Future eruptions may include pyroclastic flows and surges similar to those that occurred at Mount Pelée, Merapi, Vesuvius, Etna, the Soufrière Hills, Mount Unzen and elsewhere. During 2003, there was an increase in seismic activity at the volcano and a rift opened on the north-east flank. No eruptive activity occurred but a quantity of material, possibly liquid, was emplaced into the edifice and is estimated to have a volume of ~1011 m3. Such activity can indicate that magma is rising into the edifice, but is not always a precursor to an eruption.