Volcano:
Crack in the Earth's crust through which hot magma (molten rock) and gases well up. The magma is termed lava when it reaches the surface. A volcanic mountain, usually cone-shaped with a crater on top, is formed around the opening, or vent, by the build-up of solidified lava and ash (rock fragments). Most volcanoes occur on plate margins (see plate tectonics), where the movements of plates generate magma or allow it to rise from the mantle beneath. However, a number are found far from plate-margin activity, on hot spots where the Earth's crust is thin, for example in Hawaii. There are two main types of volcano: composite volcanoes and shield volcanoes.
The type of volcanic activity also depends on the age of the volcano. The first stages of an eruption are usually vigorous as the magma forces its way to the surface. As the pressure drops and the vents become established, the main phase of activity begins. Composite volcanoes emit pyroclastic debris, while shield volcanoes produce lava flows. When the pressure from below ceases, due to exhaustion of the magma chamber, activity wanes and is confined to the emission of gases, and in time this also ceases. The volcano then enters a period of quiescence, after which activity may resume after a period of days, years, or even thousands of years. Only when the root zones of a volcano have been exposed by erosion can a volcano be said to be truly extinct.
Many volcanoes are submarine and occur along mid-ocean ridges. The main volcanic regions are around the Pacific rim (Cape Horn to Alaska); the central Andes of Chile (with the world's highest active volcano, Guallatiri, 6,063 m/19,892 ft); North Island, New Zealand; Hawaii; Japan; and Antarctica. There are more than 1,300 potentially active volcanoes on Earth. Volcanism has also helped shape other members of the Solar System, including the Moon, Mars, Venus, and Jupiter's moon Io.
There are several methods of monitoring volcanic activity. They include seismographic instruments on the ground, aircraft monitoring, and monitoring from space using remote-sensing satellites.

There are two main types of volcano, but three distinctive cone shapes. Composite volcanoes emit a stiff, rapidly solidifying lava which forms high, steep-sided cones. Volcanoes that regularly throw out ash build up flatter domes known as cinder cones. The lava from a shield volcano is not ejected violently, flowing over the crater rim forming a broad low profile.

Mount Etna photographed in eruption. The volcano can be extremely violent, and destroyed several towns in the 1950s, yet the area at its foot is densely populated, with vineyards, orchards, and orange groves. The first recorded eruption was in c. 700 BC.



A satellite photograph showing the Augustine volcano in Cook Inlet, south of Anchorage, Alaska. Alaska is at the northern end of the Pacific rim and experiences high levels of volcanic activity.

A knife-edge ridge of volcanic rock on the Napali coast of Kauai, one of the westernmost of the Hawaiian islands. Such a ridge may be formed when lava flows along a surface and drops into a crack or crevice, filling it up; the supporting sides eventually erode away, leaving only the shape of the original fissure.

From Hawaiian shield volcanoes, lava may flow smoothly and consistently for long distances. The smoothness of flow is partly due to the chemical composition of the lava which has a comparatively low proportion of silica (silicon dioxide) and a comparatively high proportion of calcium (as feldspar) and magnesium (as pyroxene).


Alaska has a number of active volcanoes, such as the Augustine Volcano in the southwest of the state. This is because Alaska is situated at the edge of a tectonic plate, as indeed are virtually all the countries of the Pacific rim.


The slopes of Helgafell, a volcano on the island of Heimaey, Iceland. Helgafell last erupted in 1973. The eruption created the new Eldfell cone and a 3 km/1.9 mi lava flow. Although the lava slopes have stabilized, the soil remains very hot, and at a depth of 1 m/3.3 ft, the soil and rock hold temperatures up to 300°C/572°F. In the far distance another volcanic island can be seen.


Mount Rainier in Washington State is the highest volcano of the Cascade Range. Although not especially active recently it has a significant cover of ice and snow, which if melted rapidly would produce catastrophic flooding of nearby populated areas.

A large snow-capped volcano in Iceland. Located on a plate margin where the North American and European plates diverge, Iceland has about 20 active volcanoes. An extensive field of jagged and irregularly shaped blocks of volcanic rock – an old lava flow – stretches into the distance.




Volcanic plug in Assekrem, Algeria. This outcrop is the remains of a mass of volcanic material which once filled the vent of a volcano. The softer rock surrounding it has eroded away, leaving behind the more resistant ‘plug’.
VALCANO:A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, ash and gases to escape from below the surface. The word volcano is derived from the name of Vulcano island off Sicily which in turn, was named after Vulcan, the Roman god of fire.
Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the Wells Gray-Clearwater volcanic field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes.
Volcanoes can be caused by mantle plumes. These so-called hotspots, for example at Hawaii, can occur far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons.



