記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Primary tephra layers can provide isochrons in a stratigraphic sequence. Such isochrons are powerful tools in terms of correlation and chronology of strata, and they constrain a chronological framework for geology, geomorphology, archaeology and palaeo-environmental studies in the Neogene to Quaternary. However, reworking processes can re-distribute tephra materials in both time and space, so that a given tephra can form a new discrete layer later in the depositional sequence, or it can be distributed in low concentrations (no visible layers, i.e., crypto-tephras) over a range of different stratigraphic horizons. The present study, based on sedimentological, petrographical, and geochemical analyses of reworked tephras in Japan, evaluates the duration and persistence of reworking and the tephra mobilisation and delivery to watersheds. Furthermore, it discusses how a unique isochron can be constructed from tephra distribution in a sedimentary sequence. Examples presented here are from fluvial and deltaic sequences in the Japanese Quaternary, which contain several visible tephra layers and a certain amount of tephra materials from multiple sources at different stratigraphical horizons. In the Niigata Plain, 5.4 ka Numazawako tephra material continued to be reworked for more than 4000 years after the eruption of Numazawa volcano, and was re-deposited as reworked pumice grains consisting of a "visible" tephra layer in delta front deposits. Mixed tephra materials originating from an earlier eruption of Numazawa volcano and eruptions from other calderas were also identified. In the Tsugaru Plain, post-2.5 ka subsurface deposits have > 10% glass shards content throughout the sequence. Glass shards were derived from several different tephra materials, such as those from the most recent eruption of Towada volcano (AD 915), and earlier caldera forming eruptions (30 ka, 15 ka). Some of the glass shards probably originated from erosion of exposed Pliocene pyroclastic bedrock. Thus, tephra reworking processes in alluvial to shallow marine settings can continue long after an eruption has ended, and can persist even during inter-eruptive (i.e., background sedimentation) periods. As tephra reworking involves complicated processes, careful observation and interpretations are necessary to evaluate whether tephra materials can truly provide an isochron for the strata in which they are found to exist. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.

DOI： 10.1016/j.quaint.2015.03.022

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

This study reports on geomorphic and sedimentary evidence for a gigantic breakout flood from Towada caldera, Honshu Island, northeast Japan, as observed along the Oirase River downstream from the outlet of the caldera lake. A number of features of the Oirase River are inconsistent with its present discharge, including the occurrence of 1) hanging valleys and a horseshoe-shaped waterfall in the upstream gorge area, 2) boulder bars and scattered flood boulders, 3) a dry valley at a high elevation in the gorge, and 4) a large fan (the Sanbongi fan) in the downstream area of the river. The Sanbongi fan is composed of thick, lithic-rich hyperconcentrated flow deposits that include pumice clasts derived from the 15 ka Towada-Hachinohe ignimbrite and well-rounded meter-sized (and outsized) boulders derived from bedrock of welded ignimbrite. The deposits are entirely aggradational, with no major channels, indicating the absence of a major hiatus during sedimentation. The depositional facies also indicate that a single sheet-like flood event deposited the sediment within the Sanbongi fan area. Based on the age of the Sanbongi fan, the flood occurred between 15 and 12 ka, after eruption of the Towada-Hachinohe ignimbrite. The most probable water source for the flood is Towada caldera lake, as suggested by landforms and sediments along the lake outlet. A paleohydrological analysis indicates that at least 6 km(3) of water was released from the caldera at a peak discharge of >2 x 10(4) to 3 x 10(5) m(3) s(-1) during the breakout flood. Although the Sanbongi fan was previously considered to be a "normal" alluvial fan that formed during a stage of low-stand sea level, the present results show that the formation of the fan was closely related to a catastrophic flood from Towada caldera rather than perennial fluvial activity, climate change, or a change in relative sea level. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.geomorph.2010.08.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.sedgeo.2009.04.016

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：GEOLOGICAL SOC AMER, INC  

Numazawa volcano in northeast Japan erupted most recently at ca. 5 ka, forming a 2-km-diameter caldera and emplacing at least 4 km(3) of valley-confined ignimbrite. The ignimbrite dammed the Tadami River to a depth of >100 inn, temporarily impounding >1.6 km(3) of water. Overtopping of the barrier triggered breaching and catastrophic release of the dam lake. Pyroclastic material redeposited by the ensuing flood is widely distributed along the Tadami and Agano Rivers in deposits tens of meters thick as far as the coastal Niigata Plain >150 km downstream of the volcano. Evidence for damming and flooding found along the rivers includes (1) fine-grained, thinly laminated lacustrine deposits upstream of the pyroclastic blockage; (2) 30-m-thick, pumiceous debris-How and hyperconcentrated-flow deposits that show continuous sedimentation with no major hiatus downstream of the volcano; (3) fine-grained slackwater deposits at tributary river mouths; and (4) large flood boulders that form lags on stripped ignimbrite surfaces and younger terrace surfaces, or cropping out within hyperconcentrated-flow deposits. Paleohydraulic estimation techniques indicate a peak discharge of 30,000-50,000 m(3)/s at the breach point. Burial of Neolithic Jomon settlements by flood and volcaniclastic aggradational deposits at distal locations indicates that such indirect volcanogenic hazards are significant, even where direct primary consequences of volcanic eruptions are minor or absent.

DOI： 10.1130/B26159.1

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：GEOLOGICAL SOC AMER, INC  

The Pliocene Mushono tephra bed, central Japan, is characterized by fluvio-lacustrine volcaniclastic resedimentation at distal locations from the volcanic source. Sedimentary responses to an explosive eruption are well recorded in the resedimented Mushono tephra bed. Immediately after the eruption, large volumes of primary volcaniclastic material were reworked from proximal areas and discharged into the distal basin. Overloading of fluvial systems by pyroclastic debris resulted in the development of low-sinuosity active fluvial channel systems that carried sediment-laden, hyperconcentrated flows. The fluvial system flowed into a lake more than 150 km from the inferred source location, resulting in delta formation and progradation. Primary pyroclastic fall deposits are only a few centimeters thick but are overlain by reworked volcaniclastic deposits more than 5 m thick, which show coarsening-upward successions representing fluvio-lacustrine deltaic progradation. The reworked succession consists of six sedimentary facies, which can be interpreted as prodelta, mouth bar, distributary-channel, hyperconcentrated-flow, interdistributary-lowland or floodplain, and slump deposits. Rounded, cobble-sized pumice clasts in prodelta and distributary-channel deposits and thick, reworked deposits imply that the majority of resedimented volcaniclastic material was derived from voluminous proximal ignimbrite, rather than thin, fine-grained distal fallout ash material. Vertical facies changes are concordant with a decrease in sediment yields with time. Lateral facies distributions correspond to episodic influxes of volcaniclastic sediments that controlled the morphology of discrete fluvio-lacustrine deltas. The distal sedimentary response to an explosive silicic eruption is thus clearly recorded in vertical and lateral facies distribution of reworked volcaniclastic sediments.

