Indonesian officials were also trying to assess the impact of a 7.7-magnitude earthquake late Monday that caused a tsunami off Sumatra island in western Indonesia, leaving scores of villagers dead or missing. The volcano and earthquake epicenter are about 800 miles (1,300 kilometers) apart.RELATED:Indonesian volcano wakes up after 400 yearsThe powerful earthquake triggered a 10-foot (three-meter) tsunami that pounded remote island villages, killing at least 113 people and leaving scores more missing, an official said Tuesday.This vast archipelago is prone to earthquakes and volcanic activity due to its location on the so-called Pacific Ring of Fire — a series of fault lines stretching from the Western Hemisphere through Japan and Southeast Asia.Up to 20 people were injured by hot ash spewed from Mount Merapi, said an AP reporter who witnessed them being taken away for treatment.Some 11,400 villagers who live on the 9,737-foot (2,968-metre) -high mountain were urged to evacuate, but only those with four miles (seven kilometers) of the crater were forced by authorities to do so. Most of those who fled were the elderly and children. Some adults said they decided to stay to tend to homes and farms on the fertile slopes.Subandriyo, chief vulcanologist in the area, said the eruption started just before dusk Tuesday. The volcano had rumbled and groaned for hours."There was a thunderous rumble that went on for ages, maybe 15 minutes," said Sukamto, a farmer who by nightfall had yet to abandon his home on the slopes. "Then huge plumes of hot ash started shooting up into the air."Scientists have warned the pressure building beneath the dome could presage one of the biggest eruptions in years at Merapi, literally Mountain of Fire, which lies on the main island of Java, some 310 miles (500 kilometers) southeast of the capital Jakarta.The alert level for Merapi has been raised to its highest level.