Automated detection and cataloging of global explosive volcanism using the International Monitoring System infrasound network
Journal of Geophysical Research: Solid Earth RESEARCH ARTICLE 10.1002/2016JB013356 Key Points: Method to detect and locate infrasound from sustained explosive volcanic eruptions Uses global International Monitoring System infrasound data Global, multiyear infrasonic catalog of sustained explosive volcanic eruptions Supporting Information: Supporting Information S1 Movie S1 Correspondence to: R. S. Matoza, matoza@geol.ucsb.edu Citation: Matoza, R. S. D. N. Green, A. Le Pichon, P. M. Shearer, D. Fee, P. Mialle, and L. Ceranna (2017) Automated detection and cataloging of global explosive volcanism using the International Monitoring System infrasound network, J. Geophys. Res. Solid Earth, 122, 2946 2971, doi:10.1002/2016JB013356. Received 13 JUL 2016 Accepted 17 MAR 2017 Accepted article online 24 MAR 2017 Published online 22 APR 2017 Automated detection and cataloging of global explosive volcanism using the International Monitoring System infrasound network Robin S. Matoza 1 David N. Green 2 Pierrick Mialle 6 and Lars Ceranna 7 Alexis Le Pichon 3 Peter M. Shearer 4 David Fee 5 1 Department of Earth Science and Earth Research Institute, University of California, Santa Barbara, California, USA, 2 AWE Blacknest, Reading, UK, 3 CEA, DAM, DIF, Arpajon, France, 4 Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA, 5 Wilson Alaska Technical Center and Alaska Volcano Observatory, University of Alaska Fairbanks, Fairbanks, Alaska, USA, 6 CTBTO, Vienna, Austria, 7 BGR, Hannover, Germany Abstract We experiment with a new method to search systematically through multiyear data from the International Monitoring System (IMS) infrasound network to identify explosive volcanic eruption signals originating anywhere on Earth. Detecting, quantifying, and cataloging the global occurrence of explosive volcanism helps toward several goals in Earth sciences and has direct applications in volcanic hazard mitigation. We combine infrasound signal association across multiple stations with source location using a brute force, grid search, cross bearings approach. The algorithm corrects for a background prior rate of coherent unwanted infrasound signals (clutter) in a global grid, without needing to screen array processing detection lists from individual stations prior to association. We develop the algorithm using case studies of explosive eruptions: 2008 Kasatochi, Alaska; 2009 Sarychev Peak, Kurile Islands; and 2010 Eyjafjallajokull, Iceland. We apply the method to global IMS infrasound data from 2005 2010 to construct a preliminary acoustic catalog that emphasizes sustained explosive volcanic activity (long duration signals or sequences of impulsive transients lasting hours to days) This work represents a step toward the goal of integrating IMS infrasound data products into global volcanic eruption early warning and notification systems. Additionally, a better understanding of volcanic signal detection and location with the IMS helps improve operational event detection, discrimination, and association capabilities. 1. Introduction How often do the world's volcanoes erupt and with what magnitude? Attempts to keep track of Earth's presently active volcanism compile geological and geophysical data, reports, and publications from multi ple sources [e.g. Simkin and Siebert, 2000; Siebert and Simkin, 2002; Siebert et al. 2010; Mason et al. 2004; Crosweller et al. 2012; Global Volcanism Program, 2013] However, many potentially active volcanoes are not equipped with dedicated local monitoring instruments and are only observed using satellite based meth ods, which may be limited, e.g. by meteorological cloud cover [Webley and Mastin, 2009] Volcanic activity may be underreported or poorly quantified in remote regions, which lack ground based instrumentation and observers. (c)2017 Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland. MATOZA ET AL. We explore the potential use of the global International Monitoring System (IMS) infrasound network, currently under construction, to build a quantitative acoustic catalog of current global explosive volcanic activity to complement other data sources. The IMS infrasound network is designed to detect atmospheric explosions with an equivalent yield of 1 kt of TNT anywhere on the planet with at least two stations as part of the verification measures for the Comprehensive Nuclear Test Ban Treaty (CTBT) [Christie and Campus, 2010] However, simulations show that long range stratospheric ducting of infrasound significantly enhances the detection capability, with explosions of a couple hundred tons TNT equivalent being detectable globally at two or more stations on the complete network [Le Pichon et al. 2009; Green and Bowers, 2010] Data holdings from the IMS infrasound network go back to about 2002 and at present the IMS has 49 certified stations out of a planned total 60; data from 41 stations from 2005 to 2010 are used in this study (Figure 1) Each infra sound station consists of an array of at least four infrasonic sensors with a flat response from about 0.01 to 8 Hz GLOBAL VOLCANO ACOUSTIC DETECTION