DOI： 10.1130/B25379.1

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：BLACKWELL PUBLISHING LTD  

The Ebisutoge-Fukuda tephra (Plio-Pleistocene boundary, central Japan) has a well-recorded eruptive style, history, magnitude and resedimentation styles, despite the absence of a correlative volcanic edifice. This tephra was ejected by an extremely large-magnitude and complex volcanic eruption producing more than 400 km(3) total volume of volcanic materials (volcanic explosivity index=7), which extended more than 300 km away from the probable eruption centre. Remobilization of these ejecta occurred progressively after the completion of a series of eruptions, resulting in thick resedimented volcaniclastic deposits in spatially separated fluvial basins, more than 100 km from the source. Facies analysis of resedimented volcaniclastic deposits was carried out in distal fluvial basins. The distal tephra (approximate to100-300 km from the source) comprises two different lithofacies, primary pyroclastic-fall deposits and reworked volcaniclastic deposits. The resedimented volcaniclastic succession shows five distinct sedimentary facies, interpreted as debris-flow deposits (facies A), hyperconcentrated flow deposits (facies B), channel-fill deposits (facies C), floodplain deposits with abundant flood-flow deposits (facies D) and floodplain deposits with rare flood deposits (facies E). Resedimented volcaniclastic materials at distal locations originated from unconsolidated deposits of a climactic, large ignimbrite-forming eruption. Factors controlling inter- and intrabasinal facies changes are (1) temporal change of introduced volcaniclastic materials into the basin; (2) proximal-distal relationship; and (3) distribution pattern of pyroclastic-flow deposits relative to drainage basins. Thus, studies of the Ebisutoge-Fukuda tephra have led to a depositional model of volcaniclastic resedimentation in distal areas after extremely large-magnitude eruptions, an aspect of volcaniclastic deposits that has often been ignored or poorly understood.

DOI： 10.1046/j.1365-3091.2002.00445.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

An extremely large magnitude eruption of the Ebisutoge-Fukuda tephra, close to the Plio-Pleistocene boundary, central Japan. spread volcanic materials widely more than 290,000 km(2) reaching more than 300 km from the probable source. Characteristics of the distal air-fall ash (> 150 km away from the vent) and proximal pyroclastic deposits are clarified to constrain the eruptive style, history, and magnitude of the Ebisutoge-Fukuda eruption.
Eruptive history had five phases. Phase 1 is phreatoplinian eruption producing > 105 km(3) of volcanic materials. Phases 2 and 3 are plinian eruption and transition to pyroclastic how. Plinian activity also occurred in phase 3, which ejected conspicuous obsidian fragments to the distal locations. In phase 5, collapse of eruption column triggered by phase 4. generated large pyroclastic how in all directions and resulted in more than 250-350 km(3) of deposits. Thus, the total volume of this tephra amounts over 380-390 km(3). This indicates that the Volcanic Explosivity Index (VEI) of the Ebisutoge-Fukuda tephra is greater than 7. The huge thickness of reworked volcaniclastic deposits overlying the fall units also attests to the tremendous volume of eruptive materials of this tephra.
Numerous ancient tephra layers with large volume have been reported worldwide, but sources and eruptive history are often unknown and difficult to determine. Comparison of distal air-fall ashes with proximal pyroclastic deposits revealed eruption style, history and magnitude of the Ebisutoge-Fukuda tephra. Hence, recognition of the Ebisutoge-Fukuda tephra, is useful for understanding the volcanic activity during the Pliocene to Pleistocene, is important as a boundary marker bed, and can be used to interpret the global environmental and climatic impact of large magnitude eruptions in the past. (C) 2001 Elsevier Science B.V, All rights reserved.

DOI： 10.1016/S0377-0273(00)00300-0

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jvolgeores.2022.107685

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.20965/jdr.2022.p0736

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掲載種別：研究論文（学術雑誌）  

DOI： 10.5026/jgeography.131.339

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.jvolgeores.2020.107001

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.5026/jgeography.129.529

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記述言語：英語  

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掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jvolgeores.2019.106661

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jsames.2018.12.016

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   出版者・発行元：日本第四紀学会  

DOI： 10.4116/jaqua.57.65

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.23917/forgeo.v31i1.3977

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掲載種別：研究論文（学術雑誌）  

© 2016, © Emerald Group Publishing Limited. Purpose – The purpose of this paper is to present a concurrent implementation of sustainable inventory for the UNESCO World Heritage sites of Bat, Al-Khutm and Al-Ayn in the interior of Oman. Design/methodology/approach – A digital heritage inventory (DHI) was developed through an action research to realize demands of the local agent and to co-design the solution. The Ministry of Heritage and Culture of Oman, the local agent, demanded to have archaeological information of the sites shared with foreign expeditions, which had worked at the sites for decades, for efficient heritage management, scientific research, outreach, and education. To this end, the Bat Digital Heritage Inventory (BatDHI) was implemented by a combination of network-access-ready database application, open source geographical information systems, and a web-based map service to incorporate and visualize previous works, which were concurrently cross-checked and updated by ground-truth surveys. Findings – The online inventory made it possible to update information during archaeological fieldwork in real time and accelerated the decision-making process in heritage management by prompt data updates and visualization. Research limitations/implications – The DHI is extendable for other sites or regions. It should also be considered to install Arches, an open-source suite of digital heritage inventories. Practical implications – The BatDHI was implemented through the action research mentioned in the design/methodology/approach section and yielded the implications mentioned in the findings section. Originality/value – This paper is a challenging application of transdisciplinary approach to the sustainable heritage management, in which researchers and societal stakeholders collaborate for co-design of research agendas, co-production of knowledge, and co-dissemination of outcomes.

