A Surge of Bualtar Glacier, Karakoram Range, Pakistan: A Possible Landslide Trigger

Gardner, James S.; Hewitt, Kenneth

doi:10.3189/s0022143000009394

Cited by 20 publications

(20 citation statements)

References 14 publications

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“…sliding-dominated plugflow, primarily resisted by drag at the glacier margins. The important contribution of basal sliding to the total motion of both surge-type and non-surging glaciers in the Karakoram was confirmed repeatedly through both ground-based [62][63][64][65][66] and remote-sensing observations 67 . Whether and why such high sliding rates are peculiar to the region, however, remains largely unknown.…”

Section: Early Explanations Of Anomalous Behaviourmentioning

confidence: 80%

Manifestations and mechanisms of the Karakoram glacier Anomaly

et al. 2020

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Global-scale glacier shrinkage is one of the most prominent signs of ongoing climatic change. However, important differences in glacier response exist at the regional scale, and evidence has accumulated that one particular region stands out: the Karakoram. In the past two decades, the region has shown balanced to slightly positive glacier budgets, an increase in glacier ice-flow speeds, stable to partially advancing glacier termini, and widespread glacier surge activity. This is in stark contrast to the rest of High Mountain Asia, where glacier retreat and slowdown dominate, and glacier surging is largely absent. Termed the Karakoram Anomaly, recent observations show that the anomalous glacier behaviour partially extends to the nearby Western Kun Lun and Pamir. Several complementary explanations have now been presented for explaining the Anomaly's deeper causes, but the understanding is far from being complete. Whether the Anomaly will continue to exist in the coming decades remains unclear, but its long-term persistence seems unlikely in light of the considerable warming anticipated by current projections of future climate. The Karakoram is the mountain range spanning the borders of Pakistan, India, and China, with extremities reaching into Afghanistan and Tajikistan (Figure 1a). The region is geomorphologically very dynamic 1 , with intense interactions between tectonic, fluvial, and mass movement processes. The extremely steep and high topography, characteristic of the region, hosts some of the 1 tallest mountains on Earth, and very dynamic glaciers (Box 1). According to current inventories , the region features roughly 13,700 glaciers, covering an area of about 22,800 km 2. The total glacier ice volume is estimated to be in the order of 2,200 km 3 , or about 30% of the total for High Mountain Asia 3. Together with snowmelt, runoff from glaciers is the primary water source for the region's rivers 4 , which include tributaries of both the Tarim and the Indus (Figure 1a). This makes the Karakoram's glaciers of utmost importance in supplying water to millions of people downstream 5-7. Glacier melt has been shown 8 to be of particular importance during periods of drought stress, and hence to contribute to social stability in an otherwise conflict-prone region. Against this background, characterizing the region's glacier evolution is of great relevance. A peculiar behaviour of Karakoram glaciers was already suspected in early reports 9-12 of 19 th century explorers. It is difficult to ascertain, however, whether or not the reports were not biased by the perception of an unusually dramatic landscape. Modern observations, instead, are more conclusive, and indeed indicate that-at least for the past decades-Karakoram's glaciers

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Section: Early Explanations Of Anomalous Behaviourmentioning

confidence: 80%

Manifestations and mechanisms of the Karakoram glacier Anomaly

et al. 2020

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“…In many known cases, surge sources involve the upper ablation zone, as at Chiring (ID 92) Glacier in 1994. Some lie entirely within the ablation zone, as at Bualtar (ID 21) in 1986 37 . In these cases instabilities generated by the surge led to readjustments in the upper reservoir zones for years afterwards, a variety of post-surge, surge-modified effect on mass transfer in the early quiescent phase.…”

Section: Discussionmentioning

confidence: 99%

“…The landslide debris affects glacier movement and mass balance for several decades at least 5 . Some of the glaciers are also surge-type, including Bualtar (ID 21), Lokpar-Aling (ID 120), and Chillinji (ID 3) 36 , 37 (Supplementary Table S1 ).…”

Section: Introductionmentioning

confidence: 99%

Surge-type and surge-modified glaciers in the Karakoram

Bhambri

Hewitt

Kawishwar

et al. 2017

Sci Rep

168

154

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Glaciers in the Karakoram exhibit irregular behavior. Terminus fluctuations of individual glaciers lack consistency and, unlike other parts of the Himalaya, total ice mass remained stable or slightly increased since the 1970s. These seeming anomalies are addressed through a comprehensive mapping of surge-type glaciers and surge-related impacts, based on satellite images (Landsat and ASTER), ground observations, and archival material since the 1840s. Some 221 surge-type and surge-like glaciers are identified in six main classes. Their basins cover 7,734 ± 271 km2 or ~43% of the total Karakoram glacierised area. Active phases range from some months to over 15 years. Surge intervals are identified for 27 glaciers with two or more surges, including 9 not previously reported. Mini-surges and kinematic waves are documented and surface diagnostic features indicative of surging. Surge cycle timing, intervals and mass transfers are unique to each glacier and largely out-of-phase with climate. A broad class of surge-modified ice introduces indirect and post-surge effects that further complicate tracking of climate responses. Mass balance in surge-type and surge-modified glaciers differs from conventional, climate-sensitive profiles. New approaches are required to account for such differing responses of individual glaciers, and effectively project the fate of Karakoram ice during a warming climate.

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“…Much of the previous glaciological work has focused on the characteristics of unusual features, such as catastrophic glacier advances and outburst floods, as well as terminus advance and retreat patterns (e.g. Hayden, 1907; Mason, 1935; Desio, 1954; Hewitt, 1969; Mayewski and Jeschke, 1979; Goudie and others, 1984). In large part, previous work was driven by the particularly large concentration of surging glaciers that occur in the Karakoram (Hewitt, 1969, 1998, 2007, http://www.agu.org/eos_elec/97106e.htm).…”

Section: Study Area and Previous Measurementsmentioning

confidence: 99%

Glacier velocities across the central Karakoram

et al. 2009

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Optical matching of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) satellite image pairs is used to determine the surface velocities of major glaciers across the central Karakoram. The ASTER images were acquired in 2006 and 2007, and cover a 60×120km region over Baltoro glacier, Pakistan, and areas to the north and west. The surface velocities were compared with differential global position system (GPS) data collected on Baltoro glacier in summer 2005. The ASTER measurements reveal fine details about ice dynamics in this region. For example, glaciers are found to be active over their termini even where they are very heavily debris-covered. The characteristics of several surge-type glaciers were measured, with terminus advances of several hundred meters per year and the displacement of trunk glaciers as surge glaciers pushed into them. This study is the first synthesis of glacier velocities across this region, and provides a baseline against which both past and future changes can be compared.

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A Surge of Bualtar Glacier, Karakoram Range, Pakistan: A Possible Landslide Trigger

Cited by 20 publications

References 14 publications

Manifestations and mechanisms of the Karakoram glacier Anomaly

Manifestations and mechanisms of the Karakoram glacier Anomaly

Surge-type and surge-modified glaciers in the Karakoram

Glacier velocities across the central Karakoram

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