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Monitoring Temporal Changes of Earth's Crust in Binchuan, Yunnan with Air-gun Data.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Monitoring Temporal Changes of Earth's Crust in Binchuan, Yunnan with Air-gun Data./
作者:	Luan, Yi.
面頁冊數:	1 online resource (145 pages)
附註:	Source: Dissertations Abstracts International, Volume: 84-05, Section: B.
Contained By:	Dissertations Abstracts International84-05B.
標題:	Environmental science. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30159738click for full text (PQDT)
ISBN:	9798351474113

Monitoring Temporal Changes of Earth's Crust in Binchuan, Yunnan with Air-gun Data.
Luan, Yi.

Monitoring Temporal Changes of Earth's Crust in Binchuan, Yunnan with Air-gun Data. - 1 online resource (145 pages)

Source: Dissertations Abstracts International, Volume: 84-05, Section: B.

Thesis (Ph.D.)--The Chinese University of Hong Kong (Hong Kong), 2022.

Includes bibliographical references

Seismic waves shed light on the interior of the Earth. The knowledge of structure, states, and the evolution of the interior of the Earth almost entirely rely on the study of seismic waves. With the development of seismology, people are available to obtain high-resolution images of the surface and interior of the Earth. On the one hand, this mainly thanks to the expansion of the scope of observation and the improvement of observation accuracy, and on the other hand, the increasingly largely used artificial sources that launch man-made earthquakes underground to have active investigation and detection.The wave velocity of the elastic wave that travels in the subsurface medium is an important physical parameter reflecting the physical properties of the underground medium. The wave velocity structure reflects the different tectonic features of the continental crust and is an important basis for the division of the active blocks in the continent. Previous scientists have provided quantities of results showing that the seismic wave velocity and the velocity ratio between P- and S-wave will change when the seismic wave passes through the seismogenic zone before, during, and after the earthquake. Various research from laboratory and field experiments have given proof that the crustal rocks' seismic wave velocity varies significantly with stress, the changes of which will cause the microcracks' openness and closeness. Thus, 4D monitoring of wave velocity changes using both active and passive sources can help us better understand the mechanism of substructural changes and deepen our understanding of the physical processes of earthquakes.The primary problem to conduct active detection studies at the regional scale is to find a suitable source. Seismological studies at the global scale are often based on natural earthquakes because the seismic waves released by natural earthquakes are large enough to penetrate the entire interior of the Earth. Seismological studies at local scales are mainly focused on exploration surveys of minerals, oil, and gas resources, generally using small equivalent explosive sources. In regional seismological studies, natural earthquakes have limitations in both space and time; and the complexity of the earthquake source itself makes it unsuitable for regional-scale detection. The traditional artificial source like the explosions also does not meet the requirements of the accuracy for small-scale detection. Through comparing a variety of artificial sources and conducting experimental research, we found that large-capacity air gun sources have unique advantages in regional- scale detection: i) high excitation energy; ii) low signal frequency; iii) and excellent repeatability. A large capacity air gun source is rich in low-frequency signals below 10 Hz, which can detect the horizontal distance as far as 185 km and reach the depth deep to Mohodis continuity. The highly repetitive nature of the air gun source makes it particularly suitable for seismic detection in 4D seismology, which realizes real-time monitoring of the change of the velocity of the underground structure. Air gun source also has obvious advantages in terms of excitation efficiency and environmental protection.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798351474113Subjects--Topical Terms:

677245
Environmental science.
Subjects--Index Terms:

Seismic wavesIndex Terms--Genre/Form:

