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To study subglacial hydrological condition and its influence on the glacier dynamics, we drilled Johnsons Glacier on Livingston Island in the Antarctic Peninsula region. Subglacial water pressure was recorded in boreholes at two locations over 2 years, accompanied by high-frequency ice-speed measurements during two summer melt seasons. Water pressure showed two different regimes, namely high frequency and large amplitude variations during the melt season (January–April) and small fluctuations near the overburden pressure the rest of the year. Speed-up events were observed several times in each summer measurement period. Ice motion during these events substantially contributed to total glacier motion, for example, fast ice flow over 1 week accounted for ~70% of the total displacement over a 25-day long measurement period. We did not find a clear relationship between subglacial water pressure and ice speed. This was probably because subglacial hydraulic conditions were spatially inhomogeneous and thus our borehole data did not always represent a large-scale subglacial condition. Ice temperature measurements in the boreholes confirmed the existence of a cold ice layer near the glacier surface. Our data provide a basis to better understand the dynamic and hydrological conditions of relatively unstudied glaciers in the Antarctic Peninsula region.

Coseismic avalanches and rockfalls, as well as their simultaneous air blast and muddy flow, which were induced by the 2015 Gorkha earthquake in Nepal, destroyed the village of Langtang. In order to reveal volume and structure of the deposit covering the village, as well as sequence of the multiple events, we conducted an intensive in situ observation in October 2015. Multitemporal digital elevation models created from photographs taken by helicopter and unmanned aerial vehicles reveal that the deposit volumes of the primary and succeeding events were 6.81 ± 1.54 × 106 and 0.84 ± 0.92 × 106 m3, respectively. Visual investigations of the deposit and witness statements of villagers suggest that the primary event was an avalanche composed mostly of snow, while the collapsed glacier ice could not be dominant source for the total mass. Succeeding events were multiple rockfalls which may have been triggered by aftershocks. From the initial deposit volume and the area of the upper catchment, we estimate an average snow depth of 1.82 ± 0.46 m in the source area. This is consistent with anomalously large snow depths (1.28–1.52 m) observed at a neighboring glacier (4800–5100 m a.s.l.), which accumulated over the course of four major snowfall events between October 2014 and the earthquake on 25 April 2015. Considering long-term observational data, probability density functions, and elevation gradients of precipitation, we conclude that this anomalous winter snow was an extreme event with a return interval of at least 100 years. The anomalous winter snowfall may have amplified the disastrous effects induced by the 2015 Gorkha earthquake in Nepal.

Calving glaciers are rapidly retreating in many regions under the influence of ice-water interactions at the glacier front. In contrast to the numerous researches conducted on fjords in front of tidewater glaciers, very few studies have been reported on lakes in which freshwater calving glaciers terminate. To better understand ice-water interactions at the front of freshwater calving glaciers, we measured lakewater temperature, turbidity, and bathymetry near Glaciar Perito Moreno, Upsala, and Viedma, large calving glaciers of the Southern Patagonia Icefield. The thermal structures of these lakes were significantly different from those reported in glacial fjords. There was no indication of upwelling subglacial meltwater; instead, turbid and cold glacial water discharge filled the region near the lake bottom. This was because water density was controlled by suspended sediment concentrations rather than by water temperature. Near-surface wind-driven circulation reaches a depth of similar to 180 m, forming a relatively warm isothermal layer (mean temperature of similar to 5-6 degrees C at Perito Moreno, similar to 3-4 degrees C at Upsala, and similar to 6-7 degrees C at Viedma), which should convey heat energy to the ice-water interface. However, the deeper part of the glacier front is in contact with stratified cold water, implying a limited amount of melting there. In the lake in front of Glaciar Viedma, the region deeper than 120 m was filled entirely with turbid and very cold water at pressure melting temperature. Our results revealed a previously unexplored thermal structure of proglacial lakes in Patagonia, suggesting its importance in the subaqueous melting of freshwater calving glaciers.

