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11.
Remote sensing is an efficient tool for temporal monitoring of inaccessible alpine glacial terrain. This study discusses the methods of remote sensing in visible and infrared (IR) wavelengths, which are helpful in providing important information about alpine glaciers. The scope of this study covers recent advances and prospects in optical and thermal remote sensing of glacier facies, glacier velocity, mass balance, glacial hazards and automated mapping techniques. The technology is ever evolving with the advent of new remote sensors capturing data in visible/IR wavelengths and better digital computing technology. An extensive list of significant studies further helps the reader to explore a particular topic of interest. We survey recent advances in this field and additionally highlight the emerging prospects. 相似文献
12.
Mid-Ocean Ridge Basalts (MORB) from the Northern Central Indian Ridge (NCIR) were recovered between latitudes 3° and 11°S and are olivine tholeiite with higher abundances of K and Rb.They are of typical transitional MORB (T-MORB) variety and appear to have been generated from an enriched-mantle peridotite source. The primitive NCIR MORBs having Mg# ＞ 0.68 are the product of partial melting at an estimated pressure of ～ 1 GPa. It is inferred that the magma was subsequently modified at a pressure ＞ 1 GPa by crystal fractionation and spinel was the first mineral to crystallize followed by separation of relatively Fe-rich olivine with subsequent decrease in pressure. During progressive fractionation at lower pressure (between 1-0.5 GPa), the bulk composition of the magma became systematically depleted in MgO, and enriched in ∑FeO, TiO2, P2O5 and Na2O. There was,however, limited gradual depletion in Al2O3 and CaO and concomitant enrichment in K2O. With the progressive fractionation these basalts became gradually enriched in V, Co, Y, Zr and to some extent in Sr, and depleted in Ni and Cr. In addition, the ∑REE of the magma also increased with fractionation,without any change in (La/Yb)n value. 相似文献
13.
Kumar Deepak Samui Pijush Kim Dookie Singh Anshuman 《Geotechnical and Geological Engineering》2021,39(2):1049-1058
In this research, deep learning (DL) model is proposed to classify the soil reliability for liquefaction. The applicability of the DL model is tested in comparison with emotional backpropagation neural network (EmBP). The database encompassing cone penetration test of Chi–Chi earthquake. This study uses cone resistance (qc) and peck ground acceleration as inputs for prediction of liquefaction susceptibility of soil. The performance of developed models has been assessed by using various parameters (receiver operating characteristic, sensitivity, specificity, Phi correlation coefficient, Precision–Recall F measure). The performance of DL is excellent. Consistent results obtained from the proposed deep learning model, compared to the EmBP, indicate the robustness of the methodology used in this study. In addition, both the developed model was also tested on global earthquake data. During validation on global data, both the models shows good results based on fitness parameters. The developed classification models a simple, but also efficient decision-making tool in engineering design to quantitatively assess the liquefaction potential. The finding of this paper can be further used to capture the relationship between soil and earthquake parameters.
相似文献14.
This work provides an overview of various methods for estimating snow cover and properties in high mountains using remote sensing techniques involving microwaves. Satellite-based remote sensing with its characteristics such as synoptic view, repetitive coverage and uniformity over large areas has great potential for identifying the temporal snow cover. Many sensors have been used in the past with various algorithms and accuracies for this purpose. These methods have been improving with the use of Synthetic Aperture Radar sensors, working in different microwave frequencies, polarisation and acquisition modes. The limitations, advantages and drawbacks are illustrated while error sources and strategies on how to ease their impacts are also reviewed. An extensive list of references, with an emphasis on studies since 1990s, allows the reader to delve into specific topics. 相似文献
15.
Gunawat Anshuman Sharma Devesh Sharma Aditya Dubey Swatantra Kumar 《Natural Hazards》2022,111(2):2077-2096
Natural Hazards - Crop simulation models are essential tools to facilitate the evaluation and application of crop production practices under different climate scenarios. The present study analyzed... 相似文献
16.
Statistical analysis on yearly seismic moment release data to demarcate the source zone for an impending earthquake in the Himalaya 总被引：1，自引：0，他引：1
Tectonism in the Himalayan fold-thrust belt had generated great earthquakes in the past and will spawn more in the future.
Sequential cumulative moment release data of macroearthquakes (Mb ≥ 4.5) over the years 1964–2006 in four zones of the Himalaya was analysed by nonparametric RUD method. The Z values of RUD
analysis had neither rejected nor supported the null hypothesis of randomness. However, the Hurst analysis and plot, a statistical
procedure to identify clustering of low and high values in a time series, brought out a pattern for earthquake prognostication.
The pattern was a negative sloping segment representing a sluggish moment release over years, followed by a positive sloping
segment indicating a sudden high moment release with occurrence of medium/large size earthquake(s). In recent past, such a
negative sloping has been found in Zones B (1992–2006) and D (1998–2006), indicating an impending moderate/mega earthquake
event in near future. 相似文献
17.
18.
