Seismic wave records at the surface of sedimentary plain are mainly composed of main phase and surface waves. The informations of input wave record in base rock and S wave velocity distribution to base rock are enough to consider the main phase. And moreover the informations about underground structure to bed rock of all sections of plain are necessary to discuss surface wave which travels from surrounding rock range to observation point. For this items of the Osaka plain, there were some crumbs of informations. In 1988, we tried two explosions at a manmade “Hokko” island in Osaka bay. This paper shows the results: five ground structures and a countour map of depth to base rock of the Osaka plain.

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The observations of long-period (1- to 5- sec) microtremors for elucidating ground characteristics are very scarce until now, though the importance of the short-period microtremors in the earthquake engineering is well recognized. This is perhaps due to the background that almost all the buildings were constructed not so high in the past. It is, however, a fashion that recent buildings are very large both in height and width. In this new situation the technique to know the underground conditions by means of the short-period microtremors has little use. Our present purpose is to try out whether the long-period microtremors are powerful for detecting deeper ground conditions.
In 1973 an observation of the long-period microtremors was carried out in Hachinohe City, Aomori prefecture. The apparatuses employed there are 1cps electromagnetic seismometers having specially designed integration circuits to lengthen the observation capability to longer periods, DC-amplifiers, and 4chs portable magnetic data recorders.
According to the geological survey the Hachinohe area is classified into three major blocks of which bed rocks locate very shallow, moderate, and deep in depths. So, after examining whether the observation reflects differences in the blocks we set up A-line as to intersect the three blocks and observed 10 and more points. In Tokachi-oki earthquake of 1968 a very large acceleration with 2.5sec in period was recorded at Hachinohe Branch Office of the Bureau of Port and Harbor, but no appropriate interpretation to this is achieved yet. Thus the line from Hachinohe Local Meteorological Observatory lying just above the bed rock to the strong motion seismograph site was surveyed as B-line.
First we calculated the Fourier spectra of the records by means of an analog-type spectrum analyzer. Then these were classified into three peculiar types of which peaks in spectrum differ significantly. And it was ascertained that the corresponding subareas show a fairly good agreement to the geologically known blocks.
A very systematic change in the predominant period was observed along the B-line. The shortest period was 0.7sec at the point close to the Meteorological Observatory and the largest period obtained, 2.5sec, was at the same site where the strong motion seismograph had been installed. The well-known law of quarter wave length was applied to the ground structure to estimate the expected predominant periods along the B-line. The coincidence between the calculated and observed periods was very satisfactory. This suggests we might have recorded the strong motions with the periods ranging from 0.7 to 2.5sec in the Tokachi-oki earthquake, if the seismographs had been set along this line.

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The purpose of this research is to clarify the psychological and physiological effects of the seismic ground waves including vertical direction. The difference in psychological change of a youth group and an elderly-people group were considered this time. The main results were summarized as follows. 1. Although the earthquake motion was thought to be "large" and "strong" from the feeling evaluation questionnaire, an awful feeling had many people who presuppose "A few is felt." 2. As for the uneasy stress of the youth group, the significant difference was accepted by the situation where the subject was placed. However, the elderly-people group did not accept a significant difference. 3. Both a youth group and an elderly-people group had the very high consciousness to the fear of insecurity and safety to an earthquake. However, although the consciousness of a youth group tended to improve by earthquake motion experience, an elderly-people group did not change. 4. The youth group could not be easily subject to the influence according to an earthquake motion psychologically or physiologically. However, psychological influence was not seen but an elderly-people group had the tendency for systolic arterial pressure to become high as physiological effect.

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The purpose of this research is to clarify the psychological and physiological effects of the seismic ground motion. So, a few exercises which testees were experienced the observed seismic wave including a vertical vibration, were performed and analyzed by the age. The main results of physiological change are summarized as follows;
1）Systolic and diastolic blood pressure increased immediately after vibratory loading, and pulse beats rate showed the tendency which decreases conversely. 2）About the time jitter of blood pressure and cardiac beats rate, neither the youth group nor the elderly-people group accepted a significant change. 3）Blood pressure and pulse beats rate did not accept a difference with both a youth group and an elderly-people group significant in the relation just before vibratory loading and just behind vibratory loading. 4）The significant difference by the existence of vibration was seen in salivary amylase measurement.

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