Special Report: What could happen when Mauna Loa erupts

Special Report: What could happen when Mauna Loa erupts

HILO, BIG ISLAND (HawaiiNewsNow) - When Mauna Loa is erupting it's impossible to ignore. However, since its last eruption 30 years ago two generations have grown up without knowing much about its beauty, or danger.  We talked to the world's leading scientist on Mauna Loa about odds of its next eruption and what happens once it begins.

When it will happen, no one knows.  However, scientists say the chance of Mauna Loa erupting again is virtually 100% and the consequences could be disastrous.

In 1881, lava almost reached Hilo.  Princess Ruth prayed to Madam Pele and it stopped.  In 1926, a fast-moving flow 50-feet high wiped out the fishing village of Ho'opuloa.  In 1950, lava covered homes in Pahoehoe.  Residents literally ran for their lives.

When Mauna Loa erupted in 1984, media crews and tourists came from around the world.  The lava crept within a few miles of Kaumana, glowing at night.

"I stay awake all night tossing and turning... looks like it's right out the window", said a nearby resident.

As some families packed up and left their homes, scientists spent weeks learning everything they could.

"I'm gonna try to get up close and measure the temperature", said one scientist.

30 years later, the crater at Kilauea, where lava still flows, gets most of the attention.  But behind the Jaggar museum, at the Hawaiian Volcano Observatory, volcanologist Frank Trusdell says Mauna Loa is a much bigger threat.

"The eruption rates on Mauna Loa are scary compared to Kilauea", says Trusdell.  "The amount of lava actually coming out per unit is actually life threatening."

Trusdell has dozens of graphs showing past lava flows that reached the Ka'u and Kona coastlines within hours. If the next eruption is explosive, ash could drift into the airspace near the Hilo and Kona airports, cutting off flights.  And if lava was to cover a major highway, Trusdell says "we're talking about impacts to tourism, economy, distribution of goods, people going to work.  It may not even have to consume one house.  All it has to do is hit the road."

Frightening scenarios, but here's the good news: we'll all be warned that Mauna Loa is stirring."You cannot have an eruption without earthquakes", says Trusdell.

Today's GPS and seismometers are so fine-tuned; scientists can spot a coming eruption months in advance.  "When we're getting up to probably in the 5-600 earthquakes-a-day range is when we're on high alert", says Trusdell.

Scientists came close to sounding the alarm about 10 years ago.  A swarm of quakes deep under Mauna Loa signaled a pulsing of new lava into the magma chamber.  But before the molten rock made it to the surface half the mountain shifted south, creating more space for that new lava, and the eruption never happened.  But all that extra lava is still in the chamber.

"Does that mean were going to have a larger eruption?", asks Trusdell, "we cannot say."

That is one of the many unknowns about Mauna Loa.  Another is where the lava will emerge once the eruption starts.  But by then, civil defense officials would be in full emergency mode, arranging any necessary evacuations, with TV and radio stations broadcasting live alerts.

It'll be up each family to pay attention.  "If people aren't going to heed the warning they could actually die", says Trusdell.

Frank Trusdell is not a man who exaggerates.  Mauna Loa is his life's work.  He wants every family to be informed about its eventual reawakening.

"I feel very confident we can forecast the next eruption on Mauna Loa," says Trusdell.

For more information: http://hvo.wr.usgs.gov/maunaloa/

Copyright 2014 Hawaii News Now. All rights reserved.