The RING and Seismic Network: Data Acquisition of Co-located Stations

Abstract

The plate boundary between Africa and Eurasia represents an interesting geodynamical region characterized by a complex pattern of deformation. First-order scientific problems regarding the existence of rigid blocks within the plate boundary, the present-day activity of the Calabrian slab and the regional crust and upper mantle structures are still awaiting for a better understanding. For answering these open questions, INGV deployed a permanent, integrated and real-time monitoring GPS network (RING) all over Italy. The RING is now constituted by about 120 stations. The CGPS sites, acquiring at 1Hz and 30s sampling rate, are integrated either with broad band and very broad band seismometers or accelerometers to improve the monitoring of the background seismicity in the Apennines seismic belts and to better constrain the geometry of the seismogenic structures. Most of the network is connected to the acquisition centre (located in Rome and duplicated in Grottaminarda) by a satellite system (VSAT), while the remaining sites transmit data by Internet and classical phone connections. The satellite data transmission and the integration with seismic instruments makes this network one of the most innovative CGPS networks in Europe. Either the heterogeneity of the installed instrumentation and of the transmission types or the continuous increasing number of stations needed a central monitoring and acquisition system. Thus, in Grottaminarda, for the seismic monitoring we chose to use the open source system Earthworm, developed by USGS, with which we store waveforms and implement automatic localization of the seismic events occurred in the area. As most of the GPS sites are acquired by means of Nanometrics satellite technology, we decided to develop a new software (GpsView), written in Java, to monitor the state of health of those CGPS. This software receives GPS data from NaqsServer (Nanometrics acquisition system) and outputs information about the sites (i.e. position, number of satellites) in real-time. Furthermore, we developed also a web-based application for the management of the data and the metadata relative to the GPS sites of the RING. We present (a) the existing and planned CGPS site distribution, (b) the technological description of the seismic and GPS data acquisitions in Grottaminarda INGV centre, and (c) the first results of CGPS data analysis.