Full glossary

Abu volcano is a group of 56 smaller volcanic centers with no individual large central volcano, located near the Japan Sea coast in southwest Honshu, Japan, 80 km west of Hiroshima.
The group, also known as the Abu Monogenetic Volcano Group (AMVG), covers 400 sq km and consists of basaltic-to-dacitic lava flows, small shield volcanoes (some with associated cinder cones) and lava domes. Its total volume is ca. 4 cubic km, with no individual center being larger than 0.5 km3.
Irao-yama (641 m) is the highest peak. Some of the volcanic centers of Abu volcano form offshore islands or submarine vents.
The most recent eruption at the volcano was a central vent explosion at Kasa-yama ca. 8000 years ago.

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Acamarachi (also known as Cerro Pili) volcano is a stratovolcano in northern Chile. The andesitic-dacitic volcano has very steep slopes (45 deg angle) and forms the highest peak in this part of the Andes.
The volcano contains a poorly preserved summit crater and a large lava dome on the north flank. There are no known lava flows from Holocene times, suggesting the volcano might be extinct.
The summit crater contains a lake about 10-15 m in diameter, which is possibly the second highest crater lake in the world.
Acamarachi is located very close to Colachi volcano, which is only 6 km NNW, but both volcanoes have independent magma systems.

Generally, acceleration is increase of speed or velocity. During earthquakes, the shaking of ground is a swinging motion involving both acceleration and deceleration.
Its maximum value is the largest increase in velocity recorded at a particular point. It largely influences how damaging an earthquake is in this area.

Small spherical balls of volcanic ash

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An adjective describing the chemical composition of magmas (or lavas) having relatively high content of silica (SiO2). It has little to do with the use of the term in chemistry where it is used to describe low pH values found in acids.

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The big caldera of Acigöl-Nevsehir is located in central Turkey and has a size of 7-8 km diameter.

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Acotango volcano is a poorly known volcano on the Chile/Bolivia border. A young lava flow on the northern flank suggests that the volcano has had eruptions within the past 10,000 years and might be considered active.

Adatara volcano is a group of overlapping stratovolcanoes east of Bandai volcano and located 15 km SW of Fukushima City. Its highest summit is Minowa-yama stratovolcano, north of Tetsu-zan, which is the currently active stratovolcano. The group forms a N-S directed elongated chain.
The volcano is known for its hot springs and fumaroles. Io-gawa river ("Sulfur River") exits the complex to the west.
72 workers of a sulfur mine in the summit crater were killed during an eruption in 1900. Historical eruptions were all from within the 1.2-km-wide, 350-m-deep Numonotaira crater of Tetsu-zan.

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Salt lake in Ethiopia

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Aftershocks are smaller quakes that follow a usually larger earthquake in the same rupture zone. The can occur up to weeks, months or even years after, depending on the size of the main shock.

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Agate is a microcrystalline variety of quartz (silica), chiefly chalcedony, characterised by its fineness of grain and brightness of color.

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Agios Georgios is a little harbour on the Methana peninsula in Greece

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Agua de Pau stratovolcano in central Sao Miguel Island contains an outer 4 x 7 km caldera formed about 30,000 to 45,000 years ago and an inner 2.5 x 3 km caldera that was created about 15,000 years ago.

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Aguilera is a dacitic stratovolcano in the southernmost Chilean Andes and located west of Lake Argentina and NE of Peel Fjiord. Its geologic history is poorly known, but there Aguilera must have had a large explosive eruption less than about 3600 years ago, which left a prominent tephra layer.
Aguilera belongs to the Australandean Volcanic Zone of south Patagonia.

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Mount Agung or Gunung Agung is a active volcano in Bali. This stratovolcano is the highest point on the island. It dominates the surrounding area influencing the climate. The clouds come from the west and Agung takes their water so that the west is lush and green and the east dry and barren.

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Akagi or Akagisan volcano is a broad stratovolcano located in central Honshu, 110 km NNW of Tokyo. It is part of the Akagi Prefectural Par.
The volcano contains a 3 x 4 km diameter summit caldera which contains lake Ono in the NE.
It is uncertain whether the volcano has erupted in the past 2000 years. Reports about possible activity in the 9th century, in 1251 and 1938 are considered unreliable.