DOI： 10.1108/JCHMSD-01-2016-0005

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

Hole U1395B, drilled southeast of Montserrat during Integrated Ocean Drilling Program Expedition 340, provides a long (>1 Ma) and detailed record of eruptive and mass-wasting events (>130 discrete events). This record can be used to explore the temporal evolution in volcanic activity and landslides at an arc volcano. Analysis of tephra fall and volcaniclastic turbidite deposits in the drill cores reveals three heightened periods of volcanic activity on the island of Montserrat (approximate to 930 to approximate to 900 ka, approximate to 810 to approximate to 760 ka, and approximate to 190 to approximate to 120 ka) that coincide with periods of increased volcano instability and mass-wasting. The youngest of these periods marks the peak in activity at the Soufriere Hills volcano. The largest flank collapse of this volcano (approximate to 130 ka) occurred toward the end of this period, and two younger landslides also occurred during a period of relatively elevated volcanism. These three landslides represent the only large (>0.3 km(3)) flank collapses of the Soufriere Hills edifice, and their timing also coincides with periods of rapid sea level rise (>5 m/ka). Available age data from other island arc volcanoes suggest a general correlation between the timing of large landslides and periods of rapid sea level rise, but this is not observed for volcanoes in intraplate ocean settings. We thus infer that rapid sea level rise may modulate the timing of collapse at island arc volcanoes, but not in larger ocean-island settings.

DOI： 10.1002/2015GC006053

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

Recent studies hypothesize that some submarine slides fail via pressure-driven slow-slip deformation. To test this hypothesis, this study derives pore pressures in failed and adjacent unfailed deep marine sediments by integrating rock physics models, physical property measurements on recovered sediment core, and wireline logs. Two drill sites (U1394 and U1399) drilled through interpreted slide debris; a third (U1395) drilled into normal marine sediment. Near-hydrostatic fluid pressure exists in sediments at site U1395. In contrast, results at both sites U1394 and U1399 indicate elevated pore fluid pressures in some sediment. We suggest that high pore pressure at the base of a submarine slide deposit at site U1394 results from slide shearing. High pore pressure exists throughout much of site U1399, and Mohr circle analysis suggests that only slight changes in the stress regime will trigger motion. Consolidation tests and permeability measurements indicate moderately low (similar to 10(-16)-10(-17)m(2)) permeability and overconsolidation in fine-grained slide debris, implying that these sediments act as seals. Three mechanisms, in isolation or in combination, may produce the observed elevated pore fluid pressures at site U1399: (1) rapid sedimentation, (2) lateral fluid flow, and (3) shearing that causes sediments to contract, increasing pore pressure. Our preferred hypothesis is this third mechanism because it explains both elevated fluid pressure and sediment overconsolidation without requiring high sedimentation rates. Our combined analysis of subsurface pore pressures, drilling data, and regional seismic images indicates that slope failure offshore Martinique is perhaps an ongoing, creep-like process where small stress changes trigger motion.

DOI： 10.1002/2015JB012061

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

Volcanic edifice collapses generate some of Earth's largest landslides. How such unloading affects the magma storage systems is important for both hazard assessment and for determining long-term controls on volcano growth and decay. Here we present a detailed stratigraphic and petrological analyses of volcanic landslide and eruption deposits offshore Montserrat, in a subduction zone setting, sampled during Integrated Ocean Drilling Program Expedition 340. A large (6-10km(3)) collapse of the Soufriere Hills Volcano at similar to 130ka was followed by explosive basaltic volcanism and the formation of a new basaltic volcanic center, the South Soufriere Hills, estimated to have initiated <100years after collapse. This basaltic volcanism was a sharp departure from the andesitic volcanism that characterized Soufriere Hills' activity before the collapse. Mineral-melt thermobarometry demonstrates that the basaltic magma's transit through the crust was rapid and from midcrustal depths. We suggest that this rapid ascent was promoted by unloading following collapse.

DOI： 10.1002/2015GL064519

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4116/jaqua.54.21

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4116/jaqua.54.31

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.

DOI： 10.1002/2014GC005652

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記述言語：日本語   出版者・発行元：特定非営利活動法人 日本火山学会  

Chokai volcano is an andesitic stratovolcano in northeast Japan. The collapse of parts of the volcano occurred about 2500 years ago, and formed the Kisakata debris avalanche deposits. The post-2.5 ka fan (partly volcaniclastic apron) deposits are largely distributed in north to northwestern foot of the volcano. The fan deposits consist of several lithological/sedimentological units, however, most of their geological, sedimentological, and geomorphic characteristics have not been examined in previous studies. This paper, therefore, aims at understanding of geomorphology and depositional processes of these lahar deposits and mineralogical component changes in relations with different sources. Field survey in the upstream and observation of a trench in the downstream area revealed that the fan deposits consist of more than 16 units, which are composed of debris flow, hyperconcentrated flow and streamflow facies; most of them were deposited by lahar events. The lahar deposits have total thickness of 30 m, and overlie the Kisakata debris avalanche deposit. In proximal areas (with steep to moderate slopes), lahars flowed down as debris flows. Whereas in the distal area (with very gentle slopes), the lahars were transformed into hyperconcentrated flow and/or stream flows commonly, although some of them reached to the distal area with a debris flow nature. Clasts of the lahar deposits comprise altered and fresh andesites, mudstones and sandstones. Proportions of altered andesite clasts to total clasts decrease upwards in stratigraphic sequences. Matrices of the lower eight units are composed of grayish-blue clay and are different from those of the upper eight units, which are composed of brownish yellow volcanic sand. The stratigraphic variation in the matrix component is consistent with the change in matrix mineral assemblage, possibly reflecting changes in the source materials from Chokai volcano.

