scholarly journals Reconstruction of the Upper Slope Conditions of an Extraordinary Hydro-Meteorological Event Along the Jamapa Glacier Drainage System, Citlaltépetl (Pico de Orizaba) Volcano, Mexico

2021 ◽  
Vol 9 ◽  
Author(s):  
Katrin Sieron ◽  
Blake Weissling ◽  
Marco Aurelio Morales-Martínez ◽  
Sergio Teran
Keyword(s):  
Debris Flow ◽  
Drainage System ◽  
Ice Age ◽  
Precipitation Event ◽  
Groundwater Hydrology ◽  
Southern Mexico ◽  
Geological Evidence ◽  
Terminal Moraine ◽  
Upper Slope

A singular precipitation event on the summit glacial slopes of Mexico’s highest volcanic peak, Citlatépetl (also known as Pico de Orizaba), associated with the passage of Hurricane Ernesto across the southern Mexico mainland in August 2012, resulted in a debris flow at altitudes above 4,400 m asl, culminating in a hyperconcentrated flow downstream that had major impacts to a river valley’s channel morphology as well as to communities along a 25 km runout. The lahar originated at the terminal moraine and proglacial ramp of the Little Ice Age (LIA) extent of Citlaltépetl’s Jamapa glacier. Precipitation amounts were estimated based on nearby CONAGUA stations, but also on TRMM satellite images leading to an estimated 106 mm for a 3 day total, with 85 mm (80% of the total) falling on August 9th, the date when the lahar event occurred. The initial debris flow removed a minimum estimated 60,000 m3 of material from the proglacial ramp. A possible causative scenario is that the precipitation event overpressured the groundwater hydrology of an already unstable glacial-melt-saturated moraine. We demonstrate a methodology for the recreation of a pre-event landscape and the environmental conditions at the onset of the lahar, utilizing satellite products, in-situ geomorphological and geological evidence, and UAS technology.

scholarly journals Dendroglaciological Dating of a Little Ice Age Glacial Advance at Moving Glacier, Vancouver Island, British Columbia

2007 ◽  
Vol 50 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Daniel J. Smith ◽  
Colin P. Laroque
Keyword(s):  
British Columbia ◽  
Little Ice Age ◽  
Vancouver Island ◽  
Ice Age ◽  
Subalpine Forest ◽  
Terminal Moraine ◽  
Glacier Advance ◽  
Glacial Advance

ABSTRACT Dendrochronological investigations at Moving Glacier provide the first calendar-dating of a Little Ice Age glacier advance on Vancouver Island. In 1931, Moving Glacier was within 30 to 50 m of a distinct trimline and terminal moraine marking its maximum Little Ice Age extent. A reconnaissance of the site in 1993 revealed the presence of sheared in situ stumps and detrital trunks inside the 1931 ice limit. Sampling in 1994 showed the site was covered by a mature subalpine forest prior to the glacial advance which overrode the site after 1718 A.D. Following this period of expansion, which saw Moving Glacier expand to its maximum Little Ice Age position after 1818 A.D., the glacier apparently experienced only minimal retreat prior to first being photographed in 1931.

scholarly journals Architecture and structural evolution of an early Little Ice Age terminal moraine at the surge-type glacier Múlajökull, Iceland

2015 ◽  
Vol 120 (9) ◽  
pp. 1895-1910 ◽  
Author(s):  
Ívar Örn Benediktsson ◽  
Anders Schomacker ◽  
Mark D. Johnson ◽  
Alessa J. Geiger ◽  
Ólafur Ingólfsson ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Structural Evolution ◽  
Ice Age ◽  
Terminal Moraine

scholarly journals Drenagem e acumulação de ar frio em noites de arrefecimento radiativo. Um exemplo no vale de Barcarena (Oeiras)

Finisterra ◽  
2012 ◽  
Vol 30 (59/60) ◽  
Author(s):  
António Lopes
Keyword(s):  
Drainage System ◽  
Field Research ◽  
Intermittent Flow ◽  
Cold Air ◽  
Climatological Field ◽  
Irradiation Process

