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

A BRIEF HISTORY OF THE SEISMOLOGICALOBSERVATORIES IN THE BRITISH ISLES, 1896-1960G. Neilson and P. W. BurtonNatural Environment Research Council, British Geological SurveyMurchison House, West Mains Road, Edinburgh EH9 3LA, UK1. IntroductionThe earliest known application of instruments to the study of British earthquakeswas the result of the work of a committee of the British Association for the Advancementof Science, which was set up in 1840 to study the earthquake sequence thenin progress at Comrie, Scotland (British Association, 1841-1844). The secretary ofthis committee, David Milne (later Milne-Home) coined the word “seismometer”, todescribe the invention of another member of the committee, Professor J. D. Forbes(Forbes, 1844). This instrument, the basis of which was an inverted pendulum,would now be described as a seismoscope. A number of these instruments, togetherwith other, simpler types such as common pendulums, were placed around Comrie,but the results produced were disappointing. With the decrease in the frequencyand severity of the earthquakes, the committee lapsed after 1844.In 1869, following signs of renewal of seismic activity in Comrie, a new committeeof the British Association was set up to investigate the earthquakes of Scotland.This committee reported to the Association in 1870 to 1876 (British Association,1870-1876). This committee discovered that at least one of the Forbes instrumentswas still working but decided that it was not sensitive enough. A simpler device,designed by Robert Mallet was adopted (Davison, 1924). A series of upright cylindersof varying heights and diameters was set up in two lines at right angles to eachother on a bed of sand in the ‘earthquake house” in Comrie. The theory was that ashock would upset the cylinders, the orientation of the overturned cylinders wouldgive the direction of the shock, and the mass of the largest cylinder overturnedwould indicate the strength of the disturbance. Bryce, the Chairman of the committee,died in 1876, and after his death the committee lapsed. Mallet’s apparatusis reported to have only been disturbed once, but the source of the disturbance wasthe antics of local boys, not an earthquake.About the same time, E. J. Lowe erected a simple pendulum instrument to detectshocks at his observatory in Nottinghamshire (Burton and others, 1984).Credit for first demonstrating the value of seismographs to seismology belongs toworkers such as Gray, Ewing and Milne who developed various types of instrumentsin Japan from about 1880 to 1895 (Dewey and Byerly, 1969). The most influentialmember of this group was John Milne. On his return to Britain in 1895 he becamesecretary of the British Association Seismological Investigations Committee. Thiscommittee tested various types of seismographs and eventually decided that theMilne horizontal pendulum was the best instrument. It also set up a worldwidenetwork of stations equipped with these instruments to record large earthquakesand report their observations to Milne’s Observatory at Shide, Isle of Wight. Here,the epicentres of the shocks were computed and the data circulated to contributingst at ions.Historical Seisniogramsand Earthquakes of the World481Copyright 0 1988 by Academic Press, Inc.All rights of reproduction in any form reserved.