Development of an earthquake early warning system based on Earthworm; application to southwest Iberia

The main aim of this study is to demonstrate the feasibility of an earthquake early warning system (EEWS) to warn of potentially destructive earthquakes in the Cape San Vicente (SV) and Gulf of Cadiz (GC) areas in the southwest Iberian Peninsula, based on real-time broadband stations existing in the region. Historic earthquakes in this region include the 1755 Lisbon (M (sub w) 8.5) and 1969 SV (M (sub w) 7.8) events. This study illustrates the design, configuration, and first results of an EEWS prototype based on the U.S. Geological Survey Earthworm tools and developed at the Institut Cartografic i Geologic de Catalunya (ICGC). System main functionalities are real-time data acquisition, processing (P-wave picking, event detection, earthquake hypocentral location, and magnitude estimation from previously calculated peak displacement [P (sub d) ] and predominant period tau (sub c) of the P-wave signal), data archiving, and earthquake early warning dissemination. The prototype was put into operation after a setup period, during which several simulations were carried out to establish the optimal settings. After the first year of operation, one felt earthquake occurred in the area of study. Location and magnitude results are fairly good, compared with the Instituto Geografico Nacional (IGN) catalog. Lead times obtained are on the order of tens of seconds for the majority of targets, which are long enough to mitigate damage for a large area of the southern coasts of Portugal and Spain due to the GC and SV earthquakes. Preliminary results for this prototype demonstrate the possibility of a regional, reliable, and effective EEWS in southwest Iberia.