Audio frequency magneto-telluric survey of Norikura Volcano in central Japan     

Kiyoshi Fuji-ta  Yasuo Ogawa  Masahiro Ichiki  Satoru Yamaguchi  Yutaka Makino 《Journal of Volcanology and Geothermal Research》1999,90(3-4)

Norikura Volcano has not been active during the last 10,000 years in spite of the activity of the surrounding volcanic mountains. To study past volcanic activities, geological studies were carried out extensively. However, quite a few geophysical investigations were conducted to contribute to volcanology. Our objective is to detect the present subsurface structure of Norikura Volcano and to define volcanic stratifications. In the vicinity of Norikura Volcano, geothermal fields are still active. Subsurface volcanic rocks in this area have been exposed to geothermal activity and altered. To comprehend volcanic stratifications of Norikura and geothermal activity, we conducted audio frequency magneto-telluric (AMT) surveys around Norikura Volcano. AMT survey is useful in clearly defining the resistivity structure related to volcanic regions. The AMT data were acquired over a frequency range 10 Hz–10 kHz. Decomposition analysis was applied to the tensor impedance data. Subsequently, apparent resistivity and phase data were inverted using a two-dimensional magneto-telluric (MT) inversion and a model of Norikura was derived. The final model manifests that the surface resistors are in agreement with andesite lava or dacite lava. As for the deeper structure, a horizontal conductor is situated above resistive basements. The alteration of the conductor was weak, while basement rocks were strongly altered and/or heated through the thermal activity. The existence of these layers seems to indicate the degree of thermal activity of Norikura Volcano.  相似文献   

SDP and LP fluctuations observed along the coast of Sagami Bay     

Yujiro Kitade  Masaji Matsuyama  Shizuo Iwata  Isao Watabe 《Journal of Oceanography》1998,54(4):297-312

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Rheological properties and structural changes in different sections of boiled abalone meat   总被引：1，自引：0，他引：1  

Ogawa Hiroo 《中国海洋大学学报(英文版)》2003,2(1):44-48

1　Introduction　AbaloneHaliotisdiscusisaverypopularfoodthrough outtheworld .WhenAsianpeoples ,notablyJapaneseandChinese ,eatabalonedishes ,theyenjoythefirmtextureoftherawmeatandthetendernessoftheboiledmeat .InJapan ,thetoughervarietiesoftherawabalonemeatareenjoyedandtheabaloneisoftenthin lyslicedandservedraw (sashimi) ,whileinchina ,thetendernessandsoftervarietiesoflesscollagenofboiledmeatareconsideredsuitableforeating ,sotheabaloneisoftenservedbyheating .Infoodscience ,manyreportshavebeen …  相似文献   

A flare model deduced from Hinotori and millimeterwave interferometer observations     

Kin-aki Kawabata  Hideo Ogawa  Ikuro Suzuki 《Solar physics》1983,86(1-2):247-252

The -ray and white-light flare of 13 May, 1981 is used for a study of spatial distributions of energetic electrons and high-temperature plasma.  相似文献   

Diurnal variability of thermospheric N and NO     

Toshihiro Ogawa  Yutaka Kondo 《Planetary and Space Science》1977,25(8):735-742

A model for diurnal variations of neutral and ionic nitrogen compounds in the thermosphere is reconstructed on the basis of a new photochemical aspect on N(²D), together with new observations of the NO density. The NO density so far measured must be reduced by a factor 2, due to a revision of the fluorescence coefficient for the NO γ-band airglow. Incorporating the quenching reaction of N(²D) with O in the model calculation results in a reduction of the NO density at heights as low as 100 km. These two effects are combined to lead to an evaluation that the N(²D) quantum yield for various possible reactions is as large as 0.9. A smaller rate coefficient for the quenching reaction than that measured in the laboratory, i.e. 1.0 × 10^?12cm³sec^?1 is favourable for the recent NO observation in the early morning, as well as the observed emission rates of the 5200 A airglow from N(²D) The present model predicts a significant day-to-night variation of N and NO densities at heights above 100 km. Below 100 km, the NO density is fairly stable because of its long chemical time constant. Since the rate coefficient for the conversion of N(⁴S) to NO is highly temperature dependent, the relative population of N(⁴S) and NO is very sensitive to the thermospheric temperature variation. Large variations of both N(⁴S) and NO densities due to the temperature change could occur especially at night. The model is in good agreement with the NO observations so far available in low and middle latitudes, as well as the N observation by the use of a rocket in the twilight.  相似文献   

