Abstract
In this study, an analysis was made of earthquake waves recorded with a magnetic tape recorder. A velocity seismometer with a magnetic tape recorder was operated intermittently at Mt. Tsukuba from November 30, 1957 to December 9, 1957, and about 400 near-by earthquakes were recorded in 25 hours in total. Since the records are taken with a tape recorder and are therefore reproducible, various characteristics of the seismic waves other than velocity can be obtained by means of electric circuit device and investigated. First the relation between predominant periods and maximum trace amplitudes of the seismograms reproduced from the magnetic tape was studied. Acceleration seismograms were also obtained from the records of the velocity seismometer through a differentiating circuit, and the frequency distributions of maximum acceleration (α) and maximum velocity (υ) amplitudes are compared. They are found to be expressed by the following equations respectively,
N(υ)dυ=κυ-mdυ, (1)
N(α)dα=κ′α-m′dα, (2)
where, m=1.82, m′=2.05.
From these values of m and m′, we can deduce the relation between predominant periods (T) and υ; T=const.·υ0.22. This equation is transformed into the relation between T and A (maximum displacement);
T=const.·A0.18.. (3)
