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

HELWAN HISTORICAL SEISMOGRAMSR. M. KebeasyHelwan Instutute of Astronomy and GeophysicsHelwan, Cairo, EgyptSeismographic recording began at the Helwan station in September 1899 using anE -W Milne seismograph. A N-S Milne-Shaw seismograph began operation in 1922,a vertical component Galitzin-Wilip was added in 1938, and a three-componentshort-period Sprengnether was installed in 1951. All these instruments continuedto operate until 1962.In 1962 the Helwan station became a World-Wide Standard Seismograph Station,and three-component short- and long-period seismographs were installed. In1972, a three-component short-period electromagnetic Japanese-type seismographwas added to the system. A 12-channel short-period frequency analyzer, which wasconnected in parallel with the vertical component, operated continuously from 1972to 1980.In addition to the Helwan station, three other stations have operated intermittentlysince 1975 in Aswan, Abu-Simbel, and Mersa Matrouh. A radio-telemetrynetwork of nine stations was established around the northern part of Aswan Lakein 1982. This network was expanded in 1985 to include four additional stations anda digital recording system.The history of the Egyptian National Seismograph Network, its instrumentationand operational specifications, is listed in Table 1.Table 1. Egyptian Seismograph NetworkStat ion Instrument Comp. To TB Speed Magni- Operationlocation type sec sec mm/min fication periodHelwan Milne-Shaw EW 12.0 11.1 10& 15 250 1899-1962Helwan Milne-Shaw N-S 12.0 - 10 & 15 250 1922-1962Helwan Galitzin-Willip V 11.2 11.1 15 1,000 1938-1962Helwan Sprengnether 3-comp 1.5 1.05 60 3,000 1951-1962Helwan Benioff bcomp 1.0 0.74 60 50,000 1962-pres.0Helwan Sprengnether 3-comp 15.0 100. 30 3,000 1962-pre8.QHelwan J apanese 3-comp SP - 120 30,000 1972-prea.Matrouh MSK(CKM-3) 3-comp SP - 60 t0,000 1975-pres.*Aswan MSK(CKh4-3) 3-comp SP - 60 10,000 1975-pres.*Aswan MSK(CK-D) 3-comp LP - 30 2,000 1975-pres.*Abu-Simbel MSK(CKM-3) 3-comp SP - 60 20,000 1975-pres.*Aswan 11 v 1.0 Analog 30,000 1982-pres.$Telemetry 2 E W and toNetwork 2 N-S Digital 100,0002 L-GStation Codes: Helwan = HLW, Matrouh = MMT, Aswan = ASW, Abu-Simbel = ASL.Q - World-Wide Standard Seismograph Station.* - Russian Standardized Seismograph System; not continuously operated.$ - The network is under expansion and upgrading (Simpson et al., 1984) and is locatedin Northern Naaser Reservoir Area.Historical Seismogramsand Earthquakes of the World474