The volcanoes of east-central Baja California are located on the Baja California Peninsula near the Gulf of California, in the state of Baja California Sur, in Mexico.
The volcanoes of east-central Baja California are located on the Baja California Peninsula near the Gulf of California, in the state of Baja California Sur, in Mexico.
Baja California is a peninsula in Mexico, bordering the Pacific Ocean and the Gulf of California. It is made up primarily of mountains, and some coastal plains. The mountain ranges in Baja California, connected to the Pacific Coast Ranges, extend from the north-eastern to the south-western part of the peninsula. [1] Out of the 24 named ranges, the Sierra de Juárez and the Sierra San Pedro Mártir, the highest range in Baja California, are the two most significant. The slopes of the ranges vary depending on location; the slopes on the western side are gentler than those on the east. Coastal plains are mostly found in the south-west regions on the peninsula. In the center of Baja California, volcanic activity is found mostly near the San Ignacio area. [2] The landscape is a patchwork of lava flows and the hardened remains of pyroclastic flows – hot clouds of volcanic ash, dust, and rock fragments that race down the slopes of a volcano like an avalanche.
La Reforma Caldera is a volcano on the east-central Baja California. It is about 10 km (6.2 mi) in diameter and 1,300 m (4,300 ft) tall. [3] In the east-central Baja California there are several volcanoes and this one lies east of the Tres Vírgenes volcano and southeast of El Aguajito.
La Reforma is a caldera volcano, formed when a large eruption left an empty magma chamber, which the upper volcano collapsed into. La Reforma's last major eruption occurred about 10,000 years ago. Its eruptions have consisted of ash and pumice falls, pumice flows, and pantellerite tuffs. [4] The dark-colored rocks that make up the outer rim of La Reforma formed from very fluid lava. [5]
The Tres Vírgenes, a line of three connected volcanoes, are west of La Reforma Caldera. They lie NE-SW along the western Gulf of California. [6] The three are La Vírgen (The Virgin) in the southwest, El Azufre (Sulfur) in the center, and El Viejo (The Old One) in the northeast. El Viejo is the oldest and lowest peak, and La Vírgen is the youngest and tallest of the three. It has a history of pumice eruptions and explosive eruptions consisting of pyroclastic flows, dacitic and andesitic lava flows.
The volcanoes get larger and younger from northeast to southwest. They consist of stratovolcanoes, lava domes, and pyroclastic cones. Dacitic lava domes and flows have occurred at El Viejo and El Azufre.
Unlike other volcanoes in Baja California, the Tres Vírgenes are stratovolcanoes, consisting of alternate layers of ash and lava. [7] The last time one of the volcanoes was active was in 1746, with a possible eruption in 1857. [8] The evidence for the 1746 eruption came from a Spanish priest, who at the time was on a navigation in the Gulf of California. In his report, it was said that there was an ash plume from the effusive eruption, and while no tephra deposits have been discovered, there is evidence of andesitic lava flows that could have came from the 1746 eruption.[ citation needed ]
As recently as 6,500 years ago, La Vírgen experienced a Plinian eruption – a large and explosive event that creates a column of volcanic rock fragments and gas that reaches into the stratosphere. The eruption produced a column that reached at least 18 kilometers into the air and deposited ash and rock fragments over 500 square kilometers.[ citation needed ] In later stages of the eruption, pyroclastic flows (pinkish rocks) and lahars (mudflows, grayish rocks) from El Azufre Volcano paved the plain to the north all the way to the Gulf of California.[ citation needed ]
El Aguajito Caldera, also known as Santa Ana Caldera, is located northeast of the Tres Vírgenes. [9] The caldera's formation "is associated with the eruption of ignimbrites, K–Ar dated at 0.76±0.06 Ma". [10] [11] The rim of the caldera is approximately 10 km (6.2 mi) wide and is not exposed to the surface. [3] There is an active geothermal system with hot springs on the southern side of the caldera.[ citation needed ]
A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is lost. The ground surface then collapses downward into the emptied or partially emptied magma chamber, leaving a large depression at the surface. 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.
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
Rhyolite is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent to granite.
The geology of the Lassen volcanic area presents a record of sedimentation and volcanic activity in the area in and around Lassen Volcanic National Park in Northern California, U.S. The park is located in the southernmost part of the Cascade Mountain Range in the Pacific Northwest region of the United States. Pacific Oceanic tectonic plates have plunged below the North American Plate in this part of North America for hundreds of millions of years. Heat from these subducting plates has fed scores of volcanoes in California, Oregon, Washington and British Columbia over at least the past 30 million years, including these in the Lassen volcanic area.
Newberry Volcano is a large active shield volcano located about 20 miles (32 km) south of Bend, Oregon, United States, 35 miles (56 km) east of the major crest of the Cascade Range, within the Newberry National Volcanic Monument. Its highest point is Paulina Peak. The largest volcano in the Cascade Volcanic Arc, Newberry has an area of 1,200 square miles (3,100 km2) when its lava flows are taken into account. From north to south, the volcano has a length of 75 miles (121 km), with a width of 27 miles (43 km) and a total volume of approximately 120 cubic miles (500 km3). It was named for the geologist and surgeon John Strong Newberry, who explored central Oregon for the Pacific Railroad Surveys in 1855. The surrounding area has been inhabited by Native American populations for more than 10,000 years.
