A steam plume over the sea from the Ulawun is clearly visible on a satellite image. Ulawun is one of the most active volcanoes in Papua New Guinea and one of its most dangerous. It is the highest volcano in the 1000 km long Bismarck volcanic arc. Ulawun volcano is composed of lava flows interbedded with tephra.The first recorded eruption of Ulawun was in 1700. Several thousand people live near the volcano.There have been 22 recorded eruptions since the 1700s. The last few years have seen almost constant activity at Ulawun, with frequent small explosions. Eruptions originate from a central crater. Its eruptions devastated the NW flank of Ulawun and modified the summit crater. An eruption in 1980 ejected ash to 60,000 ft and produced pyroclastic flows which swept all flanks of the volcano and devastated an area of 20 sq km. The most serious volcanic hazard at Ulawun volcano is catastrophic structural collapse, producing an eruption which could devastate hundreds of sq km in area.Ulawun volcano is 400 m higher than most of the volcanoes in the Bismarck which indicates it may be at the limit of structural stability. Seismic activity remained high at Ulawun Volcano in 2008. A magnitude 5.1 earthquake hit 10 km west of Ulawun volcano on 28th May 2009. On 14-15 February 2010 ash emissions from Ulawun volcano reached a height of 3.7 km and drifted 95 km.