Journal of Palaeogeography

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A study on the time of bridge sinking into the sea at Qiaotou village in Dongzhai port,northern Hainan Province and slow sinking rate and mechanism of Dongzhai port after Qiongzhou earthquake

Qihao XU

J Palaeogeogr, 2024, 26(3): 725-752. DOI: 10.7605/gdlxb.2024.02.024

序号	地震时间	地震地点与震级(M)	调查地区	地层及地下水状况	构造及活动方式	地震时地面垂直运动幅度/m	地震后地面垂直运动速率/cm·a^-1
1	1862	俄罗斯贝加尔湖色楞格河三角洲10级地震	色楞格河三角洲	湖相沉积和湖岸现代三角洲沉积,地下水非常丰富	贝加尔湖处贝加尔裂谷(Baikal rift)带内,长636 km,最深达1637 m,是构造湖。该裂谷带是一个活动的断裂带,长1600 km,宽60~250 km,是现今大陆内部最年轻的大陆裂谷之一,围限裂谷的所有边界断裂都是正断层(局部有正断兼有逆断活动断层)(李鄂荣和张义勋,1983;Sherman等,2013)。新生代玄武岩和温泉在裂谷内广泛分布。贝加尔地堑下方莫霍面隆起约6 km,异常地幔十分接近地表,推断贝加尔裂谷正是低密度上地幔隆起对断裂的扩展使地壳受到张力形成的。裂谷带构造运动强烈,每年地震达2000余次(吴珍汉1997;杨文采2014)。由于裂谷不断扩展,湖区也不断扩大	由于地震,一大片三角洲平原3天内沉没到贝加尔湖水面下,形成一个塌陷湾	100年后湖湾水深达7.5 m,其深度比原来增大2倍,并形成了一个被称为普罗瓦尔的大片新的塌陷湾(O. K列昂节夫,1965)推测震后100年平均下沉速率约3.5 cm/a
2	1511(明正德六年).6.1	中国云南省永胜6¾级地震	永胜盆地	盆地内全新世湿地砂黏土沉积,地下水丰富	区内主要有程海断裂,是滇西北地区东缘最醒目的一条活动性大断裂,其走向近南北,全长200 km,由一系列北东走向左旋走滑正断层,和近南北向正断层及其相间的一系列拉分盆地组合而成,断裂带控制着金官、永胜、程海、期纳、宾川等盆地的边界,永胜盆地是晚更新世以来形成的盆地(刘光勋等,1986;谢富仁等,1994)	下沉	西山草海,在近屯西山下,明初原系军民田地,正德六年地震累月,遂沉为湖,田陷成湖者百有余顷,积水经年不涸(中国科学院地震工作委员会历史组,1956)。经过正德六年地震,原为西山田地的西山草海逐渐下沉成为一个范围达万米、湖周约20里的湖泊洼地(王越2004)。
3	1918.2.13	中国广东省南澎—南澳地震,M7¼级	南澳岛东侧海岸	混合花岗岩及滨海相沉积,海水覆盖,裂隙带地下水丰富	震后大速率缓慢下沉海岸主要沿南澳岛东侧NW向饶平黄岗水断裂展布。该断裂不同时期压性、张性有所展示,是1918年发震断裂之一,地震前沿断裂附近的柘林镇海滨有7个温泉,震后剩3个。震时沿断裂在饶平县东南从北山、大港,经所城镇,神前有一走向N30°W的地裂带,长7000 m,宽3~10 m。沿带喷砂冒水剧烈(张虎男等,1990),推测震前、震时及震后沿断裂都有张性活动。在震中区及附近的南澎、南澳、东山地区,岛屿众多,是新生代以来壳下隆起拉张活动,表面凹陷之处	地震时发生近岸海啸(王锋等,2005),推测极震区震时下沉,下沉地貌明显	震后60年平均下沉速率约4 cm/a(徐起浩1986d;刘以宣,1994)
4	1969.7.18 1888 1597	中国渤海湾近岸海域 M7.4 M7.5 M7.0	现代黄河入海口,东营、垦利、义和庄等处	现代滨海相沉积,现代三角洲沉积,地下水丰富	震区所在的渤海湾盆地是在前新生代构造的基础上经新生代裂陷作用发育而成的一个大型裂陷盆地。其中渤中坳陷新生代地层厚达9000余米,上第三系和第四系最厚达4800 m。震区及其附近存在北北东,北东,北西和近东西向4组断裂,地震就发生在这些断裂交汇带及其附近。这些断裂或为铲形正断层,或发育有次级正断层(徐杰等,2001)。又据研究,渤海区内地壳仅厚28~29 km,上地幔隆起,等温居里面埋深浅(为12 km),为较高热流值区(56~77 mW/m²)。认为渤海湾很可能是一个潜在的尚在发展中的地幔热柱(郝书俭和王春华,1982;滕吉文等,1997)	下沉	震后海岸地壳缓慢下沉,速率达3.2-6.8 cm/a(师长兴等,2003;别君等,2006;徐起浩,2020)
5	约距今7000 a和距今2400 a左右	中国福建省晋江市深沪湾地区全新世2次大于7级古地震	深沪湾海域和潮间带地区及沿岸深沪—金井地堑和附近地区	深沪湾地堑内及海底含薄层全新世海相砂,黏土沉积(地堑内还含风成砂沉积)透水性较好。下部为混合花岗岩及风化土和晚更新世含砾砂黏土沉积透水性不好。但控制深沪湾地堑的北东侧深沪—金井断裂和旁侧的断裂沟(乌漏沟)北东,南西端都延入海域。北西侧的衙口—州断裂的南西端、北东端也延入海域,推测地下裂隙水丰富	深沪湾—金井地堑由东南侧的北东走向的深沪—金井断裂及西北侧的衙口—州断裂控制。根据断裂两侧沉积物分析推断晚更新世末期以来,深沪—金井断裂北段(控制深沪湾段)活动量是南段的4倍之多。断裂两盘相对运动速率为0.9~2.3 mm/a,平均1.6 mm/a(陈玉仁等,1982,1983)。通过激光测距分析,根据位移矢量方向判断该断裂以拉张为主(丁祥焕等,1999)。深沪湾在距今7000 a和距今2400 a左右分别发生大的古地震(徐起浩等,2001,2002;徐起浩和施建生,2012a),衙口—州断裂在距今2400 a的大古地震时对深沪湾地堑西北侧地块产生掀斜作用,使西北侧多条古河流被断裂堵塞,形成呈线状展布的前港湖、龙湖、虺湖等地震断塞湖(徐起浩和施建生,2012a,2012b)。深沪湾及所在的深沪—金井地堑和两侧控制地堑的深沪—金井断裂及衙口—州断裂都属于东南沿海区域性的长乐—诏安断裂的破裂组成部分,该断裂的活动又与太平洋板块对大陆板块的挤压有关。由于挤压,闽东南沿海莫霍面为一隆起带(丁祥焕等,1989)。福建、特别是闽中和闽南晚更新世以来沿海地壳隆起,海岸普遍抬升(谢志平和陈园田,1995;徐起浩等,2002),长乐—诏安断裂在深沪湾拉张、破裂,发生大地震,深沪湾呈地堑形下沉	距今7000 a左右深沪湾大古地震,计算得同震下沉约3.6 m(徐起浩等,2001),深沪湾形成潟湖环境。距今2400年深沪湾又一次发生大古地震,同震下沉约3.1 m。古森林陷入更深海底(徐起浩等,2001,2002),沿岸生成龙湖、前港湖、虺湖等地震断塞湖(徐起浩和施建生,2012a,2012b)	距今约7000 a古地震后至距今2800 a震后缓慢下沉幅度约1.0 m(徐起浩等2001),平均年速率为0.24 mm/a。如果该缓慢下沉幅度主要在震后前1000 a,或前500 a,或前100 a形成,则缓慢下沉速率分别为1.0 mm/a,及2.0 mm/a和1.0 cm/a。距今2400 a至今沉积约1 m(该层底部20 cm红色砂可能为风成砂,为可能的距今2400 a的地震沉积相,未计入)。距今2400 a水动型海平面在约-0.20 m,实际震后缓慢下沉为0.80 m(徐起浩等2001)。平均下沉速率为0.3 mm/a,所以晚全新世地震后深沪湾地壳下沉幅度也是很小的.如果该幅度为震后1000 a,或500 a,或100 a内形成,则缓慢下沉速率分别为0.8 mm/a,或1.6 mm/a,或8 mm/a

