Space—time correlations between inland earthquakes in central Japan and great offshore earthquakes along the Nankai trough: Implication for destructive earthquake prediction     

Yuji Kanaori  Shin-ichi Kawakami  Kenji Yairi 《Engineering Geology》1993,33(4):289-303

Based on the tectonic framework of central Japan, including the surrounding submarine areas, the space-time relationship between destructive inland earthquakes of magnitudesM 6.4 or greater and great offshore earthquakes along the Nankai trough was examined. From east to west, four tectonic lines are defined as lines linking active faults: the Itoigawa-Shizuoka tectonic line (ISTL), the Tsurugawan-Isewan tectonic line (TITL), the Hanaore-Kongo fault line (HKFL), and the Arima-Takatsuki tectonic line (ATTL). The TITL divides central Japan into the Chubu and Kinki districts, and probably extends southward to the Nankai trough. The Chubu district is subdivided into four blocks by boundary lines linking NW-SE trending active faults having left-lateral strike slip. In the Kinki district, N-S trending, active reverse, steep-dip faults are dominant in the triangular region north of the Median Tectonic line, between the TITL and HKFL, forming a basin-and-range province.

Starting from 1586 A.D., a seismic space-time sequence of high seismic activity in the Chubu district in which earthquake occurrence migrates from the eastern to western tectonic lines of central Japan was identified. The sequence also revealed that inland earthquakes preceded great offshore earthquakes which occurred along the Nankai trough. It was also found that a destructive earthquake tends to occur on the HKFL within 30 years after the occurrence on the TITL, and that the western Nankai trough generated great earthquakes ofM≥7.0 at intervals ranging from 8 to 49 years after the HKFL earthquakes. If the eastern Nankai trough is coupled with the western Nankai trough, a forthcoming greater earthquake measuringM 8.5 may be expected. Since such great earthquakes are always accompanied by large tsunamis, much attention should be focussed on possible tsunami disasters along the Pacific coast of central Japan.

Based on its tectonic structure, a tectonic model of central Japan is proposed. The seismic space-time sequence, which attempts to explain the cause of the sequential earthquake generation, is also discussed.  相似文献   

Gas permeability evolution of cataclasite and fault gouge in triaxial compression and implications for changes in fault-zone permeability structure through the earthquake cycle   总被引：1，自引：0，他引：1  

Shin-ichi Uehara  Toshihiko Shimamoto   《Tectonophysics》2004,378(3-4):183

We report the results of permeability measurements of fault gouge and tonalitic cataclasite from the fault zone of the Median Tectonic Line, Ohshika, central Japan, carried out during triaxial compression tests. The experiments revealed marked effects of deformation on the permeability of the specimens. Permeability of fault gouge decreases rapidly by about two orders of magnitude during initial loading and continues to decrease slowly during further inelastic deformation. The drop in permeability during initial loading is much smaller for cataclasite than for gouge, followed by abrupt increase upon failure, and the overall change in permeability correlates well with change in volumetric strain, i.e., initial, nearly elastic contraction followed by dilatancy upon the initiation of inelastic deformation towards specimen failure. If cemented cataclasite suffers deformation prior to or during an earthquake, a cataclasite zone may change into a conduit for fluid flow. Fault gouge zones, however, are unlikely to switch to very permeable zones upon the initiation of fault slip. Thus, overall permeability structure of a fault may change abruptly prior to or during earthquakes and during the interseismic period. Fault gouge and cataclasite have internal angles of friction of about 36° and 45°, respectively, as is typical for brittle rocks.  相似文献   

Cloning and sequencing of the allophycocyanin genes fromSpirulina maxima (Cyanophyta)     

Song  Qin  Kojima  Hiroyuki  Kawata  Yoshikazu  Yano  Shin-ichi  Cheng-kui  Zeng 《中国海洋湖沼学报》1998,16(1):6-11

The genes coding for the α-and β-subunit of allophycocyanin (apcA andapcB) from the cyanophyteSpirulina maxima were cloned and sequenced. The results revealed 44.4% of nucleotide sequence similarity and 30.4% of similarity of deduced amino acid sequence between them. The amino acid sequence identities betweenS. maxima andS. platensis are 99.4% for α subunit and 100% for β subunit.

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Transposable genetic elements inSpirulina and potential applications for genetic engineering     

Kojima  Hiroyuki  Song  Qin  Ajith Kumar  Thankappan  Kawata  Yoshikazu  Yano  Shin-ichi 《中国海洋湖沼学报》1998,16(1):30-39

Transposable elements in cyanobacteria are briefly reviewed. Evidence is presented to show that transposable elements inSpirulina platensis is actually reflected on the phenotype change, i e., helical to straight filaments. Transposition intermediates of DNA were isolated from the extrachromosome and the transposition was related to helical variations inSpirulina. Uses of transposable elements for microalgal recombination are discussed based on the transposition mechanism.

