- 公益社団法人 日本地震学会
- 地震 第2輯 (ISSN:00371114)
- vol.44, no.Supplement, pp.41-51, 1991-07-24 (Released:2010-03-11)
Internal structure of terrestrial planets and moons are best characterized by seismological method. In the present paper, we will briefly describe the seismological instrumentation and results obtained for the moon and Mars. Since the most significant seismological data were obtained by the Apollo seismic network, emphasis is put on the lunar study. The velocity structure of the shallow moon (<120km depth) has been determined by the analysis of man-made impacts. On the other hand, the velocity structure of the mantle (120km-1, 000km) has been determined by using 41 deep moonquakes, which periodically occur at depth from 800km to 1, 150km. The velocity structure at depth below 1, 000km has not yet been established. Several petrological models are made by using the velocity structure of the mantle and other geophysical constraints such as the density distribution, moment of inertia, temperature distribution, and elastic data of the candidate minerals of the moon. These petrological models, however, are not so accurate that they do not constrain the formation process of the moon. The more detailed information on the lunar interior such as the size of core is required for clarifying the formation process of the moon. The forthcoming Japan lunar penetrator (LUNAR-A) mission, which is planned to be launched in 1996, will provide useful data on the lunar interior. A new seismic network of triangle form with about 5, 000km length will be constructed by the penetrator seismometers. We expect the results by the LUNAR-A mission to clarify several unsolved problems of the deep sturucture of the moon.