On August 12, 2014, a new 30m-50m high lava dome appeared in the summit crater. This event was preceded by inflations of the volcano (measured by precise leveling, tilt data, and GPS), and increases in sulfur dioxide gas emissions. On September 14, 2014, rockfall events at the southeastern rim of the crater and heightened seismic activity caused PHIVOLCS to increase the alert level for Mayon from 2 to 3, which indicates relatively high unrest with magma at the crater, and that hazardous eruption is possible within weeks.