A dense network of barometers, infrasound sensors, and seismometers in Alaska — operated by the Geophysical Institute’s Wilson Alaska Technical Center, Alaska Volcano Observatory, and Alaska Earthquake Center — contributed to the data.
“Our hope is that we will be better able to monitor volcanic eruptions and tsunamis by understanding the atmospheric waves from this eruption,” said Fee, who is also the coordinating scientist at the Geophysical Institute’s portion of the Alaska Volcano Observatory.“The atmospheric waves were recorded globally across a wide frequency band, and by studying this remarkable dataset we will better understand acoustic and atmospheric wave generation, propagation and recording,” he said.Red-and-blue pattern around Hunga volcano is a time snapshot image from a weather satellite showing the atmospheric disturbance created by the Lamb wave.
The researchers found particularly interesting the behavior of the eruption’s Lamb wave, a type named for its 1917 discoverer, English mathematician Horace Lamb.The largest atmospheric explosions, such as from volcanic eruptions and nuclear tests, create Lamb waves.With the Hunga eruption, the wave traveled along Earth’s surface and circled the planet in one direction four times and in the opposite direction three times — the same as observed in the 1883 Krakatau eruption.
“By understanding the Lamb wave, we can better understand the source and eruption.
The Lamb wave consisted of at least two pulses near Hunga, with the first having a seven- to 10-minute pressure increase followed by a second and larger compression and subsequent long pressure decrease.A major difference with the Hunga explosion’s Lamb wave compared to the 1883 wave is the amount of data gathered due to more than a century of advancement in technology and a proliferation of sensors around the globe, according to the paper.Scientists noted other findings about atmospheric waves associated with the eruption, including “remarkable” long-range infrasound — sounds too low in frequency to be heard by humans.The Alaska reports are the farthest documented accounts of audible sound from its source.Reference: “Atmospheric waves and global seismoacoustic observations of the January 2022 Hunga eruption, Tonga” by Robin S.The Alaska Volcano Observatory, National Science Foundation and U.S.May 11, 2022May 11, 2022