Emergency Symbology Reference - Natural Events (version 2)

Natural Events Symbology Reference (Version 2)

Natural Events - Phenomenon found in or created by naturally occuring conditions.

Use this page to cross-reference the Natural Events symbols with their definitions.

Changed or New symbols are marked by a plus sign (+) and have a light yellow background. Deleted symbols are marked by a minus sign (-) and have a light orange background.
Printable List of All Changes

Symbol Types		Symbol Image	Key Stroke	Symbol Terms and Definitions
1.)	Geologic (Theme)
2.)	After Shock (Geologic Feature)		A	After Shock (Natural Event Geologic) - An earthquake that follows a larger earthquake and originates at or near the latter's focus. (Source: Dictionary of Geological Terms, 3rd Ed.)
3.)	Avalanche (Geologic Feature)	+	B	Avalanche (Natural Event Geologic) - A large mass of snow, ice, soil, or rock, or mixtures of these materials, falling, sliding, or flowing very rapidly under the force of gravity. (Source: Dictionary of Geological Terms, 3rd Ed.)
4.)	Earth Quake Epicenter (Geologic Feature)		C	Earth Quake Epicenter (Natural Event Geologic) - The point on the earth's surface directly above the focus of an earthquake. (Source: Dictionary of Geological Terms, 3rd Ed.)
5.)	Landslide (Geologic Feature)		D	Landslide (Natural Event Geologic) - A general term for a wide variety of processes and landforms involving the down slope movement under the force of gravity of masses of soil and rock material. (Source: Dictionary of Geological Terms, 3rd Ed.)
6.)	Subsidence (Geologic Feature)		E	Subsidence (Natural Event Geologic) - Sinking or downward settling of the earth's surface. (Source: Dictionary of Geological Terms, 3rd Ed.)
7.)	Volcanic Eruption (Geologic Feature)		F	Volcanic Eruption (Natural Event Geologic) - The ejection of volcanic materials (lava, pyroclasts, and volcanic gases) from a vent or fissure in the Earth's crust. (Source: Dictionary of Geological Terms, 3rd Ed.)
8.)	Volcanic Threat (Geologic Feature)		G	Volcanic Threat (Natural Event Geologic) - A vent or fissure in the Earth's crust where volcanic eruption is believed to be imminent. (Source: logical extension of Volcanic Eruption)
9.)	Hydro-Meteorological (Theme)
10.)	Drizzle (Hydro-Meteorologic Feature)		H	Drizzle (Natural Event Hydro-Meteorologic) - Some time called mist. Very small, numerous, and uniformly dispersed water droplets that appear to float while following air currents. Unlike fog droplets, drizzle fall to the ground.
11.)	Drought (Hydro-Meteorologic Feature)		I	Drought (Natural Event Hydro-Meteorologic) - A period of abnormally dry weather sufficiently prolonged for the lack of water to cause a serious hydrologic imbalance across the affected area. Drought severity depends upon the degree of moisture deficiency, the duration, and (to a lesser extent) the size of the affected area. In general, the term should be reserved for periods of moisture deficiency that are relatively extensive in both space and time.
12.)	Flood (Hydro-Meteorologic Feature)		J	Flood (Natural Event Hydro-Meteorologic) - A relatively high stream flow that overtops the stream banks in any part of its course, covering land that is not normally under water. (Source: Dictionary of Geological Terms, 3rd Ed.) A condition that occurs when water overflows the natural or artificial confines of a stream or other body of water, or accumulates by drainage over low-lying areas.
13.)	Fog (Hydro-Meteorologic Feature)		K	Fog (Natural Event Hydro-Meteorologic) - A visible aggregate of minute water droplets suspended in the atmosphere near the earth's surface. According to international definition fog reduces visibility to less than 5/8 mile. Fog differs from clouds only in that the base of the fog is at the earth's surface while clouds are above the surface.
