scholarly journals MEASURING SURFACE DEFORMATION IN GLACIER RETREATED AREAS BASED ON PS-INSAR – GELADANDONG GLACIER AS A CASE STUDY

Author(s):  
B. Mohamadi ◽  
T. Balz

Glaciers are retreating in many parts of the world as a result of global warming. Many researchers consider Qinghai-Tibetan Plateau as a reference for climate change by measuring glaciers retreat on the plateau. This retreat resulted in some topographic changes in retreated areas, and in some cases can lead to geohazards as landslides, and rock avalanches, which is known in glacier retreated areas as paraglacial slope failure (PSF). In this study, Geladandong biggest and main glacier mass was selected to estimate surface deformation on its glacier retreated areas and define potential future PSF based on PS-InSAR technique. 56 ascending and 49 descending images were used to fulfill this aim. Geladandong glacier retreated areas were defined based on the maximum extent of the glacier in the little ice age. Results revealed a general uplift in the glacier retreated areas with velocity less than 5mm/year. Obvious surface motion was revealed in seven parts surround glacier retreated areas with high relative velocity reached ±60mm/year in some parts. Four parts were considered as PSF potential motion, and two of them showed potential damage for the main road in the study area in case of rock avalanche into recent glacier lakes that could result in glacier lake outburst flooding heading directly to the road. Finally, further analysis and field investigations are needed to define the main reasons for different types of deformation and estimate future risks of these types of surface motion in the Qinghai-Tibetan Plateau.

Author(s):  
S. J. Mi ◽  
Y. T. Li ◽  
F. Wang ◽  
L. Li ◽  
Y. Ge ◽  
...  

The Qinghai Tibetan Plateau permafrost has been the largest permafrost region in middle-low latitude in the world for its high altitude. For the large area permafrost, especially surface deformation brought by it, have serious influence on the road engineering, road maintaining and regional economic development. Consequently, it is essential to monitor the surface deformation and study factors that influent it. We monitored an area named Wudaoliang from July 25, 2015 to June 1, 2016 and 15 Sentinel images were obtained during this time. The area we chose is about 35 kilometers long and 2 kilometers wide, and the national road 109 of China passes through the area. The traditional PS-INSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) method is not suitable because less historical images in the research area and leading to the number of PS (Persistent Scatterer) points is not enough to obtain accurate deformation results. Therefore, in this paper, we used another method which named QUASI-PSInSAR (QUASI Persistent Scatterer Interferometric Synthetic Aperture Radar) to acquire deformation for it has the advantage to weaken or eliminate the effects of spatial and temporal correlation, which has proved by other scholar. After processing 15 images in the SARproz software, we got the conclusions that, 1) the biggest deformation velocity in the whole area was about 127.9mm/year and about 109.3 mm/year in the road; 2) apparent deformation which have surface deformation more than 30mm/year was about 1.7Km in the road. Meanwhile, soil moisture(SM), Land surface temperature (LST) and surface water(SW), which are primary parameters of the land surface over the same time were reversed by using Sentinel data, Landsat data and ZY-3 data, respectively. After analyzing SM, LST , SW and deformation, we obtained that wet areas which had bigger SM, lower LST and more SW, had greater percentage of severe deformation than arid areas; besides, deformation pattern were different in arid areas and wet areas. During the research time, frost heaving firstly accounted for a large proportion both in the arid and wet areas with the decrease of downward radiation from July to December; after December, thaw settlement came into prominence with the increase downward radiation in the arid areas, while in the wet areas, surface put into diverse situations because of water transformation leading to severe deformation. In summary, soil moisture is an important factor that influences the surface deformation. This relationship between deformation process and soil moisture will be researched more in our further work.


Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 331
Author(s):  
Selçuk Aksay ◽  
Susan Ivy-Ochs ◽  
Kristina Hippe ◽  
Lorenz Grämiger ◽  
Christof Vockenhuber

The Säntis nappe is a complex fold-and-thrust structure in eastern Switzerland, consisting of numerous tectonic discontinuities and a range of hillslopes prone to landsliding and large slope failures that modify the topography irreversibly. A slope failure, namely the Sennwald rock avalanche, occurred in the southeast wall of this fold-and-thrust structure due to the rock failure of Lower Cretaceous Helvetic limestones along the Rhine River valley. In this research, this palaeolandslide is examined in a multidisciplinary approach for the first time with detection and mapping of avalanche deposits, dynamic run-out modelling and cosmogenic nuclide dating. During the rock failure, the avalanche deposits were transported down the hillslope in a spreading-deck fashion, roughly preserving the original stratigraphic sequence. The distribution of landslide deposits and surface exposure age of the rock failure support the hypothesis that the landslide was a single catastrophic event. The 36Cl surface exposure age of avalanche deposits indicates an age of 4.3 ± 0.5 ka. This time coincides with a notably wet climate period, noted as a conditioning factor for landslides across the Alps in the mid-Holocene. The contemporaneity of our event at its location in the Eastern Alps provide additional support for the contention of increased regional seismic activity in mid-Holocene.


