§ 22. Volcanism. Geysers, hot springs
1. Remember how igneous rocks are formed?
2. What is magma different from the bench?
Volcanism and volcanoes. It is known that in the depths of the Earth formed magma - fiery liquid substance that is saturated with water vapor and gases. While under pressure, looking out at the magma surface. This output is crack in the earth's crust. Climbing up, paving the magma channel trubopodibnyy - craterThat the top end chashopodibnym extension - crater. Through him poured on the surface of magma, pulled out black smoke and pillars of fire vented hot stones. Out of igneous materials on the surface formed conical (or other form) mountain. Sometimes there is some craters: on top and slopes. Eruption may be accompanied by the earthquake. Totality phenomena relating to the enhancement of magma from the depths of the earth and poured it onto the surface called volcanism. Volcano - Is the output of magma on the Earth surface.
Products eruption. During volcanic eruptions on the Earth's surface receives liquid, solid and gaseous substance.
Flame-liquid lava formed from volcanic magma. She is hot 1000 0C. Although lava and flowing, but it is hard as a stone. It flows stretching for several kilometers. Sometimes rozbryzkuyetsya lava from the crater, forming high fountains.
Fixed substances future eruption much larger than the bench. Volcanic bombs - lava fragments size from several centimeters to several meters in diameter, thrown high up. Volcanic Ash- Are small pieces. It can spread thousands of kilometers. Yes, Pink ash volcano Krakatau (Indonesia), raised explosion at 80 km altitude, circled the globe and gradually osidav at different continents and oceans.
Volcanic gases and water vapor originally allocated to crater, and then - with lava flows. Gases and steam heated to very high temperatures. Their number is also extremely large. Thus, during the eruption volcano Parykutin (Mexico) allocated over 3 tons gas per day. There is a very viscous magma, freezing in the crater, clog exit gases. This leads to strong explosions. Thus, a powerful explosion volcano Mont Pele (Lesser Antilles) in 1902 begat large, heated to 700 0C, a cloud of gases. It poneslasya down slope and a few seconds covered the city. The whole city erupted, have engaged in even ships were in harbor.
Eruption Volcanoes can be brief or last for days and even months. For example, volcano Mauna Loa (Hawaii) in 1859 erupted more than 10 months. During this time the lava flow was 50 km, reaching coast and continued movement of the ocean bottom.
Active and extinct volcano.On dry land, numbering hundreds of active volcanoes. Current known volcanoes that vyverhalysya by the memory of mankind. Some of them are now at the stage of attenuation. Extinguishedconsidered volcanoes, eruptions of which has no evidence in history. Only conical shape, volcanic rocks and the crater show that Hill once (million years ago) was a volcano.
Volcanoes may be not only groundBut underwater. Last days of vyverhayutsya Seas and Oceans. At the same water over the underwater volcano crater and foams klekoche. Often after such an eruption’is new island. This volcanic mountain that is formed on the bottom and its tip arose above the water.
Volcano Krakatau (Sunda Strait) is known for a very strong explosion, which preceded the eruption in 1883 roznis explosion in pieces on top. Much of island at that flew into the air. A sound was heard even in Australia distance of 3600 km! The explosion caused a tsunami 40 meters high
Fig. Basalt lava
Fig. Eruption volcano
Spreading volcanoes. Now on the surface of the Earth more than 600 known active volcanoes. Most are concentrated in the same seismic belt, which and earthquakes. Their location as the area earthquakes concerned with outside of lithospheric plates, with a transient Earth faults cortex.
Pacific seismic zone ring frames the Pacific Ocean, forming so-called "Ring of Fire". It focused two thirds of all terrestrial active volcanoes. У Mediterranean seismic zone many extinct volcanoes - in the Caucasus mountains (Kazbek, Mount Elbrus), Iran (Ararat) et al. Extinct volcano that vyverhalysya millions of years ago, is in Ukraine. In Carpathians, they form Volcanic Ridge, Crimean mountains - mountain massif Karadag. In Atlantic zone except ground, many undersea volcanoes.
Pislyavulkanichniphenomenon.After the eruption of a volcano can form hot springs, geysers, mud volcanoes. These phenomena are related to the cooling of the volcanic center that cared volcano. They continue for thousands of years.
Hot Springs formed areas where shallow yet neostyhla magma. His warmth it heats ground water. Through cracks in the crust are can easily leak to the surface. The temperature of the sources - over 70 0S. The water is usually a lot of dissolved minerals, so it is therapeutic. On the basis of the sources are resorts and spas. For example, known throughout World Resort Karlovy selec in the Czech Republic uses the mineral springs that zihrivayutsya underground heat extinct volcano.
Geyser - A source that periodically emit fountains of hot water and steam. Posts water tower due to pressure superheated steam and gases under the ground. Fountain height up to tens of meters. For example, Grand Geyser (Iceland) on high fontanuye 30 m every 24 hours. Geyser also common in New Zealand, USA (Yellowstone National Park) on Kamchatka (Valley of Geysers). Now people have learned to use geysers and hot sources for home heating and electricity. This built Special geothermal station.
Mud volcanoes recall reduced operating model of real volcanoes. Only in such Mini vulkanchykahon the surface of volcanic gases under pressure is pushed out lava and hot mud. They are actually miniature cones - 1-2 m. The eruption is more or less quietly. Mud volcanoes are common in Kamchatka, islands of Java and Sicily. Sometimes their appearance is not associated with volcanoes. Then the mud to the surface gases push out a very different origin. "Nevulkanichnymy is mud Kerch Peninsula in Ukraine.
Fig. Mud volcanoes of the Kerch Peninsula (Ukraine)
Questions and Tasks
1. What structure is a volcano?
2. What matters volcanoes spew?
3. Which volcanoes are called current, which - extinct? As their mark on the map?
4. How can I use the hot springs?
5. Tell us how geysers work.
6. What is the pattern of allocation of volcanoes on Earth?
7. Show on map active volcanoes Vesuvius, Etna, Krakatau, Klyuchevskaya Sopka, Elbrus, Kazbek. Where are they located?