In this article, we dive into the intricate details of the recent volcanic eruption that happened in the Tonga Islands, an event that proved the power of nature and its unpredictability. This phenomenon occurred along the Ring of Fire—a zone known for its heightened volcanic and seismic activities that engulfs the Pacific Ocean basin.
The Undersea Volcanic Eruption and Its Regular Occurrences
Tonga’s volcanic eruption occurred beneath the sea, involving two small uninhabited islands, Hunga-Ha’apai and Hunga-Tonga. Over the past several years, the Hunga-Tonga-Hunga-Ha’apai volcano has displayed regular activity with eruptions noted in 2009 and 2014/15 when jets of magma and steam burst through the waves. However, these instances were overshadowed by the enormity of the eruption in January 2022. This particular event showcased the enormous explosions the volcano can produce approximately every thousand years, largely due to a phenomenon known as the Fuel-Coolant interaction.
Impact: Global Cooling Effect and Other Aftermath
The implications of huge volcanic eruptions often extend beyond their immediate vicinity. In cases where significant amounts of sulfur dioxide are emitted, temporary global cooling can occur. Following the Tonga eruption, initial satellite measurements suggested minor global average cooling of about 0.01 Celsius due to the sulfur dioxide release. The eruption also changed atmospheric pressure temporarily, which somewhat improved the fog conditions in Seattle, United States.
Furthermore, the eruption’s effects weren’t confined to the local region or the atmosphere alone. The subsequent tsunami waves it caused traversed across the Pacific, where they claimed two lives in Peru and resulted in minor damages in places ranging from New Zealand to Santa Cruz, California. According to the US Geological Survey, the eruption generated a seismic impact equivalent to a 5.8 magnitude earthquake.
Defining a Volcano and Its Eruptions
For the uninitiated, a volcano stands as an opening or rupture in the Earth’s surface that permits the escape of magma (which takes the form of hot and semi-liquid rock upon coming out), volcanic ash, and gases. These geological formations are commonly found where Earth’s tectonic plates converge. A volcanic eruption primarily happens when lava and gas are discharged from a volcano, sometimes in an explosive manner.
Undersea Volcano: A Deeper Dive
An undersea volcanic eruption refers to the occurrence of such a phenomenon in a volcano located beneath the ocean’s surface. With an estimated count of one million undersea volcanoes, most of these can be found near tectonic plate boundaries. Besides spewing lava, these underwater vents also emit ash, which accumulates on the ocean floor and contributes to the formation of sea mounds. These are underwater mountains created on the ocean bed but do not extend up to the water’s surface.
Fuel-Coolant Interaction: A Mechanism of Volcanic Explosions
Fuel-Coolant interaction plays a vital role in the intensity of volcanic eruptions. When magma slowly ascends into seawater, even at temperatures around 1200 degrees Celsius, a thin film of steam forms between the magma and water. This steam barrier insulates and cools the outer surface of the magma. However, this process is ineffective when magma is forcefully ejected from the ground, saturated with volcanic gas.
When magma penetrates water quickly, steam layers get disrupted, which brings the scorching magma in direct contact with cold water. This process mirrors weapons-grade chemical explosions, where violent blasts break apart the magma. This triggers a chain reaction—fresh magma fragments continually expose new hot interior surfaces to the water, causing repeated explosions and eventually propelling volcanic particles and blasts at supersonic speeds.