Effects of the 17 August, 1999 earthquake on the heavy metal composition of thermal waters in the Marmara Region, northwest Turkey: Is it a precursor?

Due to movement of active North Anatolian Fault Zone in the Marmara Region the two main shocks, which were epicentered on Golcuk - Izmit, and Duzce on August 17,1999 and November 12,1999 respectively, created the chemical changes on thermal waters of Bursa, Adapazari, Yalova and Kuzuluk - Adapazari geothermal areas, which are close to the active fault zone. Field measurements and chemical analyses of these waters from that date to September, 2000 have revealed considerable temporal changes. The trace element contents exhibited variations, particularly as an increase of Pb, Cu, and Ni levels, and a decrease of Fe, Mn, Zn contents after the earthquake. These analyses also collected in 2000 showed that, all these changes were temporary and became nearly normal during 2000.