Hawaii’s Kilauea volcano has entered a new destructive period of eruptions, which has happened several times since it resumed producing lava in 1983. Here’s some context behind one of the world’s most active volcanoes:
Kilauea is currently in the second phase of growth, the “shield building” stage, where it is the most active and the most voluminous.
Small eruptions below sea level.
2. Shield building
Volcanic mass grows above sea.
Magma cap flows, covers volcano.
In this stage, occurrences of lava flows and eruptions alternate. This can continue up to 2 million years.
Lava flows in past 1,000 years. Kilauea is covered with 90% young flows.
Lava eruptions have occurred at the volcano’s summit since 2008 and since 1983 on its eastern shoulder at a crater called Pu'u O'o, which collapsed on April 30, and sent lava searching for a new path downhill.
Scientists are concerned that if the lava column drops to the level of groundwater beneath Kilauea summit, it will cause more eruptions.
1. Magma column drops to water level.
Normally, when the lava lake level is high, temperatures are so hot that the groundwater in surrounding rocks is kept away from the magma.
2. Groundwater interacts with hot rock.
When lava meets the water, steam is created. Rocks can fall from walls as the lava lake lowers, and form a dam holding back steam.
3. Steam pressure builds, then explodes.
Rocks of up to 12 tons can shoot out of the volcano to a distance of half a mile. Marble-size rocks can fall for several miles, while falling ash is a concern 10 to 20 miles downwind.
Hawaii Island is made up of five volcanoes, four of which are considered active. Kohala is the oldest volcano on the island and inactive.
Sources: USGS, Smithsonian Institution, National Park Service