A review of high-performance MEMS sensors for resource exploration and geophysical applications

MEMS sensors have the advantages of small volume,lightweight,and low cost,therefore,have been widely used in the fields of consumer electronics,industry,health,defence,and aerospace.With their ever-improving performance,MEMS sensors have also started to be used in resource exploration and geophysical applications.However,the requirements of high-precision MEMS sensors for geophysical applications have not been specified in detail.Therefore,this paper systematically analyzes the requirements of high-performance MEMS sensors for prospecting and geophysical applications,including seismic surveillance,Earth tide,volcanic activity monitoring for natural disasters;seismic,gravity,and magnetic resource prospecting;drilling process monitoring and local gravity measurement for gravity aided navigation.Focusing on the above applications,this paper summarizes the state-of-the-art of research on high-performance MEMS sensors for resource exploration and geophysical applications.Several off-the-shelf MEMS sensors have been used for earthquake monitoring,seismic exploration and drilling process monitoring,and a range of MEMS research prototype sensors have successfully been employed for Earth tides measurement and are promising to be used for gravity exploration.MEMS magnetometers should have a lower noise floor to meet the demand for magnetic exploration.MEMS gravity gradiometers are still under early development and will not be deployable in short-term.Highperformance MEMS sensors hold the advantages of low-cost,high integration,and capability of working in extreme environments;therefore,they are likely to gradually replace some conventional geophysical instruments in some application areas.

Present status and prospective on the seismic hazard studies of major seismic gaps in the Sichuan-Yunnan region

Several seismic gaps have been identified along the Xianshuihe-Xiaojiang fault zone and the Longmenshan fault zone in the Sichuan-Yunnan region, including the Daofu-Shimian gap on the Xianshuihe Fault, the Anninghe-Zemuhe gap, parts of the Xiaojiang Fault, and the Dayi gap between the Wenchuan and Lushan earthquakes. The seismic hazards of the Daofu-Shimian and Dayi gaps have aroused great concern and caused considerable debate. This paper reviews the recent geophysical observations and multidisciplinary studies conducted by domestic and international researchers in these areas, focusing on seismogenic structures, seismic activity, fault locking, stress fields, as well as earthquake triggering, and further analyzes the current controversial viewpoints about the seismic hazards in these regions. Based on the comprehensive analysis, we argue that the kinematic status along the Daofu-Shimian segment may vary significantly along the fault strike. Due to limitations in data and models, there is no consensus on the seismogenic potential of this area. Conversely, the Dayi seismic gap presents a high seismic potential. Furthermore, we delve into the scientific problems associated with major seismic gaps in the Sichuan-Yunnan region and make prospects for the strategy of future work. We propose a research framework that combines dense array and distributed acoustic sensing, artificial intelligence and big data technologies, joint inversion of multiple geophysical fields, as well as numerical simulation techniques for comprehensive seismic hazard analysis in seismic gaps.