Mauna Loa’s eruption: what are the different volcanic alerts?

An eruption on Hawaii’s Mauna Loa, the largest active volcano on Earth, resulted in the alert level being upgraded from ‘advisory’ to ‘warning’ as concerns were raised on Sunday night and through the morning. There had been double digit earthquakes over 2.5 magnitude registered in just two hours, the largest recorded at 4.2.

What happened with Mauna Loa?

“At this time, lava flows are contained within the summit area and are not threatening downslope communities,” a notifcation from the U.S. Geological Service’s (USGS) volcanic activity service said, adding that aerial reconnaissance would commence to assess the potential dangers and understand more about the developing situation. They service also warned, based on their experience of similar events, that it can be difficult to determine exactly what may happen at such an early stage of the eruption.

What are the different volcanic alerts?

With the alert level being moved to ‘warning’ it is important to understand how that fits into the overall volcano alert system. The USGS Hawaiian Volcano Observatory (HVO) sets the Volcano Alert Level and Aviation Color Code (see image) for volcanoes in Hawaii and American Samoa.

The first of the two-word designation is the Volcano Alert Level, which reflects the danger the volcano poses to people on the ground and infrastructure. USGS Volcano Alert Levels were established in 2006 and the four terms (NORMAL, ADVISORY, WATCH, WARNING) were chosen to mirror those used at the time by NOAA’s National Weather Service for severe storms and floods.

NORMAL - indicates a non-eruptive background state of activity

ADVISORY - reflects an activity level elevated above background

WATCH - is used when an eruption is likely, or an eruption is occurring with limited hazards

WARNING - means a hazardous eruption is imminent, underway, or suspected.

For more detail on this check out the official page of the USGS.

How big is the Mauna Loa volcano?

I mentioned above that Mauna Loa is the world’s largest active volcano. So what does that mean?

Well, for starters it accounts for more than half of the Big Island in Hawaii, so rather significant. Rising from 13,679 feet (4,169 meters) above the Pacific Ocean, we haven’t been troubled by its noisy eruptions since early 1984. Back then, almost 30 years ago, the city of Hilo escaped its flow of lava by just five miles (8.05 km).