LONG-TERM SEISMIC MONITORING CAPABILITIES IN CHILE

The interaction of the South American plate with three other major tectonic plates originates the significant amount of seismicity observed in Chile. The largest events are located at the interface with the subducting Nazca plate. Other sources are the contact with the Scotia plate and lesser seismicity associated to the subducting Antarctic plate.

To monitor -and analyze- the seismicity taking place along these 4300-km-long strip, more than 110 six-component seismological stations (BB + strong ground motion), sending data in real time, including two devices installed on the Chilean Pacific Islands, have been deployed along the country. This system is complemented by the German/French Integrated Plate Boundary Observatory in the northern part of the country.

To rapidly characterize the size and extension of large earthquakes in the near field (because of the main thrust region is mostly concentrated between the trench and the coast with an average width of about 120-130 km) the monitoring system includes real-time GNSS capabilities with both on-site position estimations (at the receiver) as well as at a central server. In real-time applications in the near field, unsaturated direct-displacement-estimations based on GNSS observations become critical for determination of fault finiteness of M ~ 7 (and larger) earthquakes that affect the coastal part of the country, with the estimation of their associated tsunamigenic potential. Examples of these capabilities will be presented, such as the signals recorded for some large earthquakes which have taken place since the expansion of the network in 2013.

A major drawback of this monitoring system is the lack of tracking capabilities directly offshore, where most of large ruptures initiate. Continued efforts on integrating new tools, such as submarine fiber optics DAS, to rapidly characterize large events and efforts on development, as well as implementation, of a prototype earthquake early warning system will be presented. Brief comments on the evolution of the present SARS-CoV-2 pandemics and its consequences on field and headquarters operations will also be discussed.