DOI： 10.18940/kazan.60.1_1

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記述言語：日本語   出版者・発行元：一般社団法人 日本地質学会  

DOI： 10.5575/geosoc.2015.0035

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記述言語：日本語   出版者・発行元：特定非営利活動法人 日本火山学会  

Previously known lahar deposits along the Sukawa River, western slope of Adatara volcano, consist of at least 7 muddy (cohesive) units and were formed during the last 2500 years. This paper reports stratigraphy, chronology and depositional processes of the newly found lahar units that were deposited older than 2500 years ago. ^<14>C dating for wood fragments within lahar deposits and intercalated paleosol layers indicates that at least 18 lahar events occurred in the area during the last 14000 years. The newly found lahar units comprise 10 muddy matrix-rich units and one bouldery gravel unit. The muddy matrix-rich units are very poorly sorted with pebble to cobble sized andesite clasts and hydrothermally altered clasts. Bouldery gravel unit is filled with sandy matrix and composed of clasts with oxidized rind locally. Bulk chemistry of these lahar units indicates that high sulfur content in the muddy units whereas Fe_2O_3 content is higher in the bouldery gravel units. The muddy units are derived from syn- or post-eruptive lahars in relations with phreatic eruptions or degradation of hydrothermally altered source rocks nearby the Numanotaira crater at the summit. The bouldery unit distributed farther downstream may have resulted from a non-cohesive debris flow or an outburst flood from the crater or a volcanically dammed upstream area. The presence of oxidized clasts indicates that during traveling, the watery flow entrained clasts which were exposed on a gravelly riverbed in an inter-eruptive period. The two types of lahar deposits show flows with different characteristics (cohesive and non-cohesive) that originated from Adatara volcano. Proximal eruptive units in the summit area sometimes can be degraded easily and overprinted by other eruptive units that result in a paucity and difficulty in understanding the precise eruption history of a volcano. Therefore, approaching from analysis of distally deposited lahar units will give a hint to assess not only a lahar trigger but also the types, frequency and volume of volcanic eruptions.

DOI： 10.18940/kazan.60.4_461

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

DOI： 10.4116/jaqua.53.323

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その他リンク： https://jlc.jst.go.jp/DN/JLC/20001383988?from=CiNii

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

DOI： 10.4116/jaqua.53.265

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その他リンク： https://jlc.jst.go.jp/DN/JALC/10041198239?from=CiNii

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

DOI： 10.4116/jaqua.53.229

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その他リンク： https://jlc.jst.go.jp/DN/JALC/10039466937?from=CiNii

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

Marine sediments around volcanic islands contain an archive of volcaniclastic deposits, which can be used to reconstruct the volcanic history of an area. Such records hold many advantages over often incomplete terrestrial data sets. This includes the potential for precise and continuous dating of intervening sediment packages, which allow a correlatable and temporally constrained stratigraphic framework to be constructed across multiple marine sediment cores. Here we discuss a marine record of eruptive and mass-wasting events spanning similar to 250 ka offshore of Montserrat, using new data from IODP Expedition 340, as well as previously collected cores. By using a combination of high-resolution oxygen isotope stratigraphy, AMS radiocarbon dating, biostratigraphy of foraminifera and calcareous nannofossils, and clast componentry, we identify five major events at Soufriere Hills volcano since 250 ka. Lateral correlations of these events across sediment cores collected offshore of the south and south west of Montserrat have improved our understanding of the timing, extent and associations between events in this area. Correlations reveal that powerful and potentially erosive density-currents traveled at least 33 km offshore and demonstrate that marine deposits, produced by eruption-fed and mass-wasting events on volcanic islands, are heterogeneous in their spatial distribution. Thus, multiple drilling/coring sites are needed to reconstruct the full chronostratigraphy of volcanic islands. This multidisciplinary study will be vital to interpreting the chaotic records of submarine landslides at other sites drilled during Expedition 340 and provides a framework that can be applied to the stratigraphic analysis of sediments surrounding other volcanic islands.

DOI： 10.1002/2014GC005402

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

DOI： 10.4116/jaqua.53.175

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その他リンク： https://jlc.jst.go.jp/DN/JALC/10037060984?from=CiNii

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

DOI： 10.4116/jaqua.53.111

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

DOI： 10.4116/jaqua.53.103

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

Luminescence dating has been applied to scoria and lahar deposits from Somma-Vesuvius, Italy. Samples include scoria from the AD472 and 512 (or 536) eruptions and lahar deposits. In order to find a stable luminescence signal which is less affected by anomalous fading, infrared stimulated luminescence (IRSL) signals at elevated temperatures after bleaching with IR at 50 degrees C (termed post-IR IRSL; pIRIR) were tested at different preheat and elevated stimulation temperatures. The fading rates of both IRSL and pIRIR signals reduced dramatically with increasing preheat and pIRIR stimulation temperatures. A pIRIR signal measured at 290 degrees C after a preheat at 320 degrees C (60 s) and an IR stimulation at 50 degrees C (100 s) was selected to calculate the equivalent dose (D-e). The gamma spectrometry results indicate that the U-series nuclides are not in equilibrium and there is a large Ra-226 excess. The dose rates and ages were calculated by assuming a Ra-226 excess (over its parent Th-230) at deposition, and that this unsupported excess then decayed to the present level. The resulting luminescence ages of the two scoria samples agreed with the expected ages, and the ages of the lahar deposits indicate that they are associated with the AD1631 eruption. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.quageo.2013.10.005

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記述言語：日本語  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER INT PUBLISHING AG  

Onshore-offshore geophysical studies conducted on Martinique have identified major flank collapse events of Montagne Pelee that generated large submarine mass wasting deposits. Here, we evaluate the preconditioning factors involved in the deformation and failure of marine sediments related to volcano-flank collapse events. We use core logging, sedimentological and geotechnical data of the upper 200 m of core at sites U1397, U1398, U1399 and U1400 drilled during the Integrated Ocean Drilling Program (IODP) expedition 340, west of Martinique. We find that the low hydraulic conductivity of hemipelagic sediment causes low rates of dewatering of turbidites and tephra layers allowing excess pore fluid pressures to persist at depth. Overpressure generation was likely enhanced during major flank collapses, leading to low shear strength and subsequent deformation of large volumes of marine sediments, as found at Site U1400.