The word volcano is thought to derive from Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn originates from Vulcan, the name of a god of fire in Roman mythology. The study of volcanoes is called volcanology, sometimes spelled vulcanology.
Plate tectonics and hotspots

Map showing the divergent plate boundaries (OSR – Oceanic Spreading Ridges) and recent sub aerial volcanoes.

Divergent plate boundaries:


At the mid-oceanic ridges, two tectonic plates diverge from one another. New oceanic crust is being formed by hot molten rock slowly cooling and solidifying. The crust is very thin at mid-oceanic ridges due to the pull of the tectonic plates. The release of pressure due to the thinning of the crust leads to adiabatic expansion, and the partial melting of the mantle causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, therefore most volcanic activity is submarine, forming new seafloor. Black smokers or deep sea vents are an example of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, Iceland.

Indonesia - Lombok: Mount Rinjani - outbreak in 1994
Convergent plate boundaries:

Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the oceanic plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. Water released from the subducting plate lowers the melting temperature of the overlying mantle wedge, creating magma. This magma tends to be very viscous due to its high silica content, so often does not reach the surface and cools at depth. When it does reach the surface, a volcano is formed. Typical examples for this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire.

Lava enters the Pacific at the Big Island of Hawaii
Hotspots:


Hotspots are not usually located on the ridges of tectonic plates, but above mantle plumes, where the convection of the Earth's mantle creates a column of hot material that rises until it reaches the crust, which tends to be thinner than in other areas of the Earth. The temperature of the plume causes the crust to melt and form pipes, which can vent magma. Because the tectonic plates move whereas the mantle plume remains in the same place, each volcano becomes dormant after a while and a new volcano is then formed as the plate shifts over the hotspot. The Hawaiian Islands are thought to be formed in such a manner, as well as the Snake River Plain, with the Yellowstone Caldera being the part of the North American plate currently above the hot spot.
VALCONIC FEATURES:

Conical Mount Fuji in Japan, at sunrise from Lake Kawaguchi (2005)
The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit. This describes just one of many types of volcano, and the features of volcanoes are much more complicated. The structure and behavior of volcanoes depends on a number of factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater, whereas others present landscape features such as massive plateaus. Vents that issue volcanic material (lava, which is what magma is called once it has escaped to the surface, and ash) and gases (mainly steam and magmatic gases) can be located anywhere on the landform. Many of these vents give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Hawaii's Kīlauea.

Lakagigar fissure vent in Iceland, source of the major world climate alteration of 1783-84. Volcanic eruptions are experienced somewhere in Iceland on an average of once every five years.

Skjaldbreiður, a shield volcano whose name means "broad shield".


January 2009 image of the rhyolitic lava dome of Chaitén Volcano, southern Chile during its 2008-2009 eruption.

Mud volcano on Taman Peninsula, Russia

Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter, Saturn and Neptune; and mud volcanoes, which are formations often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes, except when a mud volcano is actually a vent of an igneous volcano.

