Seafloor deformation and point convergence of and between two CORK monuments off Nicoya Peninsula, Costa Rica

拟议项目的总体目标是监测哥斯达黎加尼科亚半岛外中美洲俯冲带海底的变形（垂直运动和倾斜）。在第205号立法期间安装的两个软木塞将用作海底大地测量纪念碑，并配备高分辨率的最先进的点位置监测设备。这些设备是(1)水位传感器，即压力表，在相对于平均海平面的垂直位置的环境压力下提供0.7mm的分辨率；(2)自流平双轴倾斜仪，测量两个垂直水平方向的角度位移，具有非常高的Snrad分辨率。为了控制环境条件，监测系统将包括高分辨率温度记录仪。这些测量将持续大约两年的时间，每隔几分钟采样一次，以提供全面的多尺度软木运动数据集。将详细研究地层压力变化和两个软木塞之间的微分运动等对软木塞运动的局部影响。科克运动的确定值将与全球板块构造运动模式进行比较和联系，同时由其他小组在陆地上测量。其中一个位置（1253站点）位于变形锋向海约200米的海沟中，而另一个位置（1255站点）距离1253仅600米，位于变形锋向弧形400米处。通过监测两个地点的压力和倾斜度，我们将能够测量相对和绝对变形。该公司计划在2007年秋季使用ROV/潜水器安装该系统，并在大约两年后将其回收。

The overall goal of the proposed project is to monitor seafloor deformation (vertical movement and tilt) of the seafloor at the Middle American subduction zone off Nicoya Peninsula, Costa Rica. Two CORKs, installed during Leg 205 will be used as seafloor geodetic monuments and equipped with high resolution state-of-the-art point position monitoring devices. The devices are (1) a water level sensor, i.e. a pressure meter, that provides 0.7mm resolution at ambient pressure of the vertical position with respect to mean sea level and (2) self-leveling biaxial tiltmeters that measure the angle displacements in two perpendicular horizontal directions with a very high resolution of Snrad. To control environmental conditions high resolution temperature loggers will be included in the monitoring system. The measurements will run over approximately two years at sampling intervals of some minutes to provide a comprehensive multi-scale data set of CORK motion. Local influences on CORK motion from e.g. formation pressure changes and differential motion between both CORKs will be studied in detail. The determined values of CORK motion will be compared and linked to the global plate tectonic movement pattern, measured on land at the same time by other groups. One of the locations (Site 1253) is located in the trench about 200m seaward of the deformation front whereas the other location (Site 1255) is only 600m away from 1253 and located 400m arcward of the deformation front. By monitoring pressures and tilt at both sites we will be able to measure relative as well as absolute deformation. It is planned to install the system in the fall of 2007 with a ROV/submersible and recover it about two years later.