Understanding the science behind Hawaii's erupting Kilauea volcano

When most people think of Hawaii, they envision swaying palm trees, sandy beaches and turquoise surf. But people are now being made aware of just how that tropical paradise was created.

The Big Island of Hawaii is being rocked by an eruptionfrom the massive Kilauea volcano one of the world's most active and one of five on the island.It's eruptions such as these, playing out over thousands of years, that gave rise to the more than 130 islands that make up the Hawaiian archipelago.

The most recent eruption, which occurred on May 3,hasdestroyed more than 35 structures to date and forced some 1,700 people to be evacuated from their homes as magma and toxic gases make their way to the surface.

Not your typical volcano

Talk of an erupting volcano typically brings forth a visionofa cloudof ash reaching kilometres into the skyand lavaraining down on the ground below.But that doesn't applyto Hawaii'sshield volcanoes, whichexperience"effusive" eruptions.

Rather than spewing lava and ashexplosively and suddenly upwardas Mount St.Helensdid in 1980effusive eruptionsslowly and steadily pour material outward, resulting in the formation ofa flattened dome, or shield-like shape, with broad, gently sloping sides.

Decades-long eruption

While the recent activityat Kilauea the youngest volcano on the island has grabbed a lot of headlines, it's actually beenerupting off and on for more than 30 years.

The Pu'u'O'ovolcanic vent, located in the Kilauea eastrift zone, began erupting in January 1983. Most recently,activity in the crater picked back upin early 2013, with flows continuinguntil March 2015.

In 2014, residents of the town of Pahoa were forced to evacuate as lava advanced from another eruption, causing concern it would cover the community's main road and cut it off from the rest of the island.

With this latest eruption, there are two rift zonesor areas where the volcano is splitting apartwhichprovide the easiest path for magma to make its way to the surface, when it is then called lava.

According to the United States Geological Survey (USGS), lava flows from the volcano over the years have covered 125 square kilometres.

Earthquakes

In the weeks leading up to Kilauea's latest eruption, the region experienced hundreds of earthquakes. Last Friday, a 6.9-magnitude earthquake rocked the Big Island the strongest since 1975.

According to Tina Neal, the scientist-in-charge of the USGSHawaiian Volcano Observatory, the earthquakes occur as a result of magmamoving along these rift zones, stressing the volcano.

"All of that stress is relieved in large earthquakes," Neal saidduring an update last Friday."In some ways, these are not unexpected."

She said more earthquakes are expected in the coming days,and could possibly continue for weeks to come.

Fissures and fires

As of Monday, there were at least 10 fissureslinear areas where volcanic activity opens a crack or vent in the east rift zone, though not all are currently active.

In particular,Kilauea's eruption opened up afissurein a subdivisionknown asLeilaniEstates, less than 20 kilometres from the volcano, forcing local residentsto flee the 770 homes located there.

Because some of the fissuresare new, volcanologists are trying to determine whether this recent activity could lead to a new lava field, which could permanently displace people from their homes.

The fissures release steam and gases, like toxic sulfur dioxide.Neal noted these releases are a precursorto magma makingits way to the surface.

On the plus side, because there isn't currently a significant amount ofmagma, these fissures are only active for hours at a time.

As lava begins to spew out of these fissures, much of what it touches catchesfire. The temperature of lava can be more than 1,000 C, though once it begins to flow, it can cool by as fast as hundreds of degrees per second.

But scientists say it is nearlyimpossible to predict how long theeruption will last;it could be days ormonths.