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Krakatoa (Indonesian: Krakatau), also known as Krakatau, is a volcanic island made of a'a lava in the Sunda Strait between the islands of Java and Sumatra in Indonesia. Indonesia has over 130 active volcanoes, the most of any nation. They make up the axis of the Indonesian island arc system, which was produced by northeastward subduction of the Indo-Australian Plate. A majority of these volcanoes lie along Indonesia's two largest islands, Java and Sumatra. These two islands are separated by the Sunda Strait, which is located at a bend in the axis of the island arc. Krakatoa is directly above the subduction zone of the Eurasian Plate and the Indo-Australian Plate where the plate boundaries make a sharp change of direction, possibly resulting in an unusually weak crust in the region. The name is used for the island group, the main island, and the volcano as a whole. The island exploded in 1883, killing approximately 40,000 people, although some estimates put the death toll much higher. The explosion is still considered to be the loudest sound ever heard in modern history, with reports of it being heard nearly 3,000 miles from its point of origin. The shock wave from the explosion was recorded on barographs around the globe. With a Volcanic Explosivity Index of 6, the eruption was equivalent to 200 megatons of TNT (840 PJ) — about 13,000 times the nuclear yield of the Little Boy bomb (13 to 16 kt) that devastated Hiroshima, Japan, during World War II and four times the yield of the Tsar Bomba (50 Mt), the largest nuclear device ever detonated. Eruptions at the volcano since 1927 have built a new island in the same location, named Anak Krakatau. This island currently has a radius of roughly 2 kilometres and a high point around 300 metres above sea level, growing 5 metres each year. The most recent eruption began in April 2008, when hot gases, rocks, and lava were released. Scientists monitoring the volcano have warned people to stay out of a 3 km zone around the island. There are several videos of Krakatoa uploaded onto YouTube showing recent footage of it erupting, and inside its crater filmed at the edge of the volcano rim. On 6 May 2009 the Volcanological Survey of Indonesia raised the eruption alert status of Anak Krakatau to Level Orange. [READ THE REST OF THIS ARTICLE]


Thingvellir is a place in southwestern Iceland, near the peninsula of Reykjanes and the Hengill volcanic area. Thingvellir is a site of historical, cultural, and geological importance and is one of the most popular tourist destinations in Iceland. It is the site of a rift valley that marks the crest of the Mid-Atlantic Ridge. It is also home to Țingvallavatn, the largest natural lake in Iceland. Parliament or Alțingi was established at Thingvellir in 930 and remained there until 1789. Thingvellir National Park was founded in 1930 to protect the remains of the parliament site and was later expanded to protect natural phenomena in the surrounding area. Thingvellir National Park was the first national park in Iceland and was decreed "a protected national shrine for all Icelanders, the perpetual property of the Icelandic nation under the preservation of parliament, never to be sold or mortgaged." Thingvellir was the center of Icelandic culture. Every year during the Commonwealth period, people would flock to Thingvellir from all over the country, sometimes numbering in the thousands. They set up dwellings with walls of turf and rock and temporary roofing and stayed in them for the two weeks of the assembly. Although the duties of the assembly were the real reason for going there, ordinary people gathered at Thingvellir for a wide variety of reasons. Merchants, sword-sharpeners, and tanners would sell their goods and services, entertainers performed, and ale-makers brewed drinks for the assembly guests. News was told from distant parts; games and feasts were held. Young people met to make their plans, no less than leading national figures and experts in law. Itinerant farmhands looked for work and vagrants begged. Thingvellir was a meeting place for everyone in Iceland, laying the foundation for the language and literature that have been a prominent part of people's lives right up to the present day. Thingvellir became a national park in 1928 due to its historical importance, as well as the special tectonic and volcanic environment. The continental drift between the North American and Eurasian Plates can be clearly seen in the cracks or faults which traverse the region, the biggest one, Almannagja, being a veritable canyon. This also causes the often-measurable earthquakes in the area. Some of the rifts are full of surprisingly clear water. One, Nikulasargja, is better known as Peningagja (lit. "coin fissure"), as it is littered with coins at its bottom. After being bridged in 1907 for the arrival of King Frederick VIII of Denmark, visitors began to throw coins in the fissure, a tradition based on European legends. Thingvellir is situated on the northern shore of Țingvallavatn, the largest natural lake of Iceland. The river Öxara traverses the national park and forms a waterfall at the Almannagja, called Öxararfoss. On the lake's northern shore Silfra fissure is a popular dive and snorkel tour location. [READ THE REST OF THIS ARTICLE]

