April 2015 – COLOMBIA – Nevado del Ruiz – Activity at the volcano has increased during the past week. Accompanied by elevated seismic activity, ash emissions have been occurring since 14 April. The strongest phase of activity was on 19 April, when ash plumes rose to estimated 900 meters above the summit. The Ingeominas volcano observatory in Manizales reported a change in seismicity detected since 12 April, when an increase in volcanic-tectonic (rock-fracturing) signals was detected, signs of pressurization and possible magma intrusion at depth.
Sakurajima (Kyushu, Japan): The volcano has been very active recently. Vulcanian-type explosions have been frequent (2-8 per day) and often relatively large. On 15 April, at least 8 explosions occurred, the largest of which produced ash plumes that rose to 15,000 ft (4.5 km altitude), i.e. 3.5 km above the volcano’s summit.
Aso (Kyushu, Japan): Mild strombolian activity with low-level ash emissions continue from the Nakadake crater. –Volcano Discovery