Anomalous fluid compositions in mud of the CCSD main well and their relations to two nearby earthquakes of ML 3.9

Abstract：Two earthquakes of ML 3.9 occurred near the CCSD main hole on November 30 and December 25, 2001 respectively. The daily mean variation maps show that a pronounced anomalous phenomenon existed on the curves of fluid compositions in mud of the CCSD main hole before and after the earthquakes. Analysis of the maximum correlation coefficient of the fluid components indicates that all the fluid components are well correlated except Ar and CO2 which are poorly correlated (with a mean maximum correlation coefficient of 0.632 and a mean square deviation of 0.223). Distinct anomalous fluctuations of the maximum correlation coefficient took place both before and after the earthquakes. The daily mean values and anomalous maximum correlation coefficients suggest that the fluid anomalies appearing in the CCSD main hole might have a certain relation to seismic activities in the area.