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Middle Miocene to Pleistocene radiolarian biostratigraphy in the Northwest Pacific Ocean, ODP Leg 186   总被引：2，自引：0，他引：2  

Shin-ichi Kamikuri  Hiroshi Nishi  Isao Motoyama  Saneatsu Saito 《Island Arc》2004,13(1):191-226

Abstract The Upper Cenozoic sedimentary sequences drilled at Sites 1150 and 1151, Ocean Drilling Program Leg 186, enabled establishment of radiolarian zonation and calibration of the age of bioevents in the forearc area of the northern Japan Islands. The sequences were divided into nine zones from the Pleistocene Botryostrobus aquilonaris Zone to the Upper Miocene Lipmanella redondoensis Zone at Site 1150, and 11 zones from the Pleistocene Stylatractus universus Zone to the Middle Miocene Dendrospyris? sakaii Zone at Site 1151. These zones correlate successfully with the studied sequences of many of deep‐sea cores in the Northwest Pacific Ocean and with some sections of onshore Japan. Of 67 important radiolarian bioevents recognized during the study, 29 Pleistocene to Upper Miocene events were directly tied to the geomagnetic polarity time scale through the well‐defined paleomagnetic polarity records, and 21 Upper Miocene events were calibrated based on the diatom biostratigraphy. Of these events, 24 geographically widespread events were selected to test synchroneity and usefulness as time‐horizons within the mid‐to‐high latitude of the Northwest Pacific, involving eight other offshore and onshore sections. Examination showed that most of the zonal boundary events are synchronous within the considered region, and that many diachronous events, most of which are eliminated from the zonal scheme, are unreliable events linked to rare and sporadic occurrences of the species. Radiolarian biostratigraphy of the studied cores clearly indicates three major hiatuses in the Middle Pleistocene, Late Miocene and late Middle Miocene. The latter two hiatuses can be correlated to two global oceanic hiatuses, NH6 and NH3, respectively.  相似文献   

Abundance, Biomass, Production and Trophic Roles of Micro- and Net-Zooplankton in Ise Bay, Central Japan, in Winter     

Shin-Ichi Uye  Naoki Nagano  Tetsuya Shimazu 《Journal of Oceanography》2000,56(4):389-398

We investigated the geographical variations in abundance and biomass of the major taxonomic groups of micro- and net-zooplankton along a transect through Ise Bay, central Japan, and neighboring Pacific Ocean in February 1995. The results were used to estimate their secondary and tertiary production rates and assess their trophic roles in this eutrophic embayment in winter. Ise Bay nourished a much higher biomass of both micro- and net-zooplankton (mean: 3.79 and 13.9 mg C m^–3, respectively) than the offshore area (mean: 0.76 and 4.47 mg C m^–3, respectively). In the bay, tintinnid ciliates, naked ciliates and copepod nauplii accounted for, on average, 69, 18 and 13% of the microzooplankton biomass, respectively. Of net-zooplankton biomass, copepods (i.e. Acartia, Calanus, Centropages, Microsetella and Paracalanus) formed the majority (mean: 63%). Average secondary production rates of micro- and net-zooplankton in the bay were 1.19 and 1.87 mg C m^–3d^–1 (or 23.1 and 36.4 mg C m^–2d^–1), respectively, and average tertiary production rate of net-zooplankton was 0.75 mg C m^–3d^–1 (or 14.6 mg C m^–2d^–1). Available data approximated average phytoplankton primary production rate as 1000 mg C m^–2d^–1 during our study period. The transfer efficiency from primary production to zooplankton secondary production was 6.0%, and the efficiency from secondary production to tertiary production was 25%. The amount of food required to support the zooplankton secondary production corresponded to 18% of the phytoplankton primary production or only 1.7% of the phytoplankton biomass, demonstrating that the grazing impact of herbivorous zooplankton was minor in Ise Bay in winter.  相似文献   

Extracellular release of β-lactamase by osmotic shock inSynechococcus transformant     

Yano  Shin-ichi  Kawata  Yoshikazu  Kojima  Hiroyuki 《中国海洋湖沼学报》1998,16(1):105-108

A unicellular cyanobacteriumSynechococcus sp. strain PCC 7002 was transformed with plasmid pQL1, on which β-lactamase gene (bla) and β-galactosidase gene (lacZ) were encoded. The transformant cells released β-lactamase into medium by an abrupt drop of osmotic pressure. This result indicates that this cyanobacterium recognizes and processes the signal sequence of β-lactamase, and accumulates the enzyme in periplasm. Repeated release of β-lactamase was possible by repeated osmotic shocks wihout, impairing cell viability. On the other hand, most of the β-galactosidase remained in cytoplasm under the osmotic shock.