DOI： 10.1007/978-3-319-00972-8_7

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記述言語：日本語  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

苗場山山頂の湿原堆積物に挟在するテフラ層の層相，鉱物組成，火山ガラスの形状・屈折率・化学組成を検討した．また泥炭質な湿原堆積物から¹⁴C年代値を得た．その結果，湿原堆積物は完新世に堆積した肉眼で確認できるテフラ層12層（NB1〜12）を記録しており，下位から，NB3は鬼界アカホヤテフラ（K-Ah）と妙高赤倉テフラ（My-A）との混在層，NB8は草津白根熊倉軽石層（KS-Ku），NB10は草津sp1-3テフラ層，NB11は妙高大田切川テフラ層（My-Ot），NB12は高谷池火山灰層グループc（KGc）にそれぞれ同定・対比した．それらテフラ層の間に浅間・草津白根・妙高・新潟焼山火山起源の可能性があるテフラ層が挟在する．苗場山はこれらテフラの供給源となる北関東・信越と日本海側の沖積平野との中間地点に位置するため，本研究による結果は，地域的ではあるが，周辺地域の層序や編年に参考となるテフラ層序を提供する．また，山頂での湿原環境下では，肉眼で観察できるテフラ層でも，その構成物が複数起源に由来するテフラの混在や再堆積によるものが含まれることが明らかとなった．

DOI： 10.4116/jaqua.52.241

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その他リンク： https://jlc.jst.go.jp/DN/JALC/10027165606?from=CiNii

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Luminescence dating has been applied to volcanogenic outburst flood sediments (Takuma gravel bed) from Aso volcano, Japan, and tephric loess deposits overlying the gravel bed. The poly-mineral fine grains (4-11 μm) from loess deposits were measured with pulsed optically stimulated luminescence (pulsed OSL) and post-IR infrared stimulated luminescence (pIRIR) methods, whereas the Takuma gravel bed containing no quartz, was measured with IRSL and pIRIR methods using sand sized (150-200 μm) plagioclase. The loess deposits date back at least to ∼50 ka by consistent IRSL, pIRIR and pulsed OSL ages from the lowermost part of the loess deposits from one section. The ages obtained from the bottom part of the other loess section are not consistent each other. However, we consider that the pIRIR age (72±6 ka) which showed negligible anomalous fading is most reliable, and regard as a preliminary minimum age of the Takuma gravel bed. The equivalent doses (De) for the plagioclase from the Takuma gravel bed have a narrow distribution and the weighted mean of the three samples yield an age of 89±3 ka. This age is in agreement with the last caldera-forming eruption of Aso volcano (∼87 ka) and it is likely that the pIRIR signal has not been bleached before the deposi-tion. IRSL dating without applying pIRIR using small aliquots was also conducted, however, the IRSL signal shows no clear evidence of an additional bleaching during the event of outburst flood from the caldera lake. © 2013 Silesian University of Technology, Gliwice, Poland. All rights reserved.

DOI： 10.2478/s13386-013-0135-4

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

津軽平野中部における浅層堆積物の層相および鉱物組成，火山ガラスの形状・屈折率，<SUP>14</SUP>C年代を検討した．当地域は奈良時代から平安時代初頭に有機質シルト層や未分解有機物層が堆積する湿地であったが，後の火山灰質砂層の堆積により堆積環境が激変した．火山灰質砂層は様々な堆積構造を呈し，十和田a（To-a）テフラ由来の火山ガラスを多く含むため，十和田火山AD 915噴火後のラハール堆積物と判断できる．ラハール堆積物の上位にはAD 930～940頃の白頭山-苫小牧（B-Tm）火山灰が認められ，To-aテフラの噴出後B-Tm火山灰の降灰時期までの二十数年以内でラハールが終息したと推定される．ラハール堆積物上位の土壌化層には，平安時代中期の遺物が包含される．津軽平野中部では，平安時代の遺跡が多く存在することからも，ラハールの流入で広大な砂地が形成され，人々の居住可能な場が整い，居住の増加に影響を与えたことが考えられる．

DOI： 10.4116/jaqua.51.317

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その他リンク： https://jlc.jst.go.jp/DN/JALC/10012945947?from=CiNii

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

Using temperature gradients measured in 10 holes at 6 sites, we generate the first high fidelity heat flow measurements from Integrated Ocean Drilling Program drill holes across the northern and central Lesser Antilles arc and back arc Grenada basin. The implied heat flow, after correcting for bathymetry and sedimentation effects, ranges from about 0.1 W/m(2) on the crest of the arc, midway between the volcanic islands of Montserrat and Guadeloupe, to &lt;0.07 W/m(2) at distances &gt;15 km from the crest in the back arc direction. Combined with previous measurements, we find that the magnitude and spatial pattern of heat flow are similar to those at continental arcs. The heat flow in the Grenada basin to the west of the active arc is 0.06 W/m(2), a factor of 2 lower than that found in the previous and most recent study. There is no thermal evidence for significant shallow fluid advection at any of these sites. Present-day volcanism is confined to the region with the highest heat flow.

DOI： 10.1029/2012GC004260

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jvolgeores.2012.04.009

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Geological Society of Japan  

本研究は，鮮新・更新統第二瀬戸内累層群（大阪層群・古琵琶湖層群・東海層群）の非海成層中の22テフラ層準における層相の再検討を行い，降下テフラ部と再堆積部の側方への層厚変化から，大阪・古琵琶湖・東海の3つの堆積盆への火山砕屑物流入経路を考慮し，供給源となる火山地域の推定を行った．多くのテフラ層は，厚層の再堆積部を持っていることから，テフラの空中飛来だけでなく，河川系を通じた運搬・堆積がテフラ層の形成に重要であることが明らかとなった．検討したテフラ層では，堆積盆近傍の火砕流堆積物の再堆積に由来するテフラ層15層準，九州南部や東北などの遠方の給源からの降下テフラ層5層準，を判断した．テフラ層形成の背後にある噴出源の位置や噴火様式，古地理（古水系）をより理解するためにも，降下テフラだけでなく，水流作用により堆積した再堆積部に着目することが重要である．

DOI： 10.5575/geosoc.2011.0024

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その他リンク： https://jlc.jst.go.jp/DN/JALC/10003896982?from=CiNii

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Geological Society of Japan  

越後平野は，日本海に面した沖積低地で複数の砂丘列が発達している．平野部の阿賀野川流域の沖積層において，複数のボーリング試料の堆積相や構成鉱物の特徴から，約5000年前の沼沢湖噴火によるラハール堆積物の堆積過程を検討した．<br>ラハールによる堆積物は，当時の海岸部では層厚5～8 m程度の軽石質なデルタを形成した．また，決壊洪水イベントによる膨大な量の火砕物は，デルタシステムを急速に前進させ海岸地形を変化させた．このような大規模な火砕物の再堆積作用の解明は，平野の形成過程における影響だけでなく，下流域での火山土砂災害としての予測につながる課題となるものである．

