Study of physical bioclimatology has a long history as BUETTNER (1962) as well as LANDSBERG (1972) pointed out. In the early days the term “Climate” sometimes meant bioclimatology as may be gathered from A. v. HUMBOLDT's statement (1845). Since then, human bioclimate has been studied in various sciences, for example, medical cience, human biology, sanitary science, applied meteorology, applied climatology and so on. Undoubtedly many results have been obtained in these sciences regarding bioclimatic studies; however, either study of regionality or regional structures of human bioclimatic characteristics have not been a subject of great interest. In geography or climageography, one of the most important traditional subjects is to classify climates and on the basis of such a system to divide climatic regions. However, to my regret, in the field of geography itself, the study of bioclimatic regions developed too late. Excepting TAYLOR'S famous work (1916), few research results were obtained before the 1930' regarding bioclimatic regions. It may be a remarkable fact that Section Geographie coloniale was set up on the occasion of the 15 th International Geographical Congress in Amsterdam in 1938, and several papers on acclimatization for the white race in the Tropics were presented. The study of acclimatization as well as human bioclimatology developed rapidly thereafter in the field of geography. It should be pointed out that the 15 th IGC was the turning point to develop the study of bioclimatology as well as human bioclimatic regions in the field of geography. As one of the key subjects, the study of sultry boundaries and climatic divisions on the basis of distribution of sultriness have been performed (MARNER, 1940; SCHARLAU, 1950, 1952; SCHULZE, 1956; HAVLIK, 1976; DOMROS, 1981; TILLEY, 1988 and so on). The sultry zones of the world (SCHARLAU, 1952) and vertical zonation of the bioclimatic structures, especially of the upper boundary of the distribution of sultriness in the mountainous regions in the Tropics and others may be one of the most remarkable results (SCHARLAU, 1952; Domras, 1981 and so on). Cooling power is also a very suggestive index regarding bioclimatic divisions. World maps of distribution of the Hill's cooling power in January and July performed by LAUSCHER (1951) may be one of the earliest results on bioclimatic regionality on the global scale. GREGORCZUK's work (1968) of world bioclimatic regions was performed on the basis of the distribution of air enthalpy grade which was introduced by BRAZOL (1954) as a scale of sensation of anthropological climates. Climatic systems by TERJUNG (1966, 1967, 1968) has been established on the basis of comfort indexes as well as wind effect indexes and bioclimatic divisions of the USA as well the world performed on the basis of his climatic systems should make it possible to clarfy regional structures of bioclimatic characteristics. One of the very interesting results is JUSATZ's work (1962) on the distribution of epidemic diseases as an effective index for bioclimatic classification, and his consideration of the relationship between spinal meningitis and the harmattan in Central Africa should be a representative result obtained in the field of not only medical geography but also bioclimatology. Research on the requirement of clothing as a index of human bioclimates and establishment of bioclimatic regions of the world has broken new ground in the study of bioclimatic regions (LANDSBERG, 1954; LEE et al., 1949; ALCIEMS et al., 1976, 1979, 1981, and so on). In the present paper the author comments mainly on studies of bioclimatic regions on a global scale. However, it should be of utmost importance to develop studies of bioclimatic regions on meso- as well as on microclimatic scales. DAMMANN's work (1958, 1964) should be a good example.
Sagami Trough is regarded as the boundary between the Philippine Sea plate and the northeast Japan plate. Previous studies have suggested that a great earthquake will probably occur in the near future in the Sagami Bay area, the northwest portion of Sagami Trough. In this study, active geological structures and topographies in Sagami Bay are described on the basis of detailed analyses of multi-channel and single-channel seismic profiles and topographic maps, and the tectonics of this region are discussed. The Sagami Bay fault and its landward extension, the Kozu-Matsuda fault were generally thought by previous workers to be a northeast-dipping oblique-slip fault, on which most of the relative motion between the two plates are accommodated. The Manazuru Bank situated 5-10 km west of this fault, however, are formed with strongly deformed trough fill sediments. Moreover the rupture surface of the 1923 Kanto earthquake (M. 7.9) deduced from geodetic and seismological data extends across the Kozu-Matsuda-Sagami Bay fault. These suggest that the Manazuru Bank is underlain by a north-dipping thrust fault, on which the plate motions are accommodated. I speculate that the leading edge of the thrust fault is now propagating further west to Izu Peninsula. This could explain the late Quaternary deformation of Izu Peninsula and Ashigara Plain.
Numerous evidences of paleoearthquakes have been discovered in many archaeological sites. The present writer has investigated on these evidences and comes to the following conclusions; 1) Some traces of the Paleo-Nankai and Tokai earthquakes were found mainly along the Southwestern Pacific coast. The present writer infers from these archaeological evidences and old documents that these great earthquakes occurred simultaneously in the years A. D. 1498 and A. D. 684. 2) The ages of the faultings which caused big earthquakes, were revealed in some regions. For instance, the fault movement along the northern rim of the Osaka Plain is proved to have occurred in the years A. D. 1596 and about A. D. 500. 3) Traces of sand eruption were found out in many sites. Some important behaviors of sand layers, caused by a liquefaction, were observed in these traces.