To quantify recent thinning of marine-terminating outlet glaciers in northwestern Greenland, we carried out field and satellite observations near the terminus of Bowdoin Glacier. These data were used to compute the change in surface elevation from 2007 to 2013 and this rate of thinning was then compared with that of the adjacent land-terminating Tugto Glacier. Comparing DEMs of 2007 and 2010 shows that Bowdoin Glacier is thinning more rapidly (4.1 ± 0.3 m a−1) than Tugto Glacier (2.8 ± 0.3 m a−1). The observed negative surface mass-balance accounts for −1 near the calving front. This flow regime causes longitudinal stretching and vertical compression at a rate of −0.04 a−1. It is likely that this dynamically-controlled thinning has been enhanced by the acceleration of the glacier since 2000. Our measurements indicate that ice dynamics indeed play a predominant role in the rapid thinning of Bowdoin Glacier.

A large number of glaciers and ice caps (GICs) are distributed along the Greenland coast, physically separated from the ice sheet. The total area of these GICs accounts for 5% of Greenland’s ice cover. Melt water input from the GICs to the ocean substantially contributed to sea-level rise over the last century. Here, we report surface elevation changes of six ice caps near Qaanaaq (77°28′N, 69°13′W) in northwestern Greenland based on photogrammetric analysis of stereo pair satellite images. We processed the images with a digital map plotting instrument to generate digital elevation models (DEMs) in 2006 and 2010 with a grid resolution of 500 m. Generated DEMs were compared to measure surface elevation changes between 2006 and 2010. Over the study area of the six ice caps, covering 1215 km2, the mean rate of elevation change was −1.1 ± 0.1 m a−1. This rate is significantly greater than that previously reported for the 2003–2008 period (−0.6 ± 0.1 m a−1) for GICs all of northwestern Greenland. This increased mass loss is consistent with the rise in summer temperatures in this region at a rate of 0.12 °C a−1 for the 1997–2013 period.

Geological reconstruction of the retreat history of the East Antarctic Ice Sheet (EAIS) since the Last Glacial Maximum (LGM) is essential for understanding the response of the ice sheet to global climatic change and the mechanisms of retreat, including a possible abrupt melting event. Such information is key for constraining climatic and ice-sheet models that are used to predict future Antarctic Ice Sheet AIS melting. However, data required to make a detailed reconstruction of the history of the EAIS involving changes in its thickness and lateral extent since the LGM remain sparse. Here, we present a new detailed ice-sheet history for the southern Soya Coast, Lutzow-Holm Bay, East Antarctica, based on geomorphological observations and surface exposure ages. Our results demonstrate that the ice sheet completely covered the highest peak of Skarvsnes (400 m a.s.l.) prior to ∼9 ka and retreated eastward by at least 10 km during the Early to Mid-Holocene (ca. 9 to 5 ka). The timing of the abrupt ice-sheet thinning and retreat is consistent with the intrusion of modified Circumpolar Deep Water (mCDW) into deep submarine valleys in Lutzow-Holm Bay, as inferred from fossil foraminifera records of marine sediment cores. Thus, we propose that the mechanism of the abrupt thinning and retreat of the EAIS along the southern Soya Coast was marine ice-sheet instability caused by mCDW intrusion into deep submarine valleys. Such abrupt ice-sheet thinning and retreat with similar magnitude and timing have also been reported from Enderby Land, East Antarctica. Our findings suggest that abrupt thinning and retreat as a consequence of marine ice-sheet instability and intrusion of mCDW during the Early to Mid-Holocene may have led to rapid ice-surface lowering of hundreds of meters in East Antarctica.