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Akan volcano (阿寒岳, Akan-dake) is one of Hokkaido's most active volcanoes. Akan consists of a large 24 x 13 km diameter caldera and a group of younger partly Holocene andesite cones. The highest point of the complex is the Mount Meakan (1499 m) stratovolcano.
The frequent historic eruptions occurred all from the Me-Akan group, east of Lake Akan. Me-Akan volcano (雌阿寒岳 Meakan-dake) consists of 9 overlapping cones. Its summit has 3 craters.
Me-Akan has had at least 17 small phreatic eruptions since the beginning of the 19th century and from geologic studies it is known that there were at least 4 major magmatic eruptions with pyroclastic flows have occurred in prehistoric time during the past 10,000 years.

Lake Akan is part of the Akan National Park. It is known for a rare green algae (marimo) which can grow to about the size of a soccer ball. The only town around the lake is the resort of Akankohan known for its hot springs and the "bokke", bubbling mud pools found at the lakeshore.

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Akita-Komagatake volcano is an active volcano in northern Honshu. It is located 10 km east of Tazawa Lake, near the border of Akita and Iwate prefectures, and forms the southern extremity of the Towada-Hachimantai National Park.
The volcano consists of a main edifice cut by 2 calderas that formed after 2 large explosive eruptions between 11,600 and 13,500 years ago. The calderas are partially filled by younger cones. Historic activity consists of small eruptions from cones and fissure vents inside the southern caldera.
It is suspected that Akita-Komaga-take's eruptions are often not preceded by much seismic activity, as was the case during the last eruption, in 1970.

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Akita-Yake-yama volcano is an active stratovolcano in NW Honshu. It is one of several Japanese volcanoes named Yake-yama ("Burning Mountain").
Akita-Yake-yama is the most recently active of a group of overlapping volcanoes immediately west of the Hachimantai volcanic group. Its cone is 7 km wide at the base and contains a 600 m wide summit crater containing a small lava dome, Onigajo. Most of the volcano's frequent eruptions were only phreatic and often ejected mud. The last magmatic eruption was the formation of the Onigajo lava dome in the summit crater about 5000 years ago.
There are fumaroles and hot springs around the volcano, including the strongly radioactive Tamagawa spa at the western foot of the volcano.
Tsugamori volcano to the east is a stratovolcano of roughly the same height as Yake-yama and has a 2-km-wide crater breached to the NE. The flat-topped parasitic lava dome of Kuroshimori lies 4 km south of Yake-dake.

Akrotiri is a village in the southwest of Santorini island

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Akuseki-jima volcano is a small stratovolcano in the southern Ryukyu Islands, Japan. It forms the island of the same name, which measures 2.5 x 3.2 km in diameter and is surrounded by steep cliffs with beaches present only on the SW and SE sides.
Although no direct date exists, it is plausible that Akuseki-jimais is still active.
Akuseki-jima Island
Only about 80 people live on the small island. Access to Akuseki-jima island is limited to one ferry running twice a week traveling 11 hours from Kagoshima. The island has no sources and depends on rainwater as water source.
July 22, 2009 solar eclipse
It was one of the best observation spots (one of the closest inhabited areas to the location of maximum eclipse duration) for the Solar eclipse of 22 July 2009.

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The Bodrum & Akyarlar volcanics belong to the area of the active Cos volcanic complex and are the most western volcanics of Turkey.

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Al Harrah volcano is a large basaltic volcanic field in NW Saudi Arabia near the Jordanian border. It comprises 15,200 sq km of basalt lava flows and forms the southern third of the Harrat Ash Shamah volcanic field, which extends from Syria through Jordan into northern Saudi Arabia.

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Alaid is the tallest and northernmost volcano in the Kurile Islands. Also called Atlasov as the island it forms, the symmetrical stratovolcano rises 3000 m from the sea floor and forms a small island. It has a 1.5-km-wide summit crater breached to the south. It is one of the Kuriles'most active volcanoes. Large explosive eruptions occurred in 1790 and 1981, and were among the largest in the Kuriles in historic times.

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The Alcantara is a river in Sicily.

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Aliso volcano is a newly discovered active stratovolcano complex at the eastern foot of the Ecuadorian Andes, east of Antisana volcano and SW of the town of Baeza. It contains andesitic lava flows, lava domes and pyroclastic flow deposits. Aliso volcano is dormant and has been last active about 2000 years ago.

