scholarly journals Estimation of source and site characteristics in the North-West Himalaya and its adjoining area using generalized inversion method

2019 ◽  
Vol 62 (Vol 62 (2019)) ◽  
Author(s):  
Harinarayan H ◽  
Abhishek Kumar
Keyword(s):  
Inversion Method ◽  
North West ◽  
The North ◽  
Generalized Inversion ◽  
Site Characteristics ◽  
West Himalaya ◽  
Adjoining Area

scholarly journals Estimation of path attenuation and site characteristics in the north-west Himalaya and its adjoining area using generalized inversion method

2018 ◽  
Author(s):  
Harinarayan Nelliparambil Hareeshkumar ◽  
Abhishek Kumar
Keyword(s):  
Site Amplification ◽  
Inversion Method ◽  
Predominant Frequency ◽  
S Wave ◽  
North West ◽  
Hypocentral Distance ◽  
The North ◽  
Generalized Inversion ◽  
Site Characteristics ◽  
West Himalaya

Abstract. Present work focuses on the determination of path attenuation as well as site characteristics of PESMOS managed recording stations, located in the north-west Himalaya and its adjoining region, using two-step generalized inversion technique. In the first step of inversion, non-parametric attenuation curves are developed. Presence of a kink is observed at around 105 km hypocentral distance while correlating the path attenuation with the hypocentral distance indicating the presence of Moho discontinuity in the region. Further, Qs = 105 f0.94 as S wave quality factor within 105 km, is obtained indicating that the region is possibly heterogeneous as well as seismically active. In the second step of inversion, site amplification curves are developed separately from the attenuation corrected data for horizontal and vertical components of the accelerogram. Further, site amplification spectra is computed as the ratio of the obtained horizontal and vertical components to determine the amplification function and predominant frequency for each of the PESMOS managed recording stations, exist within the study area. The predominant frequency based on generalized inversion method and based on horizontal to vertical spectral ratio of S wave portion of the accelerogram matches well. Maps showing spatial distribution of predominant frequencies and amplification functions across the study region are also developed based on the present work.

scholarly journals Determination of path attenuation and site characteristics of the North-west Himalayan region and adjoining regions within the Indian Territory using Generalized inversion method

2020 ◽  
Vol 63 (6) ◽  
Author(s):  
Nelliparanbil Harinarayan ◽  
Abhishek Kumar
Keyword(s):  
Seismic Hazard ◽  
Predominant Frequency ◽  
Site Class ◽  
North West ◽  
The North ◽  
Generalized Inversion ◽  
Site Characteristics ◽  
Generalized Inversion Technique ◽  
Recording Station

North-west Himalayas and its adjoining regions have been experiencing deadly earthqaukes from time to time and are home for a large portion of population of Indian subcontinent. Knowledge of regional path attenuation and site parameters are prerequisite while attempting seismic hazard studies towards minimizing damages during future earthqaukes for a region. Present work focuses on the determination of path attenuation and site characteristics of earthqaukes recording stations, located in the north-west Himalayas and its adjoining regions, within India. It is done using two- step generalized inversion technique. In the first step of inversion, non-parametric attenuation curves are developed by constraining attenuation to be a smooth decaying function with hypocentral distance. Qs = (105 ± 11)f (0.94 ± 0.08) as S wave quality factor is obtained indicating that the region is seismically active having high degree of heterogeneities in the crustal medium. In the second step of generalized inversion, site amplification curve, at each recording station, is computed as the ratio of site spectral amplitude of horizontal and vertical components. In addition, based on Horizontal to vertical spectral ratio (HVSR) method, predominant frequency of each recording station is calculated. Values of predominant frequencies based on HVSR and generalized inversion are found matching for each of the recording station. Based on obtained predominant frequency, site class of 101 recording stations, which at present are absent, are determined in this work. Determined path attenuation as well as site parameters can be collectively used for developing regional ground motion models and subsequently for seismic hazard studies for the selected region.

An Iron Age A site on the Chilterns

1951 ◽  
Vol 31 (3-4) ◽  
pp. 132-148 ◽  
Author(s):  
K. M. Richardson ◽  
Alison Young
Keyword(s):  
Water Supply ◽  
Iron Age ◽  
The West ◽  
North West ◽  
The North ◽  
Roman Villa ◽  
Adjoining Area ◽  
Cursory Examination ◽  
A Site ◽  
The Hill

In 1946 a visit to the barrow, which lies on the edge of the western scarp of Chinnor Common, and a cursory examination of the adjoining area, cultivated during the war, resulted in finds of pottery and other objects indicating Iron Age occupation. The site lies on the saddleback of a Chiltern headland, at a height of about 800 ft. O.D. Two hollow ways traverse the western scarp, giving access to the area from the Upper Icknield Way, which contours the foot of the hill, then drops to cross the valley, passing some 600 yards to the north of the Iron Age site of Lodge Hill, Bledlow, and rising again continues northwards under Pulpit Hill camp and the Ellesborough Iron Age pits below Coombe Hill. The outlook across the Oxford plain to the west is extensive, embracing the hill-fort of Sinodun, clearly visible some fourteen miles distant on the farther bank of the Thames. The hollow way at the north-west end of the site leads down to a group of ‘rises’ hard by the remains of a Roman villa, and these springs are, at the present day, the nearest water-supply to the site.

