Lake Ilopango is a crater lake which fills a scenic 8 by 11 km volcanic caldera in central El Salvador, on the borders of the San Salvador, La Paz, Cuscatlán departments. The caldera, which contains the second largest lake in the country and is east of the capital city, San Salvador, has a scalloped 100 m to 500 m 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. 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 sometime between 410 and 535 AD, which produced widespread pyroclastic flows and devastated Mayan cities. The eruption produced about 25 km3 of tephra, thus rating a 6 on the Volcanic Explosivity Index.
The "ash-cloud fallout blanketed an area of at least 10,000 square kilometres waist-deep in pumice and ash", which would have stopped all agricultural endeavor in the area for decades. It is theorized that the eruption and subsequent weather events and agricultural failures directly led to the abandonment of Teotihiucan by the original inhabitants. There is an opinion. Eruptions formed several lava domes within the lake and near its shore; the only historical eruption, which occurred from December 31, 1879, up to March 26, 1880, produced a lava dome and had a VEI of 3. The lava dome reached the surface of the lake. List of volcanoes in El Salvador Global Volcanism Program: Ilopango Lake Ilopango at NASA Earth Observatory website
An acid is a molecule or ion capable of donating a hydron, or, capable of forming a covalent bond with an electron pair. The first category of acids is the proton donors or Brønsted acids. In the special case of aqueous solutions, proton donors form the hydronium ion H3O+ and are known as Arrhenius acids. Brønsted and Lowry generalized the Arrhenius theory to include non-aqueous solvents. A Brønsted or Arrhenius acid contains a hydrogen atom bonded to a chemical structure, still energetically favorable after loss of H+. Aqueous Arrhenius acids have characteristic properties which provide a practical description of an acid. Acids form aqueous solutions with a sour taste, can turn blue litmus red, react with bases and certain metals to form salts; the word acid is derived from the Latin acidus/acēre meaning sour. An aqueous solution of an acid has a pH less than 7 and is colloquially referred to as'acid', while the strict definition refers only to the solute. A lower pH means a higher acidity, thus a higher concentration of positive hydrogen ions in the solution.
Chemicals or substances having the property of an acid are said to be acidic. Common aqueous acids include hydrochloric acid, acetic acid, sulfuric acid, citric acid; as these examples show, acids can be solutions or pure substances, can be derived from acids that are solids, liquids, or gases. Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid; the second category of acids are Lewis acids. An example is boron trifluoride, whose boron atom has a vacant orbital which can form a covalent bond by sharing a lone pair of electrons on an atom in a base, for example the nitrogen atom in ammonia. Lewis considered this as a generalization of the Brønsted definition, so that an acid is a chemical species that accepts electron pairs either directly or by releasing protons into the solution, which accept electron pairs. However, hydrogen chloride, acetic acid, most other Brønsted-Lowry acids cannot form a covalent bond with an electron pair and are therefore not Lewis acids.
Conversely, many Lewis acids are not Brønsted-Lowry acids. In modern terminology, an acid is implicitly a Brønsted acid and not a Lewis acid, since chemists always refer to a Lewis acid explicitly as a Lewis acid. Modern definitions are concerned with the fundamental chemical reactions common to all acids. Most acids encountered in everyday life are aqueous solutions, or can be dissolved in water, so the Arrhenius and Brønsted-Lowry definitions are the most relevant; the Brønsted-Lowry definition is the most used definition. Hydronium ions are acids according to all three definitions. Although alcohols and amines can be Brønsted-Lowry acids, they can function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms; the Swedish chemist Svante Arrhenius attributed the properties of acidity to hydrogen ions or protons in 1884. An Arrhenius acid is a substance that, when added to water, increases the concentration of H+ ions in the water. Note that chemists write H+ and refer to the hydrogen ion when describing acid-base reactions but the free hydrogen nucleus, a proton, does not exist alone in water, it exists as the hydronium ion, H3O+.
Thus, an Arrhenius acid can be described as a substance that increases the concentration of hydronium ions when added to water. Examples include molecular substances such as acetic acid. An Arrhenius base, on the other hand, is a substance which increases the concentration of hydroxide ions when dissolved in water; this decreases the concentration of hydronium because the ions react to form H2O molecules: H3O+ + OH− ⇌ H2O + H2ODue to this equilibrium, any increase in the concentration of hydronium is accompanied by a decrease in the concentration of hydroxide. Thus, an Arrhenius acid could be said to be one that decreases hydroxide concentration, while an Arrhenius base increases it. In an acidic solution, the concentration of hydronium ions is greater than 10−7 moles per liter. Since pH is defined as the negative logarithm of the concentration of hydronium ions, acidic solutions thus have a pH of less than 7. While the Arrhenius concept is useful for describing many reactions, it is quite limited in its scope.
