GRAVITY OBSERVATION DURING 2021—2023 AND MAGMA ACTIVITY IN CHANGBAISHAN-TIANCHI VOLCANO

doi:10.3969/j.issn.0253-4967.20240134

Abstract

Abstract:

Tianchi volcano at Changbai Mountain is the most eruption-prone Cenozoic active volcano in China. It experienced four major Holocene eruptions, among which the eruption around AD 946 is regarded as one of the largest worldwide in the past 2000 years. In recent years, Tianchi has shown clear signs of unrest, including a strong disturbance from 2002 to 2005 and a weaker episode from December 2020 to June 2021. The volcanic area remains under a compressional stress regime, and continued attention to regional stress conditions and magmatic activity is therefore warranted.
Gravity monitoring provides an effective means to track and investigate active volcanoes by constraining subsurface mass redistribution associated with magma and hydrothermal processes. Because magma originates in the mantle and differs in density from crustal rocks, its movement within the crust can produce microgravity changes of tens to hundreds of microgals. The observed gravity field reflects the combined effects of topography, lateral density variations within the crust and surrounding materials, and even contributions from upper-mantle structure. Differences in station elevation, changes in near-surface rock density, and magma migration(intrusion and withdrawal)can all drive measurable gravity variations, which can be quantified through high-precision repeat gravity surveys.
To assess current magmatic activity, the Second Monitoring and Application Center of the China Earthquake Administration conducted three phases of mobile gravity measurements in 2021, 2022, and 2023. Observations were collected using two Burris relative gravimeters with a nominal precision of 10×10^-8m/s^-2. Each campaign was carried out during July-August with the same instruments and a consistent observer team, thereby reducing potential influences from seasonal effects and operator-related differences. The results show that gravity changes from 2021 to 2022 ranged from -161.4 to 23.4μGal and were predominantly negative. From 2022 to 2023, changes ranged from -37.8 to 135.7μGal and were mainly positive. Over the full interval from 2021 to 2023, gravity variations ranged from -90.6 to 56.0μGal, with negative changes prevailing.
Gravity anomalies are observed within ~35km of the crater, implying the approximate extent of active magma/hydrothermal influence. Stations with changes exceeding 100μGal are concentrated within ~12km of the crater, which may reflect magma-related processes in an intermediate, roughly cylindrical conduit. The largest gravity change occurs west of the crater, suggesting the presence of a nearby deep fault. In addition, gravity changes on both sides of the crater show clustered patterns, potentially indicating activity associated with distinct slab-like magma bodies.
The combined analysis of gravity and deformation observations is widely used for long-term volcanic-hazard assessment because it provides complementary constraints on subsurface structure, mass redistribution, and/or pressure changes. The gravity-height change gradient(Δg/Δh)directly reflects the balance between mass change and surface displacement and can be interpreted using established zoning based on the relationship between Δg and Δh. Data plotting in Zone Ⅰ (below the Bouguer-corrected free-air gradient, BCFAG) indicate subsidence with negative Δg, consistent with a decrease in density or mass(e.g., magma drainage, a falling water table, void generation, or vesiculation), implying a low likelihood of eruption. Zone Ⅱ (above the free-air gradient, FAG) also indicates subsidence but with positive Δg, reflecting increased density or mass(e.g., magma input, rising water table, dyke emplacement, bubble resorption, void filling, or hydrothermal cementation), likewise suggesting a low eruption probability. Zone Ⅲ (between FAG and BCFAG)corresponds to subsidence with positive Δg and is interpreted as increased density accompanied by decreased mass, which may result from magma drainage, a falling water table, or void closure and can be associated with summit-collapse potential. Gradients plotting along or close to the ordinate indicate shallow processes such as magma and/or gas fluctuations within feeder conduits, near-surface dyke emplacement, or hydrothermal activity.
Leveling and InSAR observations since 1992 indicate short-term deformation fluctuations but low long-term deformation rates during quiescent periods. Deformation is mainly concentrated near the crater, with localized contributions from fault activity. During 2021-2023, Tianchi remained in a quiescent state with minimal deformation. Based on the observed deformation behavior, Δg/Δh is inferred to fall predominantly within Zone Ⅰ for 2021-2022 and Zone Ⅲ for 2022-2023. Given the large gravity changes and the small deformation amplitudes(within several tens of millimeters), Δg/Δh is expected to plot close to the ordinate. After accounting for density constraints and excluding the influence of water bodies, the gravity variations are best explained by subsurface mass redistribution, suggesting ongoing magma and/or gas migration within transport conduits or along faults.
Integrating magnetotelluric, seismic, and gravity constraints on the crust-mantle magmatic system beneath the crater, we propose that the minor unrest in 2020-2021 increased seismicity, likely modulated by the surrounding compressional stress field. Rising magma may have partially reopened previously obstructed pathways and migrated into pre-existing reservoirs of different sizes and depths. This process could have induced micro-fracturing in the host rock, triggering earthquakes at multiple depths and producing regional gravity changes. After April 2021, seismicity returned to background levels. The presence of substantial gravity changes without pronounced deformation suggests that magma migration primarily involved intrusion into, or withdrawal from, pre-existing voids, fractures, or fault-related spaces. The negative gravity changes observed in 2021-2022 may reflect magma withdrawal and mass loss following the 2020-2021 unrest, whereas the positive changes in 2022-2023 suggest renewed ascent of melt under compressive loading, with magma filling existing voids and fault zones. Over 2021-2023, the dominant negative trend implies that the mass withdrawn in 2021-2022 exceeded the mass added in 2022-2023. Collectively, these results indicate that magmatic activity beneath Tianchi remains ongoing.

