A mortar is a simple, man portable, muzzle-loaded weapon, consisting of a smooth-bore metal tube fixed to a base plate with a lightweight bipod mount and a sight. They launch explosive shells in high-arcing ballistic trajectories. Mortars are used as indirect fire weapons for close fire support with a variety of ammunition. Mortars have been used for hundreds of years in siege warfare. Many historians consider the first mortars to have been used at the 1453 siege of Constantinople by Mehmed the Conqueror. An Italian account of the 1456 siege of Belgrade by Giovanni da Tagliacozzo said that the Ottoman Turks used seven mortars that fired "stone shots one Italian mile high"; the time of flight of these was long enough that casualties could be avoided by posting observers to give warning of their trajectories. However, earlier mortars were used in Korea in a 1413 naval battle when Korean gunsmiths developed the Wan'gu; the earliest version of the Wan'gu dates back to 1407. Choi Hae-san, the son of Choe Mu-seon, is credited with inventing the first Wan'gu.
Early mortars, such as the Pumhart von Steyr, were large and heavy, could not be transported. Made, these weapons were no more than iron bowls reminiscent of the kitchen and apothecary mortars whence they drew their name. An early transportable mortar was invented by Baron Menno van Coehoorn; this mortar fired an exploding shell. This innovation was taken up, necessitating a new form of naval ship, the bomb vessel. Mortars played a significant role in the Venetian conquest of Morea and in the course of this campaign an ammunition store in the Parthenon was blown up. An early use of these more mobile mortars as field weapons was by British forces in the suppression of the Jacobite rising of 1719 at the Battle of Glen Shiel. High angle trajectory mortars held a great advantage over standard field guns in the rough terrain of the West Highlands of Scotland; the mortar had fallen out of general use in Europe by the Napoleonic era and interest in the weapon was not revived until the beginning of the 20th century.
Mortars were used by both sides during the American Civil War. At the Siege of Vicksburg, General US Grant reported making coehorn mortars "by taking logs of the toughest wood that could be found, boring them out for six- or twelve-pound shells and binding them with strong iron bands; these answered as Coehorns, shells were thrown from them into the trenches of the enemy". During the Russo-Japanese War, Lieutenant-General Leonid Gobyato of the Imperial Russian Army applied the principles of indirect fire from closed firing positions in the field and, with the collaboration of General Roman Kondratenko, he designed the first mortar that fired navy shells; the German Army studied the Siege of Port Arthur, where heavy artillery had been unable to destroy defensive structures like barbed wire and bunkers. As a result, they developed. Used during World War I, they were made in three sizes. World War I saw the introduction of the Stokes mortar, it was the forerunner of all modern mortars in use today.
These modern weapons are light, easy to operate, yet possess enough accuracy and firepower to provide infantry with quality close fire support against soft and hard targets more than any other means. It was not until the Stokes Mortar was devised by Sir Wilfred Stokes in 1915 during the First World War that the modern mortar transportable by one person was born. In the conditions of trench warfare, there was a great need for a versatile and portable weapon that could be manned by troops undercover in the trenches. Stokes's design was rejected in June 1915 because it was unable to use existing stocks of British mortar ammunition, it took the intervention of David Lloyd George and Lieutenant-Colonel J. C. Matheson of the Trench Warfare Supply Department to expedite manufacture of the Stokes mortar; the weapon proved to be useful in the muddy trenches of the Western Front, as a mortar round could be aimed to fall directly into trenches, where artillery shells, due to their low angle of flight, could not go.
