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Now the landslide surface and the mechanism of a landslide are commonly discussed, based on surveys by means of the internal strain meter. On case of a shattered zone typeof landslide ares, however, the data gathered in this method have a strain value of unknownorigin and have many things unsolved. This time, therefore, the observation of undergrounddeformation was made with a pipe strain meter of ordinary type and an internal strain meterof insertion type at a shattered zone type of landslide areas; Yakuaji, Kuki snd Nishiikawa.It has proved helpful for finding where the landslide surface exists.

The observations of micro-tremors over the Kamenose landslide area were carried out morethan twelve times since 1971.It has been definitely shown that tremors may be affected strongly in the frequency range (2-4 Hz) by the existence of cracks at the landslide area.The directions of invisible cracks that may suggest the direction of flow of landslide motionwere detected from observed tremors.After civil engineering works for prevention of landslide motion, it has been shown that tre-mors may be affected in more high frequency range (5-8 Hz) by generation of cracks with shal-low depth at the Yamato river side of line of long concrete piles.

Many data of the internal strain meter of the shattered zone type landslide areas are collected, and availability of these data studied from the testimonys of laboratory works, geological phenomenaand slope displacement.The writers are pointed out some problems of the internal strain meter survey. They are thehard questions of the charge of the space between bore hole and internal strain meter, and station-ing intervals of strain gauges, and discordance between the shape of pipe and the pillar-shaped graphof accumulated strain, and etc.

At Kamenose Landslide zone located in Toge, Kashiwara City, Osaka Prefecture, thegeophysical investigation to establish the perfect stabilization plan has begun at the end of1962.As the methods of the investigation the following observations are carried out.A) The sliding movement survey and the observation of tilting motion on the groundsurface by the wire extensometers and tiltmeters with horizontal pendulun type, b) The observation of groundwater level by the groundwater level indicater, c) The observation subsurface deformation by the portable underground inclinometer.Moreover seismic prospecting was carried out to study the crustal structure in thiszone.In this paper these methods and the results of the investigation and observation arediscussed.

In order to investigate the mechanisms of soil displacement and to decide the slide surface, observations have been carried out by the internal strain meter method in the T6ge Land-slide.On that mechanism, it is shown that the tension of the soil at the upper part causes themain-force of this soil displacement and it effects on the displacement in the shallow depth inthis landslide.On the slide surface, it is found that there are two slide surface; one is in about lOin depth, the other in more deep one which is almost the same as that of the slide surface of the KamenoseLandslide in 1933.

In order to know the nature of variations of the surface inclination at the landslide areaswhich were clasified into creep type when its occurred, the water-tube type inclinometers wherewere set at the suitable site were used.In this paper, the observational results on the small scale surface ground tilt at Kamenose, Muraoka and Myoban landslide areas were reported and some discussion were made.

Upheaval phenomenon at the tip part of landslide is not so rare. But the upheavalat the opposite side of the river which runs at the tip part of landslide seems to suggestthe factore of cause of the landslide.Accordingly, for the purpose of making clear the phenomenon, the study was carriedout.In beginning, the electric survey was carried Out atsome landslide areas which hadthe specific upheaval phenomenon.As the result of the investigation, the next facts were revealed:(1) The difference of the apparent resistivity between the upheaval area and thenon upheaval area was caused by the occurrence time of the upheaval phenomenon.(2) The difference of the apparent resistivity between the upheaval area and thenon upheaval area was caused by the geological factor.

In this paper, the author had studied thr relationship between variation of tiltineter andlandslide movement observing bulb type tiltmeters~ in the creep type landslides. From the resultsof them, the variation of tiltmeter in landslide is related with the landslide movement of creep type.When we make judge the landslide movement from variation of inclination on the soil surface, it is usefull to confer the standard curves that was maked by observational facts.The critical inclination for soil movement, is assumed about 4"/day as N-S and E-W com-ponent respectivelly.