On 3 September 1998, a glacial lake outburst flood (GLOF) that originated from Tam Pokhari occurred in the Hinku valley of the eastern Nepal Himalaya. This study analyses the lake's geomorphic and hydrologic conditions prior to the outburst, and evaluates the conditions that could contribute to a future flood through photogrammetric techniques. We processed high-resolution Corona KH-4A (2.7 m) and ALOS PRISM (2.5 m) stereo-images taken before and after the GLOF event, and produced detailed topographic maps (2-m contour interval) and DEMs (5 m × 5 m). We (re-) constructed lake water surfaces before (4410 ± 5 m) and after (4356 ± 5 m) the outburst, and reliably estimated the lake water surface lowering (54 ± 5 m) and the water volume released (19.5 ± 2.2 × 106 m3) from the lake, showing good agreement with the results obtained from ground-based measurements. The most relevant conditions that may have influenced the catastrophic drainage of Tam Pokhari in 1998 include the presence of: (i) a narrow (75 ± 6 m), steep (up to 50°) and high (120 ± 5 m) moraine dam; (ii) high lake level (8 ± 5 m of freeboard) and (iii) a steep overhanging glacier (>40°). The lake outburst substantially altered the immediate area, creating a low and wide (>500 m) outwash plain below the lake, a wide lake outlet channel (~50 m) and a gentle channel slope (~3–5°). Our new data suggest that the likelihood of a future lake outburst is low. Our results demonstrate that the datasets produced by photogrammetric techniques provide an excellent representation of micro-landform features on moraine dams, lake water surfaces and the changes in both over time, thereby allowing highly accurate pre- and post-GLOF (volumetric) change analysis of glacial lakes. Furthermore, it enables precise measurement of several predictive variables of GLOFs that can be useful for identifying potentially dangerous glacial lakes or prioritizing them for detailed field investigations. Copyright © 2015 John Wiley & Sons, Ltd.

Glaciar Perito Moreno (GPM) and Glaciar Ameghino (GA), Southern Patagonia Icefield, are in contact in the accumulation area, but have shown contrasting frontal variations in the past few decades. To investigate recent changes of the two glaciers and processes controlling the different responses to similar climate conditions, we measured surface elevation change from 2000 to 2008 and terminus positions from 1999 to 2012 using several types of satellite data. GPM shows no significant changes in terminus position and 0.4 ± 0.3 m a–1 thickening over the period, whereas GA retreated 55 ± 2 m a–1 and thinned 2.6 ± 0.3 m a–1. Mass-balance measurements over the period 1999/2000 show that accumulation at GPM was ten times greater than that at GA, but ablation was only three times greater. The mass-balance–altitude profile is similar for the two glaciers; differences in the mass-balance distribution are caused by differences in the accumulation–area ratio (AAR). Our results suggest that the AAR and the calving flux exert strong control on the evolution of glaciers in the region.

The grounding line (GL) of the Antarctic ice sheet forms the boundary between grounded and floating ice along the coast. Near this line, warm oceanic water contacts the ice shelf, producing the ice sheet's highest basal-melt rate. Despite the importance of this region, water properties and circulations near the GL are largely unexplored because in-situ observations are difficult. Here we present direct evidence of warm ocean-water transport to the innermost part of the subshelf cavity (several hundred meters seaward from the GL) of Langhovde Glacier, an outlet glacier in East Antarctica. Our measurements come from boreholes drilled through the glacier's similar to 400-m-thick grounding zone. Beneath the grounding zone, we find a 10-24-m-deep water layer of uniform temperature and salinity (-1.45 degrees C; 34.25 PSU), values that roughly equal those measured in the ocean in front of the glacier. Moreover, living organisms are found in the thin subglacial water layer. These findings indicate active transport of water and nutrients from the adjacent ocean, meaning that the subshelf environment interacts directly and rapidly with the ocean. (C) 2014 The Authors. Published by Elsevier B.V.

Chamlang South Tsho has been identified as one of the six high-priority glacial lakes in terms of glacial lake outburst flood (GLOF) danger in Nepal Himalaya, despite the fact that no detailed investigations of the lake had been hitherto undertaken. We conducted detailed mapping of the lake and its surroundings along with field surveys in October 2009 to determine the developmental history of Chamlang South Tsho and to assess its potential for GLOF. The lake expanded rapidly between 1964 (0.04 km2) and 2000 (0.86 km2) and has been stable ever since. Future lake expansion is improbable as its sides are confined by relatively stable landforms. The lake is 87-m deep with a water volume of approximately 34.9–35.6 × 106 m3. Hanging glaciers on the steep surrounding mountain slopes and prominent seepage water in the terminal moraine dam could be potential triggers for a future outburst flood. Additionally, the debris-covered dead-ice dam, which is higher than the lake water level, is narrow and low; therefore, it could be overtopped easily by surge waves. Furthermore, the pronounced difference in elevation between the lake and the base of the terminal moraine dam makes the lake susceptible for a large flood.