Fissure vents
Volcanic fissure vents are flat, linear cracks through which lava emerges.
Shield volcanoes
Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent, but not generally explode catastrophically. Since low-viscosity magma is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland, as well.
Lava domes
Lava domes are built by slow eruptions of highly viscous lavas. They are sometimes formed within the crater of a previous volcanic eruption (as in Mount Saint Helens), but can also form independently, as in the case of Lassen Peak. Like stratovolcanoes, they can produce violent, explosive eruptions, but their lavas generally do not flow far from the originating vent.
Cryptodomes
Cryptodomes are formed when viscous lava forces its way up and causes a bulge. The 1980 eruption of Mount St. Helens was an example. Lava was under great pressure and forced a bulge in the mountain, which was unstable and slid down the north side.
Volcanic cones (cinder cones)
Volcanic cones or cinder cones are the result from eruptions that erupt mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 meters high. Most cinder cones erupt only once. Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico, Caja del Rio is a volcanic field of over 60 cinder cones.
Stratovolcanoes (composite volcanoes)
Stratovolcanoes or composite volcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the strata that give rise to the name. Stratovolcanoes are also known as composite volcanoes, created from several structures during different kinds of eruptions. Strato/composite volcanoes are made of cinders, ash and lava. Cinders and ash pile on top of each other, lava flows on top of the ash, where it cools and hardens, and then the process begins again. Classic examples include Mt. Fuji in Japan, Mayon Volcano in the Philippines, and Mount Vesuvius and Stromboli in Italy. In recorded history, explosive eruptions by stratovolcanoes have posed the greatest hazard to civilizations.
Supervolcanoes
A supervolcano is a large volcano that usually has a large caldera and can potentially produce devastation on an enormous, sometimes continental, scale. Such eruptions would be able to cause severe cooling of global temperatures for many years afterwards because of the huge volumes of sulfur and ash erupted. They are the most dangerous type of volcano. Examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States), Lake Taupo in New Zealand, Lake Toba in Sumatra, Indonesia and Ngorogoro Crater in Tanzania. Supervolcanoes are hard to identify centuries later, given the enormous areas they cover. Large igneous provinces are also considered supervolcanoes because of the vast amount of basalt lava erupted, but are non-explosive.
Submarine volcanoes
Submarine volcanoes are common features on the ocean floor. Some are active and, in shallow water, disclose their presence by blasting steam and rocky debris high above the surface of the sea. Many others lie at such great depths that the tremendous weight of the water above them prevents the explosive release of steam and gases, although they can be detected by hydrophones and discoloration of water because of volcanic gases. Pumice rafts may also appear. Even large submarine eruptions may not disturb the ocean surface. Because of the rapid cooling effect of water as compared to air, and increased buoyancy, submarine volcanoes often form rather steep pillars over their volcanic vents as compared to above-surface volcanoes. They may become so large that they break the ocean surface as new islands. Pillow lava is a common eruptive product of submarine volcanoes. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on dissolved minerals.
Subglacial volcanoes
Subglacial volcanoes develop underneath icecaps. They are made up of flat lava which flows at the top of extensive pillow lavas and palagonite. When the icecap melts, the lavas on the top collapse, leaving a flat-topped mountain. Then, the pillow lavas also collapse, giving an angle of 37.5 degrees[citation needed]. These volcanoes are also called table mountains, tuyas or (uncommonly) mobergs. Very good examples of this type of volcano can be seen in Iceland, however, there are also tuyas in British Columbia. The origin of the term comes from Tuya Butte, which is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analyzed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near the boundary with the Yukon Territory.
Mud volcanoes
Mud volcanoes or mud domes are formations created by geo-excreted liquids and gases, although there are several different processes which may cause such activity. The largest structures are 10 kilometers in diameter and reach 700 meters high.

Erupted material:

Pāhoehoe Lava flow at Hawaii (island). The picture shows few overflows of a main lava channel.

The Stromboli volcano off the coast of Sicily has erupted continuously for thousands of years, giving rise to the term strombolian eruption ejecting lava bombs

. Mafic basalt flow created the Deccan Traps near Matheran, east of Mumbai, one of the largest volcanic features on earth.

Pāhoehoe lava from Kīlauea, Hawaii.