The Makiuchi landslide and the Gongenyama landslide had occurred at Matsushirotown, Nagano city, in Sept. 17 and Oct. 9, 1966 respectivelly. These areas where thelandslides occurred are situated at the middle part of the Matsushiro earthquake swamwhich effect on the faults, cracks, spring discharges and upheaval of crustal block.These landslides are very rare one for its clasifications, therefore we are studying naturalradioactivity survey and chemical analysis were carried out to explain the mechanismsof these landslide occurrence.Natural radioactivity of near cracks and faults from 2.5 x 10'm7/h to 6.2 x 10'm7/himplys being of active faults and hotspring activity. Farther more we continue this su-rvey to explain that the faults and cracks and hot spring activity are increasing or notby the natural radioactivity variations.Chemical analysis of the water samples from the springs which recently gushed outwas carried Out in relation to pH, Na~, Ca", Mg'~, HCO, , C1, SO4~, and solubleSiOz. The wide variation of the content of each ion from 10mg/I to 3, 000mg/I suggeststhat these water samples contain the highly mineralized water from the great depths.The concentration of ions in the spring water increased several times from Septemberto October but the increasing rate varies with the kind of ions. Therefore thevariation of the concentration of each ion can not be explained solely by the dilutionof the mineratized water by the surface water.

大和川が奈良盆地の小流を集めながら西流し, 一本となり生駒山脈を横断して大阪平野にぬける付近は, 通称"亀の瀬"と呼ばれ, 峡谷をなしている。この左岸は奈良県北葛城郡王寺町で, 明神山・二上山と続き急峻な地形となっており, この裾を関西本線・国道25号線が走り, 関西交通網の幹線となっている。また, 右岸は大阪府柏原市峠町で, はるか北の方に信貴・生駒の山並みを望み, 付近一帯は緩やかな丘陵地帯となっており, 肥沃な土壌と南の日ざしをうける傾斜地は果樹の生育に適し, 古くからぶどう・桃・みかん等の産地として有名である。このような, 一見のどかな丘陵地帯も宿命的な地すべり地で, 昔から度重なる地すべりによる被害を受けており, 中でも1931年年末から起った地すべりは, 峠部落を中心に32haの土地がすべり, 当時穐の瀬地すべり"と呼ばれてニュース面をにぎわした。この地すべり地域の西側の清水谷地域(Photo.1参照)における地すべりが最近活発化するにおよび, 建設省においては, 地すべり防止工事を実施することになり, 昭和38年度を初年度とする5カ年計画で総土量60万m3の排土が行なわれつつある。筆者らは・この排土工事に関する諸資料を得るため・昭和37年以来当地域一帯で, 地質学的・地球物理学的・土木工学的な諸調査を実施してきたが, 以下筆者の行なった地球物理学的な調査に関する地震探査・地表面の伸縮や傾斜変化などについて述べる。, At Kamenose Landslide zone located in Toge, Kashiwara City, Osaka Prefecture, the geophysical investigation to establish the perfect stabilization plan has begun at 1962.First of all, seismic prospecting along 9 traverse lines were carried out in this areaand the fractured zone distributed NW-SE, dividing this area into two blocks wascaught.The observations of ground-strain are being carried out by 74 wire type extensometersset up along 8 survey lines. Considering the distribution of strains, also the landslideblock in this area was divided in two by fractured zone and the change of strain wasthe largest near the fractured zone.In the case of landslide due to soil mass removal, the peculiar variations of ground-strain and ground-tilt were found which seemed to be the forerunning phenomena to thelandslide.

The authors resumed the geophysical observations of soil mass movement in the Kushibayashilandslide area located in Ogoto town, by internal strain meters, extensometers and tiltmeters fromJuly, 1971. Particularly, we were interested in detailed surveies of features of the distributions oftilting and extention of the ground surface, and investigated the relationship between the state ofmovement of the ground surface and the form of the slip plane by finite element method in elastictheory of plane strain. Then, we presumed the form of the slip plane from the distributions oftilting and extention, as shown in Fig. 7.