赤石山脈の主稜線部は,日本の山地の中で線状凹地の分布が最も多い地域に属する.本稿では,線状凹地の分布特性を,稜線周辺の応力場と赤石山脈を構成する堆積岩の物性との関連において考察した.
線状凹地の出現頻度は,地層の走向に平行に延びる稜線の周辺,しかも頁岩からなる地域で高い.多くの線状凹地は,正断層変位によって形成された断層地形であると考えられる.その断層面はしばしば層理面に一致する.また,正断層は斜面の最大傾斜方向に働く引張応力によって発生したと推定される.構成岩石の力学的試験によって,頁岩の層理面では引張強度が小さいために,引張破壊が容易に発生することが明らかになった.このような局地的応力場と岩石物性との関係によって,頁岩からなる稜線周辺で,しかも層理面に沿って出現頻度が高いという線状凹地の分布特性が生じたものと考えられる.

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This paper aims to estimate a long-term earthquake risk on the Japan islands from the data in “Active faults in Japan: sheet maps and inventories” (Research Group for Active Faults, 1980) and “Catalogue of historical damaging earthquakes in Japan” (Usami, 1975). The maximum magnitude of earthquakes, expectantly caused by active faults with Certainty I, is calculated from fault dimension using Matsuda's formula (1975). Seismic intensity (Japan Meteorological Agency Intensity Scale) is estimated for 161 grid points by Kawasumi's formula (1951). From recurrence interval of active faults, the probability (expectancy) in earthquake occurrence for arbitrary 1, 300 years is calculated. Accummulating the expectancy for each intensity scale, earthquake frequency per any 1, 300 years at each grid point is estimated. Considering the fact that earthquake motions with Intensity VI or higher have caused a great deal of damage in the historical period, it is adequate to discuss the earthquake risk based on the frequency of earthquakes with such intensities.
The earthquake frequency estimated from inland active faults is regarded as the inland earthquake potential, and it is compared with the frequency of historical earthquakes with the inland epicenter. Then the frequency of earthquakes in the future 1, 300 years is estimated, based on the idea that possibility of future earthquakes is high in the area where the earthquake potential has not been minimized sufficiently by historical earthquakes (Fig, 8)
In Japan, however, the damage caused by marine earthquakes has been very severe during the historical period. We must pay attention to such marine earthquakes particularly in coastal regions.

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The purpose of this symposium, held at the annual meeting of the Association of Japanese Geographers in March, 1985, was to discuss problems on the curriculum of geographical education for students of elementary and junior high school teacher courses in the faculty of education. The symposium included seven reporters and three commentators, together with many discussants. The following are the papers presented by the reporters:
SHIRAI, T.: Recent trend of taking courses by students in geography in faculties of teacher training.
TANAKA, K.: Geographic education in normal schools: the case of the Ikeda Normal School in 1930 s.
HIRASAWA, K.: Some problems on training of student teachers: a case of social studies in junior high schools.
YAJI, M.: Necessity of a curriculum on physical geography in faculties of teacher training.
KANAZAWA, T.: A methodological study on the map education in faculties of teacher training.
YAMAGUCHI, Y.: A methodological study on the curriculum of “methods of teaching in social studies” in faculties of teacher training.
NAKAGAWA, K.: A practical study on “teaching methods in social studies” in faculties of teacher training.
The commentators raised challenging questions, made constructive comments and led the discussion with attendants fruitfully. Discussions focused on the following points:
1. How to develop adequate curriculums on physical geography and cartography for students outside the geographical course in the faculties of teacher training.
2. Reconstruction of curriculum in normal schools may be necessary for the historical study of geographical education, and reevalution of them will give some ideas for geographical education today.

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