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Alligator Lake in southern Yukon, Canada, is a group of basaltic cones and lava flows (the Miles Canyon basalts). It is located at the northern extremity of the Stikine volcanic belt, 30 km southwest of the capital city Whitehorse.
The field contains 2 cinder cones on top of a small basaltic shield volcano which is eroded by glacial cover. The cones probably post-date the ice age and seem to be a few thousands years old. Lava flows from both cones traveled to the north and were erupted simultaneously. The longest lava flow extends 6 km N and reaches a width of 10 km.

El Altar is an extinct stratovolcano on the western side of Sangay National Park in Ecuador, 170 km south of Quito. Altar was last active about 2 million years ago and contains a caldera open to the west, which contains a lake.
A large rockslide caused fatalities in 2000. On 13 October 2000, a large block of andesitic breccia with a volumne of ca. 1.5 million m3 rock broke off from near the summit and slid 900 m down into a caldera lake. This impact caused a 50 m high tsunami which overflowed the caldera and produced a lahar, that killed 13 people

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A series of eruptive fissures near Dalaffilla volcano at the northern end of the Erta Ale range (Danakil desert, Ethiopia), many of which have erupted voluminous basaltic lava flows, as recently as in Nov. 2008.

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The Aluchin volcanic group is a cluster of 4 young cinder cones located in the Bilibino Region, in the Aluchin and Burgakhchan river basins in western Chukotka (Siberia). The cinder cones of Aluchin volcano could have erupted less than 10,000 years ago.

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Amasing volcano lies off the southern coast of Halmahera Island, Indonesia, on the small island of Bacan (Palau Batjan). Bukit Amasing (Amasing Hill) is the largest and NW most of 3 small andesitic volcanoes, the other two being Cakasuanggi and Dua Saundara. No recent activity is know from Amasing, and the volcanic edifice is strongly eroded, suggesting it might be extinct.

The Ambalatungan group is a cluster of several volcanoes on northern Luzon Island, Philippines, conprising Ambalatungan, Bumabag, Podakan, and Binuluan volcanoes, aligned roughly E-W.
Ambalatungan volcano is dacitic in composition, and has a steep-walled crater, inside which there are hot springs and strong fumarole vents which produce loud noises and have sulphur deposits.
Bumabag volcano is located only 3 km east of Ambalatungan and has 2 craters that also produce strong fumarolic activity.
Podakan volcano is 1 km SE of Bumabag and also has a large steam vent.
A possible steam eruption might have occurred from Mount Binuluan in 1952, which killed 12 people by a sulfur-rich debris flow.

Ambitle volcano is an active stratovolcano on the 16 km wide N-S and 13 km E-W Ambtitle Island, located 50 km off the SE coast of New Ireland, Papua New Guinea.
Ambtitle is the largest of the Feni Islands, along with the extinct Pleistocene Babase Island / volcano, which are near the SE end of a volcanic island chain north and east of New Ireland.
Ambitle volcano contains a 3 km wide caldera and lava domes. It last erupted about 2300 years ago from a vent on the east side of one of the lava domes inside the caldera forming an explosion crater (maar).
Ambitle is particularly interesting for its shallow-marine hydrothermal vent system of Tutum Bay, which emits hot, acidic, arsenic-rich fluids into sea water.

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The Amboy volcanic field covers an area of 70 km2 between Bagdad Dry Lake to the west and Bristol Dry Lake to the east in the Mojave Desert, California. It contains mainly pahoehoe lava flows. Amboy crater proper is a prominant cinder cone in the NE of the lava field.

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Ambrym is a large basaltic volcano with a 12-km-wide caldera. It is not only one of the most active volcanoes of Vanuatu, but in the world. Its most active craters often contain small lava lakes.

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Amiata is a lava dome complex located about 20 km NW of Lake Bolsena in the southern Tuscany region of Italy.

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Amorong volcano a small lava dome in NW Luzon Island, 80 km NNE of Pinatubo volcano, and belongs to the Eastern Volcanic Chain or Balungao Group, a chain of subduction volcanoes behind the Manila Trench.
It is the only of a group of several lava domes that still has fumarolic activity. It was active from about 740,000 years ago.

