There’s been a lot of activity happening on the Big Island of Hawaii in recent months. In May 2018, Kilauea Volcano had a massive eruption from one of its fissures. And lava came rolling down into streets and neighborhoods. Residents had to evacuate their homes and relocate with their family to other parts of the island.
The State of Hawaii is made up of eight main islands. But the Big Island is the only one with active volcanoes. So the question has often come up, are we safe from any volcanic eruptions here on the island of Oahu?
Oahu is a completely different island from Big Island. It is located about 200 miles from Big Island. There’s a massive ocean and four more islands in between. So Oahu is located too far away to receive any real effects from the activity happening on Big Island.
But the question of a possible eruption on Oahu still remains. To answer that question, we must first understand the geological patterns of the Earth and how the islands formed in the very beginning.
Understanding Tectonic Plates
Surrounding the Earth’s surface are various tectonic plates moving slowly to create the land masses we see today. When two of these plates collide, we feel seismic activity like earthquakes.
The largest of these plates is the Pacific Plate located beneath the Pacific Ocean where the Hawaiian Islands are currently.
Just below this tectonic plate is the Earth’s mantle. There are parts of the mantle that have unusual hotspots where large amounts of magma rise up and pierce through the plates. This is the action that produces large volcanic eruptions on the Earth’s surface.
Formation of the Islands
This process began around 5 million years ago forming the first Hawaiian Island of Kauai. Thousands and thousands of years would pass and the Pacific Plate would continue to move in a north-westwardly direction. But the hotspot located in the Earth’s mantle would remain stationary.
Around 2-3 million years ago, the Pacific Plate moved Kauai away from this hotspot. Magma began to rise again at the same hotspot forming what is now known as the island of Oahu.
The process continues. The Plate moves in the same direction. The islands move with it. This moves the already-formed islands away from the hotspot. And new islands begin to form. Maui and it’s surrounding islands were next.
Finally, Big Island begins to form over this hotspot some 500,000 years ago.
So, as we can tell, each of the islands had volcanic eruptions as the Pacific Plate moved them across the hotspot located in the Earth’s mantle. That hotspot is now located just below the Big Island. This is why Big Island is the only Hawaiian Island with active volcanoes.
The other islands have now moved several hundred miles away from this hotspot. So it’s highly unlikely they will have any volcanic eruptions.
Since the tectonic plates move at a very slow pace, it will be many more thousands of years before we see the Big Island move away from this hotspot. Therefore, Big Island will be the only island known in our lifetime to have erupting volcanoes in Hawaii. And can rest assured, there will be no eruptions on Oahu during our lifetime either.
Image By: Haiku Deck