14.)	Hail (Hydro-Meteorologic Feature)		L	Hail (Natural Event Hydro-Meteorologic) - Precipitation in the form of circular or irregular-shaped lumps of ice. (Source: The National Weather Service glossary. http://www.crh.noaa.gov/lmk/glossary.htm)
15.)	Inversion (Hydro-Meteorologic Feature)		M	Inversion (Natural Event Hydro-Meteorologic) - A departure from the standard decrease or increase with altitude of value of an atmosphere property. This term almost always means temperature inversion.
16.)	Rain (Hydro-Meteorologic Feature)		N	Rain (Natural Event Hydro-Meteorologic) - Precipitation in the form of liquid water drops which have diameters greater than 0.5mm.
17.)	Sand Dust Storm (Hydro-Meteorologic Feature)		O	Sand Dust Storm (Natural Event Hydro-Meteorologic) - A strong wind carrying sand through the air, the diameter of most of the particles ranging from 0.08 to 1 mm. In contrast to a dust storm, the sand particles are mostly confined to the lowest teo feet, and rarely rise more than fifty feet above the ground.
18.)	Snow (Hydro-Meteorologic Feature)		P	Snow (Natural Event Hydro-Meteorologic) - Precipitation composed of white or translucent ice crystals, chiefly complex branched hexagonal form and often agglomerated into snowflakes.
19.)	Thunder Storm (Hydro-Meteorologic Feature)		Q	Thunder Storm (Natural Event Hydro-Meteorologic) - A thunderstorm is a consequence of atmospheric instability and constitutes and over turning of layers in order to achieve a more stable atmosphere. In general a local storm invariably produces lightning, thunder, usually strong gusts of winds, heavy rain and sometimes hail.
20.)	Tornado (Hydro-Meteorologic Feature)		R	Tornado (Natural Event Hydro-Meteorologic) - A violently rotating column, or funnel, of air in contact with the ground and extending from the base of a thunderstorm. (Source: Modified from the National Weather Service glossary. Link at: http://www.erh.noaa.gov/er/pit/branick2d.html#Glossary)
21.)	Tropical Cyclone (Hydro-Meteorologic Feature)		S	Tropical Cyclone (Natural Event Hydro-Meteorologic) - The general term for a cyclone that originates over the tropical oceans.
22.)	Tsunami (Hydro-Meteorologic Feature)		T	Tsunami (Natural Event Hydro-Meteorologic) - A great sea wave produced by an earthquake or volcanic eruption, characterized by high speed of propagation, long wavelength, long period, and low observable amplitude on the open ocean. (Source: Dictionary of Geological Terms, 3rd Ed.) An ocean wave produced by a submarine earthquake, landslide, or volcanic eruption. These waves may reach enormous dimensions and have sufficient energy to travel across entire oceans. Tsunamis have no connection with tides as inferred by the common use of the term tidal wave.
23.)	Infestation (Theme)
24.)	Bird Infestation (Infestation Feature)	+	U	Bird Infestation (Natural Event Infestation) - A harassing or troublesome invasion of birds. (Source: derived from the definition of infestation found in the FactMonster.com dictionary)
25.)	Insect Infestation (Infestation Feature)		V	Insect Infestation (Natural Event Infestation) - A harassing or troublesome invasion of insects. (Source: derived from the definition of infestation found in the FactMonster.com dictionary)
26.)	Microbial Infestation (Infestation Feature)		W	Microbial Infestation (Natural Event Infestation) - A harassing or troublesome invasion of a microbe. (Source: derived from the definition of infestation found in the FactMonster.com dictionary)
27.)	Reptile Infestation (Infestation Feature)		X	Reptile Infestation (Natural Event Infestation) - A harassing or troublesome invasion of reptiles. (Source: derived from the definition of infestation found in the FactMonster.com dictionary)
28.)	Rodent Infestation (Infestation Feature)		Y	Rodent Infestation (Natural Event Infestation) - A harassing or troublesome invasion of rodents. (Source: derived from the definition of infestation found in the FactMonster.com dictionary)