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Amplication is the effect of increasing seismic shaking as a result of surface or subsurface topography and geology at a given spot. Various factors can focus seismic energy, in particular the geometry and composition of the rock or sediment strata.
Amplification occurs when seismic waves are reflected or bended and overlap with themselves or other seismic waves from the same quake.

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The maximum displacement of points on a wave from their equilibrium position. We measure the amplitude of seismic waves generated by an earthquake using a seismogram. The size of the waves on the seismogram gives us the amplitude.

Literally translated, "the child of Krakatau", Anak Krakatau is the youngest island of the Krakatau volcanic archipel in the Sunda Strait. It was formed during new eruptions in 1927 when a new island appeared in the caldera left by the huge eruption of Krakatau volcano in 1883.

Anatahan volcano forms the small 9 x 3.7 E-W elongated Anatahan Island in the northern Marianas, about 120 km north of Saipan, the regional Commonwealth of the Northern Mariana Islands capital.
The volcano is at the southern end of the 1500 km long chain of volcanoes formed by the Izu-Bonin-Mariana subduction-zone volcanic arc.
The island is only a tiny fraction (about 1%) of the volcano's entire volume, which rises 3700 m from the sea floor and has a basal diameter of 35 km. It is topped by a 5x2.3 km wide E-W elongated summit caldera. Its principal crater is a 1.4x1.2 km wide and 200 m deep pit crater in the eastern part of the caldera. The highest point of the island is on the western rim.
The first known volcanic activity occurred in 2003, when the volcano came back to life, and has been in a state of frequent eruptions since then.

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The Andahua-Orcopampa volcanic field is a 50 km x 30 km large field of monogenetic vents in the Andahua valley area, 20 km ENE of Nevados de Coropuna stratovolcano. It is known locally as the "Valley of the Volcanoes".
The field contains scoria cones and lava flows, some of which are very young and from historic eruptions.
Strombolian eruptions and lava flows have destroyed buildings from the time of the Incas, and there were uncertain reports of activity in 1913. Lava flows have repeatedly dammed the Río Andagua valley modified the local topography.

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Andesite is a gray to black volcanic rock with intermediate silica content, typical for lava domes and stratovolcanoes in subduction zones.

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Anjuisky volcano is a cinder cone in the south Anjuisky Range east of Kolyma River. Anjuisky cinder cone is 120 m high and has a 300 m wide and 75 m deep crater.

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The Antillanca group of stratovolcanoes is located 100 km NE of Puerto Montt in central Chile, at the eastern shore of Rupanco Lake. The cluster consists of scoria cones, maars and small stratovolcanoes and covers an area of 380 sq km.
The most prominent volcanic edifice is the Casablanca stratovolcano which erupted about 2910 and 2260 years ago.
Older stratovolcanoes of the Antillanca group include Sarnoso volcano on the SW side and Fiuchá volcano on the NW side.
Geothermal areas are found in various spots on the NW side of the group.
(source: USGS/GVP)

Antisana volcano is a large, glacier covered stratovolcano 50 km SE Quito, Ecuador. It is located on the eastern margin of the Cordillera Real, at the latitude where the volcanic chain of the Northern Volcanic Zone is widest. Antisana is one of the largest volcanoes and highest peaks in Ecuador.
The Antisana complex contains 2 generations of volcanic edifices, an older volcano cut by calderas and eroded by glaciers and a young cone. The only confirmed historical eruption was from 1801 to 1802, when a lava flow was erupted from a vent NNE of the summit.
Antisana volcano is iside the Condor Bioreserve as part of the Antisana Ecological Reserve which comprises and area of 296,000 acres.

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Antofagasta de la Sierra is a young volcanic field in Catamarca, NW Argentina, located SW of Beltran volcano and between the Salar de Antofalla on the west and the massive Cerro Galán caldera on the east.
The field contains some of the youngest volcanic vents of vents of the Argentinian Puna region. It contains young looking basaltic-andesite scoria cones and recent-looking lava flows, which could be only a few thousand years old.
Nearby Salar de Antofalla volcanic field contains scoria cones and lava flows east of the NE-SW-trending Salar de Antofalla. It, too, looks young, but no precise ages are known.