When the Hunga Tonga-Hunga Ha’apai submarine volcano erupted on January 15, 65 kilometers north of Tonga’s capital, it created a tsunami as well as a sonic boom that rippled through the world – twice.
The eruption sent a large plume of water vapor into the stratosphere, which is located between 8 and 33 miles (12 and 53 kilometers) above the Earth’s surface. That was enough water to fill 58,000 Olympic swimming pools, according to NASA satellite detections.
The detection was made by the Microwave Limb Sounder instrument on NASA’s Aura satellite. The satellite measures water vapour, ozone and other atmospheric gases. After the eruption, scientists were surprised by the water vapor readings.
They estimate the eruption delivered 146 teragrams of water to the stratosphere. A teragram equals one trillion grams, and in this case it equals 10% of the water already in the stratosphere.
That’s nearly four times the amount of water vapor that reached the stratosphere after the 1991 eruption of Mount Pinatubo in the Philippines.
“We’ve never seen anything like it,” study author Luis Millán, an atmospheric scientist at NASA’s Jet Propulsion Laboratory in Southern California, said in a statement. “We had to carefully inspect all the measurements in the plume to make sure they were trustworthy.”
Keep an eye on the Earth
The Microwave Limb Sounder instrument can measure natural microwave signals from Earth’s atmosphere and detect them even through thick ash clouds.
“MLS was the only instrument with dense enough coverage to capture the water vapor plume as it occurred, and the only one that was unaffected by the ash the volcano released” , Millan said.
The Aura satellite was launched in 2004 and since then has only measured two volcanic eruptions that have thrown substantial water vapor so high into the atmosphere. But the steam from the 2008 Kasatochi event in Alaska and the 2015 Calbuco eruption in Chile dissipated fairly quickly.
Tonga’s eruption was different because the water vapor it sent into the atmosphere can trap heat, which could lead to warmer surface temperatures. The excess water vapor could stay in the stratosphere for several years, the researchers say.
The extra water vapor in the stratosphere could also lead to chemical reactions that temporarily contribute to the depletion of Earth’s protective ozone.
Anatomy of a rash
Fortunately, the warming effect of the water vapor should be small and temporary, and will dissipate as the extra steam diminishes. Researchers don’t believe this will be enough to worsen existing conditions due to the climate crisis.
Researchers believe that the main reason for the amount of water vapor is due to the depth of the volcano’s caldera 150 meters below the ocean surface.
If it was too deep, the depth of the ocean would have dampened the eruption, and if it was too shallow, the amount of seawater heated by the erupting magma would not have matched what caused the eruption. reached the stratosphere, the researchers said.