Two seismological approaches to the Benavente earthquake (1909): from the network of citizens to the network of instruments

The 23rd April 1909 earthquake (Benavente Earthquake - BE), with catastrophic effects in Ribatejo, including Benavente, relatively close to Lisbon, was the subject of two coeval studies according to different approaches that in the conceptual framework of tectonics can be considered pioneers in the Portuguese seismology: the official one, according to dedicated questionnaires and based on a network of human observers, and the one of private initiative, according to the only seismogram registered in the Portuguese continental territory (Coimbra), but limited by the absence of a (reclaimed) network of instruments. These two studies are described with attention to the protagonists, the contexts and the contributions to the Portuguese seismology, and despite the different approaches, both claim for more instruments and the setting of a desired and necessary national network of seismic stations.