Mauna Loa has erupted for the first time in nearly four decades, causing an ashfall advisory for Hawaii’s big island and its surrounding waters. 

The volcano and its eruption is not threatening downhill communities or flights to the island of Hawaii. The Hawaii Tourism Authority tweeted Monday morning that there is still a “trace to less than one quarter inch” of ashfall which could accumulate on parts of the island, the National Weather Service in Honolulu said winds could carry ash or volcanic gas downwind. 

Reports say lava that has overflowed into the Southwest portion of the Volcano’s crater has reached the Hawaii Volcano Observatory, according to a Tweet by the Hawaii Emergency Management Agency. 

There is no immediate threat to nearby communities, and evacuation orders have yet to have been issued, the agency tweeted. As a precaution, two shelters have opened, even as almost half of recorded Mauna Loa eruptions remained in the summit area without threatening populated areas, according to another agency tweet.

Based on past events, the early stages of a Mauna Loa eruption has a “-dynamic flow and the location and advance of lava flows can change rapidly,” the observatory said. “If the eruption remains in Moku’āweoweo, lava flows will most likely be confined within the Caldera Walls. However, if the eruptive vents migrate outside its walls, lava flows may move rapidly downslope.”

Though these eruptions tend not to be dangerous to Hawaii’s inhabitants, precautions should still be taken, considering an eruption of Mauna Loa has proved fatal before. 

The eruption of Mauna Loa in the spring of 1868 and the deadly phenomena surrounding it were one of the greatest natural disasters in Hawaiian history. 77 Hawaiians died in the associated tsunami and landslides. 

As with most eruptions of Mauna Loa, the 1868 eruption began at its summit caldera, Moku‘āweoweo. On March 27, as if the volcano were sending out a warning for all to see, a column of smoke was seen emanating from the top of the mountain.

At approximately 4:00 p.m. on April 2, the great Kaʻū earthquake struck. It is thought to have been 7.9-magnitude, the same intensity as the massive quake that would later decimate San Francisco in 1906.

The authorities are taking extra precautions to rest the minds of the worried, as well as trying to prepare for Mauna Loa’s unpredictable seismic patterns and lava flow.