Key words: gravity, deformation, magma activity, magma system, Changbaishan-Tianchi volcano

摘要：

重力观测是了解火山岩浆活动状态的有效手段。2021、 2022和2023年长白山天池火山区开展了3期流动重力观测, 结果显示, 距火山口35km范围的点位出现重力变化, 说明火山区目前活动岩浆或热液可能的分布范围。2021—2022年的重力变化为-161.4~23.4μGal, 以负值变化为主, 推测经历2020—2021年火山小型扰动后, 上移岩浆的后撤和流失; 2022—2023年的重力变化为-37.8~135.7μGal, 以正值变化为主, 可能是受压应力环境再次影响, 熔融的岩浆沿着已有通道上移, 填充至既有孔隙或空间和断层。2个时间段多数点位变化超过50μGal, 远大于观测误差的影响; 重力变化量超过100μGal的点位主要位于以火山口为中心12km的范围内, 推测由中间圆柱状岩浆通道中的岩浆活动引起。火山口两侧点位的重力变化出现分群性, 可能由不同的平板状岩浆体活动引起。重力变化最大的点位于火山口西侧, 推测附近有深大断裂通过。天池火山区重力变化大, 形变量在几十毫米以下, 结合地球物理方法获取天池火山壳幔岩浆系统, 推测该时间段岩浆活动主要发生在相互联通的壳内岩浆囊与断层之间, 岩浆侵入或后撤至已存的孔隙或断层。2021—2023年2年尺度的重力变化范围为-90.6~56.0μGal, 主要以负值变化为主, 表明2021—2022年后撤和流失的岩浆多于2022—2023年上移填充的岩浆, 火山区现今岩浆仍处于活动状态。

关键词: 重力, 形变, 岩浆活动性, 岩浆系统, 长白山天池火山

HU Ya-xuan, ZHANG Guo-qing, XIONG Guo-hua, ZHUANG Wen-quan, FENG Bing, KONG Qing-jun. GRAVITY OBSERVATION DURING 2021—2023 AND MAGMA ACTIVITY IN CHANGBAISHAN-TIANCHI VOLCANO[J]. SEISMOLOGY AND GEOLOGY, 2026, 48(2): 540-560.

胡亚轩, 张国庆, 熊国华, 庄文泉, 冯兵, 孔庆军. 长白山天池火山2021—2023年流动重力观测及岩浆活动性分析[J]. 地震地质, 2026, 48(2): 540-560.

Figures/Tables 10

Fig. 1 Location of gravity and leveling stations of the study area.

Fig. 2 Time series of the vertical component at the GNSS continuous observation station(JLCB).

Fig. 3 Elevation vs. relative gravity of the stations.

Fig. 4 Gravity changes at the different times.

Fig. 5 Spatial patterns of the gravity changes at the different times.

Fig. 6 G29, G19 and G22 stations and photographs of the field observation.

Fig. 7 Deformation of the gravity stations.

Fig. 8 Changes of the magma activities, earthquakes, and deformation with time at Changbaishan Tianchi volcano.

