Deep Seismic Imaging of the Offshore Sector of the Campi Flegrei Caldera to Complement an Amphibic ICDP/IODP Drilling Initiative

Campi Flegrei Caldera 近海区域的深地震成像可补充两栖 ICDP/IODP 钻探计划

• 批准号: 279754638
• 负责人: Professor Dr. Volkhard Spieß
• 金额: --
• 依托单位: Fachgebiet Meerestechnik - Umweltforschung
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/279754638?language=en
• 关键词: Deep; Seismic; Imaging; Offshore; Sector

The Campi Flegrei Volcanic District belongs to the worlds most active volcanic systems. The most pronounced volcanic feature in that area is the half-submerged, quasi-circular Campi Flegrei caldera. It is still under debate whether the caldera formation was related to only one ignimbritic eruption namely, the Neapolitan Yellow Tuff (NYT) eruption at 15 ka, or if it is a nested-caldera system related to the NYT and the Campanian Ignimbrite eruption at 39 ka. The last volcanic eruption occurred in 1538 AD at the Monte Nuovo after 3500 years of quiescence. In the last decades, the Campi Flegrei caldera has been characterized by short-term episodes of unrest involving considerable ground deformation (uplift and subsidence of several meters), seismicity and increased temperature at fumaroles. Furthermore, long-term deformation can be observed in the central part of the caldera with uplift rates of several tens of meters within a few thousand years. Both long-term and short term uplift could be interpreted as eruption precursor, thereby posing high-concern for a future eruption, which would expose more than 1.5 million people living in the surroundings of the volcanic district to extreme volcanic risks. In order to improve the understanding of such unrest mechanisms and to correctly assess eruption hazards, the Campi Flegrei Volcanic District became subject to a joint approach for scientific drilling in the ICDP and IODP programmes. During a partially DFG funded, German-Italian expedition in 2008, high-resolution multi-channel seismic data were acquired to support the onshore and offshore drilling campaigns. The seismic data provide an insight into the evolution of the Campi Flegrei caldera since the NYT eruption and have been interpreted within the framework of an ongoing project in the DFG ICDP Priority Programme. Despite outstanding data quality of the uppermost 300 m below the seafloor, the signal penetration is not sufficient to achieve the required depths (~2 km) of the ICDP/IODP drilling campaigns. In the context of the present proposal another expedition is planned for 2015, during which a low-frequency seismic system shall be deployed in order to achieve signal penetration down to the target depth of the proposed ICDP/IODP drill sites. This to-be acquired seismic dataset may serve as a basis for the correlation of the recently completed onland ICDP drilling and proposed IODP drill sites in the Gulf of Pozzuoli and Naples Bay in order to develop a large scale picture of the study area. Eventually, the data shall be used to prepare an updated marine drilling campaign. Furthermore, the to-be acquired deep-penetrating seismic data would form an optimal complement to the already existing high-resolution seismic data. A joint interpretation of both datasets would provide not yet existing insights into the development of the Campi Flegrei caldera, including the time span before the Neapolitan Yellow Tuff eruption.

坎皮·弗莱格雷火山区属于世界上最活跃的火山系统。该地区最显著的火山特征是半淹没的准圆形Campi Flegrei火山口。火山口的形成是否只与一次不温不火的喷发有关，即15ka的那不勒斯黄色凝灰岩(NYT)喷发，还是与NYT和39ka的Campanian Ignimbrite喷发有关的嵌套破火山口系统，目前仍存在争议。最近一次火山喷发发生在公元1538年，在3500年的平静之后，位于蒙特诺沃的火山喷发。在过去的几十年里，Campi Flegrei火山口的特点是短期的动乱，涉及相当大的地面变形(隆起和下沉几米)、地震活动和喷气孔温度上升。此外，在火山口中部可以观察到长期的形变，在几千年内抬升速率可达几十米。长期和短期的抬升都可以被解释为火山喷发的前兆，从而引起对未来喷发的高度关注，这将使生活在火山区周围的150多万人面临极端的火山风险。为了增进对这种动乱机制的了解，并正确评估喷发危险，坎皮·弗莱格雷火山区在国际地球科学计划和国际地球科学计划方案中采取了科学钻探的联合办法。在2008年DFG部分资助的德国-意大利探险期间，获得了高分辨率多道地震数据，以支持陆上和海上钻探活动。地震数据提供了自纽约时报喷发以来Campi Flegrei火山口演化的洞察，并在DFG ICDP优先方案正在进行的项目框架内进行了解释。尽管海底最高300米处的数据质量很好，但信号穿透不足以达到ICDP/IODP钻探活动所需的深度(~2公里)。就本提议而言，计划在2015年进行另一次探险，在此期间，将部署一个低频地震系统，以实现信号向下穿透到拟议的ICDP/IODP钻井点的目标深度。这一待获取的地震数据集可作为将最近完成的陆地ICDP钻探与波佐利湾和那不勒斯海湾拟议的IODP钻探地点进行对比的基础，以便绘制研究区域的大尺度图景。最终，这些数据将被用于准备最新的海洋钻探活动。此外，待采集的深穿透地震数据将对已有的高分辨率地震数据形成最佳补充。对这两个数据集的联合解释将提供对Campi Flegrei火山口发育的尚未存在的见解，包括那不勒斯黄色凝灰岩喷发之前的时间跨度。