2019 ◽  
Vol 7 (4) ◽  
pp. 929-947 ◽  
Author(s):  
Michele Delchiaro ◽  
Marta Della Seta ◽  
Salvatore Martino ◽  
Maryam Dehbozorgi ◽  
Reza Nozaem

Abstract. The Seymareh landslide, detached ∼10 ka from the northeastern flank of the Kabir-kuh fold (Zagros Mts., Iran), is recognized worldwide as the largest rock slope failure (44 Gm3) ever recorded on the exposed Earth surface. Detailed studies have been performed that have described the landslide mechanism and different scenarios have been proposed for explaining the induced landscape changes. The purpose of this study is to provide still missing time constraints on the evolution of the Seymareh River valley, before and after the emplacement of the Seymareh landslide, to highlight the role of geomorphic processes both as predisposing factors and as response to the landslide debris emplacement. We used optically stimulated luminescence (OSL) to date lacustrine and fluvial terrace sediments, whose plano-altimetric distribution has been correlated to the detectable knickpoints along the Seymareh River longitudinal profile, allowing the reconstruction of the evolutionary model of the fluvial valley. We infer that the knickpoint migration along the main river and the erosion wave propagation upstream through the whole drainage network caused the stress release and the ultimate failure of the rock mass involved in the landslide. We estimated that the stress release activated a mass rock creep (MRC) process with gravity-driven deformation processes occurring over an elapsed time-to-failure value on the order of 102 kyr. We estimated also that the Seymareh damming lake persisted for ∼3500 years before starting to empty ∼6.6 ka due to lake overflow. A sedimentation rate of 10 mm yr−1 was estimated for the lacustrine deposits, which increased up to 17 mm yr−1 during the early stage of lake emptying due to the increased sediment yield from the lake tributaries. We calculated an erosion rate of 1.8 cm yr−1 since the initiation of dam breaching by the Seymareh River, which propagated through the drainage system up to the landslide source area. The evolutionary model of the Seymareh River valley can provide the necessary constraints for future stress–strain numerical modeling of the landslide slope to reproduce the MRC and demonstrate the possible role of seismic triggering in prematurely terminating the creep-controlled time-to-failure pathway for such an extremely large case study.


2016 ◽  
Vol 43 (10) ◽  
pp. 5493-5502 ◽  
Author(s):  
Joubin Nasehi Tehrani ◽  
Alistair McEwan ◽  
Jing Wang

2021 ◽  
Author(s):  
Janusz Wasowski ◽  
Maurice McSaveney ◽  
Luca Pisanu ◽  
Vincenzo Del Gaudio ◽  
Yan Li ◽  
...  

<p>Large earthquake-triggered landslides, in particular rock avalanches, can have catastrophic consequences. However, the recognition of slopes prone to such failures remains difficult, because slope-specific seismic response depends on many factors including local topography, landforms, structure and internal geology. We address these issues by exploring the case of a rock avalanche of >3 million m<sup>3</sup> triggered by the 2008 Mw7.9 Wenchuan earthquake in the Longmen Shan range, China. The failure, denominated Yangjia gully rock avalanche, occurred in Beichuan County (Sichuan Province), one of the areas that suffered the highest shaking intensity and death toll caused by co-seismic landsliding. Even though the Wenchuan earthquake produced tens of large (volume >1 million m<sup>3</sup>) rock avalanches, few studies so far have examined the pre-2008 history of the failed slope or reported on the stratigraphic record of mass-movement deposits exposed along local river courses. The presented case of the Yangjia gully rock avalanche shows the importance of such attempts as they provide information on the recurrence of large slope failures and their associated hazards. Our effort stems from recognition, on 2005 satellite imagery, of topography and morphology indicative of a large, apparently pre-historic slope failure and the associated breached landslide dam, both features closely resembling the forms generated in the catastrophic 2008 earthquake. The follow-up reconstruction recognizes an earlier landslide deposit exhumed from beneath the 2008 Yangjia gully rock avalanche by fluvial erosion since May 2008. We infer a seismic trigger also for the pre-2008 rock avalanche based on the following circumstantial evidence: i) the same source area (valley-facing, terminal portion of a flat-topped, elongated mountain ridge) located within one and a half kilometer of the seismically active Beichuan fault; ii) significant directional amplification of ground vibration, sub-parallel to the failed slope direction, detected via ambient noise measurements on the ridge adjacent to the source area of the 2008 rock avalanche and iii) common depositional and textural features of the two landslide deposits. Then, we show how, through consideration of the broader geomorphic and seismo-tectonic contexts, one can gain insight into the spatial and temporal recurrence of catastrophic slope failures  in Beichuan County and elsewhere in the Longmen Shan. This insight, combined with local-scale geologic and geomorphologic knowledge, may guide selection of suspect slopes for reconnaissance, wide-area ambient noise investigation aimed at discriminating their relative susceptibility to co-seismic catastrophic failures. We indicate the feasibility of such investigations through the example of this study, which uses 3-component velocimeters designed to register low amplitude ground vibration.</p>


2021 ◽  
Vol 56 (5) ◽  
pp. 340-350
Author(s):  
Ngoc Binh Vu ◽  
Truong Thanh Phi ◽  
Thanh Cong Nguyen ◽  
Hong Thinh Phi ◽  
Quy Nhan Pham ◽  
...  

