Alaid, Russia

Although not well-known, Alaid in the Kurile Islands has produced some of the largest explosive eruptions in the western Pacific island arc (and that includes the impressive Sarychev Peak eruption). It has been fairly quiet since the late 1990s, but in the 20 years preceding the last eruption in 1996, it had multiple VEI 2 eruptions and a VEI 4 eruption in 1981 that released almost half a cubic kilometer of volcanic ash and debris (tephra). One of the recent GVP Weekly Volcanic Activity Report noted reports of steam emissions and a thermal anomaly noticed by satellite.

Image: NASA Earth Observatory