Item

Abstract

Abstract: This thesis was carried out in the frame of the Turkish-German project on earthquake prediction research. Since 1986 radon in ground air and ground water within the Mudurnu Valley, NW Turkey, is studied aimed to detect spatial and temporal variations related to the stress build-up within the Earth's crust before a coming earthquake. To separate tectonic "signals" from non-tectonic, i.e. meteorological "noise", a multidisciplinary approach was chosen. A 60 km long segment of the North-Anatolian fault zone was investigated. The first part of this thesis is about ground air: Soil air profiling was carried out perpendicular to the fault system. At 5 multiparameter-observatories measurement sites were constructed to (i) sample ground air from different depths repeatedly and (ii) to monitor temporal radon variations quasi-continuously. The second part of the thesis deals with ground water: After mapping the physic-chemical properties of 590 spring waters about 200 of them were chosen for annually repeated measurements. Since 1989 basic ground water parameters are monitored continuously at (i) a shallow ground water spring and (ii) a thermal water. The radon distribution within the soil air is predominantly controlled by meteorological conditions. More than 95 % of the variations are explainable by related effects. As long as seism-tectonic anomalies - there were no bigger earthquakes so far - are in the same order of magnitude, ground air monitoring as a tool for earthquake prediction is of very limited value under the given climatologically conditions. More promising are the results of the ground water studies: Seasonal variations are as low as plus minus 10 %. A cluster of springs located in the eastern part of the investigated area showed significantly (150 - 200 % above the normal level) increased radon concentrations during 1990 and 1991. This time interval was characterised by increased macroseismic activity within the same area. Furthermore, radon cycles of a few months observed at the thermal spring correlate with cycles of micro-seismic activity within the Mudurnu Valley.