In the southwestern part of the Tamba highland consisting of the Paleo-Mesozoic rocks, the Mitoke fault system can be observed as lineaments distributing side by side. The general trend of these faults curves from WNW-ESE in the north to NW-SE and N-S in the south.
The writer has investigated younger fault topography of the Mitoke fault system, especially along the Mitoke, Shuzan, Seryo, Tonoda and Koshihata active faults, in order to clarify the nature of faulting during the late Quaternary period.
The results are summarized as follows;
1) Active faults of the Mitoke fault system are characterized by sinistral faulting with the uplift on the northeastern blocks accompanied by the constituent of reverse fault.
2) The mean slip rates of faulting and others are listed in Table 1, on the basis of tephrochronology of deformed terraces and dissecting valleys across the faults. The mean slip rates of faulting are calculated to be 0.18-0.66m/1, 000 years sinistrally, and 0.009-0.33m/1, 000 years vertically. The progressive faulting with the uniform rate can be estimated during the late Quaternary period.
3) The mean rates of vertical displacement and the ratio of the horizontal to vertical ones differ with the changing in the strike of the faults. This is considered to be due to the obliqueness of the trend of the fault against the compressional stress axis of E-W which predominates in southwest Japan.
4) Between the amount of stream offset (D) and the length of upstream from fault line (L), the relation D=aL can be recognized and the calculation gives the coefficient a=0.15-0.44 on these faults. They implicate that the sinistral faulting has high activity. Investigating the strike-slip faults in the Kinki district including the Mitoke and Tonoda faults, the relation S=(1-5)a can be recognized where S is the mean rate of strike-slip faulting (m/1, 000 years), however this is different from the relation S=10a that was recognized on the Median Tectonic Line and the strike-slip faults in central Japan by Matsuda (1975).
5) On the assumption of constant slip rate the sinistral faulting should have started in 0.5-0.6 m.y. ago. Before that time, these faults are infered that they had the dextral component cotrolled by N-S compressional stress field.

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The interaction between winter monsoon circulation features in East Asia and sea surface temperature (SST) variations over the western Pacific is examined. First, the relationship between diabatic heating term and horizontal or vertical advection term at the lowest layer (1, 000-850 mb) is investigated by applying the empirical orthogonal function (EOF) analysis on heat budget components over the western Pacific Ocean. Second, the atmospheric response and forcing power on the SST anomaly are discussed based on the composite analysis of SST, outgoing longwave radiation and horizontal motion associated with the strength of winter monsoon.
When the winter monsoon is active, negative SST anomalies exist in the mid-latitude region near Japan, but on the other side positive SST anomalies exist over the tropical region. Positive SST anomalies in the low latitudes enhance the strong connective activities over maritime continent. Contrastly, it is suggested that negative SST anomalies in the middle latitudes are mainly formed by heat loss of the ocean due to air-sea heat exchange and by the horizontal temperature advection within the mixing layer of the ocean. The anticyclonic (cyclonic) circulation at the 200 mb level over southern China is associated with the strong (weak) winter monsoon. This anomalous circulation seems to be coincided with one pole of the dipole pattern which has the center of circulation in both hemispheres. Thus, it is suggested that the strength of East Asian winter monsoon is partly controlled by the Matsuno-Gill type response model in which the strong convection over maritime continent acts as a heat source.

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The purposes of this study are to clarify the regional difference of year-to-year changes of winter precipitation, and to investigate the type of disturbances contributing to winter precipitation and the relationships between the precipitation and the frequency of disturbances.
First, the correlation coefficients of the precipitation for winter during forty years from 1940/41 to 1979/80 at 46 stations (Fig. 1) were calculated (Figs. 2 and 3). The area indicating the correlation coefficients above a significant level was larger on the Pacific side than on the Japan Sea side. The stations included in the semi-climatic region of the Japan Sea side (Suzuki, 1962) had similar tendencies as the Pacific side. Since the stations on the Japan Sea side correlated only to the adjacent station, on the Japan Sea side was divided into four regions; the San-in region, the Hokuriku region, the Tohoku region and the southern part of Hokkaido. On the Pacific side, the similarity of fluctuations among stations was remarkable, so the regions were not distinctly separated, but overlapped with each other. Therefore, the region west of Kanto district, the region from Kinki district to Tohoku district and the region from Kanto district to Hokkaido were combined respectively as the area having the same tendency.
Daily precipitation was classified into four groups by use of synoptic charts according to the type of disturbances; Japan Sea Lows, Pacific Coast Lows, Coupled Lows and winter monsoons. The percentage ratio of the precipitation caused by lows to the total amount of winter precipitation, was calculated (Fig. 4). The same calculation was made for each type of low (Fig. 5). Moreover, the type of disturbances having a significant influence on winter precipitation and their distribution ratios were investigated for each station (Fig. 6). On the Pacific side, the disturbances contributing to winter precipitation were: Pacific Coast Lows and Coupled Lows in the south of Tohoku district, and Japan Sea Lows and Coupled Lows in Hokkaido. Though the region west of Kanto district and the Tohoku district had the same combination of disturbances, the contribution ratio between the two types of lows varied between the regions. On the Japan Sea side, likewise, the combination of disturbances and their order varied from station to station. The main causes of winter precipitation changed in accordance with the regional difference of year-to-year changes in precipitation.
Correlation coefficients between the frequencies of lows in and around the Japanese Islands and the winter precipitation were calculated (Figs. 7 and 9). The winter precipitation at the stations in which lows were the main causes depended on the frequency of lows. That is, the precipitation on the Pacific side from the Tohoku district to Kyushu was related to the frequency of Pacific Coast Lows, and the precipitation Hokkaido and on the Japan Sea side of Tohoku district was related to the frequency of Japan Sea Lows (Figs. 8 and 10).
We can conclude that the winter precipitation at each station mainly depends on the frequency of disturbances, and the regional differences of year-to-year changes in winter precipitation is due to the fact that the frequency of disturbances varies with regions.

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