Marine gas hydrates, fluid flow, and structure at convergent margins

甲烷水合物是在水深超过600米的大陆斜坡上发现的“可燃冰”。水合物储层中甲烷的含量是巨大的。因此，水合物代表着一种巨大的潜在能源资源，并可能在控制全球气候和海底塌陷方面发挥重要作用。我研究的一个主要重点是确定温哥华岛附近甲烷水合物的分布和浓度，并随后了解它们是如何形成的。我的大部分工作将与综合海洋钻探计划（IODP）的结果联系起来，该计划目前正在温哥华岛附近钻探（2005年10月）。我的研究活动将包括分析2005年8月海底地震仪收集的海洋地震数据。我将检查地震传播时和振幅，以确定IODP计划的两个主要地点的地震速度结构；IODP的结果将校正地震模型，然后提供距钻孔1-2公里距离的水合物分布估计。计划在2007年进行一次更大规模的OBS地震调查，调查范围为5公里乘2公里，包括几个流体喷口特征，在这些特征中，海底下方已经发现了大量的水合物。此次巡航与南安普顿大学和多伦多大学合作，其独特之处在于，将使用可控源电磁设备在相同体积上收集海底电阻率的测量数据。利用电阻率和地震速度，可以大大提高水合物浓度的估计。第三个实地调查暂定在2008年，是一个OBS项目，重点关注温哥华岛外Nootka断裂带的流体喷口结构，就在大陆斜坡的海边。有关这些结构的信息可能为未来在这里进行IODP钻井提供支持。由于许多地震发生在努特卡断层上，对钻孔（可能作为海王星光纤网络的一个节点）的持续监测可能表明，火山口活动可能与地震直接相关。

Methane hydrate is "flammable ice" found on continental slopes where water depths are greater than about 600 m. The amount of methane contained in the hydrate reservoir is enormous. Hydrates thus represent a massive potential energy resource, as well as possibly playing a major role in controlling global climate and seafloor slumping. A major focus of my research is to determine the distribution and concentration of methane hydrate off Vancouver Island, and subsequently to understand how they are formed. Much of my work will be linked to results from the Integrated Ocean Drilling Program (IODP), currently drilling (Oct 2005) off Vancouver Island. My research activities will include analysis of marine seismic data collected on ocean bottom seismometers (OBSs) in Aug 2005. I will examine seismic traveltimes and amplitudes to determine the seismic velocity structure at two of the major sites of the IODP program; the IODP results will calibrate the seismic models, which then provide estimates of hydrate distribution out to distances of 1-2 km away form the drillholes. A larger-scale OBS seismic survey is planned for 2007, over an area 5 km by 2 km that includes several fluid vent features where massive hydrate has been recovered just below the seafloor. A unique feature of this cruise, which is in collaboration with the U of Southampton and the U of Toronto, is that measurements of seafloor resistivity will be collected over the same volume using controlled-source EM equipment. With both resistivity and seismic velocity, the estimates of hydrate concentration may be much improved. A third field survey, planned tentatively for 2008, is an OBS program focusing on fluid vent structures in the Nootka fault region off Vancouver Island, just seaward of the continental slope. Information on these structures may provide support for future IODP drilling here. Since many earthquakes occur on the Nootka fault, continuous monitoring of a drillhole (perhaps as a node of the NEPTUNE fibre-optic network) may demonstrate that vent activity may be directly linked to earthquakes.