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41.
Masao Ohno Tsutomu Sato Kenji Notsu Hiroshi Wakita Kunio Ozawa 《Pure and Applied Geophysics》2006,163(4):647-655
Anomalous water level changes were observed at two wells associated with seismic swarm activity off Izu Peninsula on March,
1997. These are coseismic water level drops followed by gradual postseismic water level rise at the time of large earthquakes
during the swarm activity. The post-seismic water level rises, which can be fitted by an exponential function with a time
constant of about six hours, are explained in terms of the horizontal pressure diffusion due to the pressure gradient in the
aquifer induced by the coseismic static strain. 相似文献
42.
Fog and rain water chemistry at Mt. Fuji: A case study during the September 2002 campaign 总被引:2,自引:0,他引:2
Koichi Watanabe Yusaku Takebe Nobuhiro Sode Yasuhito Igarashi Hiroshi Takahashi Yukiko Dokiya 《Atmospheric Research》2006,82(3-4):652
Measurements of fog and rain water chemistry at the summit of Mt. Fuji, the highest peak in Japan, as well as at Tarobo, the ESE slope of Mt. Fuji in September 2002. The pH of fog and rain water sampled at Mt. Fuji varied over a range of 4.0–6.8. Acidic fogs (pH < 5.0) were observed at the summit when the air mass came from the industrial regions on the Asian continent. The ratio of [SO42−]/[NO3−] in the fog water was lower at Tarobo than at the summit. High concentrations of Na+ and Cl− were determined in the rain water sampled at the summit, possibly because of the long-range transport of sea-salt particles raised by a typhoon through the middle troposphere. The vertical transport of sea-salt particles would influence the cloud microphysical properties in the middle troposphere. Significant loss of Mg2+ was seen in the rain water at the summit. The concentrations of peroxides in the fog and rain water were relatively large (10–105 μM). The potential capacity for SO2 oxidation seems to be strong from summer to early autumn at Mt. Fuji. The fog water peroxide concentrations displayed diurnal variability. The peroxide concentrations in the nighttime were significantly higher than those in the daytime. 相似文献
43.
Wataru Ootani Makoto Minowa Takayuki Watanabe Yutaka Ito Yasuhiro Kishimoto Kentaro Miuchi Yoshizumi Inoue Youiti Ootuka 《Astroparticle Physics》1998,9(4):325-329
The performance of a 21-g lithium fluoride bolometer is presented. The background spectrum was measured in the surface laboratory. We derive an exclusion plot for the spin-dependent coupled Weakly Interacting Massive Particles (WIMPs) cross section. 相似文献
44.
“Extreme boiling” model for variable salinity of the Hokko low-sulfidation epithermal Au prospect, southwestern Hokkaido, Japan 总被引:1,自引:0,他引:1
The Hokko prospect is located in the Minamikayabe area southwestern Hokkaido, Japan, where gold-bearing quartz veins of Pliocene
age are exposed at the surface. The alteration mineral assemblage is typical of low-sulfidation epithermal systems, with the
quartz veins associated with adularia alteration overprinted on Late Miocene propylitic alteration. Fluid inclusion studies
of the vein quartz reveal mean homogenization temperatures of approximately 220 °C, and the co-existence of low-salinity (<2
wt.% NaCl equivalent) and moderate salinity (2 to 12 wt.% NaCl equivalent) fluid inclusions within the same veins. The moderate
salinity fluid inclusions (2–12 wt.% NaCl equivalent) typically have relatively low homogenization temperatures between 150°
to 200 °C. The results obtained from stable isotope analysis of δ18O in quartz vein material showed a gradual decrease in δ18O signatures with increasing depth. The majority of the samples have calculated fluid source signatures (δ18OH2O) between −8.0 and −10.0‰, but there is a significant change in the composition above 185 m drill depth. The shallower samples
in particular show a wide range of oxygen isotope signatures that are associated with the moderate salinity fluid inclusions.
We interpret that low-salinity inclusions within the Hokko system represent the composition of the liquid phase of the fluid,
before boiling, and that the moderate-salinity inclusions are representative of the residual liquid phase, after extensive
non-adiabatic boiling and vapor loss in an open system. This mechanism resulted in the entrapment of fluids with variable
salinities at the same time, and in close proximity to each other. This is also reflected in the δ18OH2O values which become more variable and heavier where the moderate-salinity inclusions occur. Deposition of ore minerals within
the Hokko vein system also occurred at this time as a result of boiling and gas loss.
Received: 30 May 1997 / Accepted: 6 January 1998 相似文献
45.
地闪回击的微秒级辐射场特征及近地面连接过程分析 总被引:14,自引:6,他引:8
利用1μs时间分辨率的慢天线电场变化仪在甘肃中川地区雷暴过程中测量得到的大量地闪辐射波形地地闪回击辐射场特征及回击的慢前沿过程进行分析,发现18次正地闪和85次负地闪产在周前沿过程上升时间为19.2μs和9.4μs,84次负地闪继后回击的前沿过程为4.3 μs。YY UDA O 3.1μ; 相似文献
46.
