Rapid response to the earthquake emergency of May 2012 in the Po Plain, northern Italy

Rapid-response seismic networks are an important element in the response to seismic crises. They temporarily improve the detection performance of permanent monitoring systems during seismic sequences. The improvement in earthquake detection and location capabilities can be important for decision makers to assess the current situation, and can provide invaluable data for scientific studies related to hazard, tectonics and earthquake physics. Aftershocks and the clustering of the locations of seismic events help to characterize the dimensions of the causative fault. Knowing the number, size and timing of the aftershocks or the clustering seismic events can help in the foreseeing of the characteristics of future seismic sequences in the same tectonic environment. Instrumental rapid response requires a high degree of preparedness. A mission in response to a magnitude (ML) 6 event with a rupture length of a few tens of kilometers might involve the deployment within hours to days of 30-50 seismic stations in the middle of a disaster area of some hundreds of square kilometers, and the installation of an operational center to help in the logistics and communications. When an earthquake strikes in a populated area, which is almost always the case in Italy, driving the relevant seismic response is more difficult. Temporary station sites are chosen such as to optimize the network geometry for earthquake locations and source study purposes. Stations have to be installed in quiet, but easily reachable, sites, and for real-time data transmission, the sites might need to have optical intervisibility. The operational center can remain in a town if there is one within the damaged area, and it should coordinate the actions of the field teams and provide information to colleagues, the Civil Protection Authorities and the general public. The emergency system should operate as long as the seismic rate remains high; the duration of any mission might also depend on the seismic history of the area involved. This study describes the seismic response following the May 20, 2012, ML 5.9 earthquake in northern Italy, which included rapid deployment of seismological stations in the field for real-time seismic monitoring purposes, the coordination of further instrumental set-ups according to the spatial evolution of the seismic sequence, and data archiving.