Actually, I mainly posted this to get the name of the island into the record:

A Brand New Island in the Pacific has Survived 5 Years
universetoday.com / November 21, 2019 / Evan Gough

A “surtseyan eruption” is a volcanic eruption in shallow water. It’s named after the island Surtsey, off the coast of Iceland. In 2015, a surtseyan eruption in the Tongan Archipelago created the island Hunga Tonga-Hunga Ha‘apai. Despite the odds, that island is still there almost five years later.

Fortunately, scientists have a wealth of resources at their disposal to study this whole phenomenon. These types of eruptions are difficult to study, since they occur underwater, and often in remote locations. They also tend to get eroded away quickly. But Earth-observing satellites are changing that, and Hunga Tonga-Hunga Ha‘apai is the first of its kind to be studied intensively, especially during its formation.

Groucho: “You left out a Hunga. And you left out the main one, too!”

…

Scientist X visited the island in October 2019,

Let me guess . . . from a region of the earth that was growing a wee bit colder?

and wrote in a blog post: “We made many useful observations, collected some good data, and gained a more practical human-scale understanding of the topography of the place (such as that the adjacent pre-existing islands, and their rocky shorelines, are almost fortress-like in their inaccessibility). We also saw things not accessible from space, such as the hundreds of nesting sooty terns . . .

Well, duh. Volcano.
(Just kidding)

A Martian Connection?

X and Y

. . . in their beach chairs, with toes in the sand and drinks with umbrellas in their hands, smoking something righteous and having cosmic thoughts . . .

think that their study of this volcano is not only useful for understanding our own planet. They think it might shed light on processes on Mars.

“Using the Earth to understand Mars is of course something we do,” X said,

. . . inhaling . . .

noting the similarities in erosion on the island and scars left by ancient eruptions through shallow seas on Mars. “Mars may not have a place exactly like this, but still, it bespeaks the planet’s history of persistent water.”

Y looked over, slightly confused, but let it pass.

Mars is not without volcanoes. In fact, it’s home to the largest volcano in the Solar System, now dormant. Olympus Mons rises almost 22 km (13.6 mi or 72,000 ft) above the surface of Mars. It’s the grand-daddy of volcanoes.