The lithosphere of the Earth, the 100 kilometer thick, solid rock cover of our planet, is made up of almost a dozen mostly stiff plates which drift on the slowly deforming mantle. Where two plates collide, the energy of their movement produces especially strong effects: Mountains are uplifted, volcanoes erupt, earthquakes occur. These convergent plate boundaries are great examples of the dynamics of the lithosphere. The active deformation in these regions takes place on all timescales from seconds to millions of years.
One focus of our research is the western rim of South America. There, the Nazca and South American plates are colliding. The energy of their collision is not only piling up the Andes, it also causes many strong earthquakes. In the past century, for example, about one third of the seismic energy released in the world was released there. In several research programs, we investigate the details of what happens when plates collide. How are blocks of rock raised, how do they deform, how does the climate or volcanism influence these processes? With geophysical methods, we image underground material and thereby map the shape and position of the subducting plate. In Chile, we have installed several automatic measuring stations, which record earthquakes, and which use GPS to sense the movement of the plates with millimeter-accuracy. These measurements also allow us to evaluate the geohazard associated with the plate movement.
We are also active from the Alps to Central Asia and Taiwan, where various plates are colliding with the Eurasian continent. As in the Andes, we are investigating how plate movement controls the deformation of the Earth's crust, its uplift, and the interaction with the erosion of mountain ranges.
In accompanying experiments, we attempt to understand the detailed causes of earthquakes and the undersea landslides that in the course of history have repeatedly caused devastating tsunamis.