The earthquake that killed over 5,000 people on Indonesia's Java island is linked to the one that triggered the deadly 2004 Indian Ocean tsunami and may signal the imminent eruption of a nearby volcano, an expert said on Monday. Indonesia sits in a seismically active "ring of fire", a region marked by regular volcanic and tectonic activity, and which bore the brunt of the December 2004 quake-generated tsunami which left more than 230,000 dead or missing. Edward Bryant, a scientist specialising in natural hazards at Australia's University of Wollongong, said the tremor that generated the tsunami, Saturday's quake and increased activity at nearby Mount Merapi are all likely linked. "Merapi itself is probably a product of the follow-up from the earthquake 18 months ago," Bryant told Reuters.