Submarine boninite series volcanic rocks with quartz dacite and subordinate submarine sedimentary rocks, belonging to middle Eocene to late Oligocene in age, are widespread on Chichi-jima. Quartz-bearing boninite is found to occur as the chilled rims of dikes, east of Kiyose and southwest of Tsuri-hama. On Miyano-hama near Kiyose, boninite pillows are intruded by a multiple dike of dacite and boninite. The multiple dike suggests the existence of a density-stratified chamber capped by dacite.
The quartz-bearing boninite includes about 4 mm across corroded quartz up to several modal%, with reversely zoned orthopyroxenes carrying pale brown rounded cores and sieved orthopyroxenes. Based on the textures, these inclusions are xenocrysts, derived from quartz dacite. The chemical composition of the dike rims from Kiyose is nearly constant according to the whole rock analyses. Glasses in the same dike rims, with related ones of the Miyano-hama multiple dike, were analysed by electron probe to compare in genesis the compositions.
In the oxides (e.g., MgO)-SiO₂ relationship for the boninite series volcanic rocks of Chichi-jima, the linear relationship of MgO to SiO₂ is obvious in a quartz-bearing boninite as the dike rims from Kiyose, in a more magnesian boninite as the chilled rim of the Miyano-hama multiple dike and a quartz dacite lava. Inferring from the field and the petrological evidence, quartz-bearing boninite was formed by rapid mixing of boninitic magma and a small amount of quartz dacite magma in a similar chamber to the possible stratified chamber beneath Miyano-hama.

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While measuring illite crystallinity (IC) on the same slides, significant differences in results were recognized between two different X-ray difractometers. Hence, standardization of IC data has been performed using Crystallinity Index Standard (CIS) samples. The measured IC values show good linear correlation with the CIS values. No significant differences existed in the high crystallinity range belonging to epizone, whereas in the low crystallinity range between the lower anchizone and the diagenetic zone, the CIS calibrated values indicate lower crystallinity (higher IC values) than the non-calibrated ones. Ac-cording to these results, we re-evaluate the IC values previously presented.

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Automatic laser ranging is being carried out to monitor the activity of the tilting Udo Block along the laser paths from the Crustal Activity Observatory of Shizuoka University to Yatsuyama and Yambara. The air temperatures of the laser paths are calculated from ranged distances under the assumption of constant distance. The rangers monitor also re-fraction of the laser paths caused by the air temperature structure and intensity profile of the reflected laser using a computer controlled step motor.
The atmospheric temperature distributions and their daily and seasonal changes have been explained by the solar heating in the daytime and radial cooling in the night , resulting in lifting of warmer air masses and sinking of cooler air masses.
Systematic offsets have been detected from the calculated air temperature, and compared with the surface air temperature at the Shizuoka Station of the Japan Meteorological Agency. The offsets relate to the changes in the distance of the laser paths, caused by the crustal movement. The amount of the changes is more than several em in laser path distance. The maximum distance occurred in the middle of April 1998 just before the earthquakes to the east off Izu Peninsula, and the minimum distance occurred in the early January 2000 after the Taiwan Earthquake of September 1999. The changes in distance were correlated with tilt records of the Crustal Activity Observatory.
The Udo Block is tilting northwestward by large-scale gravity collapse along the active Kusanagi and Asabata Faults. The basal part of the collapsed Udo Block is riding on the subducting Philippine Sea Plate along the Suruga Trough The detected crustal movements have been explained by changes in the tilt of the Udo Block, controlled by the subduction of the Philippine Sea Plate under the Udo Block.
The stress in the Philippine Sea Plate is sensitively related to earthquakes along the eastern and western margins of the Philippine Sea Plate. The earthquakes on the eastern margin release the compressional stress of the westward Pacific Plate motion and the stress field changes from compressional to tensional before the earthquakes in the east off Izu Peninsula related to magma intrusion. The earthquakes on the western margin in Taiwan decrease the resistivity to subduction along the western margin, and induce the subduction. The simulated stress condition of the Philippine Sea Plate is well correlated with the detected crustal movements with reasonable a time lag.

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The most important meteorological product of the Global Positioning System (GPS) is the estimation of precipitable water vapor (PWV). Because there is a dense distribution of GPS sites in Japan and because the PWV can be estimated at short time intervals from GPS data, it is expected that GPS data may improve Japanese weather forecasting.
We compared PWV estimated from GPS with PWV obtained from radiosonde data at Wajima in Japan, in order to investigate which analysis method is the most suitable for estimating PWV. PWV obtained without estimating horizontal gradients of tropospheric path delay agreed with PWV obtained from radiosonde data better than that through estimating horizontal gradients. The difference in the PWVs obtained from GPS and radiosonde is related to the wind velocity. The difference shows that the meteorological data obtained with radiosonde is not the data just above the GPS station when there is strong wind there. From this relation, we confirmed that the horizontal gradients obtained from GPS data reflect actual azimuthally inhomogeneity in water vapor.
In order to investigate the relationship between PWV change obtained from GPS data and the front passage, we analyzed three sets of data during which cold fronts passed over Hokuriku region: March 19–20, August 24–25, and December 7–8 in 1998.
The result in March shows a clear relationship between PWV change and front passage. The PWV increased before the front passed and it decreased clearly after the front passed. The change in August was similar to that in March, but smaller. The PWV in December does not show a clear change. These results may show that the PWV change has seasonal characteristics when a cold front passes. In the case of a stationary front passage during August 26–27, 1998, the PWV increased slowly and did not change drastically.

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