Fig. 9 The interpretation of Δg/Δh data in volcano area.

Fig. 10 Shallow active magma structure below Changbaishan Tianchi volcano(modified from Hammond et al., 2020).

References 63

[1]	陈国浒, 单新建, Wooil M M, 等. 2008. 基于InSAR、 GPS形变场的长白山地区火山岩浆囊参数模拟研究[J]. 地球物理学报, 51(4): 1085—1092.
	CHEN Guo-hu, SHAN Xin-jian, Wooil M M, et al. 2008. A modeling of the magma chamber beneath the Changbai Mountains volcanic area constrained by InSAR and GPS derived deformation[J]. Chinese Journal of Geophysics, 51(4): 1085—1092 (in Chinese).
[2]	陈棋福, 艾印双, 陈赟. 2019. 长白山火山区深部结构探测的研究进展与展望[J]. 中国科学(地球科学), 49(5): 778—795.
	CHEN Qi-fu, AI Yin-shuang, CHEN Yun. 2019. Overview of deep structures under the Changbaishan volcanic area in Northeast China[J]. Scientia Sinica(Terrae), 49(5): 778—795 (in Chinese).
[3]	国家地震局. 1997. 地震重力测量规范[S]. 北京: 地震出版社.
	Seismological Bureau of China. 1997. Seismic Gravity Measurement Specifications[S]. Seismological Press, Beijing.
[4]	管彦武, 崔承赞, 杨国东, 等. 2020. 基于重力剖面的长白山天池火山地壳岩浆囊建模[J]. 岩石学报, 36(12): 3840—3852.
	GUAN Yan-wu, CHOI Sung-zan, YANG Gong-dong, et al. 2020. Changbaishan Tianchi volcano crustal magma chambers modeling with gravity profile[J]. Acta Petrologica Sinica, 36(12): 3840—3852 (in Chinese).
[5]	韩宇飞, 宋小刚, 单新建, 等. 2010. D-InSAR 技术在长白山天池火山形变监测中的误差分析与应用[J]. 地球物理学报, 53(7): 1571—1579.
	HAN Yu-fei, SONG Xiao-gang, SHAN Xin-jian, et al. 2010. Deformation monitoring of Changbaishan Tianchi volcano using D-InSAR technique and error analysis[J]. Chinese Journal of Geophysics, 53(7): 1571—1579 (in Chinese).
[6]	何平. 2014. 时序InSAR的误差分析及应用研究[D]. 武汉: 武汉大学.
	HE Ping. 2014. Error analysis and surface deformation application of time series InSAR[D]. Wuhan University, Wuhan (in Chinese).
[7]	何平, 许才军, 温扬茂, 等. 2015. 利用PALSAR数据研究长白山火山活动性[J]. 武汉大学学报(信息科学版), 40(2): 214—221.
	HE Ping, XU Cai-jun, WEN Yang-mao, et al. 2015. Estimating the magma activity of the Changbaishan volcano with PALSAR data[J]. Geomatics and Information Science of Wuhan University, 40(2): 214—221 (in Chinese).
[8]	胡亚轩, 王雄. 2009. 应用形变和重力资料分析腾冲火山区岩浆的活动特征[J]. 地震地质, 31(4): 655—663. doi: 10.3969/j.issn.0253-4967.2009.04.009.
	HU Ya-xuan, WANG Xiong. 2009. Anaysis of the characteristics of magma activity based on the deformation and gravity measurements in Tengchong volcano region[J]. Seismology and Geology, 31(4): 655—663 (in Chinese).
[9]	胡亚轩, 赵凌强, 宋尚武, 等. 2022. 长白山火山区现今地壳运动特征及动力学环境分析[J]. 大地测量与地球动力学, 42(4): 331—335.
	HU Ya-xuan, ZHAO Ling-qiang, SONG Shang-wu, et al. 2022. Present-day crustal deformation and geodynamic environment of the Changbaishan volcano[J]. Journal of Geodesy and Geodynamics, 42(4): 331—335 (in Chinese).
[10]	皇甫岗, 姜朝松. 2000. 腾冲火山研究[M]. 昆明: 云南科技出版社.
	HUANGFU Gang, JIANG Chao-song. 2000. Study on Tengchong Volcanic Activity[M]. Yunnan Science and Technology Press, Kunming (in Chinese).
[11]	刘国明, 康建红, 张宇, 等. 2022. 火山监测与研究的前沿阵地: 火山监测站[J]. 矿物岩石地球化学通报, 41(5): 1069—1072.
	LIU Guo-ming, KANG Jian-hong, ZHANG Yu, et al. 2022. The front position of volcano monitoring and research: Volcano monitoring station[J]. Bulletin of Mineralogy, Petrology and Geochemistry, 41(5): 1069—1072 (in Chinese).