Thermal inertia of material is well developed in physics and can be used for soil moisture measurement. In this study, it was clarified that the thermal inertia of soilwas able to be measured by the heat balance parameters on the earth's surface. The author has developed a model for determining soil moisture based on a thermal inertia model from an experiment carried out for the mapping of the distribution of soil moisture in Northeastern China. Also, discriminant analysis for land cover classification, computer mapping and overlay/compilation of maps were systematically utilized for soil moisture mapping. Nevertheless, improvement must be made on many points in the field measurement system. When the problem is solved, this mapping procedure is applicable to the accurate determinations of soil moisture in future studies.
The discovery of the magnetic anomaly lineations that can give ages of ocean floor is a very important role for establishment of the plate tectonics theory. The magnetic anomaly lineations also give us information of a history of movements of the oceanic plates. However, the origin of magnetic anomaly lineations still been obscured, that is, we can not clearly answer for the following questions: How thick is the source layer of magnetic anomaly lineations? How strong is the intensity of the magnetic source layer? In this paper we examined the relevant information concerning the magnetization of the oceanic crust from studies of observed marine magnetic anomalies and from rock -magnetism of oceanic basalts to get a goal of these questions in this paper. The skewness parameter that is deduced by precise magnetic anomaly lineations is important to identify marine magnetic anomalies. The magnetic polarity transition width is also important to do, though the parameter associated with this transition width has not almost utilized in the previous works. The anomalous skewness and the skewness discrepancy are often observed over the oceans. These observations might be explained not by a single-layer model but a two-layer model for magnetic source layer. The polarity transition width is defined the width which 95.4 % of the change from normal to reversed polarity occurs within. This width increases monotonically with spreading rates of ridges and/or with ages of ocean floors. This increasing is considered to be a manifestation of a more complicated crustal source consisting of two discrete layers. The analysis of the skewness parameter and transition width strongly supports that the sourc elayer of marine magnetic anomalies has a two-layer structure. The upper layer, consisting of surface lava flows of layer 2 A and possibly the sheeted dike complex, hasdi stinct and approximately vertical magnetic in the vicinity of opposite magn etized region boundaries. The lower layer, consisting of intrusive and gabbroic layers, has the boundaries gradually sloping downward away from the spreading center. Many detailed survey are carried out to reveal the structure of magnetic source layer by the multi narrow and the deep-towed magnetometer near active ridges. Inversion of magnetic layer using results of detailed surveys concluded that the magnetic source layer near the active ridges is less than 1 km in thickness. The polarity transition width of the relatively young layer is narrower than that of older oceanic floor, and the magnetic intensity of the relatively young layers higher (more than 10A/m) than that of older one. These conclusion indicate that the magnetic source layer near the active ridg es consists of a single layer structure. It is thought that the magnetic source layer grows with ages asoceanic crust by results of analysis of skewness and polarity transition width and inversion of magnetic source layer near active ridges. Several previous paleomagnetic studies indicate that intensity of natural remanent magnetization (NRM) of basaltic rocks composing the ocean crust rapidly decreases with ages in the past 10 to 20 Ma, and gradually increases older one. This change in NRM intensity is roughly proportional to the changes in intensity of saturation magnetization of the rocks and possibly due to sea-water alteration (low-temperature oxidation) of the primary ferromagnetic minerals contained in the rocks. NRM of the oceanic rocks is initially thermoremanent magnetization acquired at the time of formation of the oceanic crust. In accordance with progressive oxidation, fraction of TRM to bulk intensity decreases, while that of the secondary magnetization increases.
The Philippine Earthquake (Ms=7.8) broke out in July 16, 1990 along the Philippine Fault in Central Luzon. The Philippine Fault is seismically very active and large earthquakes of M 7 class have occurred during this century along this fault. However large earthquakes have not taken place along the active traces of the fault in the Central Luzon during this century, while two large historical earthquakes occurred along its southern trace in 1645 and its northern trace in 1796. Therefore it is considered that the 1990 earthquake was caused by the surface faulting in the seismic (aseismic) gap along the Philippine Fault. The total length of the surface fault is over 120 km and the fault is divided into two segments by the major bend near Rizal. The surface fault is rather straight and linear and general orientation of the northern segment is N 25 W and the southern segment N40W. Left-lateral displacement is dominant along most of the fault traces and the maximum horizontal displacement is about 6 m in the 60-km-long northern segment and the maximum vertical displacement is 2.0 min the 50-km-long southern section. Sense of vertical displacement changes in places and is consistent with the sense of the displacement along the pre-existing active fault traces. Average displacement along the northern segment is 5-6 m, while 2-3 m along the southern segment. Along most of the surface fault, ruptures appear exactly along the pre-existing active fault traces. Offsets of roads, foot-pass, streams are common earthquake-induced features. Local extensional and compressional jog forms related to slight change in fault strike creates characteristic features such as depressions, trenches, mole tracks, bulges etc. The rupture propagated bilaterally northward and southward from hypocenter east of Bongabon near the major bend. The source process of the earthquake deduced from the slip distribution along the surface fault from the epicenter well coincides with that deduced seismologically from the source time function.