Table 1 Earthquake examples of coseismic subsidence and subsequent sustained slow sinking rates and theirs formation environment

Other figure/table from this article

Fig.1 Distribution of some ruins formed by land falling into the sea on the shoal after low tide at Dongzhai port,Nouthern Hainan Province
Fig.2 Location of ruins of bridge and strip stone pavement at north head of bridge in Qiaotou village of Yanfeng district of Qionshan county and around landform
Fig.3 Sketch map showing ruins of bridge and strip stone pavement at north head of the bridge that sank into the sea and their surroundings in Qiaotou village of Yanfeng district of Qiongshan county,Hainan Province
Fig.4 Ruins of strip stone pavement at north head of bridge in Qiaotou village and tomb of Chen Tingluan,ancestor of Ming Dynasty of Qiaotou village people
Table 2 Tide difference of ports in northern Hainan Province
Table 3 Textual criticism for time of Chen Tingluan died of first generation of Qiaotou village
Fig.5 Sea level has risen,and coast of Dongzhai port has been eroded
Fig.6 Sea is approaching villages,and dock is destroyed
Fig.7 Bridge damage and well water becomes salty or abandoned or collapse to seabed or be buried due to sea level rise
Fig.8 Local villagers identified this as ancient lushanshi village in Dongzhai Port that is slowly sank into sea after earthquake
Fig.9 Fisherman and coastal residents of Dongzhai port measured the magnitude of sea level rise over past few decades based on experience at seaside scene
Fig.10 Map of the Holocene marine immersion range and distribution areas of ancestors living before 1605 Qiongzhou earthquake in Dongzhai port and surrounding areas of east part of northern Hainan Province
Fig.11 In the 24th year of Kangxi reign of Qing Dynasty(1685),Wenchang County picture of Guangdong and the Picture recorded three tributaries of Sanjiangshui river that has Dongzhai river(Dongzhai Port)^②
Fig.12 Geographical location map of Dongzhai port that had been one of the tributaries of Sanjiangshui river in northern Wenchang county drawn by Qiongzhou Prefecture Annals in Xinchou year of Qing Dynasty’s Daoguang reign(1841)^③
Fig.13 Location map of Dongzhai port of North Hainan Island in Wenchang County Annals in the fifth year of Xianfeng reign of Qing Dynasty(1855)^①
Fig.14 Geographical map of Dongzhai port and its surrounding areas in northern part of Wenchang county marked by Guangdong map during Tongzhi period of Qing Dynasty(1862-1874)^③

模态框（Modal）标题

Figure/Table detail