[12]	刘国明, 杨景奎, 王丽娟, 等. 2011. 长白山火山活动状态分析[J]. 矿物岩石地球化学通报, 30(4): 393—399.
	LIU Guo-ming, YANG Jing-kui, WANG Li-juan, et al. 2011. Active level analysis of the Tianchi volcano in Changbaishan, China[J]. Bulletin of Mineralogy, Petrology and Geochemistry, 30(4): 393—399 (in Chinese).
[13]	刘明军, 顾梦林, 孙振国, 等. 2004. 长白山天池火山主断裂活动与热液蚀变带[J]. 中国地震, 20(1): 64—72.
	LIU Ming-jun, GU Meng-lin, SUN Zhen-guo, et al. 2004. Activity of main faults and hydrothermal alteration zone at the Tianchi volcano, Changbaishan[J]. Earthquake Research in China, 20(1), 64—72 (in Chinese).
[14]	刘绍府, 刘冬至, 李辉. 1991. 高精度重力测量平差及其软件[J]. 地震, (4): 57—66.
	LIU Shao-fu, LIU Dong-zhi, LI Hui. 1991. Adjustment of high precision gravity measurements and its software[J]. Earthquake, (4): 57—66 (in Chinese).
[15]	马学英, 滕吉文, 刘有山, 等. 2016. 长白山火山区壳幔物性结构与深部物理场特征[J]. 地球物理学进展, 31(5): 1973—1985.
	MA Xue-ying, TENG Ji-wen, LIU You-shan, et al. 2016. Physical property structure of the crust-mantle and deep geophysical feature in Changbaishan volcanic area[J]. Progress in Geophysics, 31(5): 1973—1985 (in Chinese).
[16]	潘纪顺, 顾梦林, 赵成斌, 等. 2006. 长白山天池火山区浅部构造特征研究[J]. 地震学报, 28(4): 399—407.
	PAN Ji-shun, GU Meng-lin, ZHAO Cheng-bin, et al. 2006. Study on shallow structural features in Changbaishan Tianchi volcanic region[J]. Acta Seimologica Sinca, 28(4): 399—407 (in Chinese).
[17]	钱程, 崔天日, 唐振, 等. 2022. 基于钻井温的长白山天池火山北坡浅部岩浆房赋存深度研究[J]. 地质与资源, 31(4): 553—562.
	QIAN Cheng, CUI Tian-ri, TANG Zhen, et al. 2022. Covered depth of superficial magma chamber on the northern slope of Tianchi volcano in Changbai mountain based on borehole temperature[J]. Geology and Resources, 31(4): 553—562 (in Chinese).
[18]	仇根根, 裴发根, 方慧, 等. 2014. 长白山天池火山岩浆系统分析[J]. 地球物理学报, 57(10): 3466—3477.
	QIU Gen-gen, PEI Fa-gen, FANG Hui, et al. 2014. Analysis of magma chamber at the Tianchi volcano area in Changbai mountain[J]. Chinese Journal of Geophysics, 57(10): 3466—3477 (in Chinese).
[19]	阮帅, 汤吉, 董泽义, 等. 2020. 基于三维大地电磁 AR-QN 反演的长白山天池火山区电性结构[J]. 地震地质, 42(6): 1282—1300. doi: 10.3969/j.issn.0253-4967.2020.06.002.
	RUAN Shuai, TANG Ji, DONG Ze-yi, et al. 2020. Electric structure model of Tianchi volcano in Changbai mountains based on three-dimensional AR-QN magnetotelluric inversion[J]. Seismology and Geology, 42(6): 1282—1300 (in Chinese).
[20]	孙帮民, 吴燕冈, 管彦武. 2014. 重磁联合反演解释在长白山天池深部构造中的应用[J]. 世界地质, 33(4): 910—915.
	SUN Bang-min, WU Yan-gang, GUAN Yan-wu. 2014. Application of joint inversion interpretation of gravity and magnetism in Tianchi deep structure of Changbai Mountain[J]. Global Geology, 33(4): 910—915 (in Chinese).
[21]	汤吉, 邓前辉, 赵国泽, 等. 2001. 长白山天池火山区电性结构和岩浆系统[J]. 地震地质, 23(2): 191—200.
	TANG Ji, DENG Qian-hui, ZHAO Guo-ze, et al. 2001. Electric conductivity and magma chamber at the Tianchi volcano area in Changbaishan mountain[J]. Seismology and Geology, 23(2): 191—200 (in Chinese).
[22]	汤吉, 刘铁胜, 江钊, 等. 1997. 长白山天池火山区大地电磁测深初步观测[J]. 地震地质, 19(2): 164—170.
	TANG Ji, LIU Tie-sheng, JIANG Zhao, et al. 1997. Preliminary observations of the Tianchi volcano area in Changbaishan Mountain by MT method[J]. Seismology and Geology, 19(2): 164—170 (in Chinese).
