Mode switching in volcanic seismicity: El Hierro 2011–2013. Issue 9 (7th May 2016)

• Record Type: Journal Article
• Authors: Roberts, Nick S.; Bell, Andrew F.; Main, Ian G.
• Is Part Of: Geophysical research letters. Volume 43:Issue 9(2016)
• Page Start: 4288
• Page End: 4296
• Publication Date: 2016-05-07
• Subjects: volcano seismology -- b value -- El Hierro -- probability -- mode switching; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL068809
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The Gutenberg‐Richter b value is commonly used in volcanic eruption forecasting to infer material or mechanical properties from earthquake distributions. Such studies typically analyze discrete time windows or phases, but the choice of such windows is subjective and can introduce significant bias. Here we minimize this sample bias by iteratively sampling catalogs with randomly chosen windows and then stack the resulting probability density functions for the estimated b ˜ value to determine a net probability density function. We examine data from the El Hierro seismic catalog during a period of unrest in 2011–2013 and demonstrate clear multimodal behavior. Individual modes are relatively stable in time, but the most probable b ˜ value intermittently switches between modes, one of which is similar to that of tectonic seismicity. Multimodality is primarily associated with intermittent activation and cessation of activity in different parts of the volcanic system rather than with respect to any systematic inferred underlying process. Key Points: A new method is proposed for calculating the probability distribution of seismic b values with nonlinear errors At El Hierro mode switching behavior in the b value and values as high as 3.25 are observed The method identifies multimodal behavior attributed to clustering of seismic activity