The Stokes mortar was a simple muzzle-loaded weapon, consisting of a smoothbore metal tube fixed to a base plate with a lightweight bipod mount. When a mortar bomb was dropped into the tube, an impact sensitive primer in the base of the bomb would make contact with a firing pin at the base of the tube, detonate, firing the bomb towards the target, it could fire as many as 25 bombs per minute and had a maximum range of 800 yards firing the original cylindrical unstabilised projectile. A modified version of the mortar, which fired a modern fin-stabilised streamlined projectile and had a booster charge for longer range, was developed after World War I. By World War II, it could fire as many as 30 bombs per minute, had a range of over 2,500 yards with some shell types; the French developed an improved version of the Stokes mortar as the Brandt Mle 27, further refined as the Brandt Mle 31. These weapons were the prototypes for all subsequent light mortar developments around the world. Mortar carriers are vehicles.
Numerous vehicles have been used to mount morta
Medal of Honor
The Medal of Honor is the United States of America's highest and most prestigious personal military decoration that may be awarded to recognize U. S. military service members who have distinguished themselves by acts of valor. The medal is awarded by the President of the United States in the name of the U. S. Congress; because the medal is presented "in the name of Congress", it is referred to informally as the "Congressional Medal of Honor". However, the official name of the current award is "Medal of Honor." Within the United States Code the medal is referred to as the "Medal of Honor", less as "Congressional Medal of Honor". U. S. awards, including the Medal of Honor, do not have post-nominal titles, while there is no official abbreviation, the most common abbreviations are "MOH" and "MH". There are three versions of the medal, one each for the Army and Air Force. Personnel of the Marine Corps and Coast Guard receive the Navy version; the Medal of Honor was introduced for the Navy in 1861, soon followed by an Army version in 1862.
The Medal of Honor is the oldest continuously issued combat decoration of the United States armed forces. The President presents the Medal of Honor in Washington, D. C. at a formal ceremony, intended to represent the gratitude of the U. S. people, with posthumous presentations made to the primary next of kin. According to the Medal of Honor Historical Society of the United States, there have been 3522 Medals of Honor awarded to the nation's soldiers, airmen and Coast Guardsmen since the decoration's creation, with just less than half of them awarded for actions during the four years of the American Civil War. In 1990, Congress designated March 25 annually as "National Medal of Honor Day". Due to its prestige and status, the Medal of Honor is afforded special protection under U. S. law against any unauthorized adornment, sale, or manufacture, which includes any associated ribbon or badge. The modern-day Medal of Honor had a number of precursors; the first medal for military service in the United States was issued in 1780, after its creation in the same year by the Continental Congress.
Known as the Fidelity Medallion, it was a small medal worn on a chain around the neck, similar to a religious medal, awarded only to three militiamen from New York state. They received it for the capture of John André, a British officer and spy connected directly to General Benedict Arnold during the American Revolutionary War; the capture saved the fort of West Point from the British Army. The first formal system for rewarding acts of individual gallantry by U. S. soldiers was established by George Washington when he issued a field order on August 7, 1782, for a Badge of Military Merit to recognize those members of the Continental Army who performed "any singular meritorious action". This decoration is America's first combat decoration and was preceded only by the Fidelity Medallion, the Congressional medal for Henry Lee awarded in September 1779 in recognition of his attack on the British at Paulus Hook, the Congressional medal for General Horatio Gates awarded in November 1777 in recognition of his victory over the British at Saratoga, the Congressional medal for George Washington awarded in March 1776.
Although the Badge of Military Merit fell into disuse after the American Revolutionary War, the concept of a military award for individual gallantry by members of the U. S. Armed Forces had been established. After the outbreak of the Mexican–American War a Certificate of Merit was established by Act of Congress on March 3, 1847, "to any private soldier who had distinguished himself by gallantry performed in the presence of the enemy". 539 Certificates were approved for this period. The certificate was discontinued after the war and reintroduced in 1876 effective from June 22, 1874, to February 10, 1892, when it was awarded for extraordinary gallantry by private soldiers in the presence of the enemy. From February 11, 1892, through July 9, 1918, it could be awarded to members of the Army for distinguished service in combat or noncombat; this medal was replaced by the Army Distinguished Service Medal, established on January 2, 1918. Those Army members who held the Distinguished Service Medal in place of the Certificate of Merit could apply for the Army Distinguished Service Cross effective March 5, 1934.