[23]	唐攀攀, 单新建, 王长林. 2014. 基于PSInSAR技术的长白山天池火山形变监测[J]. 地震地质, 36(1): 177—185. doi: 10.3969/j.issn.0253-4967.2014.01.014.
	TANG Pan-pan, SHAN Xin-jian, WANG Chang-lin. 2014. Research on the deformation monitoring of Changbaishan volcano based on PSInSAR technique[J]. Seismology and Geology, 36(1): 177—185 (in Chinese).
[24]	王谦身, 安玉林, 张赤军, 等. 2003. 重力学[M]. 北京: 地震出版社.
	WANG Qian-shen, AN Yu-lin, ZHANG Chi-jun, et al. 2017. Gravitology[M]. Seismological Press, Beijing (in Chinese).
[25]	王武, 陈棋福. 2017. 长白山火山区地壳S波速度结构的背景噪声成像[J]. 地球物理学报, 60(8): 3080—3095.
	WANG Wu, CHEN Qi-fu. 2017. The crust S-wave velocity structure under the Changbaishan volcano area in northeast China inferred from ambient noise tomography[J]. Chinese Journal Geophysics, 60(8): 3080—3095 (in Chinese).
[26]	魏恋欢, 张嘉祺, 孙颖, 等. 2023. 基于时序SAR数据的长白山天池火山活动研究[J]. 地球物理学报, 66(10): 4057—4073.
	WEI Lian-huan, ZHANG Jia-qi, SUN Ying, et al. 2023. Analysis on the volcanic activity of Changbaishan Tianchi volcano with time series SAR data[J]. Chinese Journal Geophysics, 66(10): 4057—4073 (in Chinese).
[27]	吴建平, 明跃红, 苏伟, 等. 2009. 长白山火山区壳幔S波速度结构研究[J]. 地震地质, 31(4): 584—597. doi: 10.3969/i.issn.0253-4967.2009.04.002.
	WU Jian-ping, MING Yue-hong, SU Wei, et al. 2009. S-wave velocity structure beneath Changbaishan Tianchi volcano inferred from receiver function[J]. Seismology and Geology, 31(4): 584—597 (in Chinese).
[28]	吴建平, 明跃红, 张恒荣, 等. 2007. 长白山天池火山区的震群活动研究[J]. 地球物理学报, 50(4): 1089—1096.
	WU Jian-ping, MING Yue-hong, ZHANG Heng-rong, et al. 2007. Earthquake swarm activity in Changbaishan Tianchi volcano[J]. Chinese Journal Geophysics, 50(4): 1089—1096 (in Chinese).
[29]	吴建平, 明跃红, 张恒荣, 等. 2005. 2002年夏季长白山天池火山区的地震活动研究[J]. 地球物理学报, 48(3): 621—628.
	WU Jian-ping, MING Yue-hong, ZHANG Heng-rong, et al. 2005. Seismic activity at the Changbaishan Tianchi volcano in the summer of 2002[J]. Chinese Journal of Geophysics, 48(3): 621—628 (in Chinese).
[30]	熊国华, 季灵运, 刘传金. 2023. 长白山天池火山2015—2022年InSAR变形与活动状态分析[J]. 地震地质, 45(6): 1309—1327. doi: 10.3969/j.issn.0253-4967.2023.06.004.
	XIONG Guo-hua, JI Ling-yun, LIU Chuan-jin. 2023. Analysising the surface deformation and present-day magma activity of Changbaishan-Tianchi volcabo from 2015 to 2022 with InSAR technology[J]. Seismology and Geology, 45(6): 1309—1327 (in Chinese).
[31]	张成科, 张先康, 赵金仁, 等. 2002. 长白山天池火山区及邻近地区壳幔结构探测研究[J]. 地球物理学报, 45(6): 812—820.
	ZHANG Cheng-ke, ZHANG Xian-kang, ZHAO Jin-ren, et al. 2002. Study on the crustal and upper mantle structure in the Tianchi volcanic region and its adjacent area of Changbaishan[J]. Chinese Journal of Geophysics, 45(6): 812—820 (in Chinese).
[32]	张先康, 张成科, 赵金仁, 等. 2002. 长白山天池火山区岩浆系统深部结构的深地震测深研究[J]. 地震学报, 24(2): 135—143.
	ZHANG Xian-kang, ZHANG Cheng-ke, ZHAO Jin-ren, et al. 2002. Deep seismic sounding investigation into the deep structure of the magma system in Changbaishan Tianchi volconic region[J]. Acta Seismologica Sinica, 24(2): 135—143 (in Chinese).
[33]	祝意青, 刘芳, 张国庆, 等. 2022. 中国流动重力监测与地震预测[J]. 武汉大学学报(信息科学版), 47(6): 820—829.
