Chemical Variations of Ground Water Affected by the Earthquake in bam region

An earthquake with magnitude Ms = 6.5 on the Richter scale occurred in December 26th , 2003 in Bam Region in southeastern part of Iran. This study investigates the chemical variations of the groundwater resources in the effected region. For this purpose, 30 wells were selected and chemical compounds, in terms of cations (Ca+2, Mg+2, Na+, K+); anions (HCO3 , SO4 , Cl, NO2 ), as well as EC, TDS and pH were analysed from Winter 2004 to Spring 2006. Results were compared with the ones obtained from winter 2003 to winter 2004. Then, using T-test, results of before and after the earthquake was investigated. The experiments were carried out according to the Standard Method of water and wastewater which showed during the after earth- quake most chemical parameters considerably increased rather than before the earthquake date. These changes reached their peak in the first year and Summer 2004 after the earthquake. The rate of variations was estimated about 17.5 - 88.3 % throughout the Bam and Baravat plains and 7-65.5% in wells water. It can also be considered that the fluctuation of underground waters chemical characteristics after the earthquake could be mainly due to different factors as follows: A) change in water levels as a result of earthquake, B) change in water temperature that will cause more solubility, C) change in water pressure trapped in rocks and aquifers and D) mixing with water of neighboring aquifers. The rate of fluctuations of different parameters in selected wells also showed a negative trend after the earthquake.