The Himalayan fold-thrust belt has been visited by many disastrous earthquakes (magnitude > 6) time and again. This active collisional orogen bordering Indian subcontinent in the north remains a potential seismic threat of similar magnitude in the adjoining countries like India, Pakistan, Nepal, Bhutan and China. Though earthquake forecasting is riddled with all conjectures and still not a proven presumption, identifying likely source zones of such disastrous earthquakes would be an important contribution to seismic hazard assessment. In this study, we have worked out spatio-temporal clustering of earthquakes (Mb ?? 4.5; 1964?C2006) in the Himalayas. ??Point density?? spatial statistics has helped in detecting 22 spatial seismicity clusters. Earthquake catalog is then treated with a moving time-distance window technique (inter-event time 35 days and distance 100 ± 20 km) to bring out temporal clusters by recognizing several foreshock-main shock-aftershock (FMA) sequences. A total of 53 such temporal sequences identified in the process are confined within the 22 spatial clusters. Though each of these spatio-temporal clusters deserves in-depth analysis, we short-listed only eight such clusters that are dissected by active tectonic discontinuities like MBT/MCT for detail study. Spatio-temporal clusters have been used to constrain the potential source zones. These eight well-defined spatio-temporal clusters demonstrate recurrent moderate to large earthquakes. We assumed that the length of these clusters are indicating the possible maximum rupture lengths and thus empirically estimated the maximum possible magnitudes of eight clusters that can be generated from them (from west to east) as 8.0, 8.3, 8.2, 8.3, 8.2, 8.4, 8.0 and 7.7. Based on comparative study of the eight cluster zones contemplating with their temporal recurrences, historical seismic records, presence of intersecting faults and estimated magnitudes, we have guessed the possibility that Kangra, East Nepal, Garhwal and Kumaun?CWest Nepal clusters, in decreasing order of earthquake threat, are potential source zones for large earthquakes (??7.7 M) in future. 相似文献
19.
Basab Mukhopadhyay Anshuman Acharyya Manoj Mukhopadhyay Sujit Dasgupta 《Journal of the Geological Society of India》2010,76(2):164-170
An extraordinarily strong and persistent earthquake swarm (Andaman swarm 2005) originated in the Andaman back-arc following
the aftershock sequences of the 26 December 2004 Sumatra earthquake. The swarm (n = 651, mbmax= 5.9) came mainly in two phases: January 26–31 and Feb.–Aug. 2005, in an area of size 90 × 40 km2, at the centre of which lies a broad bathymetric depression and high gravity zone. The swarm demonstrates a complex faulting
series, initially the strike-slip motion followed by normal faulting in repetitive sequences, whose representative fault planes
orient at high angle to the regional faults. The swarm character as well as the distribution of stress-axes and their correlation
to tectonic features lends speculation for formation of a nascent rift segment in NW-SE direction at the doorstep of the Sewell
Seamount. The swarm has given rise to 21 episodes of rifting activities of variable time extent within 26–31 January 2005.
The r-t plots corresponding to the swarm data, modelled with variable hydraulic diffusivity (D) values 4, 6, 8 and 10 m2/s, suggest for excess pressure front from ascending magmatic fluid. This eventually heralded the rifting; causing pore pressure
perturbations that propagated in accordance with known diffusion parabolic equations. 相似文献
20.
Saumitra MISRA Horton E. NEWSOM M. SHYAM PRASAD John W. GEISSMAN Anand DUBE Debashish SENGUPTA 《Meteoritics & planetary science》2009,44(7):1001-1018
Abstract— The only well‐known terrestrial analogue of impact craters in basaltic crusts of the rocky planets is the Lonar crater, India. For the first time, evidence of the impactor that formed the crater has been identified within the impact spherules, which are ?0.3 to 1 mm in size and of different aerodynamic shapes including spheres, teardrops, cylinders, dumbbells and spindles. They were found in ejecta on the rim of the crater. The spherules have high magnetic susceptibility (from 0.31 to 0.02 SI‐mass) and natural remanent magnetization (NRM) intensity. Both NRM and saturation isothermal remanent magnetization (SIRM) intensity are ?2 Am2/Kg. Demagnetization response by the NRM suggests a complicated history of remanence acquisition. The spherules show schlieren structure described by chains of tiny dendritic and octahedral‐shaped magnetite crystals indicating their quenching from liquid droplets. Microprobe analyses show that, relative to the target basalt compositions, the spherules have relatively high average Fe2O3 (by ?1.5 wt%), MgO (?1 wt%), Mn (?200 ppm), Cr (?200 ppm), Co (?50 ppm), Ni (?1000 ppm) and Zn (?70 ppm), and low Na2O (?1 wt%) and P2O5 (?0.2 wt%). Very high Ni contents, up to 14 times the average content of Lonar basalt, require the presence of a meteoritic component in these spherules. We interpret the high Ni, Cr, and Co abundances in these spherules to indicate that the impactor of the Lonar crater was a chondrite, which is present in abundances of 12 to 20 percent by weight in these impact spherules. Relatively high Zn yet low Na2O and P2O5 contents of these spherules indicate exchange of volatiles between the quenching spherule droplets and the impact plume. 相似文献