The use of a low-cost, small-aperture array as an auxiliary tool to improve infrasound monitoring in the Azores region

Abstract

The 2022’s seismo-volcanic crisis on São Jorge Island of the Azores archipelago, has provided an opportunity to deploy a portable infrasound array (SJ1), in a collaborative work between the Research Institute for Volcanology and Risk Assessment (IVAR), of the University of the Azores (UAc), and the University of Florence (UniFI). This 4-element array became operational on 2nd April 2022. Despite being deployed in a first stage to monitor the activities related to the volcanic unrest on São Jorge Island, SJ1 integrated an infrasound monitoring network in the region in association with the IMS infrasound station IS42, located on Graciosa Island at ~ 40 km distance. This work emphasises the importance of low-cost portable infrasound arrays in improving the coverage of infrasound observations for local and regional monitoring purposes in the area of the Azores. In this regard, two events recorded by both arrays are briefly exemplified herein: a low-magnitude earthquake on São Jorge Island and a fireball which crossed the North Atlantic Ocean.