THE COLD AIR DRAINAGE DURING CALM CLEAR NIGHTS: AN EXAMPLE IN HE BARCARENA VALLEY (OEIRAS, PORTUGAL) - The cold air drainage system is a recent climatological field research in Portugal. In the valley of Barcarena, a few kilometres westward from Lisbon, it was possible to detect the intermittent flow of the cold air drainage during two calm clear nights. We came to the conclusion that the cold air lakes are formed in situ by the irradiation process and also by the accumulation of the cold air drained along the valley slopes. The rugosity of the surface and the slow down of the cold air along the slope could be responsible for the oscillations of the cold air lakes thickness

scholarly journals Radioactive Contamination due to 241Am Lightning Rod Failure

2020 ◽  
Vol 13 ◽  
pp. 262
Author(s):  
K. L. Karfopoulos ◽  
G. N. Papadakos ◽  
D. J. Karangelos ◽  
P. K. Rouni ◽  
N. P. Petropoulos ◽  
...  
Keyword(s):  
Health Risk ◽  
Gamma Ray ◽  
Surface Soil ◽  
Collection Efficiency ◽  
Drainage System ◽  
Radioactive Material ◽  
Building Roof ◽  
The Public ◽  
The People

It is estimated that until 1978 about 200000 lightning conductor rods with -a emitting sources attached to their end were installed worldwide. The sources were supposed to increase the lighting collection efficiency of these rods through the ionization of the surrounding air. Nevertheless, this improvement has never been established conclusively. Such devices are, in most cases, not accessible by the pub- lic; therefore, the dose to the population is considered insignificant. However, the possibility of radioactive material leakage, due to the source attachment failure, and the subsequent contamination of the surroundings that could lead to possible health risk of the public cannot be excluded. In this work, the case of 241Am contamination due to a lightning rod conductor failure is investigated. This contamination was accidentally detected on the surface soil around a laboratory building in the National Technical University of Athens Campus, during a routine in-situ gamma-ray measurement campaign that took place in 2003. A detailed survey revealed that this 241Am contamination was due to the leakage from two lightning rods on the building roof. Consequently the rods were removed from the building and the contamination pattern on the roof and on the surface soil around the building was examined in detail. From the results obtained so far it may be concluded that there exists well localized contamination on the roof and also around the building. It was established that the pathway through which contamination reached the ground was  the rainwater drainage system of the building. The gamma ray dose rate due to 241Am contamination found on the roof and on the surface soil is low compared to that due to its natural radioactivity and does not seem to pose any health risk to the people working in the building or to the public.

scholarly journals The mobility of Atlantic baric depressions leading to intense precipitation over Italy: a preliminary statistical analysis

2006 ◽  
Vol 6 (3) ◽  
pp. 451-458 ◽  
Author(s):  
N. Tartaglione ◽  
A. Speranza ◽  
F. Dalan ◽  
T. Nanni ◽  
M. Brunetti ◽  
...  
Keyword(s):  
Principal Component ◽  
Rain Gauge ◽  
Western Mediterranean ◽  
Precipitation Event ◽  
Rain Gauge Data ◽  
Intense Precipitation ◽  
Western Mediterranean Basin ◽  
Italian Regions ◽  
Autumn And Winter

Abstract. The speed of Atlantic surface depressions, occurred during the autumn and winter seasons and that lead to intense precipitation over Italy from 1951 to 2000, was investigated. Italy was divided into 5 regions as documented in previous climatological studies (based on Principal Component Analysis). Intense precipitation events were selected on the basis of in situ rain gauge data and clustered according to the region that they hit. For each intense precipitation event we tried to identify an associated surface depression and we tracked it, within a large domain covering the Mediterranean and Atlantic regions, from its formation to cyclolysis in order to estimate its speed. "Depression speeds" were estimated with 6-h resolution and clustered into slow and non-slow classes by means of a threshold, coinciding with the first quartile of speed distribution and depression centre speeds were associated with their positions. Slow speeds occurring over an area including Italy and the western Mediterranean basin showed frequencies higher than 25%, for all the Italian regions but one. The probability of obtaining by chance the observed more than 25% success rate was estimated by means of a binomial distribution. The statistical reliability of the result is confirmed for only one region. For Italy as a whole, results were confirmed at 95% confidence level. Stability of the statistical inference, with respect to errors in estimating depression speed and changes in the threshold of slow depressions, was analysed and essentially confirmed the previous results.

scholarly journals Dimensionless Assessment Method of Landslide Dam Formation Caused by Tributary Debris Flow Events

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Kun-Ting Chen ◽  
Xiao-Qing Chen ◽  
Gui-Sheng Hu ◽  
Yu-Shu Kuo ◽  
Yan-Rong Huang ◽  
...  
Keyword(s):  
Debris Flow ◽  
Water Depth ◽  
Debris Flows ◽  
Landslide Dam ◽  
Assessment Method ◽  
Main Stream ◽  
Deposition Thickness ◽  
The Relationship ◽  
Prepared Response

