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191.
Gentaro Kawakami Kenji Nishina Yoshihiro Kase Jun Tajika Keiichi Hayashi Wataru Hirose Tsumoru Sagayama Tatsuya Watanabe Satoshi Ishimaru Ken'ichi Koshimizu Ryo Takahashi Kazuomi Hirakawa 《Island Arc》2017,26(4)
The stratigraphy of tsunami deposits along the Japan Sea, southwest Hokkaido, northern Japan, reveals tsunami recurrences in this particular area. Sandy tsunami deposits are preserved in small valley plains, whereas gravelly deposits of possible tsunami origin are identified in surficial soils covering a Holocene marine terrace and a slope talus. At least five horizons of tsunami events can be defined in the Okushiri Island, the youngest of which immediately overlies the Ko‐d tephra layer (1640 AD) and was likely formed by the historical Oshima‐Ohshima tsunami in 1741 AD. The four older tsunami deposits, dated using accelerator mass spectrometry 14C, were formed at around the 12th century, 1.5–1.6, 2.4–2.6, and 2.8–3.1 ka, respectively. Tsunami sand beds of the 1741 AD and circa 12th century events are recognized in the Hiyama District of Hokkaido Island, but the older tsunami deposits are missing. The deposits of these two tsunamis are found together at the same sites and distributed in regions where wave heights of the 1993 tsunami (Hokkaido Nansei‐oki earthquake, Mw = 7.7) were less than 3 m. Thus, the 12th century tsunami waves were possibly generated near the south of Okushiri Island, whereas the 1993 tsunami was generated towards the north of the island. The estimated recurrence intervals of paleotsunamis, 200–1100 years with an average of 500 years, likely represents the recurrence interval of large earthquakes which would have occurred along several active faults offshore of southwest Hokkaido. 相似文献
192.
Phil R. Cummins Laura S. L. Kong Kenji Satake 《Pure and Applied Geophysics》2008,165(11-12):1983-1989
In this introduction we briefly summarize the 14 contributions to Part I of this special issue on Tsunami Science Four Years after the 2004 Indian Ocean Tsunami. These papers are representative of the new tsunami science being conducted since the occurrence of that tragic event. Most of these were presented at the session: Tsunami Generation and Hazard, of the International Union of Geodesy and Geophysics XXIV General Assembly held at Perugia, Italy, in July of 2007. That session included over one hundred presentations on a wide range of topics in tsunami research. The papers grouped into Part I, and introduced here, cover topics directly related to tsunami mitigation such as numerical modelling, hazard assessment and databases. Part II of this special issue, Observations and Data Analysis, will be published in a subsequent volume of Pure and Applied Geophysics. 相似文献
193.
We measured the electrical resistivity of face-centered-cubic (fcc) structured iron hydrides at high pressures up to 65 GPa and high temperatures in a laser-heated diamond anvil cell. The results indicate that the resistivity of stoichiometric fcc FeHx (x ~ 1.0) is smaller than that of fcc Fe at the same pressure and temperature conditions. The same behavior was also observed in fcc FeNiHx (x ~ 1.0). On the other hand, hydrogen-poor fcc FeHx (x < 0.77) showed a resistivity comparable to that of the fcc phase of pure iron. Therefore, we conclude that the stoichiometric fcc Fe (–Ni) hydride is more conductive than Fe (–Ni) with the same crystal symmetry, and the impurity resistivity of hydrogen in Fe is vanishingly small. Even if hydrogen is the major light element in the Earth's core, it would have little influence on the electrical and thermal conductivity of Fe–Ni alloys, and hence the thermal evolution of the core. 相似文献
194.
Akira Hasegawa Kenji Ohta Takashi Yagi Kei Hirose Yoshiyuki Okuda Tadashi Kondo 《Comptes Rendus Geoscience》2019,351(2-3):229-235
We measured the lattice thermal conductivities of Fe0.98O wüstite and iron-rich (Mg,Fe)O magnesiowüstite using the pulsed light heating thermoreflectance technique with a diamond anvil cell up to 61 GPa at 300 K. We found that the thermal conductivity of wüstite does not show a monotonic increase as a function of pressure, contrary to that of MgO periclase. Rocksalt (B1) to rhombohedral B1 transition is likely to induce an abnormal pressure response in the conductivity of wüstite. Our results also show that magnesiowüstite has a lower conductivity than that of MgO and FeO endmembers due to a strong iron impurity effect, which is well reproduced by a model considering phonon-impurity scattering in a binary solid solution. 相似文献
195.
