An underwater volcano off the coast of Japan that erupted with enough force to create an new island last year continues to rupture. The new, and growing, volcanic island has now essentially "eaten" a nearby island, and the eruption is showing no signs of abating, according to NASA's Earth Observatory.

In November 2013, a surge of Pacific Rim volcanic activity gave rise to a small island, dubbed Niijima, or "New Island" in Japanese, in the Ogasawara island chain about one day's boat ride from the Tokyo coast.

Niijima emerged just 500 meters from the summit of another massive submarine volcano, an island known as Nishino-shima. When Niijima first appeared, scientists predicted it would fuse with nearby Nishino-shima.

Four months after Niijima's creation, the prediction has come true, NASA reported. Satellite images from the Landsat 8 spacecraft reveal that the islands have merged.

"The Niijima portion of the island is now larger than the original Nishino-shima, and the merged island is slightly more than 1,000 meters across," NASA's Earth Observatory said in a statement. "Two cones have formed around the main vents and stand more than 60 meters above sea level, triple the highest point of the island in December."

Prior to their merger, both islands were inhabited, and they likely will remain that way.

The newly merged island measures about 1 kilometer across, according to NASA's Earth Observatory