Hawaii’s Mauna Loa volcano, located on the Big Island, has begun to erupt for the first time since 1984. Mauna Loa is the world’s largest active volcano and one of five five volcanos that make up the Big Island. Lava is threatening to reach neighborhoods as it flows downhill but so far no evacuation orders have been issued and no homes have been effected. But state health officials are urging people to cut back on outdoor exercise due to toxic smog caused by the spewing of sulfur dioxide and other volcanic gases.

According to the AP these are the hazards posed by Mauna Loa’s eruption:

-Lava: Molten rock could cover houses, farms or neighborhoods, depending on where it flows. But lava from the northeast rift zone will likely take at least a week to reach populated areas, allowing people time to evacuate if needed.

-Volcanic gas: Mauna Loa is releasing volcanic gases, mostly sulfur dioxide. The gases are present in their highest concentrations in the immediate area around the summit crater or vents. But they also combine with other particles to form vog, which can spread across the Big Island and even waft over to the state’s other islands.

The Big Island is mostly rural and hosts cattle ranches and coffee farms but it is also home to a few small cities, including the county seat of Hilo, which has a population of 45,000.

The eruption began Sunday night at its summit after a series of large earthquakes. It then spread to vents that formed in a rift zone where the mountain is splitting apart and it’s easier for magma to emerge.

Read more here.