Analysis of Factors Influencing Simulations of the 1993 Hokkaido Nansei-Oki and 1964 Alaska Tsunamis   总被引：3，自引：0，他引：3  

Edward P. Myers  António M. Baptista 《Natural Hazards》2001,23(1):1-28

The purpose of this paper is to examine factorsinfluencing numerical simulations of tsunamis, andtheir implications for hazard mitigation. We focus ona specific finite element hydrodynamic model, chosenfor its role in the systematic development ofinundation maps for regions threatened primarily byCascadia Subduction Zone (CSZ) tsunamis. However, inpart for generality and in part because of poorhistorical records for CSZ events, we discuss here theperformance of the model in the context of betterdocumented past events with epicenters locatedelsewhere: the July 12, 1993 Hokkaido Nansei-Oki andthe March 28, 1964 Alaska tsunamis. Our analysisincludes the influence of grid refinement,interactions between tides and tsunamis, artificialenergy loss, and numerical parameterization. We showthat while the ability exists to reproduce pastevents, limitations remain in the modeling processthat should be accounted for in translating modelingresults into information for tsunami mitigation andresponse.  相似文献   

Age of glacial and periglacial landforms in northern Hokkaido, Japan, using OSL dating of fine grain quartz     

R. Kondo  S. Tsukamoto  H. Tachibana  Y. Miyairi  Y. Yokoyama 《Quaternary Geochronology》2007,2(1-4):260-265

The timing of glacial advances, periglacial phenomena, and the ages of two marker tephras in northern Hokkaido were estimated by OSL dating. It appears that the glacier of Yamunai 2 stage on Rishiri Island expanded between 24 and 15 ka. In northern Hokkaido, OSL ages indicate ice wedge formation during the period 24–18 ka. These results indicate that both the glacial advance and the development of ice wedges were synchronous phenomena relating to the Last Glacial Maximum.  相似文献   

Lateral structural variation across a collision zone in central Hokkaido, Japan, as revealed by wide-angle seismic experiments     

Takaya Iwasaki  Oguz Ozel  Takeo Moriya  Shin'ichi Sakai  Sadaomi Suzuki  Gen Aoki  Takuya Maeda†  & Takashi Iidaka 《Geophysical Journal International》1998,132(2):435-457

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Fourth‐ to third‐order cycles in the Hakobuchi Formation: Shallow‐marine Campanian final deposition of the Yezo Group,Nakagawa area,northern Hokkaido,Japan     

Hisao Ando  Yoshitaka Tamura  Daisuke Takamatsu 《Island Arc》2010,19(4):567-589

The Yezo Group has a wide longitudinal distribution across Hokkaido, northern Japan. It represents a Cretaceous (Early Aptian–Late Maastrichtian) and Late Paleocene forearc basin‐fill along the eastern margin of the paleo‐Asian continent. In the Nakagawa area of northern Hokkaido, the uppermost part of the Yezo Group consists of the Hakobuchi Formation. Along the western margin of the Yezo basin, 24 sedimentary facies (F) represent 6 facies associations (FA), suggesting prevailing storm‐dominated inner shelf to shoreface environments, subordinately associated with shoreface sand ridges, outer shelf, estuary and fluvial environments. The stacking patterns, thickness and facies trends of these associations allow the discrimination of six depositional sequences (DS). Inoceramids Sphenoceramus schmidti and Inoceramus balticus, and the ammonite Metaplacenticeras subtilistriatum, provide late Early to Late Campanian age constraints to this approximately 370‐m thick final stage of deposition and uplift of the Yezo forearc basin. Six shallow‐marine to subordinately non‐marine sandstone‐dominated depositional sequences include four 10 to 110‐m thick upward‐coarsening regressive successions (FS1), occasionally associated with thin, less than 10‐m thick, upward‐fining transgressive successions (FS2). The lower DS1–3, middle DS4–5 and upper DS6 represent three depositional sequential sets (DSS1–3). These eastward prograding and westward retrograding recurring shallow‐marine depositional systems may reflect third‐ and fourth‐order relative sealevel changes, in terms of sequence stratigraphy.  相似文献   

Plio–Pleistocene Hydrothermal Activity Related to Gold Mineralization in the Seta Area, Northeastern Hokkaido, Japan     

