Tuesday 20 May, 2014

How did the Hawaiian Islands form?

Hawaiian coastline

Hawaii is no stranger to dramatic landscapes.

At this particular moment in time, the state of Hawaii officially consists of 137 islands, including the eight major islands and dozens of smaller islands, atolls, reefs and tiny islets. So where did they all come from?

It’s all thanks to a geological feature called the Hawaiian hotspot.

Deep inside the Earth, directly below the Hawaiian Islands (more specifically, below the Big Island Hawai’i), there’s a hotspot where temperatures can reach 2,500°F. Over many millions of years, the Pacific Plate has been moving very, very slowly over this hotspot, and as it does, the hotspot acts as a sort of blowtorch to the material above it, heating the rock and transforming it into hot magma. This molten rock rises up through the Earth’s crust and erupts through the sea floor, where it cools and hardens. Over time, the underwater volcano grows and grows, and eventually this mountain of cooled, hardened lava reaches the surface of the sea. An island is born.

Of course, the process doesn’t stop there. As the Pacific Plate continues its slow creep below the sea floor, the newly formed island is moved off the hotspot, and the next volcanic island in the chain is formed. This cycle is why the northwestern most Hawaiian island, the Kure Atoll, is the oldest feature of the chain, and the southeastern island Hawai’i (the Big Island) is the youngest. Hawaii’s next island, still submerged underwater for now, is a little farther to the southeast—it’s called Lo’ihi.

Hawaiian coast and palm trees

Hawaii: Born from the sea. 

On EF Explore America’s student trip to Hawaii, a visit to the Hawai’i Volcanoes National Park lets you witness this island-forming process in action. The park is home to two famous active volcanoes: Kilauea, which is one of the world’s most active volcanoes, and Mauna Loa, considered the largest volcano on Earth. The Hawaiian Islands are still being formed as we speak.