In this study, we develop a dimensionless assessment method to evaluate landslide dam formation by considering the relationship between the run-out distance of a tributary debris flow and the width of the main stream, deposition thickness of the tributary debris flow, and the water depth of the main stream. Based on the theory of debris flow run-out distance and fan formation, landslide dam formation may result from a tributary debris flow as a result of two concurrent formation processes: (1) the run-out distance of the tributary debris flow must be greater than the width of the main stream, and (2) the minimum deposition thickness of the tributary debris flow must be higher than the in situ water depth of the main stream. At the confluence, one of four types of depositional scenarios may result: (1) the tributary debris flow enters into the main stream and forms a landslide dam; (2) the tributary debris flow enters into the main stream but overflow occurs, thus preventing complete blockage of the main stream; (3) the tributary debris flow enters into the main stream, does not reach the far bank, and sediment remains partially above the water elevation of the main stream; or (4) the tributary debris flow enters into the main stream, does not reach the far bank, and sediment is fully submerged in the main stream. This method was applied to the analysis of 11 tributary debris flow events during Typhoon Morakot, and the results indicate that the dimensionless assessment method can be used to estimate potential areas of landslide dam formation caused by tributary debris flows. Based on this method, government authorities can determine potential areas of landslide dam formation caused by debris flows and mitigate possible disasters accordingly through a properly prepared response plan, especially for early identification.

Basal Drainage System Response to Increasing Surface Melt on the Greenland Ice Sheet

Science ◽  
2013 ◽  
Vol 341 (6147) ◽  
pp. 777-779 ◽  
Author(s):  
T. Meierbachtol ◽  
J. Harper ◽  
N. Humphrey
Keyword(s):  
Conceptual Models ◽  
Ice Sheet ◽  
Drainage System ◽  
Greenland Ice Sheet ◽  
System Response ◽  
Mountain Glaciers ◽  
In Situ Observations ◽  
Key Aspects ◽  
Conduit Development

Surface meltwater reaching the bed of the Greenland ice sheet imparts a fundamental control on basal motion. Sliding speed depends on ice/bed coupling, dictated by the configuration and pressure of the hydrologic drainage system. In situ observations in a four-site transect containing 23 boreholes drilled to Greenland’s bed reveal basal water pressures unfavorable to water-draining conduit development extending inland beneath deep ice. This finding is supported by numerical analysis based on realistic ice sheet geometry. Slow meltback of ice walls limits conduit growth, inhibiting their capacity to transport increased discharge. Key aspects of current conceptual models for Greenland basal hydrology, derived primarily from the study of mountain glaciers, appear to be limited to a portion of the ablation zone near the ice sheet margin.

Improved reconstruction of the southeastern Laurentide Ice Sheet deglaciation: constraining ice thinning using in-situ cosmogenic 10Be and 14C and critically evaluating different retreat rate chronometers

2020 ◽  
Author(s):  
Christopher Halsted ◽  
Jeremy Shakun ◽  
Lee Corbett ◽  
Paul Bierman ◽  
P. Thompson Davis ◽  
...  
Keyword(s):  
United States ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Ice Thickness ◽  
Northeastern United States ◽  
Terminal Moraine ◽  
Ice Volume ◽  
Ice Retreat ◽  
Exposure Ages

<p>In the northeastern United States, there are extensive geochronologic and geomorphic constraints on the deglaciation of the southeastern Laurentide Ice Sheet; thus, it is an ideal area for large-scale ice volume reconstructions and comparison between different ice retreat chronometers. Varve chronologies, lake and bog-bottom radiocarbon ages, and cosmogenic nuclide exposure ages constrain the timing of ice retreat, but the inferred ages exhibit considerable noise and sometimes disagree. Additionally, there are few empirical constraints on ice thinning, forcing ice volume reconstructions to rely on geophysically-based ice thickness models. Here, we aim to improve the understanding of the southeastern Laurentide Ice Sheet recession by (1) adding extensive ice thickness constraints and (2) compiling all available deglacial chronology data in the region to investigate discrepancies between different chronometers.</p><p>To provide insight about ice sheet thinning history, we collected 120 samples for in-situ <sup>10</sup>Be and 10 samples for in-situ <sup>14</sup>C cosmogenic exposure dating from various elevations at 13 mountains in the northeastern United States. By calculating ages of exposure at different elevations across this region, we reconstruct paleo-ice surface lowering of the southeastern Laurentide Ice Sheet during deglaciation. Where we suspect that <sup>10</sup>Be remains from pre-Last Glacial Maximum periods of exposure, in-situ <sup>14</sup>C is used to infer the erosional history and minimum exposure age of samples.</p><p>Presently, we have measured <sup>10</sup>Be in 73 samples. Mountain-top exposure ages located within 150 km of the southeastern Laurentide Ice Sheet terminal moraine indicate that near-margin thinning began early in the deglacial period (~19.5 to 17.5 ka), coincident with the slow initial margin retreat indicated by varve records. Exposure ages from several mountains further inland (>400 km north of terminal moraine) collected over ~1000 m of elevation range record rapid ice thinning between 14.5 and 13 ka. Ages within each of these vertical transects are similar within 1σ internal uncertainty, indicating that ice thinned quickly, less than a few hundred years at most. This rapid thinning occurred at about the same time that varve records indicate accelerated ice margin retreat (14.6–12.9 ka), providing evidence of substantial ice volume loss during the Bølling-Allerød warm period.</p><p>Our critical evaluation of deglacial chronometers, including valley-bottom <sup>10</sup>Be ages from this project, is intended to constrain ice margin retreat rates and timing in the region. Ultimately, we will integrate our ice thickness over time constraints with the existing network of deglacial ages to create a probabilistic reconstructions of the southeastern Laurentide Ice Sheet volume during its recession through the northeastern United States.</p>

