Ligurian Ocean Bottom Seismology and Tectonics Research (LOBSTER)

利古里亚海底地震学和构造研究（龙虾）

• 批准号: 362727397
• 负责人: Professorin Dr. Heidrun Kopp
• 金额: --
• 依托单位: Forschungseinheit Marine Geodynamik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/362727397?language=en
• 关键词: Ligurian; Ocean; Bottom; Seismology; Tectonics

The aim of the proposed LOBSTER activity field within SPP 4D-MB is twofold: 1) to deploy a network of French/German ocean bottom seismometers (OBS) in the Ligurian Sea to serve as the marine component of the seismic network of AlpArray, and 2) to correct and process the marine data in order to be compatible with onshore data. AlpArray is a European initiative with the aim to deploy several hundred closely spaced broadband seismometers that will cover the entire Alpine orogen to provide state-of-the-art imaging of subsurface structures. The offshore component of SPP 4D-MB and AlpArray involves deployment of 33 broadband OBS from France/Germany in the Ligurian Sea. The deployment of the German stations is applied for here. To this end, colleagues in France have secured ship time in 2017 for the deployment. Simultenously, a ship time proposal has been submitted in Germany and 14 days of ship time have been granted on RV Meteor/Merian for the spring of 2018 for instrument recovery in order to share ship-related costs between the two nations. OBS recordings will be essential to define subsurface structures at the transition from the Western Alps to the Apennines and improve our understanding of the 3D-geometry of the system and its kinematics. OBS are advanced instrument systems that, as a result of their subsea operating environment, differ significantly in their operation and resultant raw data from their land-based counterparts. As a result of these fundamental differences, the main task of LOBSTER is to provide OBS data compatible with onshore data. Within the framework of SPP 4D-MB a combined analysis of onshore and offshore data requires the timely correction and provision of the marine data so that the two data sets can be merged. As a consequence, a number of processing steps must be prepared and set up prior to instrument recovery so that the work may commence as soon as the data become available during the recovery cruise. The period between the deployment and recovery cruises shall be used for this preparatory phase. The first processing step involves instrumental clock error correction. With no connection to the outside world, OBS are not able to maintain synchronization with standard timing systems (via GPS or network connection). Analysis of the cross correlation of ambient seismic noise provide techniques for nonlinear clock drift corrections. OBS are deployed remotely and without intervention in a free-fall mode - therefore, their actual horizontal orientation on the seafloor is unknown. Consequently, horizontal orientation of the OBS must be determined from measured air gun shots and/or ambient noise cross correlation. In the last step of the project we will characterize the spectral behaviour of the OBS data through probability density functions of power spectral density, which provide insights on the generation and propagating of seismic noise in the Liguria Sea.

SPP 4D-MB内拟议的LOBSTER活动场有两个目的：1）在利古里亚海部署法国/德国海底地震仪网络，作为AlpArray地震网络的海洋部分，2）校正和处理海洋数据，以便与陆上数据兼容。AlpArray是一项欧洲倡议，旨在部署数百个密集的宽带地震仪，覆盖整个阿尔卑斯山脉，提供最先进的地下结构成像。SPP 4D-MB和AlpArray的海上部分涉及在利古里亚海部署来自法国/德国的33个宽带OBS。德国站的部署适用于这里。为此，法国的同事已确保2017年的部署时间。与此同时，德国也提交了一份船期建议书，并在2018年春季批准了RV Meteor/Merian的14天船期，用于仪器回收，以分担两国之间的船舶相关成本。OBS记录将是必不可少的，以确定从西阿尔卑斯山到亚平宁山脉的过渡地下结构，并提高我们对系统的三维几何形状及其运动学的理解。OBS是一种先进的仪器系统，由于其水下操作环境，其操作和生成的原始数据与陆基对应系统有很大不同。由于这些根本性的差异，LOBSTER的主要任务是提供与陆上数据兼容的OBS数据。在SPP 4D-MB框架内，对陆上和海上数据进行综合分析需要及时纠正和提供海洋数据，以便合并这两个数据集。因此，在仪器回收之前必须准备和设置一些处理步骤，以便在回收巡航期间一旦获得数据就可以开始工作。这一准备阶段应利用部署巡航和回收巡航之间的时间。第一个处理步骤涉及仪器时钟误差校正。由于与外界没有连接，OBS无法与标准定时系统保持同步（通过GPS或网络连接）。环境地震噪声的互相关分析为非线性时钟漂移校正提供了技术。OBS是远程部署的，在自由落体模式下没有干预-因此，它们在海底的实际水平方向是未知的。因此，OBS的水平取向必须根据所测量的气枪射击和/或环境噪声互相关来确定。在该项目的最后一步，我们将通过功率谱密度的概率密度函数来表征OBS数据的谱行为，这将提供关于利古里亚海地震噪声的产生和传播的见解。