FocusX temporary land-network (FXland), seismic data and preliminary analysis

Abstract

In the frame of FocusX2 project INGV (Osservatorio Nazionale Terremoti and Osservatorio Etneo) and UniCal (Laboratorio di Sismologia) are deploying, from the end of 2021 to January 2023 a temporary seismic network for an active/passive seismological experiment to record regional and global seismicity in the Ionian Sea. The goal of this experiment is to improve the detection of seismicity in the Ionian Sea area and the accuracy of the locations; to better define the crustal structure of the region and find patterns related to fault systems. The seismicity in the area is possibly the result of two types of tectonic activity at different depths: a gently NW dipping subduction interface of the Calabrian subduction zone, and the strike-slip fault systems in the Ionian Sea, well expressed in the morpho-bathymetry and observed in previous seismic profiles. The deployment of 13 temporary land stations, FocusX temporary land (network code 1J) https://doi.org/10.13127/SD/O5QWM6WJCD along the coasts of eastern Sicily and SW Calabria, is going to complement the permanent networks (network codes IV, MN and IY); in the same period OBS stations are deployed at sea: FocusX temporary OBS-network (network code XH).

The land stations are equipped with two different type of digitizers: Reftek 130 (12), and SaraSL06 (2); and with three different type of velocimeters: Trillium 120C (10), Le 5s (2) and ss08 60s (2). Continuous data are transmitted in real time at the INGV Rome acquisition system, used in the seismic surveillance, archived and distributed in EIDA https://eida.ingv.it/it/.

In the deployment period 23rd December 2021 - 9th May 2022 regional seismicity (area between Lat 36.5-38.2 Lon 14.5-16.0) include 390 events located by the INGV seismic surveillance system, two of them with magnitude larger than 4.0 as well as 56 teleseismic earthquakes with magnitude larger than magnitude 6.0, two of them larger than 7.0. The two local events with M>4.0 and some of their aftershocks, were analyzed by the analysts of the Italian Seismic Bulletin including all the stations of the FXland 1J network.