Seahorses compose the fish genus Hippocampus within the family Syngnathidae, in order Syngnathiformes. Syngnathidae also includes the pipefishes. "Hippocampus" comes from the Ancient Greek hippos meaning "horse" and kampos meaning “sea monster”. They are mainly found in shallow tropical and temperate waters throughout the world. They prefer to live in sheltered areas such as seagrass beds, coral reefs, or mangroves. Colonies have been found in European waters such as the Thames Estuary. From North America down to South America there are approximately four species, ranging from the very small (dwarf seahorses are only about 2.5 cm (1 in)) to much larger specimens off the Pacific Coast of Central America (the foot-long H. ingens). These fish form territories, with males staying in about 1 square meter (11 sq ft) of their habitat while females range about one hundred times that area. They bob around in sea grass meadows, mangrove stands, and coral reefs where they adopt murky brown and gray patterns to camouflage themselves among the sea grass. During social moments or in unusual surroundings, seahorses turn bright colors. Seahorses are named for their equine profile. Although they are bony fish, they do not have scales, but rather a thin skin stretched over a series of bony plates arranged in rings throughout their body. Each species has a distinct number of rings. Seahorses swim upright, another characteristic that is not shared by their close pipefish relatives, which swim horizontally. Seahorses have a coronet on their head, which is distinct to each individual, much like a human fingerprint. They swim very poorly by using a dorsal fin, which they rapidly flutter and pectoral fins, located behind their eyes, which they use to steer. Seahorses have no caudal fin. Since they are poor swimmers, they are most likely to be found resting, with their prehensile tails wound around a stationary object. They have long snouts, which they use to suck up food, and eyes that can move independently of each other, much like a chameleon. Seahorses eat small shrimp, tiny fish, crustaceans and plankton. The male seahorse is equipped with a brood pouch on the ventral, or front-facing, side. When mating, the female seahorse deposits up to 1,500 eggs in the male's pouch. The male carries the eggs for anywhere from 9 to 45 days until they emerge, expelling fully-developed, miniature seahorses in the water. Seahorse populations are thought to have been endangered in recent years by overfishing and habitat destruction. The seahorse is used in traditional Chinese herbology, and as many as 20 million seahorses may be caught each year and sold for this purpose. Medicinal seahorses are not readily bred in captivity as they are susceptible to disease and it is believed that they have different medicinal properties from aquarium seahorses. Seahorses are also used as medicines by the Indonesians, the Central Filipinos, and many other ethnic groups around the world. [READ THE REST OF THIS ARTICLE]

A rip current is a strong channel of water flowing away from the shoreline, typically through the surf line, and can occur on any shore that has breaking waves. The water flows seaward from near the shore. Typical flow is at 0.5 meters per second (1–2 feet per second), and can be as fast as 2.5 meters per second (8 feet per second). Rip currents can move to different locations on a beach break, up to tens of meters (a few hundred feet) a day. They can occur at any beach with breaking waves, including the world's oceans, seas, and large lakes such as the Great Lakes in the United States of America and Canada. Rip currents are a source of danger for people in ocean and lake surf. They can be extremely dangerous, dragging swimmers away from the beach and leading to death by drowning when they attempt to fight the River or ocean current and become exhausted. Although a rare event, rip currents can be deadly for non-swimmers as well: a person standing waist deep in water can be dragged out into deeper waters, where they can drown if they are unable to swim and are not wearing a flotation device. Some beaches are more likely to have stronger rip currents than others, and a few are particularly well known for them, the overall topography of the area being the main factor. Rip currents cause approximately 100 deaths annually in the United States. Over 80% of rescues by surf beach lifeguards are due to rip currents. Rip currents are stronger when the surf is rough (such as during high onshore winds, or when a strong hurricane is far offshore) or when the tide is low. Rip currents can potentially occur wherever strong longshore variability in wave breaking exists. This variability may be caused by sandbars (as above) or even by crossing wave trains. [READ THE REST OF THIS ARTICLE] is not affiliated with or endorsed by wikipedia. wikipedia and the wikipedia globe are registered trademarks of
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