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1.
Significant faulting and deformation of the ground surface has been rarely known during volcanic eruptions. Usu Volcano, Hokkaido, Japan, is a unique example of deformation due to felsic magma intrusion. Usu Volcano has a history of such types of eruptions as phreatic, pumice eruption (Plinian type), pyroclastic flowing and lava doming since 1663. On March 31, 2000, phreatomagmatic to phreatic eruptions took place after 23 years of dormancy in the western piedmont, followed by explosions on the western flank of Usu Volcano. They were associated with significant deformation including faulting and uplift. The eruptions and deformation were continuing up to the end of May 2000.We identified the faulting using total nine sets of aerial photographs taken from before the eruption (March 31, 2000) to more than 1 year (April 27, 2001) after the end of the activity, and traced deformation processes through image processing using aerial photographs. We found that some of the new faults and the associated phreatic eruptions were related to old faults formed during the 1977–1981 eruptive episode.The image processing has revealed that the surface deformation is coincident with the area of faulting forming small grabens and the phreatic explosion vents. However, the faulting and main explosive eruptions did not take place in the highest uplift area, but along the margin. This suggests that the faulting and explosive activities were affected by small feeder channels diverging from the main magma body which caused the highest uplift. 相似文献
2.
The island of Hokkaido, Japan, is subdivided into nineteen regions on the basis of regional geology and landslide distribution. Four major geologic zones characterize these regions, as follows: (1) Volcanic Rock Zone, (2) “Green Tuff” Zone, (3) Mudstone Zone, and (4) Serpentinite “Green Rock” Zone. Each zone is marked by landslides of a distinctive type. In addition, we have analyzed the relationship between landslide distribution and geologic structure for several areas. 相似文献
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4.
Although earthquakes are thought to be one of the factors responsible for the occurrence of landslides in Hokkaido, there
exist no enough records which can allow correlating many of the old slope failures in the island with earthquakes. In the
absence of these records, an attempt was done in this study to use the abundance, frequency, magnitude, depth, and distribution
of historical earthquakes to deduce that many of the slope failures in the region were triggered by strong and continuous
seismicity. The determination of the zones of influences of selected earthquakes using an existing empirical function has
also supported this conclusion. Moreover, the use of a 10% probability of exceedance of earthquake intensity in 50 years,
and the geological and slope maps has allowed preparing a landslide hazard map which explains the role of future earthquakes
in the formation of slope failures. The result indicates a high probability of occurrences of landslides in the hilly regions
of the southeastern part of Hokkaido due to expected strong seismicity and earthquake intensities in these areas. On the other
hand, the low level of intensity in the north has given rise to low probability of landslide hazard. There are also places
in the center of the island and high intensity regions in the east where the probability of landslide hazard was influenced
by the contribution of the geological and slope maps. 相似文献
5.
Sosuke Otani Yasunori Kozuki Ryoichi Yamanaka Hiromitsu Sasaoka Tetsu Ishiyama Yoshihito Okitsu Hajime Sakai Yoji Fujiki 《Estuarine, Coastal and Shelf Science》2010,86(3):434-440
The objective of this study is to elucidate the burrow structure and to clarify the role of burrows in material cycle in the tidal flat. In our work, we focused on the dominant species in muddy tidal flat, crab Macrophthalmus japonicus.Burrow structure of Macrophthalmus japonicus was investigated on a Katsuura river tidal flat in Tokushima prefecture, Japan, using in situ resin casting. Sampling was conducted in August 2006, and a total of 48 burrow casts were obtained. Burrows consisted mainly of J-shaped structures (98%) while the rest belonged to U-shaped structures (2%). The maximum measured burrow volume was 120 cm3 and wall surface area was 224 cm2, while maximum burrow length and depth were 23.2 cm and 16.5 cm, respectively. Burrow volume and surface area were strongly correlated with carapace width of M. japonicus. Investigation of the individual number of M. japonicus in 13 quadrats (50 × 50 × 20 cm) was conducted using 2 mm sieve. The number of M. japonicus was 15–31 ind./m2. Using cohort analysis we estimated that surface area of burrows was 0.07–0.15 m2/m2.CO2 emission rate was measured at the surface sediment during the period from June to December 2008. Results varied from 13.8 ± 2.2 to 49.4 ± 3.2 mg CO2/m2/h, and organic carbon decomposition was 3.8 ± 0.6–13.5 ± 0.9 mg C/m2/h. This leads the increase of organic carbon decomposition by 1.1 times, because of the expansion of the tidal flat surface area by burrowing activity. Organic carbon decomposition in burrow walls therefore contributed to organic matter decomposition in the tidal flat. These results indicated that in situ activities of Macrophthalmus japonicus significantly influence the material cycle and it is important to consider the existence of burrow in order to understand the fluxes of materials and to evaluate the purification function of the tidal flat. 相似文献
6.
We speculate that a simple biological system carrying a message and capable of self-replication in suitable environments may be one possible channel for interstellar communication. A preliminary experiment was performed to test the hypothesis that phage φC174 DNA carries a message from an advanced civilization. 相似文献
7.
