{"title":"1-D shear wave velocity structure beneath North India using surface wave dispersion study","authors":"Abhishek Kumar Gupta, Prantik Mandal, Kalachand Sain, Chinmay Haldar, Ajay Paul","doi":"10.1007/s12040-023-02211-0","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The seismological data recorded at our four semi-permanent broadband seismographs installed by the CSIR-NGRI, Hyderabad, Telangana in the Aravalli mobile belt (AMB) and Rajasthan craton in the northwest Indian shield during the period 2014–2016 are used in the study. The 16 selected regional Indian earthquakes of <i>M</i><sub><i>w</i></sub> 5.5–7.8 that occurred in the North India region recorded at the four seismic stations are used to compute the surface wave (both Rayleigh and Love waves) group velocity dispersion characteristics and average 1-D regional shear wave velocity (<i>V</i><sub><i>s</i></sub>) structure beneath the North India which covers the northern part of India between the whole Himalayan region and Rajasthan craton including AMB. First, we compute Rayleigh waves (at 7–87 s) dispersion curves and Love waves (at 7–82 s) group velocity dispersion curves by utilizing the standard frequency time analysis (FTAN) of 3-component broadband data recorded at these four 3-component broadband seismic stations. After that, using the logarithmic stacking technique, we compute the final average stacked fundamental mode dispersion curves of surface waves (both Love and Rayleigh waves) for our study area. Then, we finally invert the final average dispersion curves of surface waves (both Love and Rayleigh waves) to compute the average one-dimensional regional shear velocity structure beneath North India. Our modelling result in North India suggests a two-layered crustal structure with a crustal thickness of 39 km. The thickness of the first crustal layer (upper crust) is 20 km with a shear wave velocity (<i>V</i><sub><i>s</i></sub>) of 3.30 km/s. On the other hand, the second crustal layer (lower crust) marks a 19-km thickness with a <i>V</i><sub><i>s</i></sub> of 3.70 km/s. Our modelling result suggests that the <i>V</i><sub><i>s</i></sub> of the upper mantle is found to be 4.35 km/s below the study region.</p><h3 data-test=\"abstract-sub-heading\">Research highlights</h3><ul>\n<li>\n<p>Modelled average one-dimensional regional <i>V</i><sub><i>s</i></sub> structure below northern part of India.</p>\n</li>\n<li>\n<p>A 2-layered crustal velocity model below North India.</p>\n</li>\n<li>\n<p>Upper crust at 20 km thick with <i>V</i><sub><i>s</i></sub> of 3.30 km/s.</p>\n</li>\n<li>\n<p>And, lower crust at 19 km thick with <i>V</i><sub><i>s</i></sub> of 3.70 km/s.</p>\n</li>\n<li>\n<p>The Moho depth is 39 km and <i>V</i><sub><i>s</i></sub> below the Moho depth is found to be 4.35 km.</p>\n</li>\n</ul>","PeriodicalId":15609,"journal":{"name":"Journal of Earth System Science","volume":"269 1","pages":""},"PeriodicalIF":1.3000,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Earth System Science","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s12040-023-02211-0","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The seismological data recorded at our four semi-permanent broadband seismographs installed by the CSIR-NGRI, Hyderabad, Telangana in the Aravalli mobile belt (AMB) and Rajasthan craton in the northwest Indian shield during the period 2014–2016 are used in the study. The 16 selected regional Indian earthquakes of Mw 5.5–7.8 that occurred in the North India region recorded at the four seismic stations are used to compute the surface wave (both Rayleigh and Love waves) group velocity dispersion characteristics and average 1-D regional shear wave velocity (Vs) structure beneath the North India which covers the northern part of India between the whole Himalayan region and Rajasthan craton including AMB. First, we compute Rayleigh waves (at 7–87 s) dispersion curves and Love waves (at 7–82 s) group velocity dispersion curves by utilizing the standard frequency time analysis (FTAN) of 3-component broadband data recorded at these four 3-component broadband seismic stations. After that, using the logarithmic stacking technique, we compute the final average stacked fundamental mode dispersion curves of surface waves (both Love and Rayleigh waves) for our study area. Then, we finally invert the final average dispersion curves of surface waves (both Love and Rayleigh waves) to compute the average one-dimensional regional shear velocity structure beneath North India. Our modelling result in North India suggests a two-layered crustal structure with a crustal thickness of 39 km. The thickness of the first crustal layer (upper crust) is 20 km with a shear wave velocity (Vs) of 3.30 km/s. On the other hand, the second crustal layer (lower crust) marks a 19-km thickness with a Vs of 3.70 km/s. Our modelling result suggests that the Vs of the upper mantle is found to be 4.35 km/s below the study region.
Research highlights
Modelled average one-dimensional regional Vs structure below northern part of India.
A 2-layered crustal velocity model below North India.
Upper crust at 20 km thick with Vs of 3.30 km/s.
And, lower crust at 19 km thick with Vs of 3.70 km/s.
The Moho depth is 39 km and Vs below the Moho depth is found to be 4.35 km.
期刊介绍：
The Journal of Earth System Science, an International Journal, was earlier a part of the Proceedings of the Indian Academy of Sciences – Section A begun in 1934, and later split in 1978 into theme journals. This journal was published as Proceedings – Earth and Planetary Sciences since 1978, and in 2005 was renamed ‘Journal of Earth System Science’.
The journal is highly inter-disciplinary and publishes scholarly research – new data, ideas, and conceptual advances – in Earth System Science. The focus is on the evolution of the Earth as a system: manuscripts describing changes of anthropogenic origin in a limited region are not considered unless they go beyond describing the changes to include an analysis of earth-system processes. The journal''s scope includes the solid earth (geosphere), the atmosphere, the hydrosphere (including cryosphere), and the biosphere; it also addresses related aspects of planetary and space sciences. Contributions pertaining to the Indian sub- continent and the surrounding Indian-Ocean region are particularly welcome. Given that a large number of manuscripts report either observations or model results for a limited domain, manuscripts intended for publication in JESS are expected to fulfill at least one of the following three criteria.
The data should be of relevance and should be of statistically significant size and from a region from where such data are sparse. If the data are from a well-sampled region, the data size should be considerable and advance our knowledge of the region.
A model study is carried out to explain observations reported either in the same manuscript or in the literature.
The analysis, whether of data or with models, is novel and the inferences advance the current knowledge.
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