Petroleum systems and hydrocarbon potential of the North-West Himalaya of India and Pakistan

2018 ◽  
Vol 187 ◽  
pp. 109-185 ◽  
Author(s):  
J. Craig ◽  
N. Hakhoo ◽  
G.M. Bhat ◽  
M. Hafiz ◽  
M.R. Khan ◽  
...  
Keyword(s):  
Hydrocarbon Potential ◽  
North West ◽  
Petroleum Systems ◽  
The North ◽  
West Himalaya

Intermontane-basin development in the past 4 Myr in the north-west Himalaya

Nature ◽  
1982 ◽  
Vol 298 (5873) ◽  
pp. 432-436 ◽  
Author(s):  
Douglas W. Burbank ◽  
Gary D. Johnson
Keyword(s):  
North West ◽  
Intermontane Basin ◽  
The Past ◽  
The North ◽  
Basin Development ◽  
West Himalaya

Accuracy of wavelets, seismic inversion, and thin-bed resolution

2017 ◽  
Vol 5 (4) ◽  
pp. T523-T530
Author(s):  
Ehsan Zabihi Naeini ◽  
Mark Sams
Keyword(s):  
Seismic Data ◽  
Reservoir Characterization ◽  
Low Frequency ◽  
Seismic Inversion ◽  
Inversion Method ◽  
Frequency Content ◽  
Frequency Model ◽  
North West ◽  
The North ◽  
Well Data

Broadband reprocessed seismic data from the North West Shelf of Australia were inverted using wavelets estimated with a conventional approach. The inversion method applied was a facies-based inversion, in which the low-frequency model is a product of the inversion process itself, constrained by facies-dependent input trends, the resultant facies distribution, and the match to the seismic. The results identified the presence of a gas reservoir that had recently been confirmed through drilling. The reservoir is thin, with up to 15 ms of maximum thickness. The bandwidth of the seismic data is approximately 5–70 Hz, and the well data used to extract the wavelet used in the inversion are only 400 ms long. As such, there was little control on the lowest frequencies of the wavelet. Different wavelets were subsequently estimated using a variety of new techniques that attempt to address the limitations of short well-log segments and low-frequency seismic. The revised inversion showed greater gas-sand continuity and an extension of the reservoir at one flank. Noise-free synthetic examples indicate that thin-bed delineation can depend on the accuracy of the low-frequency content of the wavelets used for inversion. Underestimation of the low-frequency contents can result in missing thin beds, whereas underestimation of high frequencies can introduce false thin beds. Therefore, it is very important to correctly capture the full frequency content of the seismic data in terms of the amplitude and phase spectra of the estimated wavelets, which subsequently leads to a more accurate thin-bed reservoir characterization through inversion.

Colliding Continents

2013 ◽  
Author(s):  
Mike Searle
Keyword(s):  
Indian Plate ◽  
Mountain Range ◽  
Polar Regions ◽  
Geological Evidence ◽  
North West ◽  
Ice Cap ◽  
The North ◽  
West Himalaya ◽  
Tectonically Active ◽  
The Himalaya

The Himalaya is the greatest mountain range on Earth: the highest, longest, youngest, the most tectonically active, and the most spectacular of all. Unimaginable geological forces created these spectacular peaks. Indeed, the crash of the Indian plate into Asia is the biggest known collision in geological history, giving birth to the Himalaya and Karakoram, one of the most remote and savage places on Earth. In this beautifully illustrated book, featuring spectacular color photographs throughout, one of the most experienced field geologists of our time presents a rich account of the geological forces that were involved in creating these monumental ranges. Over three decades, Mike Searle has transformed our understanding of this vast region. To gather his vital geological evidence, he has had to deploy his superb skills as a mountaineer, spending weeks at time in remote and dangerous locations. Searle weaves his own first-hand tales of discovery with an engaging explanation of the processes that formed these impressive peaks. His narrative roughly follows his career, from his early studies in the north west Himalaya of Ladakh, Zanskar and Kashmir, through several expeditions to the Karakoram ranges (including climbs on K2, Masherbrum, and the Trango Towers, and the crossing of Snow Lake, the world's largest ice cap outside polar regions), to his later explorations around Everest, Makalu, Sikkim and in Tibet and South East Asia. The book offers a fascinating first-hand account of a major geologist at work-the arduous labor, the eureka moments, and the days of sheer beauty, such as his trek to Kathmandu, over seven days through magnificent rhododendron forests ablaze in pinks, reds and white and through patches of bamboo jungle with hanging mosses. Filled with satellite images, aerial views, and the author's own photographs of expeditions, Colliding Continents offers a vivid account of the origins and present state of the greatest mountain range on Earth.

Observed spatio-temporal changes of winter snow albedo over the north-west Himalaya

2016 ◽  
Vol 37 (5) ◽  
pp. 2304-2317 ◽  
Author(s):  
H. S. Negi ◽  
P. Datt ◽  
N. K. Thakur ◽  
A. Ganju ◽  
V. K. Bhatia ◽  
...  
Keyword(s):  
Temporal Changes ◽  
Snow Albedo ◽  
North West ◽  
The North ◽  
Winter Snow ◽  
West Himalaya ◽  
Spatio Temporal
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