Izu Peninsula Geology

How did the Izu peninsula get here?

The Izu peninsula was born 20 million years ago in the Pacific Ocean, about 800 kilometers southeast of where it is today. Izu began as a series of volcanic islands created by ‘hot spots’ in the ocean. What are hot spots?

The earth’s surface is actually a bunch of tectonic plates floating around on top of a mantle of molten hot magma. Sometimes magma forms into plumes that can penetrate through the crust (plate) and erupt on the surface. This happens both on land and under the ocean.

When the volcanoes build up and up under the ocean, the eventually emerge above water, cool and become islands.

Even underwater, tectonic plates are still floating on top of the earth’s molten, liquid core (mantle). As the plates move in one direction and the plumes continue to surface in the same spot, it creates a series of volcanic islands.

Hawaii is a well known example of an island chain created by hot spots.

As the Izu islands formed, they were carried on the Philippine Plate toward the eastern edge of the Eurasian plate, where Japan lies.

Look carefully at the image of the three tectonic plates, and you can see how the Philippine Plate submerges under the larger Eurasian Plate, and the Pacific Plate submerges under both.

The series of hot spots that created the Izu peninsula is still active today. New islands appeared as recently as 2013.

The islands eventually collided with Japan about 600,000 years ago, resulting in the Izu Peninsula. The islands got scraped off the top of the Philippine Plate as it submerged under the Eurasian Plate.

Pretty wild stuff, isn’t it? Izu peninsula is one of the few places on earth where this geological process has occurred.

The places where plates collide are called convergent boundaries, and there is a lot of volcanic and seismic activity. Izu is one of Japan’s most active regions, resulting in its many hot springs.

The Philippine Sea Plate moves 5.5 cm per year.
That’s almost 2 feet in 10 years!

See how volcanic hot spots are formed. 
See timeline between 02:39 – 03:48 of the video.

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