DOI： 10.5575/geosoc.117.483

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00380388842?from=CiNii

記述言語：日本語   出版者・発行元：The Geological Society of Japan  

活火山である焼岳火山を主峰とする焼岳火山群は，近年も活発な噴火活動を行なっており，近い将来も噴火する可能性が高い．この火山を起源とする過去に発生したラハールは，高原川－神通川水系を100 km以上も流下し富山平野まで達している．この見学コースでは，この大規模ラハール堆積物の観察とともに，その母材となった焼岳火山群の火山噴出物まで各段階を追って観察する．その他，焼岳火山の観測を行なっている京都大学防災研究所附属の上宝観測所や穂高砂防観測所なども見学する予定である．

DOI： 10.5575/geosoc.116.S49

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：TAYLOR & FRANCIS LTD  

It has been suggested that the sustainability of turbidity currents is derived from self-sustainment of the flow. This self-sustainment can be realized through the process of acceleration of the current as it increases its own density due to the incorporation of sediment eroded from the substrate. Although self-sustaining turbidity currents have been predicted theoretically, experimental turbidity currents to date have all been net-depositional decelerating flows. We report here the results of experiments on self-sustaining turbidity currents. In order to produce non-depositional flows, we modeled the sediment using two types of plastic particles with densities that were much lower (1.3 and 1.5 g/cm(3)) than that of silicielastic sands. After the bed was covered with sediment, a mixture of sediment and water was injected to produce a turbidity current at the upcurrent end of the flume. As a result, some experimental flows showed acceleration, and measurements using siphons revealed that the sediment concentration of the flow increased downcurrent, so indicating a trend toward self-sustaining turbidity currents.

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記述言語：日本語   出版者・発行元：日本地質学会  

DOI： 10.5575/geosoc.113.12.XIX_XX

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3720/japt.71.337

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：地学団体研究会  

DOI： 10.15080/agcjchikyukagaku.59.1_3

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本堆積学会  

前期更新世, 八千穂層群下部・中部累層の火山性湖成ファンデルタ堆積物は上部ファンデルタプレーン相に土石流堆積物・ハイパーコンセントレイティッド流堆積物を含む. ハイパーコンセントレイティッド流堆積物はその特徴とそれに関係した他の堆積物との累重関係によって認定できた. ハイパーコンセントレイティッド流堆積物は, 不明瞭な成層構造をもち, 数cm程度の細粒層と細礫～中礫層の互層状を示す. この堆積物は, アウトサイズクラストとして大礫を含むが, 内部には侵食面などをもたない. このことは, 高濃集した流れから粒子が急速に沈積したことを示す. ここでのハイパーコンセントレイティッド流堆積物は多くの場合, 非粘着性土石流堆積物に付随して見られる. このことは, ハイパーコンセントレイティッド流の発生と堆積過程が非粘着性土石流と密接に関係していることを示す. ここでは下位から, 非粘着性土石流堆積物・ハイパーコンセントレイティッド流堆積物・河川流堆積物と累重するのが認められる. この累重様式は複合した流れの流下方向への分化を表しており, 先行して流れた非粘着性土石流の背後に, そこから分化したハイパーコンセントレイティッド流があり, のさらに後を河川流が流下したと考えられる.

DOI： 10.4096/jssj1995.59.17

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：大阪市立大学  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本地質学会  

Stratigraphic horizon of the Km3 tephra layer interealated in the lower part of the Kitaura Formation, Akita Prefecture, Japan, is located above the calcareous nannofossil datum plane 11 (1.65Ma). The Km3 tephra layer, approximately 1m thick, is mainly composed of volcanic glass shards with minor amounts of plagioclase, quartz and biotite. On the basis of the stratigraphic position, lithofacies, petrographic characteristics and chemical composition of glass shards, the Km3 tephra layer is correlated to the OM-SK110 Tephra (1.65Ma). By this result, it is clarified that the Km3 tephra layer was transported more than 450km away from its probable volcanic center situated in the Hida Mountain Ranges, central Honshu Island.

DOI： 10.5575/geosoc.108.11_761

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その他リンク： http://hdl.handle.net/10191/17815

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：海洋出版  

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記述言語：日本語   出版者・発行元：地学団体研究会  

富田林市宮町の星ヶ他の東岸に露出し,大阪層群に狭在する火山灰層は,その鉱物組成,火山ガラスの形状,火山ガラスの屈折率を検討した結果,Ma3海成粘土層とMa4海成粘土層の間に狭在する狭山火山灰層に対比されることが判明した.この火山灰層は水の動きのない内湾泥底で堆積した泥層中に挟み込まれている.岩相,堆積構造,地層面の形状をもとにI, II, III, IV, Vの5つのユニットに区分できる.ユニットIは粗粒砂から中粒砂サイズの火山灰によって構成され,正級化する.下位の泥層とは整合で接する.斜交葉理や平行葉理は認められない.ユニットIは直接,火山砕屑物が降下して堆積したものである.II, III,IVのユニットは粗粒砂サイズからシルトサイズの火山灰によって構成され,基底部から上部に向かって級化する.下底は多くの場合侵食面で下位と接し,水平方向への連続性は悪い.堆積構造は級化,平行葉理,斜交葉理等が発達し,不完全なBouma (1962)のシーケンスを示す.またシルトサイズの火山灰片や泥質物からなるマッドクラストが含まれる.これらのことからこの火山灰層は乱泥流として流下し再堆積したものである.これらの乱泥流は火山灰降下後,時間をおかずに発生したと推定される.ユニットVについては,火山灰の降下が終わり,火山砕屑物の供給がなくなり,発生する乱泥流の規模が小さくなり,末端相である火山灰薄層が泥層と薄互層を成して堆積したものである.

DOI： 10.15080/agcjchikyukagaku.55.3_173

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本地質学会  

Hyperconcentrated flow deposit, in the Ebisutoge-Fukuda tephra from Mie Prefecture, is thought to be deposited from dilution of the debris flow. Debris-flow deposit (facies A) is overlain by hyperconcentrated flow deposit (facies B). Typical hyperconcentrated flow deposit (facies B1；horizontal bedding Part) changes upward into diluted hyperconcentrated flow deposit (facies B2； scour and fill structure part). These facies characteristics indicate that the debris flow changed through hyperconcentrated flow into normal streamflow by dilution during flow traveling.

