On January 14 and 15, local time, an undersea volcano erupted on Aha Apai Island in Tongahong and caused a tsunami.
The off-white gas and volcanic ash produced by the violent eruptions form a super-huge mushroom cloud, like a "flower of death" slowly blooming in space; the clearly visible ring-like shock wave spreads around, and the violently fluctuating sea water triggers a transoceanic tsunami - the scene of the eruption of the Tonga volcano captured by satellites from many countries is shocking and heart-wrenching.
Questions about Tonga's undersea volcanoes also arise.
1. Why is this volcanic eruption so violent? Also located on the Pacific Rim "Ring of Fire", why is the Hawaiian volcano calm and gentle, while the Tonga volcano is as fierce as fire?
The Pacific Ring of Fire, also known as the Pacific Ring of Fire, is an area of frequent earthquakes and volcanic eruptions around the Pacific Ocean, with a total length of about 40,000 kilometers and a horseshoe shape. Ninety percent of the world's earthquakes, 81 percent of major earthquakes, and 75 percent of volcanic eruptions occur around the Pacific Rim.
According to Zhang Jinchang, Qiu Qiang, Yang Xiaodong, Zhou Zhiyuan and other researchers at the South China Sea Institute of Oceanology of the Chinese Academy of Sciences, Tonga Volcano is located at the southwest end of the "Ring of Fire" around the Pacific Ocean. Due to the active plate movement, the geological structure of the area is complex, and volcanic and seismic disasters are frequent. But also located on the Pacific Rim "Ring of Fire", why is the Hawaiian volcano calm and gentle, while the Tonga volcano is as fierce as fire?
Zhang Jinchang explained that this is because the two volcanoes belong to different types of submarine volcanoes. Submarine volcanoes can be roughly divided into three types: ocean ridge volcanoes, trench volcanoes, and ocean basin volcanoes.
Ridge volcanoes are formed in the mid-ocean ridge, which is the boundary of the expansion of the oceanic plates and the place where the oceanic crust grows. Volcanoes of this type erupt along the mid-ocean ridge, forming long mountain ranges.
Trench volcanoes are formed in trenches, which are the boundaries where plates converge and where the oceanic crust subducts and dies. This type of volcano is distributed along the trench and takes on an arc-like volcanic island arc, such as The Krakatoa Volcano in Indonesia.
Ocean basin volcanoes are formed in the ocean basin, belong to the volcanoes inside the ocean plate, and are the places where magma erupts from mantle hot spots, mainly including submarine volcanic chains, flat-topped seamounts, ocean floor plateaus, etc., such as the Mauna Loa Volcano in Hawaii, USA.
"Hawaiian volcanoes and Tonga volcanoes are both active volcanoes that erupt from time to time, but the two volcanoes are of different types. Hawaii is a ocean basin volcano and Tonga is a trench volcano. Due to different geological origins, Hawaii volcanoes are weaker in dynamics and have relatively little material energy, so they are milder. Zhang Jinchang said.
2. What impact has the Tonga disaster had on other neighboring countries and the world at large?
An eruption of an undersea volcano in Tonga triggered a tsunami, and several countries around the Pacific Simultaneously sounded the alarm.
About 7 hours after the eruption of The Tonga Volcano, the tsunami swept across the Coast of Japan, about 8,000 kilometers from Tonga. In Kochi Prefecture, a total of 27 small boats sank or capsized in seven fishing ports.
The river flowing through the city of Taga in Miyagi Prefecture was affected by the tsunami and the river flowed counter-current. The Japan Meteorological Agency Issued Asunami Warning on the Amami Islands and others on the 16th, and at the same time issued a tsunami alert to the Pacific coastal areas of the Japanese archipelago. This is the first time japan has issued a tsunami warning since November 2016, and a total of 230,000 people have issued "evacuation instructions".
Shortly after the tsunami warning was issued, there was a congestion of vehicles in Amami City, Kagoshima Prefecture, which was going to take refuge in higher ground.
The west coast of the United States, about 8,000 kilometers from Tonga, was also affected by the tsunami. The maximum wave height on the west coast of the United States reached 1.3 meters, and a woman was slapped squarely by the waves on the shore.
△ Mobile phone video shows that some parking lots are flooded by seawater, and some vehicles are washed away by seawater.
In Chile, South America, residents of some areas are asked to evacuate to high places. Two women off the northern coast of Peru drowned in the waves.
In addition, a number of new Zealand vessels capsized or damaged as a result of the tsunami impact, and no casualties have been reported at this time.
Australia surveyed waves more than 1 metre high off the coast of the east that day, and the NSW government closed all beaches in the state. Although Australia later lowered the tsunami warning level, it still reminded residents operating on the seashore to guard against safety risks posed by abnormal currents.
3. Where has the ash gone? Is it possible to drift to the mainland?
Zhu Lin, a researcher at the Remote Sensing Application Room of the National Satellite Meteorological Center of the China Meteorological Administration, said that satellite cloud maps show that the cloud of volcanic ash particles is slowly thinning, and the gas similar to sulfur dioxide after the volcanic eruption is gradually drifting westward. At present, according to the latest monitoring situation, it has basically drifted to the east coast of Australia.
Liao Mi, senior engineer of the Remote Sensing Application Office of the National Satellite Meteorological Center of the China Meteorological Administration, said that the situation of volcanic ash drifting westward is still relatively obvious, and from the current monitoring point of view, it is mainly active in the southern hemisphere, and it is unlikely to float to the mainland in a short period of time.
4. Will the eruption of the Tonga volcano cause a "summerless year"?
Experts tell us that after the large-scale eruption of the volcano, a large amount of volcanic ash enters the stratosphere, and the volcanic ash aerosol cannot settle for a long time, forming an umbrella effect, hindering sunlight exposure, and often leading to a drop in global temperature. Historically, the eruption of Mount Tambora in the Philippines has caused a "year without summer". According to the WeChat public account "Voice of the Chinese Academy of Sciences" reported that the recent volcanic eruption in the Tonga sea of the South Pacific, although this is the largest volcanic eruption so far in this century, but compared with the eruption of Mount Tambora that caused the "year without summer" in 1816, the magnitude gap is still huge, if there is no stronger eruption in the later period, the impact of this volcanic eruption on the global climate is very limited, and it is impossible to cause a "summerless year".
Zhu Lin, a researcher at the Remote Sensing Application Department of the National Satellite Meteorological Center of the China Meteorological Administration, said that the impact of volcanic ash clouds on the climate is mainly the formation of clouds of mineral particles and sulfur dioxide in the atmosphere, which reflects and scatters the incident radiation of the sun, which may lead to temperature drops. However, whether the tonga volcanic eruption will affect the climate needs to be further analyzed by continuous observational data. We are using multi-source satellite data and products such as Fengyun-3 and Fengyun-4, and combining diffusion models and other means to continue observation.
5. Will the Tonga volcano continue to erupt on a large scale?
Xu Jiandong, director of the Volcano Research Center of the China Earthquake Administration, said that the eruption of the volcano is a systematic project, determined by the degree of magma replenishment. Volcanic eruptions generally last from a few days to several months, but are not continuous and will be spaced. Therefore, the Tonga volcano will continue to erupt in the future, but when it will erupt, in what way, and on what scale, it will depend on real-time monitoring data to judge.
Editor: Shi Wei