After an ash explosion of September 1, 2006, a general decline in the overall activity of Mayon was established. The decrease in key parameters such as seismicity, sulfur dioxide emission rates and ground inflation all indicated a waning condition. The slowdown in the eruptive activity was also evident from the decrease in intensity of crater glow and the diminishing volume of lava extruded from the summit. PHILVOLCS Alert Level 4 was lowered to Level 3 on September 11, 2006; to Level 2 on October 3, 2006; and to Level 1 on October 25, 2006.