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Volcanic aerosols from huge volcanoes (VEI>=5) directly reduce global mean sea surface temperature (SST) by approximately 0.2-0.3 °C, [1] [3] milder than global total surface temperature drop, which is ~0.3 to 0.5 °C, [4] [5] [6] according to both global temperature records and model simulations. It usually takes several years to be back to ...
A volcanic hazard is the probability a volcanic eruption or related geophysical event will occur in a given geographic area and within a specified window of time. The risk that can be associated with a volcanic hazard depends on the proximity and vulnerability of an asset or a population of people near to where a volcanic event might occur.
There are numerous reports of groups of human skeletons floating across the Indian Ocean on rafts of volcanic pumice and washing up on the east coast of Africa up to a year after the eruption. [12]: 297–298 An observation made two weeks after the eruption describes the state of the affected areas, where the village of Tjaringin once was.
Satellite view of a pumice raft from an undersea eruption in Tonga. Volcanic eruptions can have various impacts on maritime transportation. When a volcano erupts, large amounts of noxious gases, steam, rock, and ash are released into the atmosphere; fine ash can be transported thousands of miles from the volcano, while high concentrations of coarse particles fall out of the air near the ...
The conversion of sulfur dioxide to sulfuric acid, which condenses rapidly in the stratosphere to form fine sulfate aerosols. A volcanic winter is a reduction in global temperatures caused by droplets of sulfuric acid obscuring the Sun and raising Earth's albedo (increasing the reflection of solar radiation) after a large, sulfur-rich, particularly explosive volcanic eruption.
Subglacial eruptions, those of ice-covered volcanoes, result in the interaction of magma with ice and snow, leading to meltwater formation, jökulhlaups, and lahars. Flooding associated with meltwater is a significant hazard in some volcanic areas, including Iceland, Alaska, and parts of the Andes.
The volcanic materials form a vertical column or plume that may rise many kilometers into the air above the vent of the volcano. In the most explosive eruptions, the eruption column may rise over 40 km (25 mi), penetrating the stratosphere. Stratospheric injection of aerosols by volcanoes is a major cause of short-term climate change.
The 1991 eruption rated 6 on the Volcanic Explosivity Index and came some 450–500 years after the volcano's last known eruptive activity. The eruption ejected about 10 km 3 (2.4 cu mi) of material, making it the largest eruption of the 20th century since that of Novarupta in 1912 and some ten times larger than the 1980 eruption of Mount St ...