During the first year of the Civil War, a proposal for a battlefield decoration for valor was submitted to Winfield Scott, the general-in-chief of the army, by Lt. Colonel Edward D. Townsend, an assistant adjutant at the War Department and Scott's chief of staff. Scott, was against medals being awarded, the European tradition. After Scott retired in October 1861, Secretary of the Navy Gideon Welles adopted the idea of a decoration to recognize and honor distinguished naval service. On December 9, 1861, U. S. Senator James W. Grimes, Chairman on the Committee on Naval Affairs, submitted Bill S. 82 during the Second Session of the 37th Congress, "An Act to further promote the Efficiency of the Navy". The bill included a provision for 200 "medals of honor", "to be bestowed upon such petty officers, seamen and marines as shall most distinguish themselves by their gallantry in action and other seaman-like qualities during the present war..." On December 21, the bill was passed and signed into law by P
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
Oerlikon 20 mm cannon
The Oerlikon 20 mm cannon is a series of autocannons, based on an original German 20 mm Becker design that appeared early in World War I. It was produced by Oerlikon Contraves and others, with various models employed by both Allied and Axis forces during World War II, many versions still in use today. During World War I, the German industrialist Reinhold Becker developed a 20 mm caliber cannon, known now as the 20 mm Becker using the Advanced Primer Ignition blowback method of operation; this had a cyclic rate of fire of 300 rpm. It was used on a limited scale as an aircraft gun on Luftstreitkräfte warplanes, an anti-aircraft gun towards the end of that war; because the Treaty of Versailles banned further production of such weapons in Germany, the patents and design works were transferred in 1919 to the Swiss firm SEMAG based near Zürich. SEMAG continued development of the weapon, in 1924 had produced the SEMAG L, a heavier weapon that fired more powerful 20x100RB ammunition at a higher rate of fire, 350 rpm.
In 1924 SEMAG failed. The Oerlikon firm, named after the Zürich suburb of Oerlikon where it was based acquired all rights to the weapon, plus the manufacturing equipment and the employees of SEMAG. In 1927 the Oerlikon S was added to the existing product line; this fired a still larger cartridge to achieve a muzzle velocity of 830 m/s, at the cost of increased weight and a reduced rate of fire. The purpose of this development was to improve the performance of the gun as an anti-tank and anti-aircraft weapon, which required a higher muzzle velocity. An improved version known as the 1S followed in 1930. Three sizes of gun with their different ammunition and barrel length, but similar mechanisms, continued to be developed in parallel. In 1930 Oerlikon reconsidered the application of its gun in aircraft and introduced the AF and AL, designed to be used in flexible mounts, i.e. manually aimed by a gunner. The 15-round box magazine used by earlier versions of the gun was replaced by drum magazine holding 15 or 30 rounds.
In 1935 it made an important step by introducing a series of guns designed to be mounted in or on the wings of fighter aircraft. Designated with FF for Flügelfest meaning "wing-mounted", these weapons were again available in the three sizes, with designations FF, FFL and FFS; the FF fired a larger cartridge than the AF, 20x72RB, but the major improvement in these weapons was a significant increase in rate of fire. The FF weighed 24 kg and achieved a muzzle velocity of 550 to 600 m/s with a rate of fire of 520 rpm; the FFL of 30 kg fired a projectile at a muzzle velocity of 675 m/s with a rate of fire of 500 rpm. And the FFS, which weighed 39 kg, delivered a high muzzle velocity of 830 m/s at a rate of fire of 470 rpm. Apart from changes to the design of the guns for wing-mounting and remote control, larger drums were introduced as it would not be possible to exchange magazines in flight. For the FF series drum sizes of 45, 60, 75 and 100 rounds were available, but most users chose the 60-round drum.
