Scoria cone formation through a violent Strombolian eruption: Irao Volcano, SW Japan     

Koji Kiyosugi  Yoshiyuki Horikawa  Takashi Nagao  Tetsumaru Itaya  Charles B. Connor  Kazuhiro Tanaka 《Bulletin of Volcanology》2014,76(1):1-14

Scoria cones are common volcanic features and are thought to most commonly develop through the deposition of ballistics produced by gentle Strombolian eruptions and the outward sliding of talus. However, some historic scoria cones have been observed to form with phases of more energetic violent Strombolian eruptions (e.g., the 1943–1952 eruption of Parícutin, central Mexico; the 1975 eruption of Tolbachik, Kamchatka), maintaining volcanic plumes several kilometers in height, sometimes simultaneous with active effusive lava flows. Geologic evidence shows that violent Strombolian eruptions during cone formation may be more common than is generally perceived, and therefore it is important to obtain additional insights about such eruptions to better assess volcanic hazards. We studied Irao Volcano, the largest basaltic monogenetic volcano in the Abu Monogenetic Volcano Group, SW Japan. The geologic features of this volcano are consistent with a violent Strombolian eruption, including voluminous ash and fine lapilli beds (on order of 10^?1 km³ DRE) with simultaneous scoria cone formation and lava effusion from the base of the cone. The characteristics of the volcanic products suggest that the rate of magma ascent decreased gradually throughout the eruption and that less explosive Strombolian eruptions increased in frequency during the later stages of activity. During the eruption sequence, the chemical composition of the magma became more differentiated. A new K–Ar age determination for phlogopite crystallized within basalt dates the formation of Irao Volcano at 0.4?±?0.05 Ma.  相似文献   

Full-scale dynamic testing of response-controlled buildings and their components: concepts,methods, and findings     

Kazuhiko Kasai  Kazuhiro Matsuda 《地震工程与工程振动(英文版)》2014,13(1):167-181

A series of shake-table tests was conducted by inserting and replacing 4 different types of dampers, or by removing them in a full-scale 5-story steel frame building. The objective is to validate response-control technologies that are increasingly adopted for major Japanese buildings without being attested to-date by a major earthquake. Test results are briefly described, and good performance of the dampers and frame demonstrated. The concepts of the full-scale building tests and various contributions are discussed. The difficulty associated with full-scale dynamic testing is explained.  相似文献   

Detection and isolation of p-nitrophenol-lowering bacteria from intestine of marine fishes caught in Japanese waters     

Kuda T  Kyoi D  Takahashi H  Obama K  Kimura B 《Marine pollution bulletin》2011,62(8):1622-1627

To determine the existence of p-nitrophenol (PNP)-lowering bacteria in intestine of Japanese coastal fish, the gastro-intestinal contents were incubated in Brain Heart Infusion (BHI) broth and minimal medium (MM) broths containing 1 mmol/L PNP at 30 °C for 7 days. Among 26 samples of 19 fish species, 17 samples showed a decrease in PNP of 0.5-0.8 mmol/L in BHI broth, but no decrease was shown in MM broth. Eighteen PNP-lowering bacterial strains were isolated from four fishes. All of the strains were identified as Lactococcus lactis subsp. lactis. Three L. lactis strains JS1-3 isolated from Japanese seabass Lateolabrax japonicus showed the highest PNP-lowering activity (0.44 mmol/L). Optimum temperature and pH for the growth and PNP decreasing corresponded with the marine environment. These results suggested that marine fishes have PNP decreasing bacteria in their intestine. These bacteria might protect host fish from toxicities of PNP and PNP related compounds.  相似文献   

Mixing of magmatic CO₂ into volcano groundwater flow at Aso volcano assessed combining carbon and water stable isotopes     

Makoto Yamada  Shinji Ohsawa  Kohei Kazahaya  Masaya Yasuhara  Hiroshi Takahashi  Kazuhiro Amita  Hideo Mawatari  Shin Yoshikawa 《Journal of Geochemical Exploration》2011

To understand deep groundwater flow systems and their interaction with CO₂ emanated from magma at depth in a volcanic edifice, deep groundwater samples were collected from hot spring wells in the Aso volcanic area for hydrogen, oxygen and carbon isotope analyses and measurements of the stable carbon isotope ratios and concentrations of dissolved inorganic carbon (DIC). Relations between the stable carbon isotope ratio (δ¹³C_DIC) and DIC concentrations of the sampled waters show that magma-derived CO₂ mixed into the deep groundwater. Furthermore, groundwaters of deeper areas, except samples from fumarolic areas, show higher δ¹³C_DIC values. The waters' stable hydrogen and oxygen isotope ratios (δD and δ¹⁸O) reflect the meteoric-water origin of that region's deep groundwater. A negative correlation was found between the altitude of the well bottom and the altitude of groundwater recharge as calculated using the equation of the recharge-water line and δD value. This applies especially in the Aso-dani area, where deeper groundwater correlates with higher recharge. Groundwater recharged at high altitude has higher δ¹³C_DIC of than groundwater recharged at low altitude, strongly suggesting that magmatic CO₂ is present to a much greater degree in deeper groundwater. These results indicate that magmatic CO₂ mixes into deeper groundwater flowing nearer the magma conduit or chamber.  相似文献   

