The ARGONET (Greece) Seismic Observatory: An Accelerometric Vertical Array and Its Data

The ARGOstoli NETwork (ARGONET) consists of a vertical seismic array and a close by (440 m) free-field station on bedrock, located in Cephalonia, western Greece, in the vicinity of the Cephalonia transform fault zone (CTFZ) that is characterized by a high seismic activity, one of the highest in Europe. It is intended to investigate the effects of local surface geology on the incoming seismic wavefield, with emphasis on strong ground motion (nonlinearity). The vertical array is composed of accelerometer sensors placed on the ground surface at 5.6-, 15.5-, 40.1-, and 83.4-m depth. The P- and S-wave velocity ranges from surface to bottom bedrock between 600 and 2700 m=s and between 130 and 700 m=s, respectively. The ARGONET started its operation in July 2015. As of 31 December 2017, this array, which operates in continuous mode with Global Positioning System (GPS) absolute time synchronization, has recorded high-quality recordings for 478 local and regional earthquakes (from ML 1.8 to Mw 6.4 and hypocentral distance from 7 to 180 km, with peak ground acceleration (PGA) from 0.83 to 169 cm=s 2). Event dataset along with its metadata are open. The ARGONET data are expected to form the basis for further research on the effects of complex surface geology on ground motion and validation of 1D/2D/ 3D simulation methods, as well as for studying nonlinear seismic wave propagation phenomena.