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

482 G. Neilson and P. W. BurtonAfter Milne’s death in 1913 the headquarters of this organization, now known asthe International Seismological Summary (ISS), moved to Oxford under the directionof Professor H. H. Turner.British stations formed a vital part of the new worldwide network set up byMilne. Research was performed on site noise, microseisms, etc., by comparing theseismograms written at the various stations in Britain, and applying the results toall British Association stations.The scientific results from the worldwide organizations were of enormous importanceto seismology because they covered topics as diverse as deep-focus earthquakes,submarine disturbances caused by earthquakes, seismicity studies and epicenter-determinationmethods, and others.Seismology in Britain was considerably disrupted by World War I, although mostof the stations managed to continue operating throughout the war. After 1918 thesituation became normal again fairly quickly. The period between World Wars Iand I1 saw a great advance in seismology in Britain, the most significant contributionpossibly being the production of the Jeffreys-Bullen traveltime tables (Jeffreys,1939), but only two new observatories were established, Jersey and Durham.By the end of World War I1 few British observatories were operating purely inthe interests of seismology. Jersey, under the German occupation, had great difficultyfinding materials to continue recording. Edinburgh and Durham had ceasedanalysing the records for the duration of the war, although the seismographs atEdinburgh were kept in operation throughout.After World War 11, the stations in the British Isles were equipped with obsoleteequipment, efficiency at the stations had declined, and a few stations had closedaltogether. In 1960, only Kew, Durham, Jersey, and Aberdeen were operating andKew and Aberdeen closed within a few years.The Geneva Test Ban negotiations, from 1958 onwards, led to a re-awakeningof interest in seismology and provided the catalyst necessary for the renovationof instrumental seismology. In Britain this led to the establishment of the WorldWide Standard Station at Eskdalemuir and of a large array station nearby (Truscott,1964). In Ireland a World Wide Standard Station was set up at Valentia. Edinburghwas re-equipped with modern instruments recording on magnetic tape (Willmoreand Connell, 1963). An array station was set up at Rookhope, near Durham, andmany modern stations have been deployed over all the British Isles in the yearssince 1960 (Crampin and others, 1970; Browitt and others, 1985).This report deals with the period beginning with the return of Milne from Japanand ends with the renaissance of instrumental seismology in Britain, which beganin the 1960’s.2. The History of the Establishment of Seismological Observatories inthe British IslesThe principal observatories established in Britain and Ireland during 1896- 1960are shown in Figure 1 and listed in Table 1. The first observatory in Britain equippedwith a seismograph was Milne’s at Shide, Isle of Wight, set up in 1895. Milne alsoinstalled a temporary station at Carisbrooke Castle to compare records. Withintwo or three years other stations such as Edinburgh, Kew, Paisley and Bidston wereestablished. All these places had astronomical and/or meteorological observatoriesto provide an accurate source of timing for seismographic recording.