Geophysical Deep Sounding
Earthquake waves change their direction when they pass a boundary layer between two different materials within the Earth. For example, the rocks of the Earth's mantle have a different density, different elastic properties and a different temperature than the rocks of the crust above them. When seismic waves pass through this boundary, they are refracted, scattered, bent and reflected. These changes appear as additional onsets in seismograms. By analysing them, we can draw conclusions about the position and characteristics of the boundary layer. This is not only the case for horizontal boundaries, but also in regions in which continents collide like the Andes, the Himalayas, in continental rupture zones and in the great shear zones with high seismic risk like California or the Dead Sea. To improve the detail in investigations it is often necessary to complement the waves naturally produced by earthquakes with man-made seismic waves. The sources for such waves are big mechanical vibrators or explosions. The same mathematical-physical methods used on the scale of tectonic plates can also be used for investigating and monitoring geothermal resources, CO2 storage sites and unconventional hydrocarbon deposits.
Since the various layers in the Earth's interior also influence electric currents, electromagnetic waves can also be used to collect information about the conditions within. A second research group in our section specializes in magnetotelluric measurements. Here, too, the investigations are concerned with determining the breadth and depth of fault zones, and the imaging and monitoring of georeservoirs.
For extended seismic, seismological and magnetotelluric measurement campaigns, we operate the Geophysical Instrument Pool Potsdam (GIPP). It is the second largest such pool in the world and is available also to outside scientists at no cost. Our goal is to image the important processes within the Earth over many scales in time and space and to contribute to their understanding through interdisciplinary cooperation.