In 1923 chemists Johannes Nicolaus Brønsted and Thomas Martin Lowry independently recognized that acid-base reactions involve the transfer of a proton. A Brønsted-Lowry acid is a species. Brønsted-Lowry acid-base theory has several advantages over Arrhenius theory. Consider the following reactions of acetic acid, the organic acid that gives vinegar its characteristic taste: CH3COOH + H2O ⇌ CH3COO− + H3O+ CH3COOH + NH3 ⇌ CH3COO− + NH+4Both theories describe the first reaction: CH3COOH acts as an Arrhenius acid because it acts as a source of H3O+ when dissolved in water, it acts as a Brønsted acid by donating a proton to water. In the second example CH3COOH undergoes the same transformation, in this case donating a proton to ammonia, but does not relate to the Arrhenius definition of an acid because the reaction does not produce hydronium. CH3COOH is
Ometepe is an island formed by two volcanoes rising out of Lake Nicaragua in the Republic of Nicaragua. Its name derives from the Nahuatl words ome and tepetl, meaning "two mountains", it is the largest island in Lake Nicaragua. The two volcanoes are joined by a low isthmus to form one island in the shape of an hourglass, dumbbell or peanut. Ometepe has an area of 276 km2, it is 5 to 10 km wide. The island has an economy based on livestock and tourism. Plantains are the major crop; the island first became inhabited during the Dinarte phase. The first known inhabitants were speakers of Macro-Chibchan languages. Traces of this past can still be found in petroglyphs and stone idols on the northern slopes of the Maderas volcano; the oldest date from 300 BC. Several centuries Chorotega natives created statues on Ometepe carved from basalt rock. After the Spaniards conquered the Central American region in the 16th century, pirates began prowling Lake Nicaragua, they came in from the Caribbean Sea via the San Juan River.
The inhabitants of Ometepe were hard hit. The pirates kidnapped women, stole the inhabitants' animals and harvest, erected settlements on the shore, making it their refuge; this made the local population move to higher grounds on the volcanoes in search of shelter. The island was settled by the Spanish conquistadors at the end of the 16th century; the most important villages on the island are Altagracia, on the northeastern side, Moyogalpa, with its harbor on the northwestern side of the island. These two villages are the centers of the two municipalities and the island is divided between the two. Many traditions have been kept alive, thus inhabitants of Ometepe celebrate more religious and folk festivals than anywhere else in Nicaragua. Today, Ometepe is developing tourism and ecotourism, with the archaeological past and the bounty of its nature sanctuary, the exotic vegetation and bird life as drawcards. A new airport opened in 2014. Volcán Concepción is on the northwest half of the island, it has a base of 16 kilometres beneath its symmetrical cone, it is an active volcano..
Because of its symmetry, it has been considered beautiful. The pirate Edward Hume was said to have declared the sight of Ometepe more valuable than the treasure from the just-sacked city of Granada; the volcano is believed to have risen in the early Holocene epoch and, through continual eruptions, now reaches an altitude of 1,610m making Ometepe the world's highest lake island. Although it went through a long quiet period, on December 8, 1880, Concepción came back to life; this eruption was extensive, the volcano remained active for a year. More eruptions followed in 1883, 1889, 1902, 1907, 1924. In 2005, an earthquake measuring 6.2 on the Richter scale occurred as a result of increasing pressure within the volcano. Cracks appeared on roads throughout an advisory to leave the island was issued; this was the first minor eruption since 1999. The most recent eruption was in 2010 and although it was violent, few of the inhabitants heeded the order from the government in Managua to evacuate the island and little damage was done.
The southeast half of the island consists of Volcán Maderas, which has a crater lake and supports a diverse rainforest environment. Maderas is believed to have risen in the Holocene epoch and rises 1,394m above sea level, it is considered extinct or dormant. The large lagoon in its crater was discovered on April 1930, by the farmer Casimiro Murillo; the sides of the volcano are covered with coffee and tobacco plantations while the remainder is rain forest. Much of this part of the island is now a nature reserve; the volcanic ash has made the soil of this island fertile, allowing continuous planting. The volcanoes are visible from everywhere on the island, life on Ometepe revolves around them, they play an important part in the myths and legends of the island, which once served as an indigenous burial ground. Ometepe Island is included within the archaeological area of “Greater Nicoya,” which encompasses the Rivas area on the lake shore and descends into Costa Rican Nicoya Peninsula. Due to deposits of volcanic ash over millennia, the soil is fertile, allowing constant planting without fallowing.
