Hawaii’s ‘hot spot’: It makes volcanoes and islands

(CNN)Born of volcanoes, Hawaii is a place where spectacular beauty rises from intense geophysical forces that have played out over millions of years.

Tectonic plates: They make things interesting

The outer shell of the Earth is comprised of different “plates” that are rigid and in constant motion.
    The movement of the plates leads to earthquakes and volcanoes — mainly near boundaries where the plates push against and rub against one another.
    Volcanoes and earthquakes often create new land forms, such as mountains and ocean trenches.

    What is the Hawaii ‘hot spot’?

    If you pictured the Earth as an orange, the crust is akin to a very thin part of the peel.
    Beneath the hard layer of rock is a layer called the mantle. It is the zone of earth just above the core. The mantle is made of minerals, denser than what’s in the crust, said Erik Klemetti, a volcanologist, blogger and associate professor at Denison University in Ohio.
    A hot spot is the point where a plume of magma — molten rock — is protruding through the upper levels of the crust. The plate is on the outermost layer of the crust and moves over the hot spot. And then what happens?

    And how does that create volcanoes — and islands?

    The hot spot — basically, a pressure pimple in the Earth’s mantle — erupts and produces magma, which pushes up and through the surface to form volcanoes.
    Once the resulting lava cools, it is essentially new land.
    It can be quite fertile and make great farmland.
    But it can have unfortunate impact on people who live in the shadow of a volcano. By Monday morning, 35 structures — including at least 26 homes — had been destroyed in the Kilauea eruption.
    “This is potentially one of these disasters that is a long time unfolding,” said Klemetti.

    Why is the Big Island the biggest?

    For Hawaii’s western islands, the action played out millions of years ago. Their volcanoes are dormant.
    And while they remain stunningly beautiful, there’s just a little less of them to enjoy.
    That’s because waves, winds, landslides and erosion have since taken their toll.
    Because the Big Island is younger and growing, those forces haven’t whittled much of it away.

    At least 4 active volcanoes

    The Big Island has at least four active volcanoes, with Kilauea leading the way.
    “Mauna Loa has erupted 33 times since 1843, with the most recent eruption in 1984,” the US Geological Survey reports. “Loihi, the submarine volcano located off the south coast of Kilauea, erupted most recently in 1996.”
    Hualalai has erupted three times over 1,000 years.

    So is the Big Island getting bigger (right now)?

    Kilauea, the youngest and most active on the island, likes making news.
    It has been erupting almost continuously along its East Rift Zone since 1983, according to the US Geological Survey.
    The result has been a whole lotta lava that’s spilled into the Pacific Ocean.
    Klemetti, who visited the island in 2013, said it may take some time for the flow from this eruption to reach the water. For now, “This is just making the island taller.”

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