Larderello is a frazione of the comune of Pomarance , in Tuscany in central Italy , renowned for its geothermal productivity.
12-450: The region of Larderello has experienced occasional phreatic eruptions , caused by explosive outbursts of steam trapped below the surface. The water is contained in metamorphic rocks where it is turned to steam which is then trapped beneath a dome of impermeable shales and clay. The steam escapes through faults in the dome and forces its way out in the hot springs. It possesses a dozen explosion craters 30–250 m in diameter. The largest
24-490: A crater lake . These lakes may become soda lakes , many of which are associated with active tectonic and volcanic zones. A crater may be breached during an eruption, either by explosions or by lava , or through later erosion. Breached craters have a much lower rim on one side. Some volcanoes, such as maars , consist of a crater alone, with scarcely any mountain at all. These volcanic explosion craters are formed when magma rises through water-saturated rocks, which causes
36-456: A broad-spectrum poison. A 1979 phreatic eruption on the island of Java killed 140 people, most of whom were overcome by poisonous gases. Volcanic crater A volcanic crater is an approximately circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature containing one or more vents. During volcanic eruptions , molten magma and volcanic gases rise from an underground magma chamber , through
48-408: A conduit, until they reach the crater's vent, from where the gases escape into the atmosphere and the magma is erupted as lava . A volcanic crater can be of large dimensions, and sometimes of great depth. During certain types of explosive eruptions , a volcano's magma chamber may empty enough for an area above it to subside, forming a type of larger depression known as a caldera . In most volcanoes,
60-555: A pioneering experiment in the production of energy from geothermal sources in 1904, when five light bulbs were lit by electricity produced through steam emerging from vents in the ground - the first ever practical demonstration of geothermal power . Prince Piero Ginori Conti tested the first geothermal power generator on 4 July 1904, at the Larderello dry steam field in Italy. It was a small generator that lit four light bulbs. In 1911,
72-410: A way of extracting boric acid from the mud by using steam to heat cauldrons to separate the two. Leopold II, Grand Duke of Tuscany was an enthusiastic supporter of Larderel's scheme and awarded him the title of Count of Montecerboli a decade later. A town, named Larderello in honour of Larderel's work, was founded to house the workers in the boric acid production factory. The region was the site of
84-416: Is not a volcano as no eruptions of magma had occurred there at any point in history. The region was known from ancient times for its exceptionally hot springs . The Romans used its sulphur springs for bathing. During the 19th century it became one of the first places in the world where geothermal energy was exploited to support industry. In 1827, François Jacques de Larderel, a Frenchman , invented
96-626: Is the Lago Vecchienna crater which last erupted around 1282, now filled by the Boracifero Lake . Larderello now produces 10% of the world's entire supply of geothermal electricity , amounting to 4,800 GWh per year and powering about a million Italian households. Its geology makes it uniquely conducive to geothermal power production, with hot granite rocks lying unusually close to the surface, producing steam as hot as 202 °C (396 °F). Contrary to popular belief, Larderello
108-659: The 1980 Plinian eruption of the volcano . A less intense geothermal event may result in a mud volcano . Phreatic eruptions typically include steam and rock fragments; the inclusion of liquid lava is unusual. The temperature of the fragments can range from cold to incandescent . If molten magma is included, volcanologists classify the event as a phreatomagmatic eruption . These eruptions occasionally create broad, low-relief craters called maars . Phreatic explosions can be accompanied by carbon dioxide or hydrogen sulfide gas-emissions. Carbon dioxide can asphyxiate at sufficient concentration; hydrogen sulfide acts as
120-423: The crater is situated at the top of a mountain formed from the erupted volcanic deposits such as lava flows and tephra . Volcanoes that terminate in such a summit crater are usually of a conical form. Other volcanic craters may be found on the flanks of volcanoes, and these are commonly referred to as flank craters . Some volcanic craters may fill either fully or partially with rain and/or melted snow, forming
132-613: The maximum levels of the 1950s. Phreatic eruption A phreatic eruption , also called a phreatic explosion , ultravulcanian eruption or steam-blast eruption , occurs when magma heats ground water or surface water. The extreme temperature of the magma (anywhere from 500 to 1,170 °C (930 to 2,100 °F)) causes near-instantaneous evaporation of water to steam , resulting in an explosion of steam , water, ash, rock, and volcanic bombs . At Mount St. Helens in Washington state, hundreds of steam explosions preceded
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#1732776489988144-542: The world's first geothermal power plant was built in the Valle del Diavolo ("Devil's Valley"), named for the boiling water that rises there. It was the world's only industrial producer of geothermal electricity until 1958, when New Zealand built a plant of its own in Wairakei . In recent years concerns have been expressed about the sustainability of its steam supply, as a 30% drop in steam pressure levels has been recorded from
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