Station COI: Dusting Off an Old Seismic Station

Abstract

Online Material: Analysis of the background seismic noise of station COI, and yearly inventory of the historical seismograms and bulletins of station COI. The seismic station COI, located in Coimbra, Portugal, is the oldest seismic station in Portugal and among the oldest in the world. Experimental seismic recording began in 1891 with an Angot seismograph (V. G. S. S. Santos, unpublished data, 1995; Custodio et al. , 2010). Continuous recording of ground motion began in 1903 with a Milne seismograph, and is still on‐going at the same site, now with a broadband Streckeisen STS‐2 seismometer. Coimbra’s observatory owns an over 100‐year long, well‐preserved collection of seismograms, seismographs and bulletins. Station COI is taken into account in early seismological works, for example, in the 1901 compilation of stations equipped with seismographs recommended by the British Association for the Advancement of Science (BAAS, 1901), in the earthquake catalog of the International Association of Seismology for the year of 1904 (Rosenthal, 1907), in the San Francisco earthquake report (Reid, 1910) or in the classical book “Seismicity of the Earth” (Gutenberg and Richter, 1954). However, throughout time station COI lost its early importance and was progressively forgotten. Station COI is missed even by recent compilations of historical seismic data (e.g., Ferrari, 2000; Schweitzer and Lee, 2003). Recently we were able to start undusting the seismological heritage of Coimbra’s station. In this paper, we present a brief history of the station. We also describe its seismographs, seismograms and bulletins, including their present state of preservation and availability. Station COI is particularly relevant for studies of earthquakes in the pre‐digital era given that: …