中国内陆高原正极性雷电的观测实验研究 总被引:20,自引:7,他引:13
叙述了1997年夏季中日两国科学家在甘肃平凉地区合作进行的有关正极性雷电的综合观测实验情况,包括地布局,所采用的技术手 取得的主要结果。实验中采用人工引发雷电技术并取得了两次成功,其中一次是利用“空中解发”方式,即火箭拖带的细钢丝下端不直接接地,而是通过一段绝缘尼龙线与接地的另一段细钢丝相连。用这种方式可以更真实地再现自然雷电的初始过程。实验中观测到了空中导线两端先导的双向传输现象;电流、电场变化 相似文献
47.
Hm. Okada H. Watanabe H. Yamashita I. Yokoyama 《Journal of Volcanology and Geothermal Research》1981,9(4):311-334
An earthquake swarm, and the major pumice eruptions in August 1977 which followed, marked the start of the dacitic doming activity of Usu volcano in southwestern Hokkaido, Japan. The sequence of magma intrusion processes was investigated in detail by means of seismological and other geophysical data. The distribution of the abundant hypocenters shows clearly an earthquake-free zone beneath the summit crater. The hypocenters migrated in a manner consistent with the development of the observed asymmetrical surface deformations, considered due to magma intrusion into this earthquake-free zone. The earthquake mechanism solutions are mostly of dip-slip type and are interpreted in terms of the doming deformations. The existence of earthquake families (earthquakes with similar waveforms) is the main cause of the peculiar occurrence of earthquakes in space, time and magnitude. The concept of scattered barriers of different sizes and strengths can explain well the distinct characteristics of the occurrence of the swarm, and the observed episodic deformations. 相似文献
48.
Maki Morimoto Kyoko Kawanobe Osamu Abe Takayoshi Kawai Toshiyuki Kawamura Kunio Shirasawa 《水文研究》2010,24(7):904-916
In winter, lakes and lagoons at high altitudes or high latitudes have interesting hydrological cycles that differ from those in other seasons or in other regions, because water surfaces are covered with ice. Hydrological balances of lakes and lagoons are complex dynamic systems, and to elucidate them, isotopic tracers of water have been used as effective tools along with observations of precipitation, evaporation, inflows, and outflows. Here, to understand hydrological processes during freezing periods in the brackish Saroma‐ko Lagoon, Hokkaido, northern Japan, we examined horizontal and vertical distributions of salinity and isotope compositions of lagoon water and ice in 2005 and 2006. Horizontal and vertical gradients of salinity and isotope compositions were observed from the river mouth to the sea channel, and factors determining these distributions were considered. The mixing of freshwater and seawater and a freezing effect were presumed to be factors in relationships between salinity and isotopes and in relationships between surface waters and ice just above the water. A simple box model for water balance was constructed based on these putative factors to reproduce the distributions of salinity and isotope compositions of surface waters and ice. An evaluation of the model revealed that this hydrological system is controlled primarily by horizontal advection of the epilimnion, freshwater influx, and the ice growth rate. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
49.
Goh Onitsuka Akihiko Morimoto Tetsutaro Takikawa Atsushi Watanabe Masatoshi Moku Yutaka Yoshikawa Tetsuo Yanagi 《Estuarine, Coastal and Shelf Science》2009,81(3):401-408
The relationship between island-induced cyclonic eddies and chlorophyll a (chl-a) was investigated using field data and satellite images in the eastern channel of the Tsushima Straits. The maximum chl-a concentration around the leeward eddy of the Tsushima Islands was two or three times greater than that of outside the eddy. Two different mechanisms of chl-a enhancement associated with island-induced cyclonic eddies were found in the post-bloom periods. In summer, when nutrients were depleted in the surface layer, eddy pumping increased the nutrient supply in the euphotic zone, resulting in enhanced chl-a around the shallow thermocline near the eddy core. In late autumn, when the mixed layer deepened over the euphotic zone, the mixed layer depth became shallow due to the doming effect of the cyclonic eddy, therefore, the improved irradiance condition led to an increase in the chl-a concentration in the surface mixed layer. Nighttime satellite visible images showed a number of fishing vessels in the lee region of the Tsushima Islands, implying that the enhanced phytoplankton biomass may have resulted in good feeding conditions for fishes and squids in the Tsushima Straits. 相似文献
50.
Seasonal variation of horizontal material transport through the eastern channel of the Tsushima Straits 总被引:2,自引:2,他引:0
Akihiko Morimoto Tetsutaro Takikawa Goh Onitsuka Atsushi Watanabe Masatoshi Moku Tetsuo Yanagi 《Journal of Oceanography》2009,65(1):61-71
We conducted hydrographic observations ten times in the Tsushima Strait to reveal seasonal variations of horizontal material
transports such as of heat, freshwater, chlorophyll a, and dissolved inorganic nitrogen (DIN) and phosphorus (DIP) through the eastern channel of the Tsushima Strait (ECTS). The
volume, freshwater, and heat transport results are of nearly the same order as results reported in previous studies. The annual
mean DIN and DIP transports of 3.59 kmol/s and 0.29 kmol/s are large relative to those of the Changjiang and the Taiwan Strait
and are horizontally transported through the ECTS. Nutrient transports are high in July–August and October and low in April
and November. Increased nutrient transports in July–August and October are due to the appearance of a cold saline water mass
in the bottom layer of the ECTS. Changes in DIN transports in summer and autumn, which account for two-thirds of the total
annual DIN transport, would have a large effect on the nitrogen budget and biological productivity in the Tsushima Warm Current
region. 相似文献