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

HISTORICAL EARTHQUAKESSEISMOGRAMS IN TAIWANPao Hua LeeCentral Weather BureauTaipei, ChinaABSTRACTAND THEAlthough the most active seismicity in the Taiwan area is on the eastof the island, earthquake risk is greater on the west part in Chaiyi-Tainanregion. Other areas of high earthquake risk are on east Taiwan in theHw alien- Ilan and Tait un g- Lany u reg ions.The Central Weather Bureau has established a remote recording systemconsisting of 14 seismological stations. This system is linked to a VAX11/750 computer, which is used exclusively for data processing and datastudies.The accumulated seismograms are going to be microfilmed for the historicalseismogram archive. On completion, a catalogue will be publishedand seismological data exchange with other countries will be encouraged.1. IntroductionThe purpose of this paper is to describe the Seismological Observatory of theCentral Weather Bureau (CWB) and the general status of seismological activitiesfrom 1897 to 1985 in Taiwan area.Instrumental observations in the Taiwan area began on December 1, 1897, when aGray-Milne seismograph was installed at Taipei. By 1945, 16 seismological stationshad been opened in Taiwan. But in March 1945 seismic observations were haltedbecause all supplies were cut off by the air raids of World War 11. On January 1,1946, after the war ended, seismological activities were restarted, and today thereare 17 seismic stations in Taiwan.2. The Seismological Observatory, CWBThe Seismological Observatory of C WB conducts seismological research and furnishedseismicity information to the general public of the Taiwan area. To meetthese responsibilities, the Observatory maintains a network of recording stations onand around the island.In 1985, the Seismological Observatory operates 17 stations (see Figure 1 forgeographic locations). Before 1982, most seismographs of these stations - exceptAnpu, a World Standard Seismograph Network Station - were mechanical instruments,such as Wiechert, Omori, and other horizontal portable seismographs. In1982, all seismographs were upgraded and a remote recording system consisting of14 stations was completed.The upgraded seismographs consist of three types of instruments: short-periodseismometers, long-period seismometers, and strong-motion accelerographs. Eachof the 14 remote stations contains the necessary sensors, signal conditioners, microprocessors,digital printers, communication interfaces, and analog recorders. TheHistorical Seitmogramband Earthquakes of the World241Copyrighr g; 1988 by Academic Press, Inc.All rights of reproduction in any form reterbed.