Lava composition
Another way of classifying volcanoes is by the composition of material erupted (lava), since this affects the shape of the volcano. Lava can be broadly classified into 4 different compositions (Cas & Wright, 1987):
• If the erupted magma contains a high percentage (>63%) of silica, the lava is called felsic.
o Felsic lavas (dacites or rhyolites) tend to be highly viscous (not very fluid) and are erupted as domes or short, stubby flows. Viscous lavas tend to form stratovolcanoes or lava domes. Lassen Peak in California is an example of a volcano formed from felsic lava and is actually a large lava dome.
o Because siliceous magmas are so viscous, they tend to trap volatiles (gases) that are present, which cause the magma to erupt catastrophically, eventually forming stratovolcanoes. Pyroclastic flows (ignimbrites) are highly hazardous products of such volcanoes, since they are composed of molten volcanic ash too heavy to go up into the atmosphere, so they hug the volcano's slopes and travel far from their vents during large eruptions. Temperatures as high as 1,200 °C are known to occur in pyroclastic flows, which will incinerate everything flammable in their path and thick layers of hot pyroclastic flow deposits can be laid down, often up to many meters thick. Alaska's Valley of Ten Thousand Smokes, formed by the eruption of Novarupta near Katmai in 1912, is an example of a thick pyroclastic flow or ignimbrite deposit. Volcanic ash that is light enough to be erupted high into the Earth's atmosphere may travel many kilometres before it falls back to ground as a tuff.
• If the erupted magma contains 52–63% silica, the lava is of intermediate composition.
o These "andesitic" volcanoes generally only occur above subduction zones (e.g. Mount Merapi in Indonesia).
o Andesitic lava is typically formed at convergent boundary margins of tectonic plates, by several processes:
 Hydration melting of peridotite and fractional crystallization
 Melting of subducted slab containing sediments
 Magma mixing between felsic rhyolitic and mafic basaltic magmas in an intermediate reservoir prior to emplacement or lava flow.
• If the erupted magma contains <52%>45% silica, the lava is called mafic (because it contains higher percentages of magnesium (Mg) and iron (Fe)) or basaltic. These lavas are usually much less viscous than rhyolitic lavas, depending on their eruption temperature; they also tend to be hotter than felsic lavas. Mafic lavas occur in a wide range of settings:
o At mid-ocean ridges, where two oceanic plates are pulling apart, basaltic lava erupts as pillows to fill the gap;
o Shield volcanoes (e.g. the Hawaiian Islands, including Mauna Loa and Kilauea), on both oceanic and continental crust;
o As continental flood basalts.
• Some erupted magmas contain <=45% silica and produce ultramafic lava. Ultramafic flows, also known as komatiites, are very rare; indeed, very few have been erupted at the Earth's surface since the Proterozoic, when the planet's heat flow was higher. They are (or were) the hottest lavas, and probably more fluid than common mafic lavas. Lava texture Two types of lava are named according to the surface texture: ʻAʻa (pronounced [ˈʔaʔa]) and pāhoehoe ([paːˈho.eˈho.e]), both words having Hawaiian origins. ʻAʻa is characterized by a rough, clinkery surface and is the typical texture of viscous lava flows. However, even basaltic or mafic flows can be erupted as ʻaʻa flows, particularly if the eruption rate is high and the slope is steep. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Usually, only mafic flows will erupt as pāhoehoe, since they often erupt at higher temperatures or have the proper chemical make-up to allow them to flow with greater fluidity. Volcanic activity Active volcano Mount St. Helens shortly after the eruption of 18 May 1980 Damavand, highest volcano in Asia, is a potentially active volcano with fumaroles and solfatara near its summit. Shiprock, the eroded remnant of the throat of an extinct volcano. Fourpeaked volcano, Alaska, in September 2007, after being thought extinct for over 10,000 years. Scientific classification of volcanoes Philippine Institute of Volcanology and Seismology provides a scientific classification system for volcanoes.

Introduction:

What is Rice?

Rice is a grain belonging to the grass family. It is related to other grass plants such as wheat, oats and barley which produce grain for food and are known as cereals. Rice refers to two species (Oryza sativa and Oryza glaberrima) of grass, native to tropical and subtropical southeastern Asia and to Africa, which together provide more than one-fifth of the calories consumed by humans. The plant, which needs both warmth and moisture to grow, measures 2-6 feet tall and has long, flat, pointy leaves and stalk-bearing flowers which produce the grain known as rice. Rice is rich in genetic diversity, with thousands of varieties grown throughout the world.

Throughout history rice has been one of man's most important foods. Today, this unique grain helps sustain two-thirds of the world's population. It is life for thousands of millions of people. It is deeply embedded in the cultural heritage of their societies. About four-fifths of the world's rice is produced by small-scale farmers and is consumed locally. Rice cultivation is the principal activity and source of income for about 100 million households in Asia and Africa.

Rice in India:

Rice is grown in many regions across India. For about 65% of the people living in India, rice is a staple food for them. Rice is essential to life in India. It is a part of nearly every meal, and it is grown on a majority of the rural farms.





Rice Cultivation in India:

Methods of cultivating rice is not the same for all localities. It differs greatly in different localities. However, but in most Asian countries like India, the traditional hand methods of cultivating and harvesting rice are still practiced. The fields are prepared by
•Plowing (typically with simple plows drawn by buffalo)
•Fertilizing (usually with dung or sewage), and smoothing (by dragging a log over them). The seedlings are started in seedling beds and, after 30 to 50 days, are transplanted by hand to the fields, which have been flooded by rain or river water. During the growing season, irrigation is maintained in some areas. The fields are allowed to drain before cutting.
•Rice when it is still covered by the brown hull is known as paddy; rice fields are also called paddy fields or rice paddies.
•Before marketing, the rice is threshed to loosen the hulls-mainly by flailing, treading, or working in a mortar-and winnowed free of chaff by tossing it in the air
above a sheet or mat.

