Test: Our Changing Earth - 2

The location inside the Earth where an earthquake begins is called the focus (or hypocenter) of the earthquake. The point at the Earth's surface directly above the focus is called the epicenter of the earthquake. At the epicenter, the strongest shaking occurs during an earthquake.

A seismograph, or seismometer, is an instrument used to detect and record earthquakes. Generally, it consists of a mass attached to a fixed base. During an earthquake, the base moves and the mass does not.

Bhuj is a city in the state of Gujarat, western India. It’s known for its centuries-old buildings, many of which were damaged in a 2001 earthquake. Close to Harmirsar Lake, the 18th-century Aina Mahal palace is elaborately decorated with chandeliers, mirrors and semi-precious stones. Nearby, the Italian Gothic–style Prag Mahal palace has a bell tower that overlooks the city, and a courtyard containing a Hindu temple.

The 2001 Gujarat earthquake, also known as the Bhuj earthquake, occurred on 26 January, India's 52nd Republic Day, at 08:46 AM IST and lasted for over 2 minutes. The epicentre was about 9 km south-southwest of the village of Chobari in Bhachau Taluka of Kutch District of Gujarat, India.

Being near the windows may cause an injury as the tremors may lead to broken glass.

Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. Earthquakes radiate seismic energy as both body and surface waves.The epicenter is the point on the earth's surface vertically above the hypocenter (or focus), point in the crust where a seismic rupture begins.The focus is the place inside Earth's crust where an earthquake originates.
Vent is an opening that allows air, gas, or liquid to pass out of or into a confined space.

A major earthquake registers between 7 and 7.9 on the Richter scale. There are about 20 a year worldwide and they cause very serious damage. Intensity 7 is very strong. Damage is negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.

It is relatively short (up to 82 meters), but it is one the most powerful waterfalls in the world. Depending on the season, Iguazu Falls drop 1 to 3 million liters of water per second. If Iguazu Falls were a continuous veil of falling water, it would be the widest waterfall in the world.

Angel Falls is the world’s highest uninterrupted waterfall. Located in Canaima National Park, the second largest national park in Venezuela, the waterfall tumbles from a cleft near the summit of table top mountain Auyán-tepu into what is known as Devil’s Canyon, 3212 feet (979m) below. The falls are a tributary of the Carrao River, itself part of Venezuela’s Orinoco River system. Considered among the wo

Fine particles of pulverized rock blown from an explosion vent . Measuring less than 1/10 inch in diameter, ash may be either solid or molten when first erupted. By far the most common variety is vitric ash (glassy particles formed by gas bubbles bursting through liquid magma ).

The running water in the river erodes the landscape. When the river tumbles at steep angle over very hard rocks or down a steep valley side it forms a waterfall

The meander loop cuts off from the river and forms a cut-off lake know as mender lake. As the river enters the plain it twists and turns forming large bends known as meanders.

The steep rocky coast rising almost vertically above sea water is called seacliff. The sea waves deposit sediments along the shores forming beaches. Work of Ice. Glaciers are “rivers” of ice which too erode the landscape by bulldozing soil and stones to expose the solid rock below. Glaciers carve out deep hollows.

Wind is an active agent of erosion and deposition. In deserts we can see the rocks in the shape of mushroom due to the erosion of the lower part of the rock that is why mushroom rocks have wider top and narrower base.

The sea caves occur on the cliffed coast of the study area where the waves break directly on the rock cliff. Mechanical erosion along with chemical solution process is responsible for the formation of the caves. Deep inlets are formed through the zones of weakness under the force of waves and are eroded out.

In deserts you can see rocks in the shape of a mushroom, commonly called mushroom rocks. Winds erode the lower section of the rock more than the upper part. Therefore, such rocks have narrower base and wider top.

When the wind blows, it lifts and transports sand from one place to another. When it stops blowing the sand falls and gets deposited in low hill – like structures. These are called sand dunes.

Loess is an aeolian sediment formed by the accumulation of wind-blown silt, typically in the 20–50 micrometer size range, twenty percent or less clay and the balance equal parts sand and silt that are loosely cemented by calcium carbonate. Extensive loess deposits are found in northern China, the Great Plains of North America, central Europe, and parts of Russia and Kazakhstan. The thickest loess deposits are near the Missouri River in the U.S. state of Iowa and along the Yellow River in China. Loess accumulates, or builds up, at the edges of deserts.

Loess is an aeolian sediment formed by the accumulation of wind-blown silt, typically in the 20–50 micrometer size range, twenty percent or less clay and the balance equal parts sand and silt that are loosely cemented by calcium carbonate.
Coastal landforms created by erosion include headlands, bays and cliffs. Landforms created by deposition include spits, salt marshes and beaches

Conditions for delta formation by a river:

-The river must have gentle gradient in its lower course

-The river must carry large amount of sediments along it

-The coastal plains or area where mouth of river lies should be wide

Though Narmada originates far from Western Ghats and empties into the Arabian Sea, the river flows through a rift valley at a steep gradient which increases its speed. Also, the west coastal plains are less wider than that required for delta formation by Narmada.