DOI： 10.5575/geosoc.106.897

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その他リンク： http://hdl.handle.net/10191/17814

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.5575/geosoc.106.189

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記述言語：日本語   出版者・発行元：経済産業省産業技術総合研究所地質調査所  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Association for Quaternary Research  

西日本の四国・近畿・東海地方などの火山灰稀産地域の段丘では,火山灰層の発見は稀で,しかもそれを連続的に追跡することが困難である.そのため,火山灰に注目した層序・編年学的研究は露頭あるいは狭い地域に限定されたものとならざるを得ず,一般的な調査・研究法とはなっていない.このため,火山灰稀産地域における段丘の層序・編年は,火山灰多産地域に比べ精度が悪い.三重県鈴鹿川流域の段丘もまた,このような火山灰稀産地域に属している.そこで,筆者らは従来の地形・地質学的方法に加え,段丘構成層の上位に発達する細粒堆積物に注目して,この堆積物中に極微量に含まれる火山ガラスから火山灰降下の痕跡を見いだした.そして,これらから段丘の層序を検討し,編年を行った.本研究の結果,次のことが明らかとなった.(1)調査地域の段丘面(段丘構成層)は,高位のものから大谷池面(大谷池段丘層)・丸岡池面(丸岡池段丘層)・神戸面(神戸段丘層)・関面(関段丘層)・古廐面(古廐段丘層)に区分され,さらに神戸面および関面は,高位のものから神戸1面・神戸2面・神戸3面,関1面・関2面に細分できる.(2)各段丘構成層の上位にのる細粒堆積物の層相とそれらに含まれる火山ガラスの性質・含有量の特徴,関段丘層に挾まれる姶良Tn火山灰層(25～21ka),神戸段丘層中の海成粘土層などから,大谷池段丘層・丸岡池段丘層は最終間氷期以前に,神戸段丘層は最終間氷期に,関段丘層は最終氷期に,古廐段丘層は最終氷期以降にそれぞれ形成されたと考えられる.<br>今回行った段丘構成層の上位にのる細粒堆積物に極微量に含まれる火山ガラスを用いた層序・編年の試みは,今後,火山灰稀産地域でのより広域な段丘の対比・編年の可能性を示唆する.

DOI： 10.4116/jaqua.36.263

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00049978711?from=CiNii

記述言語：英語   掲載種別：機関テクニカルレポート，技術報告書，プレプリント等  

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

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記述言語：英語   掲載種別：機関テクニカルレポート，技術報告書，プレプリント等  

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記述言語：日本語   出版者・発行元：新潟大学災害・復興科学研究所  

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記述言語：日本語   出版者・発行元：新潟大学災害・復興科学研究所  

2013年度の共同研究では，山形県肘折カルデラの約1.2万年前の火砕流噴火を対象として，1）火砕流堆積物と降下テフラ層の層相記載，2）堆積物に含まれる軽石・火山ガラス・鉱物の岩石学的検討，3）地形調査と地中レーダ（GPR）探査に基づき火砕流堆積物および二次堆積物の内部構造と堆積過程を明らかにした．この噴火は背弧域（日本海側）での突発的な火砕流噴火であり，本研究の成果は多雪地域かつ高流量の河川系への災害予測・対策のための基礎資料となる．

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記述言語：日本語   出版者・発行元：新潟大学災害・復興科学研究所  

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記述言語：日本語   出版者・発行元：新潟大学災害・復興科学研究所  

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記述言語：日本語   出版者・発行元：新潟大学災害・復興科学研究所  

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記述言語：日本語   出版者・発行元：日本堆積学会  

DOI： 10.4096/jssj.71.69

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記述言語：英語  

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記述言語：日本語   出版者・発行元：新潟大学災害復興科学センター  

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その他リンク： http://hdl.handle.net/10191/5965

記述言語：日本語   出版者・発行元：海洋出版  

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：新潟応用地質研究会  

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記述言語：日本語   出版者・発行元：東北大学大学院工学研究科東北地区自然災害資料センター  

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記述言語：日本語   出版者・発行元：新潟大学  

Niigata-ken Chuetsu earthquake (M6.8) was occurred in the Chuetsu district in Niigata Prefecture at 17:56 23rd October, 2004. Damage becomes the large disaster of fatalities 46 persons, serious or slight injury person 4,791 persons, complete collapsed house 2,827, half collapsed house 12,746, partly failure house 100,453 at 18th March. Serious damages such as Kawaguchi Town and Ojiya City, which recorded seismic intensity of 7, are unevenly distributed. The localization of this damage seemed to appear by many factors such as strong motion, surface geology, structure and actual age of the houses etc. ln this study, distribution of building damage and subsurface deformation were mapped out in the western part of the Uonuma City (ex-Horinouchi Town) at the eastern part of the hypocenter. From the distribution of the completely collapsed house, the concentration of the damage of the western part of the Shin-Doujima were caused by the strong motion from the hypocenter. In the future, ground and geological structure will be examined from field investigations, seismic prospecting, etc.

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その他リンク： http://hdl.handle.net/10191/39267

記述言語：日本語   出版者・発行元：新潟大学  

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その他リンク： http://hdl.handle.net/10191/39266

記述言語：日本語   出版者・発行元：新潟大学  

The Niigata Chuetsu earthquake occurred on October 23, 2004 (magnitude 6.8), caused severe hazards and extensive damages in the Chuetu area, Niigata Prefecture. This region is characterized by agricultural lands and hence, there is little variation of buildings and houses. Many Japanese style wooden houses were severely damaged. We investigated the damage of Japanese wooden houses and structures in the Tamugiyama district, Kawaguchi Town. Initially we examined the geomorphological and geological aspects of the land on which the houses are situated. Most of the houses and buildings in the district are situated on poor-sort admixture consisting of sand and mud gravel beds that has low resistance to ground motion. The house damages are concentrated in the east of the district probably due to the intensive spread of strong motion and earthquake energy. Also, the damages are obvious on the edges of terrace surfaces and on steep slopes of small-scale alluvial fans (taluses) accompanied with rupture of ground surfaces.

