Lakes Enriquillo and Azuei, the two largest lakes in Hispaniola and in the Caribbean, have risen 10 and 5 m respectively within the last 8 years. Higher lake levels have submerged towns, road systems, agricultural lan...Lakes Enriquillo and Azuei, the two largest lakes in Hispaniola and in the Caribbean, have risen 10 and 5 m respectively within the last 8 years. Higher lake levels have submerged towns, road systems, agricultural lands and utilities, and have threatened to submerge the major overland highway that connects the Dominican Republic and Haiti. In this study, we use CHIRP seismic data, satellite imagery, and regional meteorological data to quantify and assess controls on the recent lake level rises. Although data are limited, the analyses indicate that the lakes’ water level changes may be attributed to a combination of increased rainfall and natural or man-made changes to the hydraulic connectivity of the various water bodies within the drainage basin. We show that a weak correlation exists between changes in Lake Enriquillo’s and Azuei’s water levels and precipitation rates (0.2 and 0.08 respectively, 1984-2012) and that both lakes experience periods of anti-correlation where, for example, water level drops at Lake Azuei (~20 masl) coincide with water level rises at Lake Enriquillo (41 mbsl). From these observations, we propose that the lakes experience intermittent periods of hydraulic connectivity along reactivated or newly developed stratigraphic-controlled sub-surface transport pathways. We also note that moderately small earthquakes along the large active fault system that extends through both lakes may promote or limit hydraulic conductivity on decadal or shorter time scales. The extents to which recent earthquakes have triggered changes in groundwater flow at this site remain unclear but represent an important topic of future research.展开更多
文摘Lakes Enriquillo and Azuei, the two largest lakes in Hispaniola and in the Caribbean, have risen 10 and 5 m respectively within the last 8 years. Higher lake levels have submerged towns, road systems, agricultural lands and utilities, and have threatened to submerge the major overland highway that connects the Dominican Republic and Haiti. In this study, we use CHIRP seismic data, satellite imagery, and regional meteorological data to quantify and assess controls on the recent lake level rises. Although data are limited, the analyses indicate that the lakes’ water level changes may be attributed to a combination of increased rainfall and natural or man-made changes to the hydraulic connectivity of the various water bodies within the drainage basin. We show that a weak correlation exists between changes in Lake Enriquillo’s and Azuei’s water levels and precipitation rates (0.2 and 0.08 respectively, 1984-2012) and that both lakes experience periods of anti-correlation where, for example, water level drops at Lake Azuei (~20 masl) coincide with water level rises at Lake Enriquillo (41 mbsl). From these observations, we propose that the lakes experience intermittent periods of hydraulic connectivity along reactivated or newly developed stratigraphic-controlled sub-surface transport pathways. We also note that moderately small earthquakes along the large active fault system that extends through both lakes may promote or limit hydraulic conductivity on decadal or shorter time scales. The extents to which recent earthquakes have triggered changes in groundwater flow at this site remain unclear but represent an important topic of future research.
文摘根据前人的汇编结果,活动走滑区域地质构造背景中发育大型油气田的盆地仅占全球总数的很小一部分(大约5%) o虽然从全球范围来看,走滑边缘发育的油气田数量相对较少,但诸如美国加利福尼亚州南部圣华金盆地(San Joaquin)和洛杉矶盆地(LosAngeles)等多个活动走滑盆地已产出了数十亿桶石油,因而勘探家有必要专门对其开展分析,研究控制其石油生产能力的区域地质条件和应力状态。本文的目的是对世界上发育大型油气田的四个活动走滑构造区的构造参数进行对比分析。它们分别是加利福尼亚中南部地区圣安德烈亚斯(San Andreas )断裂系统的断层和主要陆上盆地;委内瑞拉及特立尼达和多巴哥境内加勒比板块南缘及与之相关的陆上和海上盆地;苏门答腊和东南亚地区陆上和海上板块边缘的走滑断裂及相关盆地;中国东部渤海湾盆地陆上和海上走滑断裂和盆地。采用地理信息系统技术,基于由公开来源获取的资料,对这四个发育大型油气田的走滑构造区的主要地质和构造参数进行了汇编。这些参数包括根据全球定位系统(GPS)大地测量数据确定的区域板块运动方向;根据基底深度资料汇编结果确定的走滑断裂沿线的盆地类型,如大型走滑断裂侧翼的局部拉分盆地和更区域性的扭压盆地;基于地上和地下地质研究成果(大都与油气勘探有关)建立并详细描述的走滑断裂沿线的构造样式;以及这个四个地质区内研究比较深入的发育大型油气聚集的构造和地层圈闭。本次研究再一次证实了以往得出的有关大型走滑断裂沿线区域应力与构造关系的认识,并指出了远处的俯冲带可能控制着平行于板块边缘的活动走滑断裂的应力状态。