Step by Step Analysis of Rice Cultivation in India:


Climatic Conditions for Rice in India
Rice Growing Seasons in India
Rice Soils of India
Rice Eco System
Rice Seeds
Rice Cropping Pattern in India
Methods of Rice Cultivation in India

Climatic Conditions for Rice in India:

India is a large country. The wide variety of terrain leads to a wide variety of climatic conditions. These range from permanent snowfields to tropical coast lands; from areas of virtual desert in the north-west to fertile, intensively cultivated rice fields in the north-east. Generally, we consider India to lie between 8° and 35° N latitude, with a tropical and sub-tropical climate. The subcontinent has eight climatic zones all of which only have the monsoon rains in common. But even the monsoon comes to different parts of the country at different times.

Different Climatic Factors Affecting Rice Cultivation in India

There are many varieties of rice which are cultivated with differential response to climatic factors, such as :

Rainfall
Rainfall is the most important weather element for successful cultivation of rice. The distribution of rainfall in different regions of the country is greatly influenced by the physical features of the terrain, the situation of the mountains and plateau. The regions experiencing very heavy rainfall in the country are :
•Western Ghats (the western slopes and the coastal region)
•In the Assam region.
•The sub-mountain Himalayan region, Deccan plateau, Eastern Ghats with coastal plains and the vast Gangetic plains.
Temperature
Temperature is another climatic factor which has a favorable and in some cases unfavorable influence on the development, growth and yield of rice. Rice being a tropical and sub-tropical plant, requires a fairly high temperature, ranging from 20° to 40°C. The optimum temperature of 30°C during day time and 20°C during night time seems to be more favorable for the development and growth of rice crop.

Day length or Sunshine
Sunlight is very essential for the development and growth of the plants. In fact, sunlight is the source of energy for plant life. The yield of rice is influenced by the solar radiation particularly during the last 35 to 45 days of its ripening period. The effect of solar radiation is more profound where water, temperature and nitrogenous nutrients are not limiting factors. Bright sunshine with low temperature during ripening period of the crop helps in the development of carbohydrates in the grains.

Rice Growing Seasons in India:

In India, rice is grown under widely varying conditions of altitude and climate. The climate of India is difficult to lay due to the country's large geographic size and varied topography. Many regions have their own micro climates (e.g. in mountain tops), and the mean climatic conditions in Kashmir (extreme north) are very different from those in the extreme south. India's climate is strongly influenced by The Himalaya and the Thar Desert. The Himalaya ensure, by acting as a barrier to the cold north winds from Central Asia, that northern India is warm or mildly cool during winter and hot during summer. So, India as a whole is considered to be a tropical country.

Therefore, the rice growing seasons vary in different parts of the country, depending upon temperature, rainfall, soil types, water availability and other climatic conditions. In eastern and southern regions of the country, the mean temperature is found favourable for rice cultivation through out the year. Hence, two or three crops of rice are grown in a year in eastern and southern states. In northern and western parts of the country, where rainfall is high and winter temperature is fairly low, only one crop of rice is grown during the month from May to November.

Three Seasons for Rice Cultivation in India

There are three seasons for growing rice in India. These three seasons are named according to the season of harvest of the crop.

Rice Soils of India:

Rice is grown in many regions across India. India alone has about 45 million hectares of area, and it produces on an average 93 million metric tons of rice since 2001 onwards. Rice cultivation has been carried into all regions having the necessary warmth and abundant moisture favorable to its growth, mainly subtropical rather than hot or cold.

In India, rice is grown in different types of soils. Experts point out that in India, rice is grown in such varied soil conditions that it is difficult to point out the soil on which it cannot be grown. However, soils having
•Good water retention capacity.
•Good amount of clay and organic matter are considered ideal for rice cultivation.
It grows well in soils having a pH range between 5.5 and 6.5. The classification of soils has been done depending upon the soil texture, colour of the soil etc.