A new interpretation of the 1304 Å triplet airglow intensity ratio with the fine structure levels $\text{O}{}^3\text{P}{}_{\mathrm{j}}\text{)}$ in local thermodynamic equilibrium     

Toshihiro Ogawa 《Planetary and Space Science》1982,30(1):39-44

The intensity ratios of the 1304 Å triplet airglow of atomic oxygen observed by Fastie and Crosswhite (1964) are interpreted on the basis of the radiative transfer formulation for a model with complete frequency redistribution in a Voigt line profile. A model for the fine structure levels $\text{O(}{}^3\text{P}{}_{\mathrm{j}}\text{)}$ in local thermodynamic equilibrium is favorable to the observed intensity ratios, as far as a Voigt profile is applicable. In view of large cross sections as calculated theoretically by Allison and Burke (1969), the mutual relaxation among the ³P_j levels should occur rapidly enough to allow the population in the ³P_j levels to be in thermodynamic equilibrium with the ambient neutral gases.  相似文献   

Researches on the stability of porphyra-334 solution and its influence factors     

ZHANGZhaohui GAOXin YuriTashiro ShingoMatsukawa HirooOgawa 《中国海洋大学学报(英文版)》2004,3(2):166-170

1　Introduction　Ultravioletradiationisahighlyactivecomponentofsolarspectrum .Ultravioletradiationhasdetrimentaleffectsonlivingthingsexposedtosunlight ,includingthedestructionofDNA ,proteinsandothermolecules(Harm ,1980 ) ,inhibitionofphotosynthesisandgrow…  相似文献   

Silicate to Nitrate Ratio of the Upper Sub-Arctic Pacific and the Bering Sea Basin in Summer: Its Implication for Phytoplankton Dynamics   总被引：2，自引：0，他引：2  

Isao Koike  Hiroshi Ogawa  Toshi Nagata  Rumi Fukuda  Hideki Fukuda 《Journal of Oceanography》2001,57(3):253-260

Consumption of silicate and nitrate (Si:N molar ratio) in the upper layer of the pelagic subarctic Pacific in summer was evaluated by a regression analysis of silicate vs. nitrate concentrations at the upper 100 m depth. Based on data of three cruises, the pelagic subarctic Pacific can be classified into two groups. First group is characterized by roughly 1:1 consumption of silicate and nitrate, and occupies rather larger area of subarcfic Pacific, i.e., the Gulf of Alaska and the Western Subarctic gyre (averaged slope of Si:N linear regression: 1.21, n = 10 and 1.45, n = 9, respectively). Second group is the regions of the Bering Sea basin and the Oyashio region, and showed higher silicate consumption compared to that of nitrate (averaged slope of Si:N linear regression: 2.14, n = 9 and 2.36, n = 3, respectively). The Si:N difference observed is possibly attributed to relative contribution of diatoms production among the phytoplankton assemblages in the regions, i.e., dominance of diatoms production in the regions of the second group. Higher accumulation of ammonium at the bottom of euphotic layer in the summer Bering Sea basin would also contribute to increase consumption ratio of Si:N amounts.  相似文献   

Some factors affecting the survival of coliform bacteria in seawater     

Kazunari Ogawa 《Journal of Oceanography》1974,30(2):54-60

Some experiments were carried out to explain thein situ phenomena that the number of coliform organisms decreased rapidly from estuaries to offshore, and also at deeper layer, and that the appearance of coliform types varied.In natural seawater, experimental results did not show thatEscherichia coli was extinct by self-purification or anti-biosis action of seawater, but it showed that this organism decreased mainly because of their starvation caused by lack of nourishment. Although the decreasing rate of bacterial density was delayed in enriched seawater, addition of nutrient even at the time of bacterial extinction promoted the appearance of variated form of this bacteria with floc formation.Flocculation of bacterial cells was influenced by quality and quantity of added nutrients. Temperature was shown to have an effect on the floc formation, but appearance of variated form in flocculated cells ofE. coli was not affected by temperature. Flocculated particles of coliform bacteria were adsorbed on suspended particles in seawater and precipitated rapidly. This phenomenon seems to be a cause of the rapid disappearance of coliform bacteria in coastal waters.In bottom deposits the coliform bacteria probably survive longer as physiologically variated forms when suitable nutrients were supplied.  相似文献   

Geochemical characteristics of hydrous basaltic magmas due to assimilation and fractional crystallization: the Ikoma gabbroic complex,southwest Japan     

N. Koizumi  T. Okudaira  D. Ogawa  K. Yamashita  Y. Suda 《Mineralogy and Petrology》2016,110(5):639-662

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