Masahiro YAHATA  Hiroharu MATSUEDA 《Resource Geology》1999,49(3):131-145

Abstract: Plio–Pleistocene hydrothermal activity resulted in high grade low sulfidation epithermal gold mineralization in the Seta area, the southern end of the Monbetsu-Kamishihoro Graben of northeastern Hokkaido, Japan. Hydrothermal activity and accompanying hydrothermal eruptions began at approximately 2 Ma along NNW-SSE trending faults, the Tohbu-ko fault I and II. This activity resulted in two main zones of gold mineralization, the west quartz-adularia veins(QAV) and east stock-work zone(STZ), formed between 1. 8 and 1. 2 Ma. A smectite-chlorite alteration zone is observed at deeper levels, while kaolinite and kaolinite-smectite zones occur at shallower levels with an acid-leached zone present near the surface. The kaoli-nite and kaolinite-smectite zones are also distributed along faults and the STZ, to depths of several hundred meters. δ³⁴S values of pyrite and alunite from the kaolinite and silicified zones indicate alunite formed by the oxidation of sulfide, either H₂S(vapor) or mineral.
Formation of the STZ and the southern part of the QAV took place during lacustrine sedimentation, while formation of the northern part of the QAV took place after eruption of andesitic lava; the latter being associated with widespread alteration formed under neutral-pH conditions. δ¹⁸O values of quartz veins and silicified rocks indicate that the paleo-hydrothermal waters have a large meteoric component, increasing with decreasing depth in the STZ. Acid hydrothermal waters, resulting from near surface oxidation of H₂S were responsible for acid-leaching and kaolinization of surrounding rocks. Between 1. 4 and 0. 3 Ma, the acid hot waters drained back along the STZ to depths of at least 500m, as a result of a fall in the paleo-water table level.  相似文献   

Late Miocene Magmatic-Hydrothermal Systems in the Jozankei-Zenibako District, Southwest Hokkaido, Japan     

Yasushi WATANABE  Eijun OHTA 《Resource Geology》1999,49(2):59-74

Abstract: Hydrothermal systems related to magmatic intrusions in the Jozankei-Zenibako district, southwest Hokkaido are examined, based on field observations, K-Ar ages, and alteration mineral assemblages. The study reveals five major magmat–ic–hydrothermal systems of Late Miocene in age, comprising Ogawa (9. 7 Ma), Jozankei (9. 5–9. 0 Ma), Otarunaigawa (8. 7 Ma), Asarigawa (8. 8 and 6. 7 Ma) and Hariusu (6. 7 Ma). The Ogawa system is related to granodiorite, and the Jozankei, Otarunaigawa and Asarigawa systems are related to quartz porphyry.
The Ogawa system includes potassic, sericitic, propylitic and advanced argillic alteration as well as base-metal mineralization, represented by the Toyotomi deposit. The Jozankei and Otarunaigawa systems lack significant potassic alteration, and are accompanied by sericitic and propylitic alteration. The Otarunaigawa system is associated with base-metal mineralization at Toyohiro and Inatoyo. The Asarigawa and Hariusu systems include advanced argillic and argillic alteration, as well as iron sulfide deposits. The presence of potassic alteration only in the Ogawa system is ascribed to deeper emplacement (˜3 km from the surface) of the intrusive magma. These systems formed in terrestrial environments that existed from ca. 11 Ma to 8. 5 Ma and after 7. 5 Ma in the district.
Age–data compilation shows that the major advanced argillic alteration events in southwest Hokkaido, including those in the Jozankei-Zenibako district, formed during the periods from 9. 7–6. 5 Ma and 3. 5–1. 5 Ma. These periods correspond to the timing of normal subduction of the Pacific plate beneath the Northeast Japan arc. Normal, in contrast to oblique, plate subduction is characterized by andesitic, polygenetic volcanism and associated advanced argillic alteration.  相似文献   

Palaeotemperature curve for the Late Cretaceous of the northwestern circum-Pacific     

Yuri D. Zakharov  Nataliya G. Boriskina  Alexander V. Ignatyev  Kazushige Tanabe  Yasunari Shigeta  Alexander M. Popov  Tamara B. Afanasyeva  Haruyoshi Maeda 《Cretaceous Research》1999,20(6):685

In the northwestern circum-Pacific, two main trends in Late Cretaceous temperatures can be recognized. (1) In general, a recurrent warming trend is thought to have begun in the Turonian–Campanian, reaching temperature maxima in the early Late Santonian and early Late Campanian, and temperature minima in the earliest Santonian and perhaps early Campanian. (2) During the Maastrichtian, temperatures dropped sharply, with only a slight warming in the early Late Maastrichtian. The existence of a thermal maximum at the Coniacian–Santonian transition has previously been expected, but is not confirmed by new isotopic results.  相似文献