Mount Mazama is a complex volcano in the state of Oregon, United States, in a segment of the Cascade Volcanic Arc and Cascade Range. Most of the mountain collapsed following a major eruption approximately 7,700 years ago. The volcano is in Klamath County, in the southern Cascades, 60 miles (97 km) north of the Oregon–California border. Its collapse formed a caldera that holds Crater Lake. The mountain is in Crater Lake National Park. Mount Mazama originally had an elevation of 12,000 feet (3,700 m), but following its climactic eruption this was reduced to 8,157 feet (2,486 m). Crater Lake is 1,943 feet (592 m) deep, the deepest freshwater body in the US and the second deepest in North America after Great Slave Lake in Canada.
Mount Katmai is a large stratovolcano on the Alaska Peninsula in southern Alaska, located within Katmai National Park and Preserve. It is about 6.3 miles (10 km) in diameter with a central lake-filled caldera about two by three miles in size, formed during the Novarupta eruption of 1912. The caldera rim reaches a maximum elevation of 6,716 feet (2,047 m). In 1975 the surface of the crater lake was at an elevation of about 4,220 feet (1,286 m), and the estimated elevation of the caldera floor is about 3,400 ft (1,040 m). The mountain is located in Kodiak Island Borough, very close to its border with Lake and Peninsula Borough.
The Volcán de Colima, 3,820 m (12,533 ft), also known as Volcán de Fuego, is part of the Colima Volcanic Complex (CVC) consisting of Volcán de Colima, Nevado de Colima and the eroded El Cántaro. It is the youngest of the three and as of 2015 is one of the most active volcanos in Mexico and in North America. It has erupted more than 40 times since 1576. One of the largest eruptions was on January 20–24, 1913. Nevado de Colima, also known as Tzapotépetl, lies 5 kilometres (3.1 mi) north of its more active neighbor and is the taller of the two at 4,271 meters (14,015 ft). It is the 26th-most prominent peak in North America.
Cerro El Cóndor is a stratovolcano in Argentina.
Cerro Azul, sometimes referred to as Quizapu, is an active stratovolcano in the Maule Region of central Chile, immediately south of Descabezado Grande. Part of the South Volcanic Zone of the Andes, its summit is 3,788 meters (12,428 ft) above sea level, and is capped by a summit crater that is 500 meters (1,600 ft) wide and opens to the north. Beneath the summit, the volcano features numerous scoria cones and flank vents.
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. Explosive eruptions can send rocks, dust, gas and pyroclastic material up to 20 km (12 mi) into the atmosphere at a rate of up to 100,000 tonnes per second, traveling at several hundred meters per second. This cloud may then collapse, creating a fast-moving pyroclastic flow of hot volcanic matter.
Lake Ilopango is a crater lake which fills an 8 by 11 km 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 100 m (330 ft) to 500 m (1,600 ft) 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.
Tres Vírgenes is a complex of volcanoes located Mulegé Municipality in the state of Baja California Sur, on the Baja California Peninsula in northwestern Mexico. This Volcano is part of a volcanic ridge that extends from Baja California towards the Guaymas Basin.
Quetrupillán is a stratovolcano located in Araucanía Region of Chile. It is situated between Villarrica and Lanín volcanoes, within Villarrica National Park. Geologically, Quetrupillán is located in a tectonic basement block between the main traces of Liquiñe-Ofqui Fault and Reigolil-Pirihueico Fault.
El Aguajito is a caldera volcano located on the Gulf of California in Mexico.
Lake Taupō, in the centre of New Zealand's North Island, is the caldera of a large rhyolitic supervolcano called the Taupō Volcano. This huge volcano has produced two of the world's most violent eruptions in geologically recent times.
Calabozos is a Holocene caldera in central Chile's Maule Region. Part of the Chilean Andes' volcanic segment, it is considered a member of the Southern Volcanic Zone (SVZ), one of the three distinct volcanic belts of South America. This most active section of the Andes runs along central Chile's western edge, and includes more than 70 of Chile's stratovolcanoes and volcanic fields. Calabozos lies in an extremely remote area of poorly glaciated mountains.
Nevados de Pastos Grandes is a Miocene volcanic centre in the Puna, Salta province, Argentina. It is a volcanic complex with several centres named El Queva, Gordo and Azufre. Some minor Pleistocene glaciation has affected the volcanic complex.
La Reforma is a Plio-Pleistocene caldera on the Baja California Peninsula in Mexico. It is part of eleven volcanoes in Baja California, which formed with the Gulf of California during the Miocene, about ten million years ago. Previously, a volcanic arc had existed on the peninsula. The caldera's basement consists of granites and monzonites, formed between the Cretaceous and the Middle Miocene.
Ubinas is an active stratovolcano in the Moquegua Region of southern Peru, approximately 60 kilometres (37 mi) east of the city of Arequipa. Part of the Central Volcanic Zone of the Andes, it rises 5,672 metres (18,609 ft) above sea level. The volcano's summit is cut by a 1.4-kilometre-wide (0.87 mi) and 150-metre-deep (490 ft) caldera, which itself contains a smaller crater. Below the summit, Ubinas has the shape of an upwards-steepening cone with a prominent notch on the southern side. The gently sloping lower part of the volcano is also known as Ubinas I and the steeper upper part as Ubinas II; they represent different stages in the volcano's geological history.