Rice Eco System:

Rice farming is practiced in several agro ecological zones in India. No other country in the world has such diversity in rice ecosystems than India. Because cultivation is so widespread, development of four distinct types of ecosystems has occurred in India, such as:
•Irrigated Rice Eco System
•Rainfed Upland Rice Eco System
•Rainfed Lowland Rice Eco System
•Flood Prone Rice Eco System
Irrigated Rice Eco System
•Irrigated ecosystems are the primary type found in East Asia.
•Irrigated ecosystems provide 75% of global rice production.
•In India, the total area under irrigated rice is about 22.00 million hectares, which accounts about 49.5% of the total area under rice crop in the country.
•Rice is grown under irrigated conditions in the states of Punjab, Haryana, Uttar Pradesh, Jammu & Kashmir, Andhra Pradesh, Tamil Nadu, Sikkim, Karnataka, Himachal Pradesh and Gujarat.
•Irrigated rice is grown in bunded (embanked), paddy fields.
Rainfed Upland Rice Eco System
•Upland zones are found in Asia, Africa, and Latin America.
•In India, the total area under upland rain fed rice in the country is about 6.00 million hectares, which accounts13.5% of the total area under rice crop in the country.
•Upland rice areas lies in eastern zone comprising of Assam, Bihar, Eastern M.P., Orissa, Eastern U.P., West Bengal and North-Eastern Hill region.
•Upland rice fields are generally dry, unbunded, and directly seeded.
•Land utilized in upland rice production can be low lying, drought-prone, rolling, or steep sloping.
Rainfed Lowland Rice Eco System
•Rainfed low-land rice is grown in such areas as East India, Bangladesh, Indonesia, Philippines, and Thailand, and is 25% of total rice area used worldwide.
•In India, low land rice area is about 14.4 million hectares, which accounts 32.4 % of the total area under rice crop in the country.
•Production is variable because of the lack of technology used in rice production.
•Rainfed lowland farmers are typically challenged by poor soil quality, drought/flood conditions, and erratic yields
Flood Prone Rice Eco System

Flood-prone ecosystems are prevalent in South and Southeast Asia, and are characterized by periods of extreme flooding and drought. Yields are low and variable. Flooding occurs during the wet season from June to November, and rice varieties are chosen for their level of tolerance to submersion.

Rice ecosystems in India represent 24% of irrigated areas, 34% of rainfed lowlands, 26% of flood-prone areas and 37% of rainfed uplands cultivated to rice in the entire world.

Rice Seeds:

Seed is an important and basic input for achieving higher crop yield and increasing a country's agricultural economy. Thus it is very important to maintain seed quality by understanding the right mechanism. Seed markets are generally built around hybrid varieties, which do not reproduce and so force farmers to purchase new seeds every season. Rice, however, is a self-pollinating crop, making hybrid rice seed production costly and difficult, and nearly all rice in Asia is still grown with farmer-saved seeds.

Rice Cropping Pattern in India:

Rice cropping pattern in India vary widely from region to region and to a lesser extent from one year to another year depending on a wide range of soil and climatic conditions.

Some of the rice based cropping patterns being followed in the country are as follows :
•Rice-Rice-Rice
•Rice-Rice-Cereals (other than rice)
•Rice-Rice-Pulses
•Rice-Groundnut
•Rice-Wheat
•Rice-Wheat-Pulses
•Rice-Toria-Wheat
•Rice-Fish farming system
Rice-Rice-Rice:

This is most suitable for areas having high rainfall and assured irrigation facilities in summer months, particularly, in soils which have high water holding capacity and low rate of infiltration. In some canal irrigated areas of Tamil Nadu, a cropping pattern of 300% intensity is followed. In such areas three crops of rice are grown in a year.

Rice-Rice-Cereals:
(other than rice)
This cropping pattern is being followed in the areas where the water is not adequate for taking rice crop in summer. The alternate cereal crops to rice being grown are Ragi, Maize and Jowar.

Rice-Rice-Pulses:
In the areas where, there is a water scarcity to take up cereal crops other than rice in summer, the short duration pulse crops are being raised.

Rice-Groundnut:
This cropping pattern is being followed by the farmers of Andhra Pradesh, Tamil Nadu and Kerala. After harvesting of rice crop, groundnut is grown in summer.

Rice-Wheat:

This crop rotation has become dominant cropping pattern in the Northern parts of the country.

Rice-Wheat-Pulses:

In this sequence of cropping pattern, after harvesting of wheat green gram and cowpea as fodder are grown in the alluvial soil belt of Northern states. Besides, cowpea is grown in red and yellow soils of Orissa and black gram is grown in the black soils.

Rice-Toria-Wheat:

Rice-wheat cropping pattern is the most common and largest one. The Rice-wheat cropping pattern is being practiced in the Indo-Gangetic plains of India since long time.