The 1930s were a period of global re-armament, a number of foreign firms took licenses for the Oerlikon family of aircraft cannon. In France, Hispano-Suiza manufactured development of the FFS as the Hispano-Suiza HS.7 and Hispano-Suiza HS.9, for installation between the cylinder banks of its V-12 engines. In Germany, Ikaria further developed the FF gun as firing 20x80RB ammunition, and the Imperial Japanese Navy, after evaluating all three guns, ordered developments of the FF and FFL as the Type 99-1 and Type 99-2. The incorporation of the improvements of the FFS in a new anti-aircraft gun produced, in 1938, the Oerlikon SS. Oerlikon realized further improvements in rate of fire on the 1SS of 1942, the 2SS of 1945 which achieved 650 rpm. However, it was the original SS gun, adopted as anti-aircraft gun, being widely used by Allied navies during World War II; this gun used a 400-grain charge of IMR 4831 smokeless powder to propel a 2,000-grain projectile at 2,800 feet per second. The Oerlikon FF was installed as armament on some fighters of the 1930s, such as the Polish PZL P.24G.
Locally produced derivatives of the Oerlikon cannon were used much more extensively, on aircraft, on ships and on land. In the air, the Ikaria MG FF was used as armament on a number of German aircraft, of which the most famous is the Messerschmitt Bf 109; the Japanese Navy used their copy of the FF, designated the Type 99 Mark One cannon on a number of types including the Mitsubishi A6M Zero. In the war, they equipped fighters including the Zero with the Type 99 Mark Two, a version of the more powerful and faster-firing Oerlikon FFL; the French firm of Hispano-Suiza was a manufacturer of aircraft engines, it marketed the moteur-canon combination of its 12X and 12Y engines with a H. S.7 or H. S.9 cannon installed between the cylinder banks. The gun fired through the hollow propeller hub, this being elevated above the crankcase by the design of the gearing; such armament was installed on the Morane-Saulnier M. S.406 and some other types. Similar German installations of the MG FF were not successful.
The Oerlikon became best known in its naval applications. The Oerlikon was not looked upon favorably by the Royal Navy as a short-range anti-aircraft gun. All through 1937-1938 Lord Louis Mountbatten a Captain in the Royal Navy, waged a lone campaign within the Royal Navy to set up an unprejudiced trial for the Oerlikon 20 mm gun, but it was all in vain, it was not until the Commander-in-Chief of the Home Fleet, Admiral Sir Roger Backhouse, was appointed First Sea Lord tha
Battle of Okinawa
The Battle of Okinawa, codenamed Operation Iceberg, was a major battle of the Pacific War fought on the island of Okinawa by United States Marine and Army forces against the Imperial Japanese Army. The initial invasion of Okinawa on April 1, 1945, was the largest amphibious assault in the Pacific Theater of World War II; the 82-day battle lasted from April 1 until June 22, 1945. After a long campaign of island hopping, the Allies were planning to use Kadena Air Base on the large island of Okinawa as a base for Operation Downfall, the planned invasion of the Japanese home islands, 340 mi away; the United States created the Tenth Army, a cross-branch force consisting of the 7th, 27th, 77th, 96th infantry divisions of the US Army with the 1st, 2nd, 6th divisions of the Marine Corps, to fight on the island. The Tenth was unique in that it had its own tactical air force, was supported by combined naval and amphibious forces; the battle has been referred to as the "typhoon of steel" in English, tetsu no ame or tetsu no bōfū in Japanese.