This rich environment has allowed the island to be continuously inhabited since the Dinarte phase. There is a time period classified as the “Ometepe period” or "Greater Nicoyan Period", which corresponds to the Mesoamerican Postclassic period; this period is associated with the migration of the Nicarao into the area of Greater Nicoya. The archaeologists who have done fieldwork on the island over the years are: 1880s: J. F. Bransford. Dr. Gordon Willey and Albert Norweb excavated the Cruz site, on the North East part of the island; this site is important because it produced nearly 30,000 sherds, most of which belonged to the Late Polychrome Period. The upper levels of the site produced the diagnostic ceramic types which came to define the Late Polychrome Period for the whole of the Rivas area. Pieces were found from the San Jorge phase of the Zoned Bichrome Period; the Ceramic Type "Ometepe Red Slipped-Incised" is found on Ometepe Island. It is a Late Polychrome Period ceramic type, it is found in the form
The rim or edge of an impact crater is the part that extends above the height of the local surface in a circular or elliptical pattern. In a more specific sense, the rim may refer to the circular or elliptical edge that represents the uppermost tip of this raised portion. If there is no raised portion, the rim refers to the inside edge of the curve where the flat surface meets the curve of the crater bottom. Smaller, simple craters retain rim geometries similar to the features of many craters found on the Moon and the planet Mercury. Large craters are those with a diameter greater than 2.3 km, are distinguished by central uplifts within the impact zone. These larger craters can form rims up to several hundred meters in height. A process to consider when determining the exact height of a crater rim is that melt may have been pushed over the crest of the initial rim from the initial impact, thereby increasing its overall height; when combined with potential weathering due to atmospheric erosion over time, determining the average height of a crater rim can be somewhat difficult.
It has been observed that the slope along the excavated interior of many craters can facilitate a spur-and-gully morphology, including mass wasting events occurring due to slope instability and nearby seismic activity. Complex crater rims observed on Earth have anywhere between 5X – 8X greater height:diameter ratio compared to those observed on the Moon, which can be attributed to the greater force of gravitational acceleration between the two planetary bodies that collide. Additionally, crater depth and the volume of melt produced in the impact are directly related to the gravitational acceleration between the two bodies, it has been proposed that “reverse faulting and thrusting at the final crater rim one of the main contributing factors forming the elevated crater rim”. When an impact crater is formed on a sloped surface, the rim will form in an asymmetric profile; as the impacted surface’s angle of repose increases, the crater’s profile becomes more elongate. The rim type classifications are full-rim craters, broken-rim craters, depressions
Caldera De Coatepeque is a volcanic caldera in El Salvador in Central America. The caldera was formed during a series of minor rhyolitic explosive eruptions between about 72,000 and 57,000 years ago. Since basaltic cinder cones and lava flows formed near the west edge of the caldera, six rhyodacitic lava domes have formed; the youngest dome, Cerro Pacho, formed after 8000 BC. Lake Coatepeque is a large crater lake in the east part of the Coatepeque Caldera, it is in Coatepeque Santa Ana, El Salvador. There are hot springs near the lake margins. At 26 square kilometres, it is one of the largest lakes in El Salvador. In the lake is the island of Teopan, a Mayan site of some importance. List of volcanoes in El Salvador "Coatepeque Caldera". Global Volcanism Program. Smithsonian Institution. N/a
Chile the Republic of Chile, is a South American country occupying a long, narrow strip of land between the Andes to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, the Drake Passage in the far south. Chilean territory includes the Pacific islands of Juan Fernández, Salas y Gómez and Easter Island in Oceania. Chile claims about 1,250,000 square kilometres of Antarctica, although all claims are suspended under the Antarctic Treaty; the arid Atacama Desert in northern Chile contains great mineral wealth, principally copper. The small central area dominates in terms of population and agricultural resources, is the cultural and political center from which Chile expanded in the late 19th century when it incorporated its northern and southern regions. Southern Chile is rich in forests and grazing lands, features a string of volcanoes and lakes; the southern coast is a labyrinth of fjords, canals, twisting peninsulas, islands.
Spain conquered and colonized the region in the mid-16th century, replacing Inca rule in the north and centre, but failing to conquer the independent Mapuche who inhabited what is now south-central Chile. After declaring its independence from Spain in 1818, Chile emerged in the 1830s as a stable authoritarian republic. In the 19th century, Chile saw significant economic and territorial growth, ending Mapuche resistance in the 1880s and gaining its current northern territory in the War of the Pacific after defeating Peru and Bolivia. In the 1960s and 1970s, the country experienced severe left-right political polarization and turmoil; this development culminated with the 1973 Chilean coup d'état that overthrew Salvador Allende's democratically elected left-wing government and instituted a 16-year-long right-wing military dictatorship that left more than 3,000 people dead or missing. The regime, headed by Augusto Pinochet, ended in 1990 after it lost a referendum in 1988 and was succeeded by a center-left coalition which ruled through four presidencies until 2010.
