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

Historical Seismograms and the Microfilming Project 417the seismograms at the auxiliary stations have been kept untouched. When we askedfor the seismograms of the 1935 Hsinchu-Taichung, Taiwan earthquake, Stuttugarthas sent us the seismograms of its auxiliary stations, Messtetten and Ravensburg,because the records of Stuttgart were lost.Considering the above comments, it is recommended that an auxiliary stationbe selected in the same region of a representative station. It is probably easy toinclude a visit to the auxiliary station in the itinerary of the filming team.3.2. Name, Code, and Coordinates of StationsName, code, and coordinates of the selected stations are, of course, basic forthe filming project. International 3- or 4-letter codes in use are most convenientto identify the stations, especially when there are several stations having the samenames, or if a station was moved its location several times.The U. S. National Earthquake Information Service (NEIS) has a general policyto give a different code for a new station that is moved more than 1 km from theold station. This policy is reasonable for teleseismic studies, as far as arrival timesare concerned. However, for the study of local earthquakes, 1 km may be too large.Moreover, if we study the seismogram, including amplitude and period characteristics,even a separation of less than 1 km may become important, especially wherethe foundations are different. It appears to be better to label seismograms of oldand new stations with same name, but to give them different station codes.In preparing the Directory of Seismographic Stations in Asia (Miyamura, 1985),I have tried to give tentative station codes to differentiate between old and newstation sites.Many networks use station codes rather carelessly, which eventually introduceconfusion. To avoid duplicating codes, an uptc+date list of station codes shouldbe published frequently, and institutions operating seismological stations should beasked not to use codes already registered by other stations.In addition, ISC should examine duplicate station codes and cancel one of them,e.g., GZS and GOZ for Gozaisho, Japan; KRZ and KAZ for Karuizawa (not Kuruizawa),Japan; KMT and KNT for Kinomoto, Japan; AAI and AM0 for Ambon,Indonesia, etc. Perhaps it is better to denote KAZ for the site (36.3333 N,138.6000 E) used in 1941-49 near KRZ, and to denote KRZ for the site (36.3400 N,138.5517 E) used since 1911 to the present. Similarly, we may use AM0 for Ambonbefore World War 11, and AAI for the new station in the same place since 1975.Hamburg was one of the representative stations in Europe before World War 11,but was destroyed by a catastrophic air raid in 1945. After the War, a new Hamburgstation was established in Harburg, on the other side of the River Elbe. It isregistered by ISC as Hamburg with station code HAM. A closed station of Hamburg,N.Y., U.S.A. is identified by the code HMB. But the historically importantstation at Hamburg in the city (reportedly moved once) is not registered in ISC,although its historical seismograms are kept at the Harburg station. Many famousold stations, including some of John Milne’s worldwide network stations are notlisted by ISC, although many closed stations of minor importance are registeredwith proper station codes.In using the seismograms and/or station bulletins, careful examination of thestation coordinates is necessary. For the April 20, 1935 Hsinchu-Taichung, Taiwan,earthquake, ISS lists the readings at the Leipzig station and I have requested a copy