The research aimed to study 24 rock slope surfaces along the road around Hon Lon Island, Kien Hai district, Kien Giang province, Vietnam. The analytical results have determined slope failure, wedge failure, and toppling, which occurred on almost slope surface and the average percentage of plane failure is the largest. The average percent of plane failure is 19.23%, the wedge failure is 15.35%, and the toppling fault is 6.73%. Besides, the analytical results have also identified the slope surfaces which can be the key blocks: ND-13, 18, 23, 25, 34, 37, 45, 51, 62, 63. The other analytical results show that the existence of key blocks at the rock slope surfaces in the N-S direction, dip to E at the survey locations: ND-13, 23, 63 and dip to W at the survey locations: ND-37, 45; in the NE-SW direction, dip to SE at the survey locations: ND-15, 62 and dip to NW at the survey locations: ND-18, 34; in the NW-SE direction, dip to SW at the survey location ND-51. These results have important significance to support for protecting slope surface safety.


Author(s):  
Mike Searle

My quest to figure out how the great mountain ranges of Asia, the Himalaya, Karakoram, and Tibetan Plateau were formed has thus far lasted over thirty years from my first glimpse of those wonderful snowy mountains of the Kulu Himalaya in India, peering out of that swaying Indian bus on the road to Manali. It has taken me on a journey from the Hindu Kush and Pamir Ranges along the North-West Frontier of Pakistan with Afghanistan through the Karakoram and along the Himalaya across India, Nepal, Sikkim, and Bhutan and, of course, the great high plateau of Tibet. During the latter decade I have extended these studies eastwards throughout South East Asia and followed the Indian plate boundary all the way east to the Andaman Islands, Sumatra, and Java in Indonesia. There were, of course, numerous geologists who had ventured into the great ranges over the previous hundred years or more and whose findings are scattered throughout the archives of the Survey of India. These were largely descriptive and provided invaluable ground-truth for the surge in models that were proposed to explain the Himalaya and Tibet. When I first started working in the Himalaya there were very few field constraints and only a handful of pioneering geologists had actually made any geological maps. The notable few included Rashid Khan Tahirkheli in Kohistan, D. N. Wadia in parts of the Indian Himalaya, Ardito Desio in the Karakoram, Augusto Gansser in India and Bhutan, Pierre Bordet in Makalu, Michel Colchen, Patrick LeFort, and Arnaud Pêcher in central Nepal. Maps are the starting point for any geological interpretation and mapping should always remain the most important building block for geology. I was extremely lucky that about the time I started working in the Himalaya enormous advances in almost all aspects of geology were happening at a rapid pace. It was the perfect time to start a large project trying to work out all the various geological processes that were in play in forming the great mountain ranges of Asia. Satellite technology suddenly opened up a whole new picture of the Earth from the early Landsat images to the new Google Earth images.


Author(s):  
Eelco J. Rohling

Several independent series of observations demonstrate that there has been about 1°C of warming since the start of the industrial revolution. We discussed that there is some variability in solar output, and that these variations may be recognized in records of past climate, but also that solar variability can only account for warming by 0.1°C to an unlikely maximum of 0.35°C since the end of the Little Ice Age. Based on energy balance considerations, we have found that our emissions of external carbon are the main culprit. In response to this disturbance of the energy balance, the climate simply has to change toward a warmer Pliocene- like state, even if we could manage to stabilize CO2 at its current level of about 400 ppm. From discussion of several slowly adjusting processes within the climate system, we now understand that it will take, from the beginning, several centuries to approximate the full Pliocene- like warming. But we are almost two centuries down the road, and warming to date already amounts to about 1°C. The slow components in the climate system will cause continuing warming by another 1°C or so. In other words, we are already committed to further warming, even if we managed to make the massive jump to a zero- emissions society from today and thus stabilize CO2 levels. The urgency of slashing back the current level of annual emissions (10 GtC) cannot be overstated. Every year of inaction brings us closer to the inevitability of a future climate that will exceed even the warm Pliocene state, with global temperatures at least 2 or 3°C higher than the pre- industrial level. If we allow ourselves to reach the Paris Climate Conference’s agreed maximum of 2°C warming by the year 2100, then the further commitment over coming centuries would take us toward 4°C, even if we achieved zero emissions by 2100. That is considerably warmer than during the Pliocene. We have seen that the consequences are grave. Progression toward a Pliocene- like climate state will be accompanied by continued migration of global and regional climate zones and by intensification of the evaporation and precipitation cycle, placing many areas at risk of increasing extremes, including aridity, flooding, and lethal heat.


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