On May 3, Kilauea, an active volcano on the southeast corner of Hawaii island, erupted after a powerful earthquake hit its coast.
The magnitude 6.9 quake was the largest to shake the island in 42 years.
As lava seeped out of fissures and traveled onto the land, nearby residents were evacuated as quickly as possible. Since then, several more earthquakes and eruptions have been taking place. More than 35 homes have been damaged so far, but the lava continues to flow since new fissures keep opening up.
A Giant Hotspot
Under the present-day Big Island lies a giant hotspot (a weak spot in the Earth's crust) that releases hot magma from within the Earth.
The hotspot does not move, but the Pacific plate on which the islands rest is moving ever so slightly in the north-west direction. This explains why some of the other Hawaiian islands have dormant volcanoes. They were once over the hotspot millions of years ago, but have since moved away.
Kilauea is one of the youngest and the most active volcanoes in the world. It is believed to be 300-600,000 years old and has been erupting continuously since 1983. The first Hawaiians who arrived on the islands by canoes were in awe of the volcano and named it Kilauea, after the Hawaiian word for “spewing” or “much spreading.”
A Slow-Growing Volcano
You might imagine an eruption to be like a lava fountain coming out of the central vent of a volcano. But Kilauea is different.
It is a shield volcano with a flat dome shape, similar to a shield. This type of volcano is formed from lava spewing out of the sides of the volcano through many thin branching vents. This allows the lava to smoothly come out of the volcano instead of pressure building up and lava exploding from the central vent.
The lava builds up and hardens as many layers on the volcano, making shield volcanoes some of the largest ones in the world. The slow-moving lava also gives enough time for people to escape.
Other types of volcanoes are cinder cones, composite volcanoes, and lava domes.
- Cinder cones have only one central vent where the lava builds pressure and explodes out of the volcano in a huge eruption.
- Composite volcanoes or stratovolcanoes have branching vents that are thicker than those of a shield volcano. As a result, the lava bursts out of the volcano instead of oozing out slowly.
- Lava domes are created out of lava that is too thick to flow very far. The lava clumps up around the volcano, and if there is enough material, the volcano will explode violently.
If volcanologists can conclude that the lava will stabilize, people will return home in a few days. Unfortunately, fissures keep appearing, and the volcano is found to release sulfur dioxide, a dangerous gas. Residents have also been warned about volcanic smog and acid rain, and to take precautions. For now, it appears that evacuations will continue for a period of time, dislocating nearby communities.
Sources: NYT, UniverseToday, Gizmodo, Wikipedia, USGS