	ZHU Yi-qing, LIU Fang, ZHANG Guo-qing, et al. 2022. Mobile gravity monitoring and earthquake prediction in China[J]. Geomatics and Information Science of Wuhan University, 47(6): 820—829 (in Chinese).
[34]	Bagnardi M, Poland M P, Carbone D, et al. 2014. Gravity changes and deformation at Kīlauea Volcano, Hawaii, associated with summit eruptive activity, 2009-2012[J]. Journal of Geophysics Research, 119(9): 7288—7305.
[35]	Battaglia M, Roberts C, Segall P. 1999. Magma intrusion beneath Long Valley caldera confirmed by temporal changes in gravity[J]. Science, 285(5436): 2119—2122.
[36]	Battaglia M, Segall P, Roberts C. 2003. The mechanics of unrest at Long Valley caldera, California: 2. Constraining the nature of the source using geodetic and micro-gravity data[J]. Journal of Volcanology and Geothermal Research, 127(3-4): 219—245.
[37]	Biggs J, Ebmeier S K, Aspinall W P, et al. 2014. Global link between deformation and volcanic eruption quantified by satellite imagery[J]. Nature Communications, 5(4): 3471.
[38]	Brown G C, Rymer H, Stevenson D. 1991. Volcano monitoring by microgravity and energy budget analysis[J]. Journal of the Geological Society, 148(3): 585—593.
[39]	Carbone D, Budetta G, Greco F, et al. 2007. A data sequence acquired at Mt. Etna during the 2002-2003 eruption highlights the potential of continuous gravity observations as a tool to monitor and study active volcanoes[J]. Journal of Geodynamics, 43(2): 320—329.
[40]	Choi S C, Oh C W, Götze H J. 2013. Three-dimensional density modeling of the EGM2008 gravity field over the Mount Paekdu volcanic area[J]. Journal of Geophysical Research: Solid Earth, 118(7): 3820—3836.
[41]	Gottsmann J, Berrino G, Rymer H, et al. 2003. Hazard assessment during caldera unrest at the Campi Flegrei, Italy: A contribution from gravity-height gradients[J]. Earth and Planetary Science Letters, 211: 295—309.
[42]	Gottsmann J, Rymer H. 2002. Deflation during caldera unrest: Constraints on subsurface processes and hazard prediction from gravity-height data[J]. Bulletin of Volcanology, 64(5): 338—348.
[43]	Hammond J O S, Wu J P, Ri K S, et al. 2020. Distribution of partial melt beneath Changbaishan /Paektu volcano, China/Democratic People’s Republic of Korea[J]. Geochemistry, Geophysics, Geosystems, 21: e2019GC008461.
[44]	Jousset P, Dwipa S, Beauduce F, et al. 2000. Temporal gravity at Merapi during the 1993-1995 crisis: An insight into the dynamical behaviour of volcanoes[J]. Journal of Volcanology and Geothermal Research, 100(1-4): 289—320.
[45]	Kim J R, Lin S Y, Hong S, et al. 2014. Ground deformation tracking over Mt. Baekdu: A pre-evaluation of possible magma recharge by D-InSAR analysis[J]. KSCE Journal of Civil Engineering, 18(5): 1505—1510.
[46]	Kim S W, Won J S. 2004. Slow deformation of Mt. Baekdu stratovolcano observed by satellite radar interferometry[C]. Proceedings of the FRINGE 2003 Workshop(ESA SP-550), 1—5 December 2003, ESA/ESRIN, Frascati, Italy.
[47]	Lee C W. 2014. Baekdusan volcano time-series analysis from 1992 to 1998 using multi-interferogram InSAR processing[J]. Terrestrial Atmospheric and Oceanic Sciences, 25(6): 743—754.