The Patagonia Icefields are characterized by a large number of outlet glaciers calving into lakes and the ocean. In contrast to the recent intensive research activities on tidewater glaciers in other regions, very few observations have been made on calving glaciers in Patagonia. We analysed satellite images of Glaciar Upsala, the third largest freshwater calving glacier in the Southern Patagonia Icefield, to investigate changes in its front position, ice velocity and surface elevation from 2000 to 2011. Our analyses revealed a clear transition from a relatively stable phase to a rapidly retreating and fast-flowing condition in 2008. The glacier front receded by 2.9 km, and the ice velocity increased by 20–50%, over the 2008–11 period. We also found that the ice surface lowered at a rate of up to 39 m a−1 from 2006 to 2010. This magnitude and the rate of changes in the glacier front position, ice velocity and surface elevation are greater than previously reported for Glaciar Upsala, and comparable to recent observations of large tidewater glaciers in Greenland. Our data illustrate details of a rapidly retreating calving glacier in Patagonia that have been scarcely reported despite their importance to the mass budget of the Patagonia Icefields.

This study used Corona KH-4A and Advanced Land Observing Satellite (ALOS) PRISM images to generate digital terrain models (DTMs) of the distal part of Imja Glacier, where a few supraglacial ponds (similar to 0.07 km(2)) expanded into the large Imja Glacier Lake (Imja Tsho, similar to 0.91 km(2)) between 1964 and 2006. DTMs and subsequently derived topographical maps with contour intervals of 1 m were created from the high-resolution images (Corona in 1964 and ALOS in 2006) in the Leica Photogrammetric Suite (LPS) platform. The DTMs and topographic maps provided excellent representation of the elevation and micro-topography of the glacier surface, such as its supra-glacial ponds/lake, surface depressions, and moraine ridges, with an error of about +/- 4 m (maximum). The DTMs produced from the Corona and ALOS PRISM images are suitable for use in studies of the surface change of glaciers. The topographical maps produced from the Corona data (1964) showed that part of the dead ice in the down-glacier area was even higher than the top of the lateral moraine ridges, while the glacier surface in the up-glacier area was noticeably lower than the moraine crests. This suggests more extensive melting of glacier ice in the up-glacier area before 1964. The average lowering of the glacier surface from 1964 to 2006 was 16.9 m for the dead-ice area west of the lake and 47.4 m for the glacier surface east of the lake; between 1964 and 2002, the lake surface lowered by 82.3 m. These figures represent average lowering rates of 0.4, 1.1, and 2.2 m/year for the respective areas.

Ice originating near the inland ice divide of the ice sheet can reappear as marginal ice at the surface near the ice terminal in the ablation area. We have analyzed δ18O values and ion concentrations of the Skallen, Skarvsnes and Hamna terminal ice sections, located along the estuary line in the Sôya drainage basin, East Antarctica. The data suggest that the upper part of the Skallen terminal ice section could have originated from inland precipitation on the Shirase drainage basin during marine isotope stage (MIS) 5e, while the upper part of Skarvsnes and Hamna terminal ice sections could have originated from inland precipitation on the Sôya drainage basin. We calculate past elevation maps for the Antarctic ice sheet using the three-dimensional model, SICOPOLIS. This model suggests that the upstream portion of the Sôya drainage basin during the glacial period (MIS 2, 3 or 4) was located to the northeast of its present location. A flow history is proposed wherein ice from the inland Shirase drainage area flowed over the present ice-divide line from the Shirase to the Sôya drainage basin during the glacial period. The ice in the Sôya drainage basin then flowed to the marginal part of the sheet after the ice divide had assumed its present position.

A circular hole was discovered on the downstream side of a glacier dam in the Yatude Valley, Langhovde, East Antarctica, during the 2005–2006 austral summer. The opening of this hole is the first opportunity enabling us to observe the interior of the dam. The opening led to a large cave in the dam, raising the possibility of meltwater drainage through the dam. The Yatude Valley is an approximately U-shaped fluvial valley. The valley floor has been incised to form a box-shaped inner valley that contains fluvial terraces and large boulders upon the valley floor. The origin of these features can be explained by a large amount of running water; however, we consider it unlikely that a regular current has flowed through this site for a long period. Instead, it is more likely that large quantities of lake water have been periodically discharged due to collapse of the glacier dam or spilling out through a tunnel channel within the cave. The discovered hole and the ice cave are key features in understanding the historical development of the Yatude Valley in relation to the melting history of the Antarctic ice sheet.