The nicknames refer to the ferocity of the fighting, the intensity of Japanese kamikaze attacks, the sheer numbers of Allied ships and armored vehicles that assaulted the island. The battle was one of the bloodiest in the Pacific, with 160,000 casualties on both sides: at least 75,000 Allied and 84,166–117,000 Japanese, including drafted Okinawans wearing Japanese uniforms. 149,425 Okinawans were killed, committed suicide or went missing, a significant proportion of the estimated pre-war 300,000 local population. In the naval operations surrounding the battle, both sides lost considerable numbers of ships and aircraft, including the Japanese battleship Yamato. After the battle, Okinawa provided a fleet anchorage, troop staging areas, airfields in proximity to Japan in preparation for the planned invasion. In all, the Army had over 102,000 soldiers, over 18,000 Navy personnel. At the start of the Battle of Okinawa, the 10th Army had 182,821 personnel under its command, it was planned that General Buckner would report to Turner until the amphibious phase was completed, after which he would report directly to Spruance.
Although Allied land forces were composed of American units, the British Pacific Fleet provided about ¼ of Allied naval air power. It comprised a force. Although all the BPF aircraft carriers were provided by Britain, the carrier group was a combined British Commonwealth fleet with Australian, New Zealand and Canadian ships and personnel, their mission was to neutralize Japanese airfields in the Sakishima Islands and provide air cover against Japanese kamikaze attacks. Most of the air-to-air fighters and the small dive bombers and strike aircraft were US Navy carrier-based airplanes; the Japanese land campaign was conducted by the 67,000-strong regular 32nd Army and some 9,000 Imperial Japanese Navy troops at Oroku naval base, supported by 39,000 drafted local Ryukyuan people. The Japanese had used kamikaze tactics since the Battle of Leyte Gulf, but for the first time, they became a major part of the defense. Between the American landing on April 1 and May 25, seven major kamikaze attacks were attempted, involving more than 1,500 planes.
The 32nd Army consisted of the 9th, 24th, 62nd Divisions, the 44th Independent Mixed Brigade. The 9th Division was moved to Taiwan before the invasion, resulting in shuffling of Japanese defensive plans. Primary resistance was to be led in the south by Lieutenant General Mitsuru Ushijima, his chief of staff, Lieutenant General Isamu Chō and his chief of operations, Colonel Hiromichi Yahara. Yahara advocated a defensive strategy, whilst Chō advocated an offensive one. In the north, Colonel Takehido Udo was in command; the IJN troops were led by Rear Admiral Minoru Ōta. They expected the Americans to land 6–10 divisions against the Japanese garrison of two and a half divisions; the staff calculated that superior quality and numbers of weapons gave each US division five or six times the firepower of a Japanese division. To this, would be added the Americans' abundant naval and air firepower. In Okinawa island, middle school boys were organized into front-line-service Tekketsu Kinnōtai, while Himeyuri students were organized into a nursing unit.
The Japanese Imperial Army mobilized 1,780 middle school boys aged 14–17 years into front-line-service. They were named "Tekketsu Kinnōtai"; this mobilization was conducted by the ordinance of the Ministry of Army, not by law. The ordinances mobilized the student as a volunteer soldier for form's sake. In reality, the military authorities ordered schools to force all students to "volunteer" as soldiers. Sometimes they counterfeited the necessary documents. About half of Tekketsu Kinnōtai were killed, including in suicide bomb attacks against tanks, in guerrilla operations. After losing the Battle of Okinawa, the Japanese government enacted new laws in preparation for the decisive battles in the main islands; these laws made it possi
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaiʻi in the south to northernmost Kure Atoll. The group was known to Europeans and Americans as the Sandwich Islands, a name chosen by James Cook in honor of the First Lord of the Admiralty John Montagu, 4th Earl of Sandwich; the contemporary name is derived from the name of Hawaii Island. The U. S. state of Hawaii now occupies the archipelago in its entirety, with the sole exception of Midway Island, which instead separately belongs to the United States as one of its unincorporated territories within the United States Minor Outlying Islands. The Hawaiian Islands are the exposed peaks of a great undersea mountain range known as the Hawaiian–Emperor seamount chain, formed by volcanic activity over a hotspot in the Earth's mantle; the islands are about 1,860 miles from the nearest continent. Captain James Cook visited the islands on January 18, 1778, named them the "Sandwich Islands" in honor of John Montagu, 4th Earl of Sandwich, one of his sponsors as the First Lord of the Admiralty.
