Tonga eruption could offer clues on planet formation

The massive volcanic blast which rocked Tonga last week sent out shockwaves close to the speed of sound and tsunami waves across the Pacific Ocean.

And now one expert says it could also provide valuable clues about the formation of other planets.

"I got a call and they said 'It blew, you don't have an island anymore.'"

That's one of NASA's chief scientists, James Garvin, who says they've been studying the volcano for seven years.

Now they're examining what's left of the islands, Hunga Tonga and Hunga Ha'apai.

"So, we took that volume of mass ejected and the energetics to explosively fragment it, and calculated using fairly classical techniques, how much energy that would take, to break rock that you could build a city building on, to break it up into little bits and throw it as ash and steam up to, I mean, to hundreds of thousands of feet. And so we did that calculation and we got numbers that range from something equivalent to the blast of a small asteroid that would hit the earth - about 10 metric, megatons of TNT or equivalent - to things even bigger."

The Hunga-Tonga-Hunga-Ha'apai volcano sits on the seismically active Pacific Ring of Fire.

The eruption on January 15 was so powerful that it could be heard over a thousand miles away, and huge clouds of ash could be seen from space.

Garvin says studying the impact of these volcanoes on Earth tells us what they may have done to other planets.

"It's a fossil record of landscapes preserved in time on earth, better preserved on planets like Mars and the moon and Venus. So we use earth as our training ground to project what we know from places like this to other planets that might have oceans, that might have volcanos, that erupt under water."

Many in Tonga are still reeling from the physical and psychological trauma of last week's blast, as relief aid continues to pour in.