Theme: Unity through Catastrophe
An avalanche is a very large slide of snow (or rock) down a mountainside, caused when a buildup of snow is released down a slope, and is one of the major dangers faced in the mountains. An avalanche consists of rapidly moving granular material that has exceeded the critical static friction threshold and thereby causes additional material to exceed its threshold as well, in a cascading effect.
In an avalanche, lots of material or mixtures of different types of material fall or slide rapidly under the force of gravity. Avalanches are often classified by what they are made of, for example snow, ice, rock or soil avalanches. A mixture of these would be called a debris avalanche.
In meteorology, a cyclone is an area of low atmospheric pressure characterized by inward spiraling winds that rotate counter clockwise in the northern hemisphere and clockwise in the southern hemisphere of the Earth.[1][2] Since the generic term covers a wide variety of meteorological phenomena, such as tropical cyclones, extratropical cyclones, and tornadoes, meteorologists rarely use it without additional qualification.
This article is about the natural seismic phenomenon. For other uses, see Earthquake (disambiguation).
An earthquake is a phenomenon that results from the sudden release of stored energy in the Earth's crust that creates seismic waves. At the Earth's surface, earthquakes may manifest themselves by a shaking or displacement of the ground and sometimes cause tsunamis, which may lead to loss of life and destruction of property. An earthquake is caused by tectonic plates getting stuck and putting a strain on the ground. The strain becomes so great that rocks give way and fault lines occur.
Earthquakes may occur naturally or as a result of human activities. In its most generic sense, the word earthquake is used to describe any seismic event—whether a natural phenomenon or an event caused by humans—that generates seismic waves.
A hurricane is a severe tropical storm that forms in the North Atlantic Ocean,
the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E. Hurricanes need warm tropical oceans, moisture and light winds above them. If the right conditions last long enough, a hurricane can produce violent winds, incredible waves, torrential rains and floods. In other regions of the world, these types of storms have different names.
Typhoon — (the Northwest Pacific Ocean west of the dateline)
Severe Tropical Cyclone — (the Southwest Pacific Ocean west of 160E or Southeast Indian Ocean east of 90E)
Severe Cyclonic Storm — (the North Indian Ocean)
Tropical Cyclone — (the Southwest Indian Ocean)
Hurricanes rotate in a counterclockwise direction around an "eye." A tropical storm becomes a hurricane when winds reach 74 mph. There are on average six Atlantic hurricanes each year; over a three-year period, approximately five hurricanes strike the United States coastline from Texas to Maine. The Atlantic hurricane season begins June 1 and ends November 30. The East Pacific hurricane season runs from May 15 through November 30, with peak activity occurring during July through September. In a normal season, the East Pacific would expect 15 or 16 tropical storms. Nine of these would become hurricanes, of which four or five would be major hurricanes.
When hurricanes move onto land, the heavy rain, strong winds and heavy waves can damage buildings, trees and cars. The heavy waves are called a storm surge. Storm surge is very dangerous and a major reason why you MUST stay away from the ocean during a hurricane.
Earthquakes may occur naturally or as a result of human activities. In its most generic sense, the word earthquake is used to describe any seismic event—whether a natural phenomenon or an event caused by humans—that generates seismic waves.
A hurricane is a severe tropical storm that forms in the North Atlantic Ocean,
the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E. Hurricanes need warm tropical oceans, moisture and light winds above them. If the right conditions last long enough, a hurricane can produce violent winds, incredible waves, torrential rains and floods. In other regions of the world, these types of storms have different names.Typhoon — (the Northwest Pacific Ocean west of the dateline)
Severe Tropical Cyclone — (the Southwest Pacific Ocean west of 160E or Southeast Indian Ocean east of 90E)
Severe Cyclonic Storm — (the North Indian Ocean)
Tropical Cyclone — (the Southwest Indian Ocean)
Hurricanes rotate in a counterclockwise direction around an "eye." A tropical storm becomes a hurricane when winds reach 74 mph. There are on average six Atlantic hurricanes each year; over a three-year period, approximately five hurricanes strike the United States coastline from Texas to Maine. The Atlantic hurricane season begins June 1 and ends November 30. The East Pacific hurricane season runs from May 15 through November 30, with peak activity occurring during July through September. In a normal season, the East Pacific would expect 15 or 16 tropical storms. Nine of these would become hurricanes, of which four or five would be major hurricanes.
When hurricanes move onto land, the heavy rain, strong winds and heavy waves can damage buildings, trees and cars. The heavy waves are called a storm surge. Storm surge is very dangerous and a major reason why you MUST stay away from the ocean during a hurricane.
A tornado is a violently rotating column of air which is in contact with both a cumulonimbus (or, in rare cases, cumulus) cloud base and the surface of the earth. Tornadoes can come in many shapes, but are typically in the form of a visible condensation funnel, with the narrow end touching the earth. Often, a cloud of debris encircles the lower portion of the funnel.
Most tornadoes have winds of 110 mph (175 km/h) or less, are approximately 250 feet (75 meters) across, and travel a few miles (several kilometers) before dissipating. However, some tornadoes can have winds of more than 300 mph (480 km/h), be more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 kilometers).[1][2][3]
Tornadoes have been observed on every continent except Antarctica; however, most of the world's tornadoes occur in the United States.[4] Other areas which commonly experience tornadoes include New Zealand, western and southeastern Australia, south-central Canada, northwestern and central Europe, Italy, south-central and eastern Asia, east-central South America, and Southern Africa.[5]
Most tornadoes have winds of 110 mph (175 km/h) or less, are approximately 250 feet (75 meters) across, and travel a few miles (several kilometers) before dissipating. However, some tornadoes can have winds of more than 300 mph (480 km/h), be more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 kilometers).[1][2][3]
Tornadoes have been observed on every continent except Antarctica; however, most of the world's tornadoes occur in the United States.[4] Other areas which commonly experience tornadoes include New Zealand, western and southeastern Australia, south-central Canada, northwestern and central Europe, Italy, south-central and eastern Asia, east-central South America, and Southern Africa.[5]
A tsunami is a series of waves generated by an impulsive disturbance in the ocean or in a small, connected body of water. These waves sometimes inflict severe damage to property and pose a threat to life in coastal communities. NGDC and the co-located World Data Center for Solid-Earth Geophysics have compiled a unique set of tsunami-related products as part of a continuing program to support the interests of engineers, oceanographers, seismologists, and the general public. These data products include historic tsunami data, technical publications, and photographs. Please see the Copyright Notice if you plan to use data from this web site or government agency.