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Geographical and seasonal variations in biomass and estimated production rates of net zooplankton in Yatsushiro Bay, Japan   总被引：1，自引：1，他引：0  

Miwa Hayashi  Shin-ichi Uye 《Journal of Oceanography》2008,64(6):877-889

The biomass and production rate of net zooplankton were studied at eight stations in Yatsushiro Bay, Japan, monthly from May 2002 to April 2003. Based on environmental conditions, the bay was divided into three regions, viz. northern (average depth, salinity and chlorophyll a concentration: 11 m, 31.8 and 6.5 μg l⁻¹, respectively), central (30 m, 32.8 and 3.2 μg l⁻¹, respectively) and southern (43 m, 33.4 and 1.9 μg l⁻¹, respectively). Net zooplankton biomass was high in warm months and low in cold ones, with annual averages of 20.2, 38.8 and 16.4 mg C m⁻³ in the northern, central and southern regions, respectively. Copepods were the most important constituent (>ca. 70% of net zooplankton biomass) in all regions. The northern region was characterized by the dominance of Oithona spp. in summer and Acartia spp. in winter-spring. In the central region, Microsetella norvegica was most pronounced in summer-fall. In both central and southern regions, Calanus sinicus and Eucalanus spp. dominated in winter-spring and fall, respectively. The annual average net zooplankton secondary production rate was 4.4, 7.5 and 3.9 mg C m⁻³d⁻¹ in the northern, central and southern region, respectively. Combining the results from the present study with those from other collaborative works on microzooplankton allowed us to determine the trophic interactions in Yatsushiro Bay. If the secondary producers depend entirely on phytoplankton for food, their daily carbon requirement is equivalent to 12.5, 21.6 and 19.1% of the phytoplankton biomass in the respective regions.  相似文献   

Reaction of forsterite with hydrogen molecules at high pressure and temperature     

Ayako?ShinozakiEmail author  Hisako?Hirai  Hiroyuki?Kagi  Tadashi?Kondo  Taku?Okada  Daisuke?Nishio-Hamane  Shin-ichi?Machida  Tetsuo?Irifune  Takumi?Kikegawa  Takehiko?Yagi 《Physics and Chemistry of Minerals》2012,39(2):123-129

High pressure and temperature reactions of a mixture of forsterite and hydrogen molecules have been carried out using a laser heated diamond anvil cell at 9.8–13.2 GPa and ~1,000 K. In situ X-ray diffraction measurements showed no sign of decomposition or phase transitions of the forsterite under these experimental conditions, indicating that the olivine structure was maintained throughout all runs. However, a substantial expansion of the unit cell volume of the forsterite was observed for samples down to ~3 GPa upon quenching to ambient pressure at room temperature. The Raman spectroscopy measurements under pressure showed significant shifts of the Raman peaks of the Si–O vibration modes for forsterite and of the intramolecular vibration mode for H₂ molecules toward a lower frequency after heating. Additionally, no OH vibration modes were observed by Raman and FT-IR spectroscopic measurements. These lines of evidence show that the observed volume expansion in forsterite is not explained by the incorporation of hydrogen atoms as hydroxyl, but suggest the presence of hydrogen as molecules in the forsterite structure under these high pressure and temperature conditions.  相似文献   

Movement of radiocaesium fallout released by the 2011 Fukushima nuclear accident     

Koji Minoura  Tsutomu Yamada  Shin-ichi Hirano  Shinji Sugihara 《Natural Hazards》2014,73(3):1843-1862

The moment magnitude (M _w) 9.0 Tohoku-Oki Earthquake occurred on March 11, 2011, generating an unusually large tsunami. The seismic shocks and tsunami inundation severely damaged the Fukushima Daiichi Nuclear Power Plant. Radionuclide emission due to reactor breakdown contaminated wide areas of Fukushima and its surroundings. Heavy rainfall causes runoff across surface soil, and fine soil particles are susceptible to uptake by the flowing water. The high radioactivity of grains suspended in floodwater indicates that radioactive fallout was streamed into rivers in particulate form and transported downstream under high-flow conditions. Here, we investigated the diachronic mode of ¹³⁴Cs and ¹³⁷Cs in central Fukushima, through which the contaminated air mass drifted and caused wet deposition of radionuclides. Stratigraphic measurements of radioactivity in sediment cores is the method employed in this study to determine the basin-wide movement of ¹³⁴Cs and ¹³⁷Cs, to evaluate the significance of the erosion–transportation–accumulation processes on natural decontamination in terrain characterized by steep slopes and high precipitation. Stratigraphic results illustrate the process of fluvial sediment discharge, and the massive deposition of radiocaesium suggests basin-wide movement of fallout during concentrated rainfall. Grain suspension in torrential currents is an important pathway for transportation of radionuclides from land to sea, and the appearance of hotspots on floodplains and the offshore sea floor is the consequence of erosion and transportation under seasonal heavy precipitation. Radioactive horizons occur in offshore sediment columns and thus radiocaesium discharged from the estuary will persist forever under the sea floor if no artificial disturbance occurs.  相似文献