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

SEISMOGRAMS MADE BEFORE 1963 AT STATIONSIN THE SOUTH- WEST PACIFICG. A. EibySeismological ObservatoryP.O. Boz 1320, Wellington, New ZealandABSTRACTThis paper outlines the history of the seismograph stations in theSouth-West Pacific and neighbouring parts of Antarctica and gives particularsof the present custody and condition of the records. Instrumentalrecords were made in New Zealand in 1884, with a horizontal penduluminstalled at the Colonial Museum in Wellington, and there are earlier referencesto the design and construction of seismoscopes in the country.The oldest surviving records come from Milne seismographs establishedin Wellington and Christchurch in 1900 and 1901, and from a Wiechert instrumentinstalled at the Apia Observatory, Western Samoa, a year later.About 1923 a third Milne instrument began recording at Suva, Fiji. Thenumber and quality of New Zealand stations steadily improved, and therecord archive in Wellington is now by far the largest in the region. In1957 the first stations of a comparable network covering New Caledoniaand the New Hebrides (now Vanuatu) were installed. The InternationalGeophysical Year led to the improvement of many stations, and the installationof new ones in Antarctica and on islands in the Pacific. Manyof these stations have continued to operate. Whether records made in theRoss Sea Dependency by the Scott Polar Expedition in 1902 and ByrdExpedition in 1940 still exist cannot be confirmed. Most station files areincomplete. The missing records are usually early ones or those of largeteleseisms. In almost every case they have been interpreted and somedata published, though not always in the detail that a modern seismologistcould wish.1. IntroductionThis paper outlines the history of instrumental seismology in the South-WestPacific up until the year 1963, and documents the present location and condition ofthe surviving records. The area considered extends from Fiji and Samoa in the northto Addlie Land and the Ross Sea Dependency in the Antarctic (Figure 1). There aremany earthquakes in the region, but it is mainly ocean, with no great land-massesor large centres of population. Nevertheless, by the end of the period covered in thispaper extensive networks of seismographs had been established in New Zealand andin French Pacific territories, and single stations set up in the Antarctic possessionsof those countries, and on a number of the smaller and widely scattered islands,the most important being Samoa, Fiji, Raoul Island, and Chatham Island. Thelargest archives of seismograms are in Wellington, at the Geophysics Division of theNew Zealand government’s Department of Scientific and Industrial Research, and inHistorical Seismogramsand Earthquakes of the World455 Copyright 0 19x8 by Academic Press, Inc.All rights of reproduction in any form reserved.