Understanding rapid changes in Earth's magnetic field: timing, spatial extent, and causes of geomagnetic spikes and excursions

点击翻译按钮获取中文摘要

Earth's constantly changing magnetic field is generated by the geodynamic motion of electrically conductive fluid in Earth's outer core. Rapid and extreme changes of the field not only compromise Earth's magnetic shielding protection from harmful cosmic rays and solar wind but also pose serious threat to the navigation technology and electrical infrastructure that underpin modern society. Alarmingly, palaeomagnetic records covering the last few tens of thousand years reveal that geomagnetic field has experienced rapid excursions and spike events during which its intensity either drops to only a few percent of the present level or show extreme values greater than any observed in present and historical field. These extreme changes place crucial constraints on the dynamics of the geodynamo. Yet, the lack of well dated high-resolution and continuous records from key locations has prevented us from answering many basic questions. For example, do geomagnetic spikes/excursions grow/decay in situ or move spatially through time? This project aims to make a step change in our understanding of extreme and rapid changes of the field by reconstructing continuous records of geomagnetic excursion and spike events at unprecedented resolution using multiple types of geological archives from a longitudinal transect around the globe.