We have devised a new, simple and easy technique to measure the viscosity of hydrous silicate melts by combining an autoclave for melt hydration and the fiber elongation method for viscosity measurement. Using this, we measured the viscosity of hydrous rhyolitic melts whose water content ranges from 0.02 to 0.58 wt%. We observed a drastic decrease in viscosity against water content: 0.1 wt% water decreases the viscosity about an order of magnitude. Even when the water content is only 0.02 wt%, the viscosity decreased about half an order of magnitude. These results clearly demonstrate that the effect of water on viscosity should not be ignored even when it occurs as a trace constituent. We compared our experimental data with those derived from a non-Arrhenian viscosity model, which is considered to be applicable to calc-alkaline samples. This model succeeded in expressing the viscosity variation against water content but was unable to accurately predict the measured viscosity of liquids.Editorial responsibility: D. Dingwell 相似文献
8.
Landslides in Sado Island of Japan: Part I. Case studies, monitoring techniques and environmental considerations 总被引：1，自引：0，他引：1
Lulseged Ayalew Hiromitsu Yamagishi Hideaki Marui Takami Kanno 《Engineering Geology》2005,81(4):419-431
A sufficient knowledge on the kinematics and development of landslides helps to adopt proper measures that can be used to protect slopes and the environment in general. This can be achieved by adequate monitoring programs. This paper presents the findings of intensive monitoring activities carried out on Shiidomari and Katanoo landslides found in Sado Island of Japan. More than one year of observation of the two landslides allowed defining some peculiar futures of their kinematics and style of development. The problem of slope instability in the two areas is generally accredited to various factors. But, both landslides were triggered by heavy rainfalls and snowmelt. Because of the outline of the area and the presence of relict topographic features, the Shiidomari landslide is considered to be a large-scale reactivation of old slope failures. The Katanoo landslide is, however, a first-time case. Geophysical investigations and drilling activities in Shiidomari indicated the presence of two slip planes. The deepest (80–100 m) of these is controlled by existing lineaments. Monitoring data suggests that the body of the landslide has subsided as much as 1.16 m just below the main scarp, but a centimeter in the central region. The toe sector also experienced a significant amount of subsidence, but this was counter-balanced by an uplift on the opposite side of the landslide. Hence, the landslide seems not any more active along the deepest slip surface, although it may extend upward and define a series of shallow shear planes around the crown. In the case of Katanoo, the landform characteristics, differential weathering, the road cut and groundwater fluctuations appeared to contribute much to determine the exact location of the landslide. Extensional cracks that preceded the landslide can be related to heavy rainfalls and the cold and warm cycles thereafter. Subsurface investigations and monitoring works indicated that the landslide has two slide blocks with different slip planes. During the observation period, the upper part of the landslide responded more effectively to rainfall and snowmelt than the middle and lower sections. The corresponding movements, however, appeared to settle about three months after failure. There were also little strain transmissions in boreholes and no significant change in the characteristics of the landslide. The kinematics of deformation of many of the slopes in Sado Island resembles that of Shiidomari landslide. But mass movements along highways and mountain roads are usually similar to Katanoo. Landslides of the type like Shiidomari may not show sudden and drastic failures, but are usually long lasting and can reactivate repeatedly along new, shallow shear planes. Monitoring works and long-term supervisions in these types of landslides are useful to identify impending failures and take the right measures before they brought about large-scale destruction to the environment. 相似文献
9.
An Application of Hydraulic Tomography to a Large‐Scale Fractured Granite Site,Mizunami, Japan 
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下载免费PDF全文 Yuanyuan Zha Tian‐Chyi J. Yeh Walter A. Illman Tatsuya Tanaka Patrick Bruines Hironori Onoe Hiromitsu Saegusa Deqiang Mao Shinji Takeuchi Jet‐Chau Wen 《Ground water》2016,54(6):793-804
While hydraulic tomography (HT) is a mature aquifer characterization technology, its applications to characterize hydrogeology of kilometer‐scale fault and fracture zones are rare. This paper sequentially analyzes datasets from two new pumping tests as well as those from two previous pumping tests analyzed by Illman et al. (2009) at a fractured granite site in Mizunami, Japan. Results of this analysis show that datasets from two previous pumping tests at one side of a fault zone as used in the previous study led to inaccurate mapping of fracture and fault zones. Inclusion of the datasets from the two new pumping tests (one of which was conducted on the other side of the fault) yields locations of the fault zone consistent with those based on geological mapping. The new datasets also produce a detailed image of the irregular fault zone, which is not available from geological investigation alone and the previous study. As a result, we conclude that if prior knowledge about geological structures at a field site is considered during the design of HT surveys, valuable non‐redundant datasets about the fracture and fault zones can be collected. Only with these non‐redundant data sets, can HT then be a viable and robust tool for delineating fracture and fault distributions over kilometer scales, even when only a limited number of boreholes are available. In essence, this paper proves that HT is a new tool for geologists, geophysicists, and engineers for mapping large‐scale fracture and fault zone distributions. 相似文献
10.
Tomikazu Namikawa Hiromitsu Hamabata Yasusi Hosoya S. Matsushita 《Planetary and Space Science》1983,31(8):913-921
Propagation characteristics of hydromagnetic waves in a cold plasma mixed with a hot plasma under a uniform static magnetic field are investigated. The existence of cold plasma seriously affects the polarization properties of the waves. The results are applied to the interpretation of Pcl and Pc5 with righthand polarizations guided along the geomagnetic field line. 相似文献