This name was in use until the 1840s, when the local name "Hawaii" began to take precedence. The Hawaiian Islands have a total land area of 6,423.4 square miles. Except for Midway, an unincorporated territory of the United States, these islands and islets are administered as Hawaii—the 50th state of the United States; the eight main islands of Hawaii are listed here. All except Kahoolawe are inhabited. Smaller islands and reefs form the Northwestern Hawaiian Islands, or Hawaiian Leeward Islands: Nihoa Necker French Frigate Shoals Gardner Pinnacles Maro Reef Laysan Lisianski Island Pearl and Hermes Atoll Midway Atoll Kure Atoll The state of Hawaii counts 137 "islands" in the Hawaiian chain; this number includes all minor islands and islets, or small islands, offshore of the main islands and individual islets in each atoll. These are just a few: Ford Island Lehua Ka'ula Kaohikaipu Mānana Mōkōlea Rock Nā Mokulua Molokini Mokoliʻi Moku Manu Moku Ola Moku o Loʻe Sand Island Grass Island This chain of islands, or archipelago, developed as the Pacific Plate moved northwestward over a hotspot in the Earth's mantle at a rate of 32 miles per million years.
Thus, the southeast island is volcanically active, whereas the islands on the northwest end of the archipelago are older and smaller, due to longer exposure to erosion. The age of the archipelago has been estimated using potassium-argon dating methods. From this study and others, it is estimated that the northwesternmost island, Kure Atoll, is the oldest at 28 million years; the only active volcanism in the last 200 years has been on the southeastern island, Hawaiʻi, on the submerged but growing volcano to the extreme southeast, Loʻihi. The Hawaiian Volcano Observatory of the USGS documents recent volcanic activity and provides images and interpretations of the volcanism. Kīlauea has been erupting nearly continuously since 1983. All of the magma of the hotspot has the composition of basalt, so the Hawaiian volcanoes are composed entirely of this igneous rock. There is little coarser-grained gabbro and diabase. Nephelinite is exposed on the islands but is rare; the majority of eruptions in Hawaiʻi are Hawaiian-type eruptions because basaltic magma is fluid compared with magmas involved in more explosive eruptions, such as the andesitic magmas that produce some of the spectacular and dangerous eruptions around the margins of the Pacific basin.
Hawaiʻi island is the youngest island in the chain, built from five volcanoes. Mauna Loa, taking up over half of the Big Island, is the largest shield volcano on the Earth; the measurement from sea level to summit is more than 2.5 miles, from sea level to sea floor about 3.1 miles.. The Hawaiian Islands have many earthquakes caused by volcanic activity. Most of the early earthquake monitoring took place in Hilo, by missionaries Titus Coan, Sarah J. Lyman and her family. From 1833 to 1896 4 or 5 earthquakes were reported per year. Hawaii accounted for 7.3% of the United States' reported earthquakes with a magnitude 3.5 or greater from 1974 to 2003, with a total 1533 earthquakes. Hawaii ranked as the state with the third most earthquakes over this time period, after Alaska and California. On October 15, 2006, there was an earthquake with a magnitude of 6.7 off the northwest coast of the island of Hawaii, near the Kona area of the big island. The initial earthquake was followed five minutes by a magnitude 5.7 aftershock.
Minor-to-moderate damage was reported on most of the Big Island. Several major roadways became impassable from rock slides, effects were felt as far away as Honolulu, nearly 150 miles from the epicenter. Power outages lasted for several hours to days. Several water mains ruptured. No deaths or life-threatening injuries were reported. On May 4, 2018 there was a 6.9 earthquake in the zone of volcanic activity from Kīlauea. Earthquakes are monitored by the Hawaiian Volcano Observatory run by the USGS; the Hawaiian Islands are subjec