Earth and Planetary Magnetism
The Earth and Planetary Magnetism (EPM) group is working on models to clarify invisible processes in the Earth's interior and so to understand the mechanisms that lead to the convection currents and the dynamo effect.
The Earth is surrounded by a magnetic field that protects us against extraterrestrial radiation. The field originates in the Earth's interior: surrounding an inner core of solid iron lies an outer core of molten iron and light elements such as oxygen, silicon and sulphur. As a result of temperature differences in the outer core the fluid is in constant motion, and convection currents arise. These cause electrical currents, which in turn are the origin of magnetic fields. The generation of the magnetic field from convection currents is known as the “dynamo effect”.
Based on measurements of the magnetic field on the Earth's surface and with the aid of orbiting satellites, the appearance of the magnetic field at the surface of the liquid outer core can be deduced. To simulate the physical conditions that underlie convection currents, complex calculations must be carried out.
For this purpose the research group led by Andrew Jackson makes use of the Swiss National Supercomputing Centre (CSCS) in Manno, Ticino. The results will help us to clarify the origin of the Earth's magnetic field, which has existed for billions of years. It may also be possible to acquire a better understanding of why the magnetic field reverses polarity from time to time – the most recent occurrence being 780,000 years ago. The simulations could also be useful in astronomy and allow conclusions about the magnetic activity of other planets in the solar system.
In addition to the magnetic fields of the Earth and planets, the EPM group also researches the magnetic properties of natural materials. They measure, for example, the magnetism of minerals and lake sediments that have been recovered from drill cores. The results deliver information about the composition of the environment. In addition, human tissue is the subject of magnetic research in the group: the magnetic composition is being studied for indicators related to certain neurological illnesses such as Alzheimer's disease.
Andrew Jackson's group is also developing new techniques, based on magnetic principles, to study the deformation of rocks. Most experiments are carried out in the Laboratory for Natural Magnetism, a building constructed so as to be almost free of magnetic fields, located on the edge of the city.
Contact
Head of Institute of Geophysics
Institut für Geophysik
Sonneggstrasse 5
8092
Zürich
Switzerland