Rice-Fish farming system:

The field with sufficient water retaining capacity for a long period and free from heavy flooding are suitable for rice-fish farming system. This system is being followed by the small and marginal poor farmers in rain fed lowland rice areas.

Methods of Rice Cultivation in India:

The systems of rice cultivation in various rice-growing areas of the country are largely dependent upon the rice-growing conditions prevalent in the respective regions. The method of cultivation of rice in a particular region depends largely on factors such as situation of land, type of soils, irrigation facilities, availability of labourers intensity and distribution of rainfalls. The principal systems followed in India are :

Tsunamis
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Tsunami, also known as seismic sea waves, are caused by sudden changes in the seafloor, generally earthquakes and more rarely large landslides. Tsunami are sometimes mistakenly called "tidal waves", but they are not caused by tidal action. Not all earthquakes are tsunami-genic (generate tsunami); to generate a tsunami, the earthquake must occur under or near the ocean, be large, and create vertical movements of the seafloor. It is thought that tsunami-genic earthquakes release their energy over a couple of minutes, much more slowly than the sudden lurching earthquakes, which release their energy in seconds. In fact, some tsunami-genic earthquakes can not be felt by people, so gradual is their energy release. Much of the earthquake's energy, which can be equivalent to many atomic bombs, is transferred to the water column above it, producing a tsunami. All oceanic regions of the world can experience tsunami, but the Pacific Ocean is especially vulnerable because of the many large earthquakes associated with the "Ring of Fire" along its margins.
In the deep ocean, tsunami have very small amplitudes (wave heights are only a few inches), wavelengths of up to 1000 kilometers, and speeds of more than 800 kilometers per hour (500 miles per hour), the speed of a jetliner. The slope of a tsunami surface at sea is only about a centimeter per kilometer (an inch per mile). A tsunami may take 4-6 hours to reach Hawaii from the Aleutian Islands, 7-8 hours from Japan, and 14-15 hours from Chile, but its energy will only dissipate slightly as it crosses the entire ocean. In fact, once the tsunami reaches the other side of the ocean thousands of kilometers from its source, it can bounce off the land and return in the direction it came, although its energy will decrease from the reflection. It is easy to see that at these scales the Pacific Ocean becomes like a pond to the tsunami.
A tsunami carries an enormous amount of energy that is spread over a large volume of water in the deep sea. However, when a tsunami reaches shallow water, such as a coastline, the energy is concentrated into a smaller volume and the wave's power overwhelms whatever is in its path. In shallow water, its speed decreases and its amplitude increases to dangerous heights, sometimes 50 feet or higher, and it spreads inland many hundreds of feet (in some cases a mile or more). A tsunami is not a single wave, but a set that may last for several hours, and the first wave is not always the largest.
How do they form?
Tsunamis are formed as a result of earthquakes, volcanic eruptions, or landslides that occur under the sea. When these events occur under the water, huge amounts of energy are released as a result of quick upward bottom movement. For example, if a volcanic eruption occurs, the ocean floor may very quickly move upward several hundred feet. When this happens, huge volumes of ocean water are pushed upward and a wave is formed. A large earthquake can lift thousands of square kilometers of sea floor which will cause the formation of huge waves. The Pacific Ocean is especially prone to tsunamis as a result of the large amount of undersea geological activity.
How big do they get?
In the open ocean tsunamis may appear very small with a height of less than 1 meter (3 feet). Tsunamis will sometimes go undetected until they approach shallow waters along a coast. These waves have a very large wavelength (up to several hundred miles) that is a function of the depth of the water where they were formed. Although these waves have a small height, there is a tremendous amount of energy associated with them. As a result of this huge amount of energy, these waves can become gigantic as they approach shallow water. Their height, as they crash upon the shore, depends on the underwater surface features. They can be as high as 30 m (100 feet) or more. In 1737 , a huge wave estimated to be 64m (210 feet) in height hit Cape Lopatka, Kamchatka (NE Russia). The largest Tsunami ever recorded occurred in July of 1958 in Lituya Bay, Alaska. A huge rock and ice fall sent water surging up to a high water mark of 500m (1640 feet). It's no wonder that these waves can cause such massive destruction and loss of life.
How fast do they move?
In the deep open sea, tsunamis move at speeds approaching a jet aircraft (500 mph or more). As they approach the shore, they slow down. When a tsunami arrives at the shore, it usually does so as a rapidly rising tide moving at about 70 km/hour (45 mph).

