With this experiment, by putting only a little pressure on the drilling fluid, we were able to produce 400 earthquakes, the strongest of which could be registered at a distance of 150 km in the city of Leipzig.
(Fig.44,45)
There are several lines of evidence clearly indicate that the borehole clearly reached the present- day brittle-ductile transition in the continental crust. This is for example demonstrated by a significant and very abrupt change in the deformation patterns of the mineral quartz which is a dominant mineral in the paragneissic rocks. There is a sudden decrease of dislocation densities with depth. There is an increasing rate of thermally activated recovery process, and this a picture taken from transmission electron microscope. There are very clear features for present-day on- going solution-precipitation creep phenomena.
(Fig.46)
Well this shows the situation as it is today. The two boreholes are filled with water, accessible for a variety of experiments. This was the field laboratory - the information centre. Actually still even now, more than 800,000 visitors have visited the KTB location. This is an important component of such an expensive program - also to tell the public where you spend the money for.
(Fig.47,48)
This is the present-day situation. We already conducted a large variety (number) of experiments and will use the two boreholes in future within the frame of the International Continental Scientific Drilling Program, ICDP.
(Fig.49)
The ICDP was born about 5 years ago at a conference on continental drilling which was held at Potsdam under the auspices of IUGS and IUGG and in the presence of the two presidents of these international organizations. At this conference the 250 invited experts from 28 countries reached the unanimous conclusion that there is an essential role for continental scientific drilling, and that full realization of that role requires a comprehensive international program, and that, at that time it appeared timely to grasp the opportunity to embark on such a program.
(Fig.50,51)
The results of this conference are laid down in a voluminous document. All the individual experts contributed according to their special expertise. We indicated a number of research themes which require drilling and which can be done by drilling on the continents. Many of them are similar to the research themes which have been discussed and which are being investigated in the framework of the ODP program.
(Fig.52)
Actually these themes cover a large number of pressing questions of contemporary earth sciences that are critically relevant to both the societal needs and an improved understanding of the workings of our planet. Among these are the physical and chemical processes responsible for earthquakes and volcanic eruptions, the manner in which earth's climate has changed in the recent past and the reasons for such changes, the effects of major impacts on climate and mass extinction; how oil deposits are formed in diverse geological settings, and not the least how to safely dispose of radioactive and other toxic materials.
