Aid agencies and Earth scientists were sent into a flurry of activity after the explosion of the Hunga volcano. It had been nearly 140 years since the last eruption of this scale.
The strongest waves from a volcano since the Krakatau eruption were measured by a team of 76 scientists from 17 nations. The size of the waves from the eruption was similar to those from Krakatau, according to the team's work. The data gives a better idea of the wavefield compared to what was available in the historic event.
The first comprehensive account of the eruption's atmospheric waves was published in the journal Science.
Evidence shows that an eruption sank the volcano's main vent below sea level the day before the explosion. There were booms heard 6,200 miles away in Alaska. It created a pulse that caused the unusual occurrence of a tsunami-like disturbance an hour before the actual earthquake began.
Matoza is an associate professor at UC Santa Barbara's Department of Earth Science.
The atmospheric waves were recorded globally across a wide frequency band, according to co-author David Fee.
The implications for monitoring nuclear explosions, volcanoes, earthquakes and a variety of other phenomena is what Fee said.
The researchers were interested in the behavior of the atmospheric wave known as a Lamb wave. These are longitudinal pressure waves, similar to sound waves. The effects of gravity must be taken into account. Lamb waves are associated with large eruptions and nuclear detonations, but the wave characteristics differ between the two sources. They can last for a long time.
After the eruption, the waves traveled along Earth's surface and circled the planet in one direction four times and in the opposite direction three times. Scientists observed the same thing in the Krakatau eruption. The Lamb wave reached an altitude of about 280 miles and was 700 mph.
Lamb waves are very rare. Fee said that they have very few high-quality observations of them. It is related to the volcanic eruption and the higher-frequency acoustic waves that followed it.
The Lamb wave had at least two waves. The first had a 7- to 10-minute pressure increase followed by a second and larger compression and a long pressure decrease.
The amount and quality of data scientists were able to gather was a major difference between the accounts of Hunga's Lamb waves and Krakatau's.
Remarkable long-range infrasound sounds too low in Frequency to be Heard by Humans, and other findings about atmospheric waves associated with the eruption were noted by scientists. After the Lamb wave, audible sounds were heard in some regions.
The sounds were heard around the state, but Fee didn't think it was from a volcanic eruption.
The scientists think the sounds heard in Alaska were not from Hunga. Matoza said that standard sound models cannot explain how audible sounds are generated over extreme distances.
There is a long list of studies looking at the many different aspects of these signals.
More information: Robin S. Matoza, Atmospheric waves and global seismoacoustic observations of the January 2022 Hunga eruption, Tonga, Science (2022). DOI: 10.1126/science.abo7063. www.science.org/doi/10.1126/science.abo7063 Journal information: Science Citation: Massive eruption of Tongan volcano provides an explosion of data on atmospheric waves (2022, May 12) retrieved 12 May 2022 from https://phys.org/news/2022-05-massive-eruption-tongan-volcano-explosion.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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