For the past several weeks, Kilauea volcano on the island of Hawaii (Big Island) has been continuously erupting — opening dozens of fissures around the volcano and sending lava throughout the area. Thousands of residents have evacuated and buildings have been destroyed.

Now, the latest threat is methane gas.

According to the U.S. Geological Survey (USGS), blue flames were spotted along road cracks beginning on May 23. The flames are methane gas, a byproduct produced from burning plants and shrubs that are buried under lava.

While the flames may be mesmerizing, they pose a huge risk. As USGS officials explain, "methane gas can seep into subsurface voids and explode when heated, or as shown in this video, emerge from cracks in the ground several feet away from the lava."

Methane is just the latest in a string of hazards since the volcano erupted on May 3.

Once the lava reached the Pacific Ocean on May 19, the mixture of water and lava produced "laze," which releases hydrochloric acid and volcanic gas into the air and can be lethal.

The USGS also warned people about ballistic projectiles shooting out from the volcano. "At any time, activity may again become more explosive, increasing the intensity of ash production and producing ballistic projectiles very near the vent," the agency's website stated.

For the latest updates, check out the Hawaii County Civil Defense's active alerts page.

Kilauea's blue flames spark fear of explosions
The flames are caused by methane gas from underground.