Replacement of temperature loggers in CORKed ODP boreholes off Costa Rica and analysis of long-term temperature records

自2002年以来，对海洋钻孔的长期温度和压力监测一直是一项更大的协调努力的一部分，以调查通过哥斯达黎加尼科西亚半岛外俯冲带棱柱趾部的俯冲通量和流体流动。我们的近期目标是在微型温度记录仪（MTL）的存储容量被超过之前（2009年8月）恢复它们，用新的MTL取代它们，以确保未来十年的连续温度数据，并下载密封钻孔的循环障碍物改造套件（CORK）-II记录的压力数据。随后，将使用接下来四年的新温度和压力数据验证基于时间序列的前两年的关于边缘水文的初步结论。具体来说，我们预计新的观测瞬态温度和压力事件与慢滑事件已被检测到的陆上全球定位系统（GPS）和地震网络。在温度和压力数据分析中，潮汐引起的变化-通过频率分析分离-提供有关水文形成参数的信息，剩余的信号代表锋面俯冲带的水文状态。除了慢滑事件之外，未来的MTL和CORK数据还可能记录大地震（Mw >7：5）的响应，该地震被预期为一系列历史事件（1853年、1900年和1950年）之一。

Since 2002, long-term temperature and pressure monitoring in marine boreholes have been part of a larger coordinated effort to investigate subduction fluxes and fluid flow through the toe of the subduction-zone prism off Nicoya Peninsula, Costa Rica. Our immediate goals are to recover miniaturized temperature loggers (MTLs) before their memory capacity is exceeded (August 2009), to replace them with new MTLs that will ensure continuous temperature data for the next decade, and to download pressure data recorded by Circulation Obviation Retrofit Kit (CORK)-IIs that seal the boreholes. Subsequently, tentative conclusions regarding the hydrology across the margin—based on the first two years of the time series—will be verified using the new temperature and pressure data of the following four years. Specifically, we anticipate new observations of transient temperature and pressure events correlated with slow slip events that have been detected by onshore Global Positioning System (GPS) and seismic networks. In temperature and pressure data analysis, tidally induced variations—separated by frequency analysis—provide information about hydrological formation parameters and the remaining signal represents the hydrological state of the frontal subduction zone. In addition to slow slip events, future MTL and CORK data may also document the response of a large earthquake (Mw >7:5) that is anticipated as one of a sequence of historical events (1853, 1900, and 1950).