It created amazing fountains of fire, drew curious on lookers and threatened the Big Island's biggest town.
1984 was the last time Mauna Loa erupted, and since then, we've learned a lot about the volcano.
When the world's largest volcano woke up 30 years ago, powerful fountains of fire spewed 100 feet into the air and rivers of molten lava spread across the mountain side. A nine year silence ended with an angry rage on March 25, 1984.
"It was pretty spectacular, and the eruptions themselves were phenomenal," said Volcanologist Frank Trusdell.
Trusdell remembers that eruption vividly. He was one of the scientists on the ground studying Mauna Loa's firey flow.
For 22 days the mountain rumbled as lava flowed at rates as fast as 700 feet per hour. In all, more than 220-million cubic meters of lava spewed from the volcano.
"It was very impressive. The channels themselves were many folds larger than what I've seen on Kilauea, and then being on the ground and watching the flows go by – sometimes you'd have these standing waves that were three to five times my height," Trusdell recalled.
As lava flowed down the volcano's northeastern rift, it threatened Kulani Correctional facility and flowed toward Hilo town, putting many on high alert. Three weeks of fear in a remarkably close call.
"This is the leading edge of the front of the '84 flow that ended right around Apr. 15 of that year. You can see the nearest subdivision is about four miles from the eruption, [and] where it terminated and stopped," said Darryl Oliveria.
Oliveria is the Hawaii County Civil Defense Coordinator. He says even though it's been 30 years since Mauna Loa's violent spectacle, the potential for danger on the Big Island still exists to this day.
"It reminds us that the whole island, primarily in those hazard areas, is vulnerable to an eruption, so we need to keep that in mind with development and where we live," said Oliveria.
Is another eruption on Mauna Loa imminent? No. Could the volcano erupt again? Yes.
"Looking at the eruption history of Mauna Loa, which I've been studying for at least a couple decades now -- long term average, the volcano erupts once every six years," said Trusdell.
That's the average, but right now there has not been much activity. In fact you can see it in the seismic plots of the most recent eruptions in 1975 and 1984, and the slowed activity in seismic plots for the last two years.
If Mauna Loa were to erupt again, scientists -- using data from the '84 eruption -- can now better track the lava flow and pinpoint areas of impact. That is something they could not do before.
Crucial information such as the location of where the eruption occurs on the mountain, can determine the speed of the flow. For example, an eruption on the southwest side could go from 11,000 feet to the ocean in just three hours, while on the east side, it could take days or months.
Mauna Loa is a site so many flock to see and a moneymaking opportunity for some.
"It shot up here for about eight hours and it kind of stopped," said Kurt Wakimoto.
Wakimoto, a long time Hilo resident, lived through the 1984 eruption. He is a t-shirt producer and made big bucks selling shirts to tourists who came to witness Mother Nature's firey fury.
"Well it king of dictated the economy here which is a good thing I think. Madam Pele brings us money," said Wakimoto.
Whether it's for the money or to view the molten lava, we wait for the next time this volcano wakes up again.