The Higo High-Grade Metamorphic Rocks in Japan as a Part of the Collisional Terrane Between the Sino-Korean and Yangtze Craton     

Yasuhito Osanai  Takuji Hamamoto  Hiroo Kagami  Kazuhiro Suzuki  Masaaki Owada  Atsushi Kamei   《Gondwana Research》1999,2(4):599-601

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Ostwald ripening of garnet in high P/T metamorphic rocks     

Kazuhiro Miyazaki 《Contributions to Mineralogy and Petrology》1991,108(1-2):118-128

This paper presents a theoretical formulation of Ostwald ripening of garnet and discusses the importance of the process during high pressure and low temperature (high P/T) metamorphism. The growth rate of garnet due to Ostwald ripening is formulated for the system consisting of minerals and an intergranular medium. Crystal size distribution (CSD) of garnets are examined and compared with the theoretical distribution for Ostwald ripening. Two types of CSDs are recognized. One is consistent with the theoretical prediction of size distribution while the other is wider than the theoretical distribution. The former CSD applies to samples in which garnets show homogeneous spatial distributions. The latter CSD applies to samples in which garnets show heterogeneous spatial distributions such as in clusters or layers. These relations suggest that the heterogeneity of spatial distributions results in a heterogeneity of concentration of garnet, causing the wide distributions. The mean diameter (dg) has a large variation in samples having narrow distributions. Ostwald ripening explains well the similar patterns of CSD in these samples with different dg because of a scaling law. Compositional profiles of garnets with different size are consistent with Ostwald ripening rather than nucleation and growth kinetics. This suggests that the CSDs result from Ostwald ripening. Magnitude of heating rate will determine which mechanism controls CSD. Nucleation and growth kinetics are dominant when heating rate is large. On the other hand, Ostwald ripening is dominant when heating rate is small. CSDs of garnets in high P/T metamorphic rocks are consistent with the latter case.  相似文献   

Numerical study for specifying the major origin of low salinity water associated with <Emphasis Type="Italic">Chattonella</Emphasis> (Raphidophyceae) blooms in Tachibana Bay,Japan     

Kazuhiro?AokiEmail author  Manabu?Shimizu  Hiroshi?Kuroda  Toshifumi?Yamatogi  Naoya?Ishida  Shigeru?Kitahara  Keiji?Hirano 《Journal of Oceanography》2016,72(5):811-816

In both 2009 and 2010, massive Chattonella blooms occurred in Tachibana Bay. Observation results show that high cell densities of Chattonella were distributed in the central area of Tachibana Bay with low salinity water. Model results indicate that the low salinity water originated from the Ariake Sea and intruded into Tachibana Bay during the northerly or weak winds. It is suggested that low salinity water was mainly discharged from the northern area of the Ariake Sea. Northerly wind enhanced the horizontal advection of the low salinity water intruding into Tachibana Bay originating from the northern area of the Ariake Sea.  相似文献   

Segmentation of Main Boundary Thrust and Main Central Thrust in Western Himalaya for assessment of seismic hazard     

Singh Mridula  Amita Sinvhal  Hans Raj Wason  Swati Singh Rajput 《Natural Hazards》2016,84(1):383-403

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Application of finite volume coastal ocean model to hindcasting the wind-induced sea-level variation in Fukuoka bay     

Kazuhiro Aoki  Atsuhiko Isobe 《Journal of Oceanography》2007,63(2):333-339

The wind-induced sea-level variations at Hakata tidal station in winter are reproduced realistically using a one-way nested model. This nested model is constructed with a structured finite-difference Princeton Ocean Model (POM) for the Tsushima-Korea Straits, and an unstructured Finite Volume Coastal Ocean Model (FVCOM) for Fukuoka Bay divided into triangular-cell grids. The correlation coefficient and root-mean-square error between observed and modeled results are 0.742 and 1.88 [cm], respectively. Moreover, the results show that the nested model with FVCOM is more accurate than the model in which FVCOM is replaced with a high-resolution POM for Fukuoka Bay. This indicates that the nested model constructed with structured and unstructured models works effectively in hindcasting the wind-induced sea-level variations.  相似文献   

Growth inhibition of a red tide flagellate,Chattonella antiqua by copper     

Nakamura  Yasuo  Sawai  Kazuhiro  Watanabe  Masataka 《Journal of Oceanography》1986,42(6):481-486

Journal of Oceanography - Copper toxicity inChattonella antiqua (Raphidophyceae) was examined using an artificial seawater medium. The growth rate (Μ) was found to be a unique function of...  相似文献