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

Historical Seismogram Filming Project 377World Data Center-A for Solid Earth Geophysics and the National GeophysicalData Center have also translated into English a very important study of earthquakesin the U.S.S.R. Methodologies are developed in the text to relate historical feltinformation to location, origin, date, time, intensity, and magnitude of about 6,000earthquakes in the U.S.S.R. from 2100 B.C. through 1977 A.D. (Kondorskaya etal., 1982).5. Future PlansIt is expected that seismogram copies will be received in the near future from theHelwan Observatory, Egypt, and from CERESIS for a number of South Americanstations. World Data Center-B in Moscow will probably complete the filming ofthe U.S.S.R. stations within the next few months. WDC-A should also completefilming the Baguio records in the near future.Plans are being formulated to prepare an inventory of historical seismograms thatwill not be filmed as part of this project. Funding restraints make it impossible tofilm seismograms from many important stations. A list of these seismograms andtheir locations can be an extremely important source of information. We, therefore,urge those who have knowledge of seismogram collections to send the informationto WDC-A.WDC-A will be working with the IASPEI/UNESCO Working Group on projectsrelating to global and regional earthquake catalogs. The work will involve encouragingadditional nations to develop historical event catalogs for their region,recommending standards, and improving quality control.6. Recommended Filming Techniques (from Glover and Meyers, 1982)6.1. Seismogram PreparationSeismograms should be inspected and repaired if necessary, before filming. If therecords are damaged, they can be mended using transparent tape on the back side.Rolled or folded records can be laid out and pressed flat under heavy weights, andthose on photographic paper can be rewetted and pressed between blotters to dry.A monthly log that indicates which records axe present and missing should becompiled for filming with the seismograms. Information that was written on therecords at the time of recording (such as instrument type, component, on-off times,and polarity) should be recopied on the seismograms where necessary for readability.Additional technical information about the instruments (such as pendulum period,damping ratio, and magnification) and any other useful data (e.g., a brief stationhistory) should be compiled if available and filmed or spliced on each roll of film. Inaddition, voluminous data such as station logs, time determinations, and earthquakereports if available can be filmed separately.6.2. Cameras UsedHistorical seismograms have been filmed at the WDC-A/NGDC facility usingtwo cameras. A Micro Instrument Corporation 35-mm rotary camera was used tofilm station-years of seismograms. This camera was chosen for its ease of operationand its capability of filming many seismograms in a short time. The camera can