DLP earthquakes. Another possible mechanism is related to time-varying viscous traction forces because of the intermittent magma flow.