The crustal movements should be represented not only by the crustal extensions, but also by the rotational strains. The present author has devised the rotational strainmeter to observe the crustal movements and tidal shear strains of the earth. The rotational strainmeter consists of two canti-levers which are about 8 meters in length, 6 centimeters in width and 0.2 centimeters in thickness, and then the levers are set along two parallel lines, about 13 cm. distant each other. The changes of the distance of these inner free ends of both levers are transformed first into the changes of the tiltings of an axis of a horizontal pendulum, then the rotations of the pendulum of the tiltmeter are amplified with optical lever on the photographic recording papers. The sensitivity of the instrument is about 2 x 10-9 per one millimeter on the record. According to the observations with this instrument, the phase of the tidal shear strain just agrees with the theoretically calculated one.

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In order to clarify the vertical movement of the earth's crust in relation to the swarm earthquake at Matsushiro, Nagano Pref., the leveling surveys revised several times in the past in the northern part of the Chubu district are arranged. The vertical movements in the periods between the unified epochs of survey, 1893. 8, 1927. 9, 1956.5 and 1966. 4 are calculated, and the mean vertical movement per year for the respective period is shown in Figs. 2, 3 and 4. In the periods shown in Figs. 2 and 3, upheaval of the crust in the central mountaneous region (southwards from the line connecting Matsumoto to Karuizawa), and subsidence in the coastal area of the Japan Sea had been progressed steadily. In the third period of recent duration of 9 years, however, the pattern of movement which had been continued in nearly steady state in the past 60 years, was interrupted, and the new pattern of inclination of which axis can be taken in the central region along the south-north directors is seen. That is, the western side including the zone of the northern Japan Alps shows upheaval, and the eastern side shows subsidence. In the central region between these two sides, the mountaneous region between Matsumoto and Ueda is upheaving, and the alluvial region near Iiyama is subsiding. The yearly movements of the earth's crust in the concerned 3 periods along a line connecting Matsumoto to Iiyama which is shown in Fig. 4 are shown in Fig. 5. A nordal portion is seen in the middle of the line in concern. This is near Matsushiro. But the apparent invariability of this portion does not mean the area concerned has been inactive during the 9 years. This is due to the reason that the total amount of slow subsidence in the past 60 years has been compensated by the accute upheaval in quietly the recent month. Accordingly, the crustal movement in relation to the Matsushiro Earthquake should be investigated both in Fig. 5 which shows the macroscopic condition of the moving crust in space, and in Figs. 29 and 30 which show the recent condition of the moving crust in time. Next, in order to predict magnitude of earthquake, a relation between the earthquake volume and magnitude of earthquake is discussed. According to a conception by C. Tsuboi, the maximum stress energy per unit volume accumulated in rock material is nearly constant, and magnitude of earthquake is proportional to the earthquake volume. Then some clear corelation should hold between magnitude of earthquake and area of crustal surface deformed by the earthquake. As the earthquake volume, the author takes r3 regardless of its coefficient, where r is radius or reduced radius of the crustal surface deformed at an earthquake. The radiuss is directly determined from the crustal movement accompanied by an earthquake along a leveling line. The reduced radius is determined from the area when a chart of the crustalmovement can be utilized. It is found that there are 3 modes of crustal movement accompanied by earthquakes, that is, single, double, and multiple movements. Typical examples of the respective mode are shown in Figs. 7, 18 and 9. When the movement is double or multiple type, the summation of r3 is adopted for the total earthquake volume. Fig. 25 shows the relation between the earthquake volumes thus obtained and the magnitudes for 19 earthquakes occurred in Japan in the period from 1891 to 1964. By the least square method, the numerical relation of 1.53 M+8.18 = log r3 (A) is obtained, where M is the magnitude and the unit of r is in cm. The standard deviation of each earthquake from this relation is about ±0.8.

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