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

PRELIMINARY EVALUATION OF THE LARGE CARACASEARTHQUAKE OF OCTOBER 29,1900, BY MEANS OFHISTORICAL SEISMOGRAMSG. E. Fietller B.Chief, Seismological Institute CAR (retired)Apartado postal 5407 Garmelitas, Caracas 1010-A, Venezuela1. IntroductionOn the 29th of October, 1900, at about 9:ll GMT, which is equal to 4:41 a.m.former Venezuelan legal time or 5:11 a.m. actual Venezuelan legal time (HLV, sinceJan. 1, 1965), Caracas and its surroundings were hit by an earthquake. The rnaximumintensity of this earthquake can be estimated to be 9 on the Mercalli-Cancani-Sieberg-Scale (MCS). The observed duration of the ground motion in Caracas wasup to 50 seconds. About 100 victims were counted and great destruction occurredin Caracas, La Guaira, Macuto, and the rest of the so called Litoral Guaireiio, andalso in Guarenas, Guatire, Higuerote and other places. If we include intensity I11(MCS), this earthquake was felt over the whole country. Specific macroseismic informationcan be found in the following publications: Ceriterio Grau (1900, 1940),Fiedler (1961, 1968, 1980), Jakubovicz and Larotta (1974), Sievers (1905), Troconisde Veracoechea (1979) and others.Richter (1958) published the following epicentral ISC-data for this earthquake:Date = October 29, 1900; Origin tirue = 0:ll GMT; Epiceritral coordinates =11.0’ N, 66.0” W; Magnilude = 8.4. This epicenter is located at a point some 65kin west of Tortuga Island or 115 km northeast of Caracas, on a physiographicallyvery important zone, formed of platfornis and smaller oceanic basins.As far as the author of this paper knows, no seismographic records were shownor iriterpretatioris besides that of C. F. Richter used in the many publications writtenabout this event. Therefore, an effort was made to find such seismograms andderived seismographic interpretations. In most cases, world wars and other circurnstanceshave resulted in the destruction of photographic or smoked paper recordsof that event, but two good quality seismograms in the form of copies were obtained:one from Parnpleniousses Observatory, Mauritius Island, built in the year1898, and another from Kew observatory, England. These two records are shownin Figures 1 and 2. Seisrnographic record readings were published, as far as couldbe found out, by: Scliutt (1900), Hamburg, Germany (seismic service opened in theyear 1898); Laibacli, Yugoslavia (1897), Pola arid Casamicciola, Italy; Anonymous(1900), Toronto (1897) arid Victoria, Canada; Anoriyrrious (1900), Vacoas, Mauritius(Panipleniousses, 1898); Anonymous (1908), Port of Spain, Trinidad (1900);ISC-data arid seismogram, Kew, England (1898); Omori (19031, Tokyo, Japan;Kortazzi (1903), Nicolajew, USSR; Mazelle (1901), Triest, Italy.This event is included in the “Important Earthquake of the Northern Andes”(Gutenberg, 1929, p. 973), and its isoseismal map is also shown in Gutenberg (1929,p. 975). However, Gutenberg (1929) mistook this earthquake to have occurred in1910 instead of 1900. After the 1900 event, the next Caracas earthquake occurredon December 12, 1915, which is similar to the 1900 event but without damage andwith an intensity of about 5 (MCS) in the region of Caracas, Guareiias, Guatire,Higuerote, Macuto, and La Guaira.Historical Seismogramsand Earthquakes of the World201Copyright @ 1968 by Academic Press, Inc.All rights of reproduction in any form reserved.