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その他リンク： http://hdl.handle.net/10191/39274

記述言語：日本語   出版者・発行元：新潟大学  

The Niigata Chuetsu earthquake (M6.8) occurred on October 23, 2004. It caused widespread hazards and damages in the Chuetsu area, Niigata Prefecture, which including 46 deaths, house destruction of more than 100,000, a great deal of land deformation and structures. Especially, a seismometer installed in the Kawaguchi Town, where located in the eastern part of the epicenter, recorded seismic intensity of 7. We investigated the earthquake hazards and property damages in the Wanazu district, Kawaguchi Town, and preliminary examined the geomorphological and geological aspects of land on which the houses are situated. Most of properties in this district are situated on four terrace surfaces, flood plain, natural levee and two alluvial fans. The house damages are concentrated on steep slopes of alluvial fans overlying terrace and gently slopes of alluvial fan deposits, and are also comparatively concentrated on terraces in the left bank of the Uono River. On the other hand, the house damages situated on terraces in the right bank of the Uono River are less than on which in the left one. Therefore, it is inferred that ground in the Wanazu district were received strong motion by the Niigata Chuetsu earthquake on the left bank of the Uono River.

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その他リンク： http://hdl.handle.net/10191/39260

記述言語：日本語   出版者・発行元：新潟大学  

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開催年月日： 2016年

青森県鶴田町の岩木川下流部において，従来のものと異なる年代を示す埋没林を見いだした．本発表では，埋没林の¹⁴C年代測定，樹種同定を行った結果を報告し，これらを基に津軽平野下流部における地形発達に関する若干の考察を行う．

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開催年月日： 2015年

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開催年月日： 2014年11月

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開催年月日： 2014年11月

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開催年月日： 2014年11月

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開催年月日： 2014年

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開催年月日： 2013年9月

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開催年月日： 2013年9月

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開催年月日： 2013年

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開催年月日： 2011年9月

記述言語：日本語  

決壊洪水型のラハールは，大量の水の流出が瞬時にして起こることから，特に危険な噴火後現象といえる。決壊洪水型ラハールは，噴火現象以上に甚大な被害を引き起こす可能性があり，火山災害の予測という視点からは，過去に発生した火山性の決壊洪水を残存する地形や地層から復元することが重要である。しかし，このような決壊洪水については歴史資料や直接的な観察も極限られているため，その実体は明らかでなく，流れの特徴や発生起因についても不明な点が多く残されている。本報告では，東北日本に位置する2種類のカルデラ火山（沼沢火山と十和田火山）の火砕流噴火後に起きたと考えられる2種類の決壊洪水型ラハールを紹介する。

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開催年月日： 2011年

本研究では，津軽平野中部の完新世段丘と蛇行帯に注目して，その発達史を明らかにするとともに，地形変化をもたらした要因について検討した．蛇行帯を構成する堆積物は，深度約１m以浅において上方粗粒化し，さらに上方細粒化する部分が共通する．また，そこには平行葉理やリップル葉理が認められ，軽石の散在が顕著である．下位の層準から得られた¹⁴Cの年代は，それらが約2,000年前以降に堆積したことを示す．さらに，含まれる火山ガラスの形状（吉川（1976）のC,Tタイプ）から判断すると，これらは主として十和田火山の915年噴火の噴出物を母材とした洪水堆積物であると考えられる．津軽平野中部に発達する完新世段丘は，約2,000年前以前の離水後に，十和田平安噴火によって生じたラハールの流入によって一時的に堆積の場となった可能性がある．

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開催年月日： 2008年9月

記述言語：日本語  

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記述言語：日本語  

<BR>1．はじめに<BR> ピナトゥボ火山は1991年6月15日に大規模火砕流の噴出を伴う大噴火を起こした．この火砕流堆積物は，その後の降雨に伴ってLahar（ラハール）となって移動し，下流域のPampanga州，Tarlac州などに大きな被害をもたらした．日本のODAなどによる巨大堤防の設置などにより，その被害は減少しつつあるが，現在でも雨期には洪水によって小規模なラハールが発生し，場合によってはラハールが河岸の農地などに溢流している状況が確認できる．経済的基盤が弱いフィリピンにおいて，これらの小規模な土砂移動に対しては，大規模な土木工事以外の対策を取ることも必要となろう．<BR> 著者等は，ピナトゥボ火山周辺においてラハール堆積物の堆積構造などの調査を行っているが，その調査過程において，河畔に成立しているタケを中心とする河畔林がラハール堆積物を捕捉（スクリーニング）することによって自然堤防を発達させ，背後の耕作地への土砂の侵入を阻止している状況を確認した．本発表では，この河畔林によるラハール堆積物の補足状況について報告し，フィリピンにおける今後の砂防対策立案の一助にしたい．<BR><BR>２．河畔林による土砂補足状況<BR> 今回，観察を行った河畔林は，タルラック（Tarlac）州パニキ（Panique）地区のタルラック川沿いに成立している，叢生するタケを中心に，一部にエンジュなどが混生しており，樹高はおよそ12～15mに達している．地元住民が周囲にいなかったため充分な聞き取り調査は行えなかったが，カウンターパートのフィリピン人研究者の弁では，自然に成立した森林であろうとのことであった．<BR> この河畔林の横断方向に測線を設定し，ハンドレベルとレーザー測距儀を用いて地形断面図を作成した．河畔林の部分は後背地の農地に比べ，約1m程度高い．この高くなった部分でピット（写真）を掘削すると，層厚数mmに成層した砂層が確認され，層内には円磨されたパミス粒が見られる．このことから，高くなった部分は河畔林がラハール堆積物を捕捉しつつ上方に発達させた自然堤防であると判断される．一方，河畔林前面では，河道からの側方浸食が河畔林の直前面まで及んでいることも確認される．これは，河畔林の根茎が河川の側方浸食を防いでいることを予測させる．また，表土部分の粒度は，河畔林前面で粗砂が主体であるのに対し，自然堤防上では中～細砂画分が多くなり，河畔林背面ではシルト画分が多くなる．これは，粗度が高い河畔林を洪水流が通過することによって流速が低下し，後背地には粗い土砂が運搬されないことを示す．このように，河畔林は洪水流とそれに含まれる土砂を制御していると判断される．<BR><BR>３．まとめ<BR> 河畔林が洪水流や浸食を制御し，土砂を捕捉して自然堤防の発達を促す効果を，日本では伝統的に「水害防備林」として利用してきた．今回調査した河畔林は自然林とのことであるが，同様の河畔林は数カ所で観察できた．こうした森林の効果を積極的に治水に活用することが，フィリピンのような土木工事予算が限られた国では効果的であるし，日本の知識や経験が有効に利用できるであろう．

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記述言語：英語   会議種別：口頭発表（招待・特別）  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

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記述言語：英語   会議種別：口頭発表（基調）  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

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