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

ANALYSIS OF HISTORICAL SEISMOGRAMS FROM THEPOTSDAM STATION (GDR) IN THE PERIOD 1902 -1910E. Hurtig and G. KowalleCentral Institute Physics of the Earth, Academy of Science of GDRDDR-1500 Potsdam, Telegrafenberg, German Democratic Republic1. German Seismology at the Beginning of the 20th CenturyThe former German Empire had a long seismological tradition. In 1904 Gerlandpublished proposals for a station network, distinguishing between the central station(in Strasbourg), main regional stations, and stations of 2nd order. This paperoutlines the history of four stations within what is now the territory of the GermanDemocratic Republic during the years 1902 to 1910. These stations are:Potsdam: main station for the province of Brandenburg.Leipzig: main regional station for the Kingdom of Saxony.Plauen: auxiliary station of Leipzig.Jena: main regional station for the Thuringian dukedoms.Figure 1 shows the location of these stations, and Table 1 their instrumentationwhen routine observations began. An excellent international review of the state ofdevelopment of seismometers and recording equipment at the end of the last century,Ehlert (1898), shows that all four stations were well equipped by the standards ofthose times. They produced excellent seismograms of both teleseismic and localearthquakes. Up to the First World War, all these stations were well maintainedand their records are well interpreted and documented. Figure 2 shows the dataobtained from the first records of the Leipzig station (Etzold, 1902). Similar detailedbulletins were published for all the stations, but unfortunately, many of the originalseismograms were lost during the Second World War.2. The Potsdam Station from 1902 to 19102.1 InstrumentationThe seismological observations at Potsdam were carried out in the former GeodeticInstitute by Hecker from 1902 to 1908, and by Meissner in 1909 and 1910. Aspecial earthquake recording house had been built with elaborate precautions tokeep the temperature variations as small as possible. Routine observations beganin April 1902, continuing the earlier work of Rebeur-Paschwitz and Hecker (Hurtig,1981).The following instruments were used in the period 1902-1910: (1) A horizontalpendulum with two components. This instrument was in operation from April 1,1902 to June 7, 1909. Its characteristics are given in Table 2. (2) A Wiechertaststic seismometer. This instrument was in operation from October 13, 1903 tothe mid 1970s, and its characteristics are listed in Table 3. The natural period wasdetermined in November 1905, and again on September 26, 1910 by Schweydar. Hefound large changes (%component: 12.5 sec; N-component: 19.8 sec) which suggestthat the period was very unstable, and that the data given in Table 3 should notbe accepted without further investigation.Historical Seismogramsand Earthquakes of the World51 Copyright G 1988 by Academic Press, Inc.All rights of reproduction in any form reserved.