542853
Electronic books.

Monitoring Temporal Changes of Earth's Crust in Binchuan, Yunnan with Air-gun Data.
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502 $a Thesis (Ph.D.)--The Chinese University of Hong Kong (Hong Kong), 2022.
504 $a Includes bibliographical references
520 $a Seismic waves shed light on the interior of the Earth. The knowledge of structure, states, and the evolution of the interior of the Earth almost entirely rely on the study of seismic waves. With the development of seismology, people are available to obtain high-resolution images of the surface and interior of the Earth. On the one hand, this mainly thanks to the expansion of the scope of observation and the improvement of observation accuracy, and on the other hand, the increasingly largely used artificial sources that launch man-made earthquakes underground to have active investigation and detection.The wave velocity of the elastic wave that travels in the subsurface medium is an important physical parameter reflecting the physical properties of the underground medium. The wave velocity structure reflects the different tectonic features of the continental crust and is an important basis for the division of the active blocks in the continent. Previous scientists have provided quantities of results showing that the seismic wave velocity and the velocity ratio between P- and S-wave will change when the seismic wave passes through the seismogenic zone before, during, and after the earthquake. Various research from laboratory and field experiments have given proof that the crustal rocks' seismic wave velocity varies significantly with stress, the changes of which will cause the microcracks' openness and closeness. Thus, 4D monitoring of wave velocity changes using both active and passive sources can help us better understand the mechanism of substructural changes and deepen our understanding of the physical processes of earthquakes.The primary problem to conduct active detection studies at the regional scale is to find a suitable source. Seismological studies at the global scale are often based on natural earthquakes because the seismic waves released by natural earthquakes are large enough to penetrate the entire interior of the Earth. Seismological studies at local scales are mainly focused on exploration surveys of minerals, oil, and gas resources, generally using small equivalent explosive sources. In regional seismological studies, natural earthquakes have limitations in both space and time; and the complexity of the earthquake source itself makes it unsuitable for regional-scale detection. The traditional artificial source like the explosions also does not meet the requirements of the accuracy for small-scale detection. Through comparing a variety of artificial sources and conducting experimental research, we found that large-capacity air gun sources have unique advantages in regional- scale detection: i) high excitation energy; ii) low signal frequency; iii) and excellent repeatability. A large capacity air gun source is rich in low-frequency signals below 10 Hz, which can detect the horizontal distance as far as 185 km and reach the depth deep to Mohodis continuity. The highly repetitive nature of the air gun source makes it particularly suitable for seismic detection in 4D seismology, which realizes real-time monitoring of the change of the velocity of the underground structure. Air gun source also has obvious advantages in terms of excitation efficiency and environmental protection.
520 $a 地震波是一種能夠照亮地球內部結構的明燈。了解地球內部的結構、狀態及演化過程幾乎完全依賴對地震波的研究。隨著地震學的發展，人們已經可以獲取更高分辨率的地球表面及地球內部圖像。這主要歸功於：1.隨著儀器精度的提高，提升探測精度及拓寬探測範圍；2.越來越多的使用人工震源探測地下介質。根據地震波的傳播範圍，可以把地震學的研究概括為全球尺度、區域尺度及地方性尺度的研究。全球尺度的研究主要針對地球內部深至深至下地幔地核的範圍，探測範圍超過數千公裏。區域尺度研究的是數十公裏深的地殼的探測範圍通常是幾百公裏。區或巖石圈，它域尺度的主動源探測主要致力於獲取巖石圈的演變，並且是探索地震預測方法的主要途徑。地方性尺度研究地球淺層結構或非常淺層部分的沈積層結構，探測距離通常為幾公裏。在本文中我們更加關註區域尺度及地方性尺度地下結構的探測。由於我們需要對地下介質的結構和狀態進行監測，研究地下介質屬性及應力狀態變化對深入了解地震的孕育、發生及震後恢復過程有重要作用。在地下介質中傳播的地震波的各項物理參數中，波速特征是反映地下介質物理特性非常重要的參數。同時，地震波速度的測量精度最高並可以最直接的反映地下應力狀態。大量科學家研究結果發現在地震發生前、震中及震後，由於同震破壞和震後愈合效應，存在地震波波速及P波和S波波速比（Vp/Vs）的變化。大量實驗室巖石物理實驗及野外實驗發現，地殼巖石的地震波速度明顯地隨應力而變化，這種依賴關系是由於作用在裂隙表面的應力變化導致微裂隙的張開、閉合所致。因此，應力變化可以通過測量地震波速度變化獲得，而精確測量地下介質的源及高質量、可控的重復性人工震源。為了對區域尺度及地方性尺度地下結構進行主動的地震波速度變化探測，首要問題是選擇合適的震源。全球尺度的地震學研究通常基於天然地震，但是由於天然地震的發生受地震重復性以及時空分布的制約，且不可控制，因此通常使用主動震源來監測地震波速度的變化，以期為孕震深度的巖石應力變化及巖石破裂愈合狀態的研究提供信息。目前，利用重復地震及主動源（如壓電陶瓷、氣槍陣列、可控震源、炸藥等）已經進行了許多探測地下速度結構變化的有意義的嘗試。通過野外實驗研究對比了一系列主動震源後，我們發現大容量氣槍震源對於區域尺度範圍的而研究有著獨特的優越性，主要表現在頻率低（小於單次激發橫向傳播距離可達185千米10Hz）、能量大，，傳播深度可深至莫霍面，完全可以用於上百公裏尺度的區域地下結構探測。其次，氣槍震源可以組合形成氣槍陣列，可以激發高重復性信號，對於4D地下介質速度結構變化的實時監測具有天然優越性。同時，相較於陸上炸藥震源，氣槍震源具有很好的能量激發效率，並且不會對介質產生不可逆的破壞，更加環保。.
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653 $a Seismology
653 $a Wave velocity
655 7 $a Electronic books. $2 lcsh $3 542853
690 $a 0768
690 $a 0725
710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a The Chinese University of Hong Kong (Hong Kong). $3 1017547
773 0 $t Dissertations Abstracts International $g 84-05B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30159738 $z click for full text (PQDT)