Tonga volcanic blast spreads shock waves all the way to Minnesota 

NASA scientists are estimating the volcanic blast Saturday in the Pacific Ocean had the power of about 500 World War II atom bombs, and the shock waves reached all the way to Minnesota.  

NASA experts tell National Public Radio that the blast was likely the equivalent of a 10-megaton explosion, probably the loudest event since a 19th century volcanic blast in Indonesia. 

Weather instruments detected the blast early Saturday morning around Minnesota, as a spike in barometric pressure over several hours. 

Hennepin County Emergency Management officials on Monday posted a graph of the rise. 

“It was big enough where the change over the course of about an hour was far larger than anything we were expecting during the day, weather wise,” said Tyler Hasenstein, a meteorologist with the National Weather Service in Chanhassen, Minn. “It would take a very strong weather system to produce that kind of blip, so we knew that in this case it was likely from the eruption itself.” 

Hasenstein said it was unlikely that most people would have felt the change. 

In the South Pacific, the blast obliterated a volcanic island and set off a tsunami believed to have caused at least two deaths. It has covered nearby islands with ash and severed a key communication link for the island nation of Tonga. 

NASA posted time-lapse satellite images of the explosion Tuesday: 

Scientists say they believe the explosion was relatively brief and didn’t produce ash or smoke that would have long-term effects on the climate.  

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