Takashi Ninomiya Shoichi Shimoyama Koichiro Watanabe Kenji Horie Daniel J. Dunkley Kazuyuki Shiraishi 《Island Arc》2014,23(3):206-220
The Taishu Group, a marine formation with a thickness of >5400 m, crops out on Tsushima Island, located in the southwestern Japan Sea. The group, which is generally regarded as early Eocene to early Miocene in age, provides important information about the tectonic setting of the Japan Sea. In this study, we present new SHRIMP U–Pb dates for igneous zircons from the Kunehama Tuff, which is in the basal part of the Taishu Group, and the Oobaura Tuff, which is in the uppermost part of the group. Results show that the Taishu Group was deposited rapidly, during the short interval of 17.9–15.9 Ma (early–middle Miocene), and is equivalent to other early–middle Miocene strata found in the Japan Sea region. Our results provide new constraints on the geological history of the Japan Sea and its islands. 相似文献
196.
Eleazar Padrón Pedro A. Hernández Nemesio M. Pérez Theofilos Toulkeridis Gladys Melián José Barrancos Giorgio Virgili Hirochika Sumino Kenji Notsu 《Bulletin of Volcanology》2012,74(6):1509-1519
Measurements of visible and diffuse gas emission were conducted in 2006 at the summit of Sierra Negra volcano, Galapagos, with the aim to better characterize degassing after the 2005 eruption. A total SO2 emission of 11?±?2?t day?1 was derived from miniature differential optical absorption spectrometer (mini-DOAS) ground-based measurements of the plume emanating from the Mini Azufral fumarolic area, the most important site of visible degassing at Sierra Negra volcano. Using a portable multigas system, the H2S/SO2, CO2/SO2, and H2O/SO2 molar ratios in the Mina Azufral plume emissions were found to be 0.41, 52.2, and 867.9, respectively. The corresponding H2O, CO2, and H2S emission rates were 562, 394, and 3?t day?1, respectively. The total output of diffuse CO2 emissions from the summit of Sierra Negra volcano was 990?±?85?t day?1, with 605?t day?1 being released by a deep source. The diffuse-to-plume CO2 emission ratio was about 1.5. Mina Azufral fumaroles released gasses containing 73.6?mol% of H2O; the main noncondensable components amounted to 97.4?mol% CO2, 1.5?mol% SO2, 0.6?mol% H2S, and 0.35?mol%?N2. The higher H2S/SO2 ratio values found in 2006 as compared to those reported before the 2005 eruption reveal a significant hydrothermal contribution to the fumarolic emissions. 3He/4He ratios measured at Mina Azufral fumarolic discharges showed values of 17.88?±?0.25?R A , indicating a mid-ocean ridge basalts (MORB) and a Galapagos plume contribution of 53 and 47?%, respectively. 相似文献
197.
Toshiya Katano Kenji Yoshino Tadashi Matsubara Yuichi Hayami 《Journal of Oceanography》2012,68(4):497-507
The raphidophyte Chattonella and the bacillariophyte Skeletonema are representative bloom-causing organisms in the Ariake Sea, Japan. Changes in their abundance were monitored to clarify the role of river discharge in the red tides caused by these organisms in the innermost area of the sea. In late June 2010, heavy rain occurred and subsequently river discharge increased. A Chattonella bloom occurred after heavy rain on July 5, although Chattonella abundance was very low (<1?cell?ml?1) before the heavy rain (June 29). Maximum cell density reached 4.2?×?103?cells?ml?1 at the surface. Thus, the bloom developed as the river plume extended in the estuary. During the course of extension of the river plume, the Chattonella population rapidly developed using the nutrients supplied by the river. Just after the Chattonella bloom, heavy rain occurred again and a very large quantity of river water flowed into the estuary. Consequently, the salinity of the surface decreased to 5 in the study area on July 16. Chattonella did not migrate to the surface probably because of the overlying low-salinity water; Chattonella formed a thin layer (20–50?cm in thickness) at the depth where salinity was 10. However, a Skeletonema population developed at the surface. On July 20, Skeletonema density at the surface exceeded 105?cells?ml?1. With the decline of the Skeletonema abundance due to the nutrient limitation, Chattonella again formed bloom probably using deep-nutrient pool by their vertical migration behavior. The present study clearly demonstrates that the Chattonella can form dense bloom after the heavy rain. The seed population awaiting the river discharge is probably essential to the rapid development of Chattonella in the estuary. 相似文献
198.
199.
200.
Contribution of CO2 and H2S emitted to the atmosphere by plume and diffuse degassing from volcanoes: the Etna volcano case study 总被引:1,自引:0,他引:1