An island formed by an underwater volcano close to Tonga in 2015 is surprising scientists with its tenacity to stay intact. The island, unofficially named Hunga Tonga-Hunga Ha’apai was formed when the underwater volcano spewed out ash and rock. Scientists expected the island to erode away in a few months, much like other temporary volcanic landforms. But two years later the island is still looking solid and scientists predict it may even last for another 3 decades. “We haven’t had an island like this sustain itself in 50 years,” Jim Garvin, chief scientist of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, told press at a NASA press conference this week.
Rare volcanic conditions cause island to stay put
The solidity of the island is due to the special circumstances in which it was formed. When the volcano erupted it sent up hot magma from deep under the earth’s core to connect with the cool ocean water. This sent ash and rock skyward to form the island. Similar volcanic conditions formed the island, Surtsey, a landform off the coast of Iceland that formed in the 1960s and still continues to this day. NASA believes Hunga Tonga-Hunga Ha’apai island has exceeded its lifespan predictions because chemical interactions between warm surface seawater and volcanic material caused the island's shoreline to harden soon after the eruption which has protected its inner softener parts from erosion.
Island is evolving but not eroding
Scientists have been watching the phenomena since the eruption in 2015 and have had the chance to capture the island undo several major changes. The island initially formed a rough oval shape with its eruption crater in its center. But ocean currents and waves slowly eroded the 400m high cliffs around the crater's edge breaking down one side, creating an interior lake with an opening to the ocean. Scientists thought this may spell the end for the island but a sandbar formed soon after that protected the remaining cliffs. The island is now essentially two land masses connected by a peninsula. While the shape of the overall island has changed dramatically in the last two years its overall mass hasn’t shifted much at all, leading scientists to conclude that the island is determined to stick around.
Tiny landmass may unlock the secrets of Mars
While monitoring an island grow and evolve provides huge opportunity to better understand volcanic and oceanic activity. NASA is also excited about the possibilities Hunga Tonga-Hunga Ha’apai has for learning more about Mars. Garvin elaborated on the connection explaining that Mars features small volcanoes “very similar to Hunga Tonga-Hunga Ha’apai in appearance, but we don’t know the context in which they formed.”
By examing the formation of this island in comparison with volcanic evidence on Mars may give clues to how its surface was created. Similarities may indicate the presence of long extinct oceans or other water bodies. “We think [this is] a real opportunity for learning,” Garvin said.