北海道東部，知床半島のほぼ中央に位置する羅臼火山は，過去約2,200年間のうち3時期にマグマ噴火したことが知られており，それぞれ降下テフラ（Ra-1 : 500～700 cal BP, Ra-2 : ca. 1,400 cal BP, Ra-3 : ca. 2,200 cal BP）および火砕流を噴出した．これら羅臼起源のテフラは，いずれも斜方輝石および単斜輝石を含むなど鏡下での特徴が類似するが，脱水ガラス屈折率は異なり，識別が可能である．羅臼火山の南西約4.5kmに位置する天頂山火山から約1,900年前に噴出した天頂山aテフラ（Ten-a）は，多量の石質岩片のほか，フレーク状火山ガラス，斜長石，斜方輝石などの本質物質を含む．その火山活動はマグマ水蒸気噴火だったと推定される．Ten-aの噴出量は約0.02km3である．羅臼岳の南～南南西方向約5km付近，標高500～750mの地域には，羅臼湖など多数の沼沢地や湿原が点在する．複数の湿原での掘削調査の結果，駒ヶ岳c1テフラ（AD1856），樽前aテフラ（AD1739），駒ヶ岳c2テフラ（AD1694），Ra-1，摩周bテフラ（774～976 cal BP），Ten-a, 一の沼火山灰の存在と層序が明らかになった．そのほか，知床半島の南部には，摩周起源の摩周lテフラ（ca. 13,000 cal BP）が分布する．

Bilchenok Glacier is a surging glacier in the Kamchatka Peninsula, Russia, which most recently surged in 1982 and is currently in its quiescent phase. Field research in 1998 revealed an ogive-like repeated pattern of transverse ridges and intervening gently sloping ice at the surface of the ablation area of this glacier. It was also observed that most of the glacial surface was covered by volcanic rocks and ash, and the debris thickness on the ridges was more than 1 m, whereas the gently sloping ice was covered by thin debris. We posit that the pattern of the debris thickness is caused by the unique conditions of Bilchenok Glacier, namely, the restricted position of its debris supply at the foot of the rock walls beside the icefall and its surging behavior. The distance between the ridges might indicate the total horizontal displacement attributable to surges. The dependence of the ablation rate on the debris thickness can result in a highly undulating ice surface between the ridge and the gently...

The Bilchenok Glacier in the central part of the Kamchatka Peninsula is located on the Ushkovsky Volcano (3900 m a.s.1.) and is regarded as a surging glacier. A tephrochronological study reveals Holocene fluctuations of the Bilchenok Glacier. Field survey and satellite and aerial photo interpretation indicate that five groups (moraines a to e) of moraines are present around the Bilchenok Glacier. Stratigraphic relationships among glacial deposits and marker tephras define the age of each moraine. Three glacial advances during the Neoglacial period are estimated to have occurred at 8 ka BP, 3 ka BP, and 1 ka BP. The glacier possibly expanded at 2 ka BP. No glacial landforms in the Little Ice Age were identified. Glacier expansion during the Little Ice Age was, therefore, on a smaller scale than that of glacial surges in the 1960s, and the other Holocene advances.

