Magnitude scale for lp events: A quantification scheme for volcanic quakes

Abstract

The peculiar source characteristics of long-period seismic events (time persistency of thesource, low-frequency peaks in the source spectrum, absence of high-frequency radiation)prevent the formation of a definite high-frequency coda in the seismograms. In contrast, this iswell formed in volcano-tectonic quakes. For this reason, the widely used duration magnitudescale that is based on the proportionality between the energy and the coda duration cannotbe used for long-period estimation. In observatory practice, the long-period magnitude issometimes estimated using the same duration magnitude scale, leading to confusing results. In this report, we show a new method to estimate the magnitude of long-period events thatgenerally occur for volcanoes, with some application examples from data for Mt Etna (Italy),Colima Volcano (Mexico) and Campi Flegrei (Italy).© The Authors 2013.