Volcano Hazards Program Office

A USGS scientist walks along a lava flow from the April 2, 1984 Mauna Loa eruption. The scientist stops to observe a standing wave of lava at the end. The lava flow is moving at 64 km/hr (40 mph) towards Hilo, Hawai'i. 
 

Erupting vents on Mauna Loa’s northeast rift zone near Pu‘u‘ula‘ula (Red Hill) on Mar. 25, 1984, sent massive ‘a‘ā lava flows down the rift toward Kūlani.

Pohaku Hanalei cinder-spatter cone (upper left) is located about 3.2 km (2 mi) NE from the north edge of the caldera rim. Eruption rates were as high as 2.9 million m3 per hour during the first 6 hours of the eruption, then diminished to about 0.5 million m3 per hour for the next 12 days. Sizable pahoehoe flows formed only during the first day of the eruption and within a

Aa lava flows erupting from Mauna Loa.

Harry's Ridge monitoring station, 8 km (5 mi) north of Mount St. Helens' crater.

The May 18, 1980 debris avalanche from Mount St. Helens covered over 24 square miles (62 square kilometers) of the upper Toutle River valley and blocked tributaries of the North Fork Toutle River. New lakes such as Castle Lake (pictured here) and Coldwater Lake were created.

Debris avalanche deposit with hummocky terrain resulting from the May 18, 1980 eruption of Mount St. Helens. View to the east toward Coldwater Lake.

Low fountain, approximately 50 meters high, from Pu'u 'O'o on Hawai'i Island's Kilauea Volcano (viewed from the north). Lava issuing from the breach in the northeast rim of the crater produced an 'a'a flow that extended more than 4 kilometers. Eruption episode 8.

Pu'u 'O'o fountain approximately 100 meters high during eruption episode 8 on Hawai'i Island's Kilauea Volcano. Dark clots of spatter land near the base of the fountain, contributing to the growth of the cone. Less dense cinder, visible in the upper right, is carried downwind of the cone.

Accretionary lava ball comes to rest on the grass after rolling off the top of an 'a'a flow in Royal Gardens subdivision on Hawai'i Island's Kilauea Volcano. Accretionary lava balls form as viscous lava is molded around a core of already-soldified lava.

View at dusk of the young Pu'u 'O'o cinder-and-spatter cone, with fountain 40 meters high, on Hawai'i Island's Kilauea Volcano (episode 5).