A new software tool has been developed as part of the EUROVOLC project to help track and locate tremor signals from volcanic eruptions.

Volcanic tremor is a sustained seismic signal associated with volcanic unrest, which due to its emergent nature, cannot be located using travel-time based methods. Similar seismic signals can be produced by other surface processes such as flooding or lahars, so being able to locate and track the source of tremor signals is important for volcano monitoring. Small clusters, or arrays, of seismic stations, are particularly suited for analyzing volcanic tremor, yet costs associated with installation and maintenance have meant few long-term or permanent seismic arrays in use for routine or real-time monitoring of volcanoes.

RETREAT is a python-based software tool that uses array data and array processing techniques to analyze and locate volcanic tremor signals, by using beamforming to point towards the location of the source. The tool has been tested using real-time streaming seismic data from an array in Spitsbergen, Svalbard as well as on data from the 2014 eruption of Bárðarbunga volcano, Iceland. In addition to seismic data, RETREAT can also be used for infrasound (low-frequency sounds waves) and was also tested on infrasonic array data recorded at Mt. Etna, Italy in July 2019.

Given the potential for wider usage of arrays, it is hoped that RETREAT will enhance volcano monitoring capacity and facilitate greater use of arrays in tracking volcanic tremor sources in real-time.
An article by Patrick J. Smith and Christopher J. Bean has been published in Fronties in Earth Science. A direct link is provided here: https://doi.org/10.3389/feart.2020.586955