Microseismic observations reveal that internal waves intensify seabed methane release  

作　　者：Zhaoyang TIAN Yonggang JIA Junjiang ZHU Tian CHEN Hui WANG Chunsheng JI Chengyu LIU Longyu LU Manchao HE 

机构地区：[1]Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering,Ocean University of China,Qingdao 266100,China [2]Frontiers Science Center for Deep Ocean Multispheres and Earth System,Key Lab of Submarine Geosciences and Prospecting Techniques,MOE and College of Marine Geosciences,Ocean University of China,Qingdao 266100,China [3]Guangzhou Marine Geological Survey,China Geological Survey,Guangzhou 511458,China [4]Shandong Earthquake Agency,Jinan 250014,China [5]State Key Laboratory for Tunnel Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China

出　　处：《Science China Earth Sciences》2024年第10期3186-3203,共18页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No.41831280)。

摘　　要：Internal waves transport material and energy from the upper water column to the deep ocean, disturbing seabed sediments and resulting in phenomena such as seabed erosion and changes in topography. On the northern slope of the South China Sea and in many coastal margins worldwide, the zones with internal wave action closely overlap with areas where natural gas hydrates are present. However, due to significant differences in the spatial and temporal scales, understanding the influence of internal waves on methane releases from deep seabeds is challenging. In this study, in situ observations of seabed microseismicity and internal waves are conducted at water depths of 655 meters and 1450 meters in the Pearl River Canyon of the South China Sea. The microseismicity caused by internal waves and seabed methane releases is identified, and a method to establish the correlation between internal waves and seabed methane releases through the use of microseismic recordings is proposed, aiming to obtain direct observational evidence of internal waves intensifying seabed methane releases. The results show that internal waves and seabed methane releases generate significant microseismic signals, indicating the continuous influence of internal waves on the deep seabed of the northern slope of the South China Sea and revealing active methane release phenomena on the seabed. At both long and short time scales, internal waves increase the frequency of seabed methane releases by 4.2 times and 2.4 times, respectively, while also enhancing the intensity of these releases. These changes are influenced by the alterations in seabed flow velocity, pressure, and temperature that are induced by internal wave activities. This study emphasizes that microseismic signals are effective carriers of information for multiscale geological processes on seabeds and suggests that internal waves exacerbate marine geological hazards and contribute to global climate change by intensifying seabed methane releases.

关 键 词：Internal waves Seabed methane release Microseismic observation Ocean bottom seismometer Northern slope of the South China Sea 

分 类 号：P73[天文地球—海洋科学]