Hot spring


A hot spring is a spring that is produced by the emergence of geothermally-heated groundwater from the earth's crust. There are hot springs all over the earth, on every continent and even under the oceans and seas.

Definitions

There is, unfortunately, no universally accepted definition of a hot spring. For example, one can find the phrase hot spring defined as

The related term "warm spring" is defined as a spring with water temperature less than a hot spring by many sources, although Pentecost et al (2003)[19] suggest that the phrase "warm spring" is not useful and should be avoided. The US NOAA Geophysical Data Center defines a "warm spring" as a spring with water between 20°C and 50°C (between 68°F and 122°F).

Sources of heat

The water issuing from a hot spring is heated by geothermal heat, i.e., heat from the Earth's interior. In general, the temperature of rocks within the earth increases with depth. The rate of temperature increase with depth is known as the geothermal gradient. If water percolates deeply enough into the crust, it will be heated as it comes into contact with hot rocks. The water from hot springs in non-volcanic areas is heated in this manner.

In volcanic zones such as Yellowstone National Park, water may be heated by coming into contact with magma (molten rock). The high temperature gradient near magma may cause water to be heated enough that it boils or becomes superheated. If the water becomes so hot that it builds steam pressure and erupts in a jet above the surface of the Earth, it is called a geyser. If the water only reaches the surface in the form of steam, it is called a fumarole. If the water is mixed with mud and clay, it is called a mud pot.

Note that hot springs in volcanic areas are often at or near the boiling point. People have been seriously burned and even killed by accidentally or intentionally entering these springs.

Warm springs are sometimes the result of hot and cold springs mixing but may also occur outside of volcanic areas, such as Warm Springs, Georgia (frequented for its therapeutic effects by paraplegic U.S. President Franklin D. Roosevelt, who built the Little White House there).

Flow rates

Hot springs range in flow rate from the tiniest "seeps" to veritable rivers of hot water. Sometimes there is enough pressure that the water shoots upward in a geyser, or fountain.

A very low flow rate hot spring fed the closed resort, Fales Hot Ditch, which is north of Bridgeport, California. There is a huge subterranean lake below Tonopah, Arizona, which provides natural hot mineral waters to several hot springs. These hot springs were used by the seven or more hot spring spas that once operated in Tonopah. The ruins of two such spas are still visible in Tonopah.

High flow hot springs

See main article on Hot spring properties.<br>

There are many claims in the literature about the flow rates of hot springs. Some of the hot springs with high flow rates and high claimed flow rates[20] include:

Therapeutic uses

Because heated water can hold more dissolved solids, warm and especially hot springs also often have a very high mineral content, containing everything from simple calcium to lithium, and even radium. Because of both the folklore and the proven medical value some of these springs have, they are often popular tourist destinations, and locations for rehabilitation clinics for those with disabilities. [23] [24]

Infections from hot springs

Unfortunately, hot springs can create ideal conditions to spread infections. For example:

Hot springs around the world

There are hot springs on all continents and in many countries around the world. Countries that are renowned for their hot springs include Iceland, New Zealand, Chile and Japan, but there are interesting and unique hot springs in many other places as well:

See also

Further reading and external links

Citations