SACHA PFEIFFER, HOST:
International help is on its way to the South Pacific island nation of Tonga, where a massive underwater volcano erupted yesterday. The eruption was reported to be heard and felt hundreds of miles away, and it sent tsunami warnings ringing out across the Pacific, including here in the U.S. For more on this, we turn to reporter Ashley Westerman. She's based in Manila, Philippines. Ashley, welcome.
ASHLEY WESTERMAN, BYLINE: Thanks for having me.
PFEIFFER: Tell us more about this volcano. Where exactly is it?
WESTERMAN: So it was the Hunga Tonga Hunga Ha'apai volcano that erupted. It's located, as you mentioned, in Tonga, which sits in the western South Pacific, roughly 3,000 miles from Australia. The volcano itself is on the outer rim of the Tongan archipelago, and it is massive - about a mile high and 13 miles across. And it sits just about 500 feet under the surface between two small islands.
PFEIFFER: And what happened when it erupted?
WESTERMAN: So on Saturday, the volcano began to erupt, sending a plume of volcanic ash nearly 20 miles up in the air. Photos of it have been circulating on social media. And it is incredible, Sacha. The U.S. tsunami warning system recorded it as a 7.8 magnitude earthquake. And there are reports that it was heard by surrounding Pacific Island nations as far away as Samoa, over 500 miles away. I got a hold of Sonja Ruggiero (ph), who lives in Suva, Fiji, over 470 miles away from the volcano. And she told me about being at home on Saturday and hearing what she thought was thunder.
SONJA RUGGIERO: It was very quick, and I think it was maybe about an hour or so that people began to realize this is not thunder at all. This is the sound of the actual volcano erupting. And we have - you know, we've never experienced anything like this.
PFEIFFER: People 500 miles away heard it. That is very dramatic. Volcanic eruptions are common in that part of the world, though. Was this eruption unique?
WESTERMAN: Yes, so this is the second eruption of this volcano in less than a month. And Tonga officials told New Zealand media that it was seven times stronger than last time. I spoke with Shane Cronin, a volcanologist at Auckland University, who says the eruption was significant because of three distinct things it produced laterally - a pressure wave in the atmosphere...
SHANE CRONIN: Very much like nuclear explosions or very large explosions. And this pressure wave travelled across the entire world, in fact, has been recorded as far away as Finland.
WESTERMAN: ...A cloud of ash...
CRONIN: I think the most remarkable thing about its explosivity was not so much just the height but the speed with which the plume expanded laterally. So within 30 minutes of the eruption onset, the ash plume above the volcano was about 180 miles across.
WESTERMAN: ...And, of course, The tsunami waves that prompted warnings all the way from New Zealand to Japan to the west coast of the U.S. Many of those warnings have since been called off, but rough seas and flooding have been reported in Hawaii and New Zealand.
PFEIFFER: Ashley, what do we know about the people in Tonga and how they've been affected?
WESTERMAN: So we don't know a lot because telecoms have been down since yesterday, but the last images we saw out of Tonga was a darkened sky and ash raining down on the main island of Tongatapu. And so far, no casualties have been reported. Likely, residents will be dealing with a continued threat of tsunamis moving forward, as well as ash fall and acid rain. The volcano is still erupting at a lower intensity, by the way. And help is on the way. Both Australia and New Zealand have combined their efforts to send assistance.
PFEIFFER: That's reporter Ashley Westerman in Manila.
Ashley, thank you.
WESTERMAN: Thanks for having me.
(SOUNDBITE OF SHAWN LEE SONG, "KISS THE SKY") Transcript provided by NPR, Copyright NPR.
