Natural Disasters

Flash floods most often occur in normally dry areas that have recently received precipitation but may be seen anywhere downstream from the source of the precipitation, even many miles from the source. In areas on or near volcanoes, flash floods have also occurred after eruptions when glaciers have been melted by the intense heat. Flash flooding can also be caused by extensive rainfall released by hurricanes and other tropical storms as well as the sudden thawing effect of ice dams. Human activities can also cause flash floods to occur. When dams, constructed for hydro-electricity, have failed, large quantity of water can be released and can destroy everything within its path.

Tsunami waves do not resemble normal sea waves because their wavelength is far longer. Rather than appearing as a breaking wave, a tsunami may initially resemble a rapidly rising tide and for this reason they are often referred to as tidal waves.

In deserts, flash floods can be particularly deadly for several reasons. First, storms in arid regions are infrequent but they can deliver an enormous amount of water in a very short time. Second, these rains often fall on poorly absorbent and often clay-like soil, which greatly increases the amount of runoff that rivers and other water channels have to handle. These regions tend not to have the infrastructure that wetter regions have to divert water from structures and roads, such as storm drains, culverts and retention basins.

On November 25, 1839, an enormous cyclone caused a 40-foot storm surge that hit the ancient city of Coringa in present Andhra Pradesh. The cyclone wiped out the harbour city, destroyed 25,000 ships and vessels in its bay and killed 3,00,000 people. Survivors never entirely rebuilt the city. City of Coringa was known for ship building and repairing.
This storm caused the third largest loss of life from any tropical cyclone worldwide, tied with Vietnam’s 1881 Haiphong typhoon (also causing 300,000 fatalities). Storms in the Bay of Bengal actually account for seven of the 10 deadliest hurricanes, typhoons and cyclones recorded in history.

The National Disaster Response Force (NDRF) is a disaster response agency under National Disaster Management Authority (NDMA) created by the Ministry of Home Affairs, Government of India. It was established in 2009 in Delhi for the purpose of specialised response to natural and man-made disasters. It consists of eight battalions of Indian Armed forces, including two each of the BSF, CRPF, CISF and ITBP.

The 2009 North Indian Ocean cyclone season was an event in the annual cycle of tropical cyclone formation.
Cyclone Aila was the second tropical cyclone of the 2009 North Indian Ocean cyclone season. A relatively strong tropical cyclone, it caused extensive damage in India and Bangladesh.
Cyclone Bijli was the first tropical cyclone to form during the 2009 North Indian Ocean cyclone season.

Zone 5 covers the areas with the highest risk zone that suffers earthquakes of intensity MSK IX or greater. The state of Kashmir, the western and central Himalayas, the Northeast Indian region and the Rann of Kutch fall in this zone. The Andaman and Nicobar Islands fall in Zone 3.

The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, 26 December, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The resulting tsunami was given various names, including the 2004 Indian Ocean tsunami, South Asian tsunami, Indonesian tsunami and the Boxing Day tsunami.
With a magnitude of MW 9.1–9.3, it is the third largest earthquake ever recorded on a seismograph. The earthquake had the longest duration of faulting ever observed, between 8.3 and 10 minutes.

The San Andreas Fault is a continental transform fault that runs a length of roughly 810 miles (1,300 km) through California in the United States. It forms the tectonic boundary between the Pacific Plate and the North American Plate. On September 28, 2004, at 10:15 A.M. PDT, a magnitude 6.0 earthquake struck California on the San Andreas Fault. It was felt across the state, including the San Francisco Bay Area.

The Alpide belt is a mountain range which extends along the southern margin of Eurasia. Stretching from Java to Sumatra through the Himalayas, the Mediterranean and out into the Atlantic, it includes the Alps, the Carpathians, the mountains of Anatolia and Iran, the Hindu Kush and the mountains of Southeast Asia. The Alpide belt is being created by ongoing plate tectonics namely the process of collision between the northward-moving African, Arabian and Indian plates and the Eurasian plate. The most seismically active zone in the world is the Pacific Ring of Fire. Alpide Belt falls on the second position behind it in terms of seismicity.

The epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates. Thus, focus and hypocentre are synonymous terms, whereas epicentre is a related but distinct concept.

The moment magnitude scale (abbreviated as MMS; denoted as MW or M) is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the earth multiplied by the average amount of slip on the fault and the size of the area that slipped. The MMS is the scale used to estimate magnitudes for all modern large earthquakes by the United States Geological Survey.
The Richter magnitude scale (often shortened to Richter scale) was developed to assign a single number to quantify the energy released during an earthquake.

All have the potential to generate a tsunami.

Megathrust earthquakes occur at subduction zones at destructive plate boundaries (convergent boundaries), where one tectonic plate is subducted (forced underneath) under another. Due to the shallow dip of the plate boundary, which causes large sections to get stuck, this type of earthquakes are the planet's most powerful. Since 1900, all six earthquakes of magnitude 9.0 or greater have been megathrust earthquakes. The 2004 Indian Ocean earthquake was an undersea megathrust earthquake.

The river Kosi is known as the 'Sorrow of Bihar' as it flows from Nepal to India and has caused widespread human suffering in the past through flooding and very frequent changes in course. It is river Damodar which is often labelled as the ‘Sorrow of Bengal’.
Over the last 250 years, the river Kosi has shifted its course over 120 km (75 miles) from East to West. Its unstable nature has been attributed to the heavy silt it carries during the monsoon season which causes flooding in India that has extreme effects.