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

30 Hiroo KanamoriNagamune, T. (1971). Source regions of great earthquakes, Geophys. Mag., 35, 333-399.Okal, E. A. (1976). A surface-wave investigation of the rupture mechanism of the Gobi-Altai (Dec. 4, 1957) earthquake, Phys. Earth Planet. Int., 12, 319-328.Okal, E. A. (1977). The July 9 and 23, 1905, Mongolian earthquakes: A surface waveinvestigation, Eorth Planet. Sci. Lett., 34, 326-331.Richter, C. F. (1958). Elementary Seismology, W. H. Freeman and Company, San Franciscoand London, 768 pp.Silver, P. G., and T. H. Jordan (1982). Optimal estimation of scalar seismic moment,Geophys. J. Roy. Astr. Soe., 70, 755-788.Singh, S. K., G. Suarez, and T. Dominguez (1985a). The great Oaxaca, Mexico, earthquakeof 15 January 1931: Lithospheric normal faulting in subducted COCOS plate, Nature,317, 56-58.Singh, S. K., L. Ponce, and S. P. Nishenko (1985b). The great Jalisco, Mexico earthquakeof 1932 and the Rivera subduction zone, Bull. Seism. Soc. Am., 75, 1301-1314.Singh, S. K., T. Dominguez, R. Castro, and M. Rodriguez (1984). P waveform of large,shallow earthquakes along the Mexican subduction zone, Bdl. Seism. Soe. Am., 74,2135-2156.Stein, S., and E. A. Okal (1978). Seismicity and tectonics of the Ninetyeast ridge area:Evidence for internal deformation of the Indian plate, J. Geophys. Res., 83, 2233-2245.Stein, S., N. H. Sleep, R. Geller, S. C. Wang, and G. Kroeger (1979). Earthquakes alongthe passive margin of eastern Canada, Geophys. Res. Lett., 6, 537-540.Thatcher, W., J. A. Hileman, and T. C. Hanks (1975). Seismic slip distribution alongthe San Jacinto fault zone, southern California and its implications, Geol. SOC. Am.Bull., 86, 1140-1146.Wang, S. C. (1981). Tectonic Implications of Global Seismicity Studies, Ph.D thesis,Stanford University, 70 pp.Wyss, M., and J. N. Brune (1967). The Alaska earthquake of 28 March 1964: A complexmultiple rupture, Bull. Seism. Soc. Am., 57, 1017-1023.APPENDIXIn order to evaluate the usefulness of historical seismograms for various seismologicalresearch, the recording thresholds for various seismographs have been computedand compared with that of the WWSSN seismograph. For this purpose, we chooseeight representative seismographs listed in Table 3, and compute the amplituderesponse curves which are shown in Figure 8.For the mechanical seismographs, the instrument response can be given by 3 constants,pendulum period, T, darnping ratio, E, (or damping constant h), and thestatic magnification V (see, Richter, 1958, p. 219 ). The response of the Galitzinseismograph is often given by 4 constants, I, T, Al, and k (see Macelwane andSohon, 1932, Vol. 2, p. 84). T is the period of the pendulum and the galvanometer(for the Galitzin seismograph, the pendulum and the galvanometer always have thesame period.), and k is the transfer factor. Then the peak magnification is givenby V, = 0.32 k A1 T /K~.In Figure 8, the response of a representative IDA (International Deployment ofAccelerographs) instrument is also shown for comparison.At a period range from 1 to 5 sec, the responses of the Milne-Shaw, Galitzin-1,Wiechert-2 and Mainka seismographs are more or less comparable to the WWSSNLP instrument. Therefore, for body-wave studies the records obtained by theseseismographs should be almost as useful as those obtained by the WWSSN (LP)seismograph. In order to compare the recording thresholds for long-period surfacewaves, we compute the peak-to-peak amplitude of the ground displacement which