噴火と火山に発生する地震との研究 : 第2報 特に浅間火山の噴火予知の問題に関して

抄録

Firstly, the writers will give an outline of the seismographs and the method of seismometrical observations used at Volcano Asama over the past several years. For the recent seismometrical investigations of volcanoes in Japan, the writers used a series of telerecording seismographs. At Asama, transducers were set near the summit crater, on the mountainside and at the foot of the volcano and as these transducers were connected with the respective recorders in the Observatory by means of sealed wires, their records could be obtained at the Volcano Observatory. The earthquakes originating from Asama discussed in this paper are mainly those observed by the transducers which were set at 0.9km (No. I) and 2.5km (No. II) from the crater. These seismographs were adjusted to 4000 in magnification of displacement amplitude ranging from 0.3sec to 0.7sec of vibration period. It may be remarked that earthquakes originating from Asama are markedly similar to those (1956～1957) of Sakura-zima in the nature of earthquake motion and in the mode of seismic activity. Therefore, it may be said that the two volcanoes Asama and Sakura-zima are similar not only in the seismological features but also in chemical and physical properties of erupted lava, the position of eruption (i.e. at the summit crater), and in the nature of eruption.