The modern sovereign state of Chile is among South America's most economically and stable and prosperous nations, with a high-income economy and high living standards. It leads Latin American nations in rankings of human development, income per capita, state of peace, economic freedom, low perception of corruption, it ranks high regionally in sustainability of the state, democratic development. Chile is a member of the Organisation for Economic Co-operation and Development, joining in 2010, it has the lowest homicide rate in the Americas after Canada. Chile is a founding member of the United Nations, the Union of South American Nations and the Community of Latin American and Caribbean States. There are various theories about the origin of the word Chile. According to 17th-century Spanish chronicler Diego de Rosales, the Incas called the valley of the Aconcagua "Chili" by corruption of the name of a Picunche tribal chief called Tili, who ruled the area at the time of the Incan conquest in the 15th century.
Another theory points to the similarity of the valley of the Aconcagua with that of the Casma Valley in Peru, where there was a town and valley named Chili. Other theories say Chile may derive its name from a Native American word meaning either "ends of the earth" or "sea gulls". Another origin attributed to chilli is the onomatopoeic cheele-cheele—the Mapuche imitation of the warble of a bird locally known as trile; the Spanish conquistadors heard about this name from the Incas, the few survivors of Diego de Almagro's first Spanish expedition south from Peru in 1535–36 called themselves the "men of Chilli". Almagro is credited with the universalization of the name Chile, after naming the Mapocho valley as such; the older spelling "Chili" was in use in English until at least 1900 before switching to "Chile". Stone tool evidence indicates humans sporadically frequented the Monte Verde valley area as long as 18,500 years ago. About 10,000 years ago, migrating indigenous Peoples settled in fertile valleys and coastal areas of what is present-day Chile.
Settlement sites from early human habitation include Monte Verde, Cueva del Milodón and the Pali-Aike Crater's lava tube. The Incas extended their empire into what is now northern Chile, but the Mapuche resisted many attempts by the Inca Empire to subjugate them, despite their lack of state organization, they fought against his army. The result of the bloody three-day confrontation known as the Battle of the Maule was that the Inca conquest of the territories of Chile ended at the Maule river. In 1520, while attempting to circumnavigate the globe, Ferdinand Magellan discovered the southern passage now named after him thus becoming the first European to set foot on what is now Chile; the next Europeans to reach Chile were Diego de Almagro and his band of Spanish conquistadors, who came from Peru in 1535 seeking gold. The Spanish encountered various cultures that supported themselves principally through slash-and-burn agriculture and hunting; the conquest of Chile began in earnest in 1540 and was carried out by Pedro de Valdivia, one of Francisco Pizarro's lieutenants, who founded the city of Santiago on 12 February 1541.
Although the Spanish did not find the extensive gold and silver they sought, they recognize
A fumarole is an opening in a planet's crust which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrogen chloride, hydrogen sulfide. The steam forms when superheated water condenses as its pressure drops when it emerges from the ground; the name solfatara is given to fumaroles. Fumaroles may occur along long fissure, or in chaotic clusters or fields, they occur on the surface of lava or pyroclastic flows. A fumarole field is an area of thermal springs and gas vents where shallow magma or hot igneous rocks release gases or interact with groundwater; when they occur in freezing environments, fumaroles may cause fumarolic ice towers. Fumaroles may persist for centuries if located above a persistent heat source; the Valley of Ten Thousand Smokes, for example, was formed during the 1912 eruption of Novarupta in Alaska. Thousands of fumaroles occurred in the cooling ash from the eruption, but over time most of them have become extinct. An estimated four thousand fumaroles exist within the boundaries of Yellowstone National Park in the United States.
In April 2006 fumarole emissions killed three ski-patrol workers east of Chair 3 at Mammoth Mountain Ski Area in California. The workers were overpowered by toxic fumes. Another example is an array of fumaroles in the Valley of Desolation in Morne Trois Pitons National Park in Dominica. Fumaroles emitting sulfurous vapors form surface deposits of sulfur-rich minerals. Boiling Lake Cold seep Hydrothermal vent Mazuku Mofetta Mudpot Mud volcano Sulfur Mining on Gunung Welirang Volcano Chisholm, Hugh, ed.. "Fumarole". Encyclopædia Britannica. 11. Cambridge University Press. Pp. 300–301