Collaborative Research: Event response to an eruption at Axial Seamount

2015年4月24日，美国国家科学基金会资助的海洋观测站倡议（OOI）电缆阵列探测到轴向海山可能爆发，预示着8000次小地震和火山口中心海底迅速下沉2.4米。岩浆在山顶火山口内或附近喷发的证据包括OOI电缆阵列上的仪器记录的急剧温度上升-事件发生后数周内持续高于环境温度0.6-0.7°C。这次喷发很可能极大地扰乱了山顶火山口内及周围的热液和生物系统，并提供了难得的机会来解决时间紧迫的科学问题，这些问题只能通过近期的海底调查来调查。2015年8月，由美国国家科学基金会和美国国家海洋和大气管理局资助，由ROV Jason和AUV Sentry组成的R/V Thompson船将前往轴向海山进行巡航，这为此类响应提供了绝佳的机会。这项研究为这次航行增加了3天的时间，以促进时间关键事件响应科学。通过船上多波束声纳和近底哨兵测量，详细的海底测绘将覆盖火山口和邻近裂谷区的区域，这些区域是预计的喷发地点。如果找到新的岩石，将使用210Po-210Pb技术进行采样和定年。热液羽流将被CTD铸件和传感器拖带识别。系泊系统将配备微型自主羽流记录仪，用于测量温度、光衰减和氧化还原电位。海上小组计划为更广泛的科学界提供样本和数据，以对海底过程进行有针对性的研究。

On 24 April 2015, the NSF-funded Ocean Observatories Initiative's (OOI) Cabled Array detected the onset of a probable eruption at Axial Seamount, heralded by a swarm of 8000 small earthquakes and a rapid subsidence of the seafloor by 2.4 meters at the center of the caldera. Evidence that lava was erupted in or near the summit caldera includes a dramatic temperature rise recorded by instruments on the OOI Cabled Array-- up to 0.6-0.7°C above ambient sustained for weeks after the event. This eruption is likely to have significantly perturbed the hydrothermal and biological systems in and around the summit caldera, and provides the rare opportunity to address time-critical scientific questions that can only be investigated with the near-term seafloor investigations. A currently scheduled NSF and NOAA funded cruise to Axial Seamount on R/V Thompson with ROV Jason and AUV Sentry in August 2015 provides an excellent opportunity for such a response. This study adds 3 days onto this cruise to facilitate time-critical event response science.Detailed seafloor mapping with shipboard multi-beam sonar and near-bottom Sentry surveys will cover areas of the caldera and adjacent rift zones that are expected eruption site(s). Fresh rock, if located, will be sampled and dated using the 210Po-210Pb technique. Hydrothermal plumes will be discerned with CTD casts and sensor tows. A mooring will be deployed with Miniature Autonomous Plume Recorders to measure temperature, light attenuation, and redox potential. The at-sea team plans to make samples and data available to the broader science community for targeted research on seafloor processes.