[48]	Meng Z, Shu C, Yang Y, et al. 2022. Time series surface deformation of Changbaishan volcano based on Sentinel-1B SAR data and its geological significance[J]. Remote Sensing, 14(5): 1213.
[49]	Pan B, Liu G, Cheng C, et al. 2021. Development and status of active volcano monitoring in China[J]. Geological Society, London, Special Publications, 510(1): 227—252.
[50]	Rymer H, Brown G C. 1989. Gravity changes as a precursor to volcanic eruption at Poas volcano, Costa Rica[J]. Nature, 342: 902—905.
[51]	Rymer H, Murray J B, Brown G C, et al. 1993. Mechanisms of magma eruption and emplacement at Mt. Etna between 1989 and 1992[J]. Nature, 361(6411): 439—441.
[52]	Rymer H, Vries B V W D, Stix J, et al. 1998. Pit crater structure and processes governing persistent activity at Masaya Volcano, Nicaragua[J]. Bulletin of Volcanology, 59(5): 345—355.
[53]	Rymer H, Williams-Jones G. 2000. Volcanic eruption prediction: Magma chamber physics from gravity and deformation measurements[J]. Geophysical Research Letters, 27(16): 2389—2392.
[54]	Savage J C. 1984. Local gravity anomalies produced by dislocation sources[J]. Journal of Geophysics Research: Solid Earth, 89(B3): 1945—1952.
[55]	Song J L, Hetland E A, Wu F T, et al. 2007. P-wave velocity structure under the Changbaishan volcanic region, NE China, from wide-angle reflection and refraction data[J]. Tectonophysics, 433(1-4): 127—139.
[56]	Trasatti E, Tolomei C, Wei L, et al. 2021. Upward magma migration within the multi-Level plumbing system of the Changbaishan Volcano(China/North Korea)Revealed by the modeling of 2018-2020 SAR data [J]. Frontiers in Earth Science, 9: 741287.
[57]	Wang D Z, Zhao B, Liu D Y, et al. 2021. Geodetic monitoring of the Changbaishan volcano activity and its relationship with earthquakes[J]. Geodesy and Geodynamics, 12(4): 239—248.
[58]	Wei L H, Sun Y, Pan X Y, et al. 2024. Dynamics of the 2021 unrest at Changbaishan Tianchi volcano from ALOS-2/PALSAR-2 and seismic data[J]. International Journal of Applied Earth Observation and Geoinformation, 128:103775.
[59]	Williams-Jones G, Rymer H. 2002. Detecting volcanic eruption precursors: A new method using gravity and deformation measurements[J]. Journal of Volcanology and Geothermal Research, 113(3-4): 379—389.
[60]	Xu J D, Liu G M, Wu J P, et al. 2012. Recent unrest of Changbaishan volcano, northeast China: A precursor of a future eruption?[J]. Geophysics Research Letters, 39(16): L16305.
[61]	Yang B, Lin W L, Hu X Y, et al. 2021. The magma system beneath Changbaishan-Tianchi Volcano, China/North Korea: Constraints from three-dimensional magnetotelluric imaging[J]. Journal of Volcanology and Geothermal Research, 419(11): 107385.
[62]	Zhao L Q, Zhan Y, Kiyan D, et al. 2024. Magnetotelluric evidence for the deep causes of different eruptive styles of Changbaishan Tianchi and Longgang volcanoes. Scientific Reports, 14:24897.
[63]	Zhu H X, Tian Y, Zhao D P, et al. 2018. Seismic structure of the Changbai intraplate volcano in NE China from joint inversion of ambient noise and receiver functions[J]. Journal of Geophysical Research: Solid Earth, 124: 4984—5002.