Late Quaternary glacial fluctuations in the Esaoman-Tottabetsu Valley, inthe northern Hidaka Range, central Hokkaido were reconstructed based on stratigraphy of glacial landforms and sediments. By mean of tephrochronology, the two previously known stadials of the Last Glacial Stage, the Poroshiri and Tottabetsu Stadials, were reassessed. Shikotsu 1 tephra overlain by the terminal moraine of the Poroshiri Stadial at the river bed of 850m a. s. l. indicates that the glacier reached its maximum at around 40ka (Oxygen Isotopic Stage 3: OIS-3). This advance should have been initiated in the preceding cold period of 01S-4. Kuttara 6 tephra (86 ka) in the proglacial outwash deposits indicates that a glacier fluctuated in the vicinity of the cirque bottom even in the relatively warm period of the early Last Glacial Stage (01S-5b). Contrary to this stadial, the glacial and proglacial deposits including Eniwa a tephra (18 ka) show that the glacial advance during the Tottabetsu Stadial (LGM) in this region was restricted within the cirque bottom. The penultimate glaciation, named the Esaoman Glaciation in this study, was suggested by the discontinuously traceable remnant bed topography along the river basin. These features recommend that the glacial advance of this stage reached at 750m a. s. l., lower than during the Last Glacial Stage.

The formation of the glacial erosional bedforms at the Soya Coast of Lützow-Holm Bay, East Antarctica is discussed. The streamlined bedforms in the studied area are classified into crescentic transverse ridges and tadpole rocks, and these bedforms are accompanied by small erosional marks (s-forms) which suport the interpretation of subglacial meltwater erosion. Some tadpole rocks are superimposed on a large roche moutonnée, and these two kinds of landform are interpreted to have different modes of formation. Observations and interpretations of these bedforms are used to reconstruct the historical development of the glacial erosional bedforms, and to draw attention to the significance and implications of subglacial meltwater erosion on the marginal area of the Antarctic Ice Sheet in the past. An initial episode of glacial plucking and abrasion produced roches moutonnées and basic large-scale landforms. Subglacial meltwater flowing peiodically into the Lützow-Holm Bay sculptured s-forms and streamlined bedforms in bedrock over much of the area. During this period, except for water-flowing phases, ice again came in contact with the bedrock to form striations superimposed on the s-forms and the hillocks.

Two characteristic landforms, landslide blocks and drainage channels, were investigated in Adventdalen, central Spitsbergen. The landslides in the middle reaches of Adventdalen comprise large-scale bedrock slumps which form a hummocky surface on the south slope of Arctowskifjellet. The fourteen recognized landslide blocks are divided into upper and lower sections, according to altitude. The drainage channels consist of tributary rivers to Adventelva which flow in two distinct directions, either parallel with or oblique to the direction of the main river. Glacial deposits were found to cover the ridges between these tributary channels. The upper and lower landslide divisions may indicate former positions of the ice surface, and the channels appear to have originated during the existence of lateral moraine ridges with high ice content. These geomorphological findings have allowed reconstruction of former ice marginal positions, and they strongly suggest the existence of stagnant ice or minor re-advance phases during the course of deglaciation in Adventdalen.

The Taiwanese high mountain range is not glaciated at present, and the modern theoretical equilibrium line altitude (ELA) was calculated at about 3950 ± 100 m. Large erosional glacial landforms are evidence for a high glacier surface elevation in the central parts of the mountain massifs at the maximum stage of the last glacial cycle, but corresponding glacial terminal deposits are still sparsely known and age control is weak. Luminescence dating from Hsueh Shan suggests the widest glacier extent during MIS 4 with an ELA depression of > 1000 m. Surface exposure and luminescence ages of glacial deposits in Nanhuta Shan above 3100 m a.s.l. indicate a subsequent late glacial to early Holocene glacier advance with an ELA depression of 510–610 m.

A general introduction to the Quaternary glaciations in the Japanese high mountains is presented. Particular attention is paid to the two most significantly-glaciated mountain ranges, and recent knowledge of the glacial history in the Japanese Alps and Hidaka Mountains is presented. Six glacial advances are recognised in the Japanese Alps that occurred during the penultimate glacial cycle, the Last Glaciation, and the Holocene. In the high Japanese mountains, the maximum advance during the Last Glaciation is commonly recognised during Marine Isotope Stage (MIS) 4 with subsequent advances occurring just before 24 ka BP, 18–20 ka PB, 11–10 ka BP and in the early Holocene. In the Hidaka Mountains, recent tephrochronological investigations have revealed the age and extent of the maximum glacier advance during MIS 5a, MIS 3, MIS 2 and MIS 6. Mountain glaciers in Japan were less extensive during the Last Glacial Maximum. This is out of phase with the continental ice sheets in the northern hemisphere.