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Volcanic Winter
A volcanic winter is a reduction in global temperatures caused by volcanic ash and droplets of sulfuric acid and water obscuring the Sun and raising Earth's albedo (increasing the reflection of solar radiation) after a large, particularly explosive volcanic eruption. Long-term cooling effects are primarily dependent upon injection of sulfur gases into the stratosphere where they undergo a series of reactions to create sulfuric acid which can nucleate and form aerosols. Volcanic stratospheric aerosols cool the surface by reflecting solar radiation and warm the stratosphere by absorbing terrestrial radiation. The variations in atmospheric warming and cooling result in changes in tropospheric and stratospheric circulation. Historic examples The effects of volcanic eruptions on recent winters are modest in scale, but historically have been significant. Toba supereruption A proposed volcanic winter occurred around 71,000–73,000 years ago following the supereruption of Lake Toba o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as ''tephra''), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away. Due to its wide dispersal, ash can have a number of impacts on society, including animal and hu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hekla 3 Eruption
The Hekla 3 eruption (H-3) circa 1000 BC is considered the most severe eruption of Hekla during the Holocene. It threw about 7.3 km3 of volcanic rock into the atmosphere, placing its Volcanic Explosivity Index (VEI) at 5. This would have caused a volcanic winter, cooling temperatures in the Northern Hemisphere for several years afterwards. An eighteen-year span of global cooling that is recorded in Irish bog oaks has been attributed to H-3. The eruption is detectable in Greenland ice cores, the bristlecone pine sequence, and the Irish oak sequence of extremely narrow growth rings. Andy Baker's team of researchers dated it to 1021 BC ±130. A "high chronology" (earlier) interpretation of the above results is preferred by Baker, based also on growth of stalagmites. In Sutherland, northwest Scotland, a spurt of four years of doubled annual luminescent growth banding of calcite in a stalagmite is datable to 1135 BC ±130. A rival, "low-chronology" inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Core
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old. The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core. The proportions of different oxygen and hydrogen isotopes provide information about ancient temperatures, and the air trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as carbon dioxide. Since heat flow in a large ice sheet is very slow, the borehole temperature is another indicator of temperature in the past. These data can be combined to find the climate m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.Oxford University Press – Why Geography Matters: More Than Ever (book) – "Holocene Humanity" section https://books.google.com/books?id=7P0_sWIcBNsC The Holocene corresponds with the rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of gl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Segara Anak
Segara Anak is a crater lake in the caldera that formed during the explosive volcanic eruption of Mount Samalas in 1257. The caldera is next to Mount Rinjani on Lombok Island in Indonesia. "Segara Anak" means "child of the sea" and refers to the blue lake's resemblance to the sea. The volcanic cone Gunung Barujari is at the eastern end of the lake and is responsible for its crescent shape. The lake temperature is , which is 5-7 °C (9-13 °F) higher than normal for a lake at its altitude. Hot magma below the lake is responsible for this anomaly. Gas bubbles escape from the lake floor, helping the lake to have a pH of 7-8. The surface of Segara Anak is above mean sea level (AMSL) and is Indonesia's second-highest caldera lake with an active volcano. The peak of Gunung Baru Jari is AMSL. The lake covers , with dimensions of , and has a maximum depth of . Fish breeding There were no fish in Segara Anak. In 1969, volcanologists from the Geological Society of London examined t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is gone. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018. Etymology The term ''caldera'' comes from Spanish ', and Latin ', meaning " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1257 Samalas Eruption
