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Japan is famous as a hot spring country and Oita Prefecture is particularly blessed with hot springs. Oita residents have been close to hot springs from time immemorial, a fact made clear by a historical account of hot and mineral springs in the "Bungo Fudoki (Oita Regional Topography)" that was edited during the Nara Era.

Most Hot Springs Are Volcanic
Most hot springs are volcanic as their source of heat and chemical elements is the magma generated from volcanoes. In Oita, the magma sources are the new volcanoes of Tsurumi, Yufu and Kuju ranging from east to west at the center of the prefecture. The Beppu, Yufuin and Kuju areas form the core of the sources and each place is known as a major hot spring area in Japan. The center part of Oita Prefecture is a part of each of these areas and thus is one of the world's most prominent hot spring district.
Without new volcanic activity these days, it was said to be difficult to find new hot springs in the northern and southern area. But another usable hot spring was found by boring over 1,000m deep into the earth for groundwater that is non-volcanic but rather, heated by heat currents inside the earth. A typical example is the kind of hot springs in Oita Plain which have been developed since 1975, and Oita City is now one of the most famous hot spring cities in Japan.

High Temperatures and a Variety of Hot Springs
In Oita Prefecture, 38 cities, towns and villages have hot springs, according to figures as of the end of March, 2000. The total number of spring sources is 4,749, including unused ones, and this makes up 18% of all the sources in Japan. The output of the hot spring water is about 26,000l per minute, which accounts for 10% of the amount produced by the whole country. Although Oita occupies less than 2% of the total land area in the country, a large number of hot springs are concentrated in this small area.
The remarkable thing is that about 85% of the sources have water temperatures over 42, and some sources in the volcanic area produce hot water and steam at boiling point. Moreover, the quality of the water varies with every spring, except for radioactive water. That is to say, Oita's hot springs not only boast of a large number of spring sources and high output of springs, but also of a quantity of high temperature springs and a variety of water quality.

The Best Hot Spring Prefecture in Japan
The basic elements of hot springs are water, heat and chemical elements. On one hand, the southewestern area in Japan abounds in rainfall due to the humid and mild climate. On the other hand, when the Philippines Sea Plate swept toward Kyushu Island in a dynamic movement of the earth, it sank under the island and generated magma. The magma generated heat and chemical elements, and then split up the island into north and south, crushed the land and made the spots where the rainwa t e r, heat, and chemical elements meet. That was how the hot springs were generated, and Oita Prefecture is located right where the activity took place.
The Philippines Sea Plate's sinking raised the underground temperature ofthis area. As the underground temperature on Oita Plain increases by about 5to 6.5for every 100m deeper it goes, the water is hot enough at 800m deep and may be used as a non-volcanic spring.
With the development of non-volcanic springs added to the old volcanic ones, Oita Prefecture, "The best hot spring prefecture in Japan", is improving where natural assets are concerned.
 
Kuju Mountain Ranges


Steam rising from hot springs (Beppu City)

(Outline of Hot Springs in Japan)
Top5 prefectures in the number of hot spring sources

 Number of sources
Oita prefecture 4,762vents
Kagoshima prefecture 2,804vents
Shizuoka prefecture 2,289vents
Hokkaido 2,200vents
Kumamoto prefecture 1,345vents
 
Top5 prefectures in output of spring water
 Output of Spring Water
Hokkaido 300,920
l/min
Oita prefecture 266,228l/min
Kagoshima prefecture 200,028l/min
Aomori prefecture 166,526l/min
Nagano prefecture 132,187l/min




Sujiyu Hot Spring (Kokonoe Town)


Nagayu Kaniyu Hot Spring (Naoiri Town)


qOutline of Hot Springs in Oita prefecturer
Top5 cities,towns and villeges in the number of hot spring sources

 Number of sources
Beppu City 2,850vents
Yufuin Town 888vents
Kokonoe Town 303vents
Oita City 185vents
Amagase Town 117vents
 
Top5 cities,towns and villeges in output of spring water
 Output of Spring Water
Beppu City 95,434l/min
Kokonoe Town 61,704l/min
Yufuin Town 44,699l/min
Oita City 16,196l/min
Amagase Town 10,548l/min