Historical Seismograms - Evidence from the AD 2000 Izu Islands ...

Historical Seismograms Recorded in Venezuela 463Figure 1. The historical building of the former Observatory uJuan Manuel Cagigal,"Caracas, seen from south-west towards the mountain Avila, which is covered by clouds.The building, which has resisted well the Caracas earthquake of 29 October 1900, unfortunatelywas razed in the years 1953-54.the recording device of the Wiechert seismometer, and just handwritten time markswere noted on the smoked paper. It is surprising, that besides the high developmentof exploration geophysics in Venezuela during the years 1930 to 1950 or earlier, -and besides the occurrence of about 5 Venezuelan earthquakes with M 2 6 (PAS)between 1900 and 1950, - nobody from inside or outside the country has shown anyeffective interest for the improvements of the Venezuelan earthquake seismology,during the first half of this century.2. Geographical and Geophysical Constants of the SeismologicalInstitute of the Cagigal Observatory, Caracas (CAR)For investigation or comparison, a few important constants of CAR may be useful.The data were computed by Cambridge University, Wisconsin University, theNational Cartographic Office, the Ministry of Energy and Mines, and CAR itself.The kmeter-deep seismometer piers rest on strongly weathered schist of Upper(Late) Cretaceous age.The legal time in Venezuela (HLV) before January 1, 1965 was Universal TimeCoordinated (UTC) minus 4 hours 30 minutes. But from that date to the presentit is UTC minus 4 hours, which refers to the 60' W meridian. Other data:Geographic longitudeGeographic latitudeGeocentric latitude66.9230' W10.5056' N10.4375' N