In 1257, a catastrophic eruption occurred at the Samalas volcano on the Indonesian island of Lombok. The event had a probable Volcanic Explosivity Index of 7, making it one of the largest volcanic eruptions during the current Holocene epoch. It left behind a large caldera that contains Lake Segara Anak. Later volcanic activity created more volcanic centres in the caldera, including the Barujari cone, which remains active. The event created eruption columns reaching tens of kilometres into the atmosphere and pyroclastic flows that buried much of Lombok and crossed the sea to reach the neighbouring island of Sumbawa. The flows destroyed human habitations, including the city of Pamatan, which was the capital of a kingdom on Lombok. Ash from the eruption fell as far as away in Java; the volcano deposited more than of rocks and ash. The aerosols injected into the atmosphere reduced the solar radiation reaching the Earth's surface, causing a volcanic winter and cooling the a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
946 Eruption Of Paektu Mountain
The 946 eruption of Paektu Mountain in Korea and China, also known as the Millennium Eruption or Tianchi eruption, was one of the most powerful volcanic eruptions in recorded history and is classified as a VEI-7 event. The eruption resulted in a brief period of significant climate change in Manchuria. The year of the eruption has not been precisely determined, but a possible year is A.D. 946. The eruption ejected about of tephra and collapsed the mountain into a caldera, which now contains the crater lake named Heaven Lake. The eruption began with a strong Plinian column, and ended with voluminous pyroclastic flows. An average of of Plinian ashfall and co–ignimbrite ashfall covered about of the Sea of Japan and northern Japan. This ash layer has been named the "Baegdusan-Tomakomai ash" (B-Tm). It probably occurred in winter in late A.D. 946. This was one of the largest and most violent eruptions in the last 5,000 years, along with the Minoan eruption of Thera, the Hatepe e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
El Salvador
El Salvador (; , meaning " The Saviour"), officially the Republic of El Salvador ( es, República de El Salvador), is a country in Central America. It is bordered on the northeast by Honduras, on the northwest by Guatemala, and on the south by the Pacific Ocean. El Salvador's capital and largest city is San Salvador. The country's population in 2022 is estimated to be 6.5 million. Among the Mesoamerican nations that historically controlled the region are the Lenca (after 600 AD), the Mayans, and then the Cuzcatlecs. Archaeological monuments also suggest an early Olmec presence around the first millennium BC. In the beginning of the 16th century, the Spanish Empire conquered the Central American territory, incorporating it into the Viceroyalty of New Spain ruled from Mexico City. However the Viceroyalty of Mexico had little to no influence in the daily affairs of the isthmus, which was colonized in 1524. In 1609, the area was declared the Captaincy General of Guatemal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Ilopango
Lake Ilopango is a crater lake which fills an 8 by 11 km (72 km2 or 28 sq mi) volcanic caldera in central El Salvador, on the borders of the San Salvador, La Paz, and Cuscatlán departments. The caldera, which contains the second largest lake in the country and is immediately east of the capital city, San Salvador, has a scalloped to high rim. Any surplus drains via the Jiboa River to the Pacific Ocean. An eruption of the Ilopango volcano is considered a possible source for the extreme weather events of 535–536. The local military airbase, Ilopango International Airport, has annual airshows where international pilots from all over the world fly over San Salvador City and Ilopango lake. Eruptive history Four major dacitic–rhyolitic eruptions occurred during the late Pleistocene and Holocene, producing pyroclastic flows and tephra that blanketed much of the country. The caldera collapsed most recently sometime between 410 and 535 AD (based on radiocarbon dati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Winter Of 536
The volcanic winter of 536 was the most severe and protracted episode of climatic cooling in the Northern Hemisphere in the last 2,000 years. The volcanic winter was caused by an eruption, with several possible locations proposed in various continents. Most contemporary accounts of the volcanic winter are from authors in Constantinople, the capital of the Eastern Roman Empire, although the impact of the cooler temperatures extended beyond Europe. Modern scholarship has determined that in early AD 536 (or possibly late 535), an eruption ejected massive amounts of sulfate aerosols into the atmosphere, which reduced the solar radiation reaching the Earth's surface and cooled the atmosphere for several years. In March 536, Constantinople began experiencing darkened skies and cooler temperatures. Summer temperatures in 536 fell by as much as 2.5 degrees Celsius (4.5 Fahrenheit degrees) below normal in Europe. The lingering impact of the volcanic winter of 536 was augmented in 539–540, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
