Anatahan Island

From Wikipedia:

Anatahan Volcano is a small volcanic island located 120 km (80 miles) north of Saipan Island and 320 km (200 miles) north of Guam. The island is about 9 km (5.6 miles) long and 3 km (2 miles) wide. Anatahan began erupting suddenly from its east crater at about 5:00 p.m. on May 10, 2003.

Since then it has continued to alternate between eruptive and calm periods. On April 6, 2005, approximately 50,000 cubic meters of ash and rock were ejected, causing a large, black cloud to drift southward over Saipan and Tinian. Recent eruptions have caused some commercial flights to re-route.