Climatic Changes in South-East India during Early Palaeolithic Times

1932 ◽  
Vol 69 (5) ◽  
pp. 193-205 ◽  
Author(s):  
F. J. Richards ◽  
L. A. Cammiade ◽  
M. C. Burkitt
Keyword(s):  
East Africa ◽  
Climatic Changes ◽  
East African ◽  
Geological Evidence ◽  
Arid Conditions ◽  
Lower Palaeolithic

HUMAN artifacts can often be very useful to the geologist. When they occur in sufficient numbers and are characteristic, prehistorians can be definite in assigning the industries to a certain culture or cultures, and they can then be utilized by the geologist in the same way as are fossils. In Europe during a part of Quaternary times Lower Palaeolithic cultures flourished. Now Quaternary times in Europe can, of course, be readily subdivided into glacial and interglacial periods, but these naturally did not occur further south. In East Africa geological evidence has been adduced to show that intense pluvial periods took the place of our European glaciations, while during the interglacial phases the African areas suffered from arid conditions. Lower Palaeolithic industries are found at certain levels in East Africa and they enable the geologist to correlate the East African and European sequences. South-East India (Madras) is also not an area where glaciations ever occurred: but, we ask, can geological evidence be adduced to demonstrate climatic changes corresponding to those found to have occurred in East Africa ? Lower Palaeolithic industries occur in great numbers in South-East India; whereas most of them have been merely collected from the surface, and are therefore useless for the purposes of exact dating, a number of finds in situ in definite layers have been made, and as in East Africa these can be used as datum lines for correlating purposes.

scholarly journals Mass balance of the Lambert Glacier–Amery Ice Shelf system, East Antarctica: a comparison of computed balance fluxes and measured fluxes

2000 ◽  
Vol 46 (155) ◽  
pp. 561-570 ◽  
Author(s):  
Helen A. Fricker ◽  
Roland C. Warner ◽  
Ian Allison
Keyword(s):  
Mass Balance ◽  
Drainage System ◽  
Radar Altimeter ◽  
Drainage Basins ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Ice Sheet Mass Balance ◽  
Lambert Glacier ◽  
Lambert Glacier Basin

AbstractWe combine European Remote-sensing Satellite (ERS-1) radar altimeter surface elevations (Fricker and others, 2000) with six different accumulation distributions to compute balance fluxes for the Lambert Glacier–Amery Ice Shelf drainage system. These interpolated balance fluxes are compared with fluxes derived from in situ measurements of ice thickness and velocity at 73 stations of the Lambert Glacier basin traverse and at 11 stations further downstream, to assess the system’s state of balance. For the upstream line we obtain a range of imbalance estimates, from −23.8% to +19.9% of the observed flux, reflecting the sensitivity to the accumulation distributions. For some of the accumulation distributions the imbalance estimates vary significantly between different parts of the line. Imbalance estimates for the downstream line range from −17.7% to +70.2%, with four of the estimates exceeding +30%, again reflecting the sensitivity of the result to input accumulation, and strongly suggesting that the mass balance of the region between the two lines is positive. Our results confirm the importance of accurate estimates of accumulation in ice-sheet mass-balance studies. Furthermore, they suggest that it is not possible to accurately determine the state of balance of large Antarctic drainage basins on the basis of currently available accumulation distributions.

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