How much destruction do they cause?
Beyond the tremendous destruction of life that tsunamis cause, they have also caused massive physical damage. They have entirely destroyed buildings and left towns looking like a nuclear war zone. They have lifted boats high out of the water and violently hurled them against the shore, smashing them to pieces. They have bent parking meters all the way down to the ground. In one incredible story, during the huge tsunami in Lituya Bay, Alaska (mentioned above), a boat with two people in it was carried from the bay, over tree tops and over the land out into the ocean. The people survived to tell the tale.
Can we detect them before they hit?
Yes. About 35 years ago, 24 countries around the Pacific set up the Pacific Tsunami Warning System. A group of seismic monitoring stations and a network of tide gauges are used for detection. The biggest problem with this system is that it is difficult to predict how large and destructive the resulting waves will be. Scientists are currently working on better predictive tools.

When you hear a tsunami warning, move at once to higher ground and stay there until local authorities say it is safe to return home.
BEFORE
Find out if your home is in a danger area.
Know the height of your street above sea level and the distance of your street from the coast. Evacuation orders may be based on these numbers.
Be familiar with the tsunami warning signs.
Because tsunamis can be caused by an underwater disturbance or an earthquake, people living along the coast should consider an earthquake or a sizable ground rumbling as a warning signal. A noticeable rapid rise or fall in coastal waters is also a sign that a tsunami is approaching.
Make sure all family members know how to respond to a tsunami.
Make evacuation plans.
Pick an inland location that is elevated. After an earthquake or other natural disaster, roads in and out of the vicinity may be blocked, so pick more than one evacuation route.
Teach family members how and when to turn off gas, electricity, and water.
Teach children how and when to call 9-1-1, police or fire department, and which radio station to listen for official information.
Have disaster supplies on hand.
• Flashlight and extra batteries
• Portable, battery-operated radio and extra batteries
• First aid kit and manual
• Emergency food and water
• Nonelectric can opener
• Essential medicines
• Cash and credit cards
• Sturdy shoes
Develop an emergency communication plan.
In case family members are separated from one another during a tsunami (a real possibility during the day when adults are at work and children are at school), have a plan for getting back together.
Ask an out-of-state relative or friend to serve as the "family contact." After a disaster, often it's easier to call long distance. Make sure everyone knows the name, address, and phone number of the contact person.
DURING
Listen to a radio or television to get the latest emergency information, and be ready to evacuate if asked to do so.
If you hear an official tsunami warning or detect signs of a tsunami, evacuate at once. Climb to higher ground. A tsunami warning is issued when authorities are certain that a tsunami threat exists.
Stay away from the beach.
Never go down to the beach to watch a tsunami come in. If you can see the wave you are too close to escape it.
Return home only after authorities advise it is safe to do so.
A tsunami is a series of waves. Do not assume that one wave means that the danger over. The next wave may be larger than the first one. Stay out of the area.
AFTER
Stay tuned to a battery-operated radio for the latest emergency information.
Help injured or trapped persons.
Give first aid where appropriate. Do not move seriously injured persons unless they are in immediate danger of further injury. Call for help.
Remember to help your neighbors who may require special assistance--infants, elderly people, and people with disabilities.
Stay out of damaged buildings. Return home only when authorities say it is safe.
Enter your home with caution.
Use a flashlight when entering damaged buildings.
Open windows and doors to help dry the building.
Shovel mud while it is still moist to give walls and floors an opportunity to dry.
Check food supplies and test drinking water.
Fresh food that has come in contact with flood waters may be contaminated and should be thrown out.
INSPECTING UTILITIES IN A DAMAGED HOME
Check for gas leaks--If you smell gas or hear a blowing or hissing noise, open a window and quickly leave the building. Turn off the gas at the outside main valve if you can and call the gas company from a neighbor's home. If you turn off the gas for any reason, it must be turned back on by a professional.
Look for electrical system damage--If you see sparks or broken or frayed wires, or if you smell hot insulation, turn off the electricity at the main fuse box or circuit breaker. If you have to step in water to get to the fuse box or circuit breaker, don't do it! Wait for professionals.
Check for sewage and water lines damage--If you suspect sewage lines are damaged, avoid using toilets. If water pipes are damaged, contact the water company and avoid the water from the tap. You can obtain safe water by melting ice cubes.
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Tsunami Destruction


Tsunami Destruction Which Carried This School 200 Feet Before It Locked Up On Surrounding Palm Trees

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TEN DESTRUCTIVE TSUNAMIS