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

Historical Seismograms and the Microfilming Project 403Table 1. Earthquakes in Duda (1965) (DU) with MDU L 7.5, not listed inGutenberg and Richter (1954) (GR) and Abe and Noguchi (1983a, b) (AN, AN’).Year190519071908190919101913191519161917Date03.1810.2105.0412.1212.0905.2208.0102.2802.0102.0612.29Time00:5811 :0106:5112:0823:2306:2517:lO18:5907:3621:5122.50Lat. O27.5 s42.0 N07.5 S14.0 S10.0 s42.0 N47.5 N23.6 N29.5 N48.5 N15.0 NLon. O173.0 W042.0 E153.7 E078.0 W165.0 E145.0 E155.5 E123.5 E131.5 E178.5 E097.0 WDepthss8ss8sssBsMDU7.57.57.77.57.77.78.07.77.7Rem.Remarks: (1) GR: 12:54.9 26.5 N, 97 E, MGR = 7.5 (26N360); MAN = 7.6, MA” =7.0. (2) GR: 23:28.8 12 N, 144.5 E, h = 50 km, MGR = 7.4 (17N780); MAN = 7.1,MAN/ = 6.8. cf. Remark (2) in Table 2.and Meyers, 1981); but in the fourth report (Glover and Meyers, 1982), the globaland U.S. lists have been combined into one catalog for 1900-1962.The global catalog for 1900-1962 in Meyers and Lee (1979) [hereafter SE22 ] is acomputer-readable version based on the earthquake catalog of Rika Nenpyo (ScienceAlmanac) compiled by T. Usami (1975) [hereafter RN]. SE22 stated that RN isbased on Gutenberg (1956) [hereafter G 1, Gutenberg and Richter (1954) [ GR 1, andRothB (1969) [hereafter RO ] for the periods 1900-1903, 1904-1952, and 1953-1962,respectively. However, the catalog is not so simple. It includes earthquakes withM 2 7.0, and this M is the largest value among different sources. Unfortunately,the reference sources are not given explicitly. It is clear that the earthquakes in andnear Japan prior to 1925 are taken from the catalog of the Central MeteorologicalObservatory (CMO) (1950), because it explains that: (1) M for those earthquakesare converted from the Kawasumi intensity magnitude Mk and generally are 0.5units larger than the instrumental magnitude by the Japan Meteorological Agency(JMA), MJ; and (2) the number of earthquakes prior to 1925 is larger than thenumber of earthquakes in the later period. Japanese earthquakes after 1926 aretaken from JMA data. In addition, damaging earthquakes having M < 7.0 areincluded, but neither the data source nor the selection criteria are given.Computer output should be carefully examined visually. SE22 includes the followingerrors:(1) “1905 Feb 21 41.5N 142.5W 7.0 North Pacific Ocean” should be“1905 Feb 21 41.5N 142.53 7.0 Hokkaido”,(2) “1906 Mar 16 23.53 120.5E 8.5 Australia” should be“1906 Mar 16 23.5N 120.5E 8.5 Taiwan”, and(3) “1906 Apr 18 38.0s 123.0W 8.25 South Pacific Ocean” should be“1906 Apr 18 38.ON 123.0W 8.25 California”.Similar printing mistakes were found in DV, i.e. “W” should be “E” in the followingearthquakes: February 1, 1938; November 10, 1942; May 3, 1943; and November25, 1953.