What is the Shirasu Plateau? The Secret of Kagoshima's Water, Created by a Natural Filter
Have you ever heard the term "Shirasu Plateau" mentioned as a reason why Kagoshima Prefecture's water is so delicious?
In fact, many areas of Kagoshima Prefecture are characterized by a unique topography known as the "Shirasu Plateau."
Over long periods, this Shirasu Plateau acts like a natural filter, purifying rainwater and nurturing high-quality groundwater.
Tarumizu City in Kagoshima Prefecture, where Onsensui99 is sourced, also has a deep connection with the Shirasu Plateau.
This article will explain in an easy-to-understand way what the Shirasu Plateau is, and the secret behind why it fosters Kagoshima's delicious water.
What is the Shirasu Plateau?
The Shirasu Plateau is a volcanic plateau primarily located in Southern Kyushu.
Approximately 20,000 to 30,000 years ago, a massive eruption occurred at the Aira Caldera, located at the back of the current Kagoshima Bay.
The Shirasu Plateau was formed by the accumulation of a large amount of pyroclastic flows and volcanic ash erupted at that time.
It is widely distributed, especially in Kagoshima Prefecture, and the Shirasu Plateau also extends around Tarumizu City.
What is Shirasu?
Shirasu refers to pyroclastic flow deposits mixed with volcanic ash, pumice, and other materials.
It looks like whitish sand or soil, but it contains countless small pores.
This structure allows water to permeate easily, playing an important role in nurturing groundwater.
Why the Shirasu Plateau is called a natural filter
The biggest characteristic of the Shirasu Plateau is its high water permeability.
Rainwater infiltrates deep underground as it passes through the Shirasu layer.
In this process, it is naturally filtered over long periods and stored as groundwater.
Acting like a giant natural filter, the Shirasu Plateau is known for supporting Kagoshima's rich water resources.
Kagoshima's spring water and the Shirasu Plateau
Kagoshima Prefecture has numerous spring water sources.
Rainwater that infiltrates the Shirasu Plateau is stored underground and emerges as spring water at the base of the plateau or mountainsides.
Such spring water has long supported local life, used for agriculture and drinking water.
This is one of the reasons why Kagoshima is said to be an "area with delicious water."
The relationship between the Shirasu Plateau and Sakurajima
Sakurajima, Kagoshima's representative active volcano, is also indispensable when discussing the natural environment of this region.
The current topography and groundwater environment of Kagoshima were formed by past large-scale volcanic activity.
The Shirasu Plateau is one such landform that conveys this history, and it is an important element supporting the richness of Kagoshima's nature.
Why Kagoshima's water is said to be easy to drink
The deliciousness of water involves various factors.
For example,
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Geology
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Groundwater environment
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Mineral balance
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Hardness
and so on.
Groundwater nurtured by the Shirasu Plateau is naturally filtered over long periods.
As a result, Kagoshima has many high-quality groundwater resources.
If you wish to learn more about soft and hard water, please refer to the related article.
→ [What is the difference between soft water and hard water?]
The relationship between the Shirasu Plateau and Tarumizu City
Tarumizu City in Kagoshima Prefecture, where Onsensui99 is sourced, is located across from Sakurajima.
This region is blessed with a rich natural environment, and deep underground, groundwater that has been nurtured over many years exists.
The geological environment around Tarumizu City is also one of the important factors supporting Kagoshima's rich water resources.
How water reaches 750m underground
Rainwater permeates from the surface to underground, moving through geological layers over a long period.
Water that has undergone natural filtration deep underground accumulates while balancing its mineral content.
Onsensui99 draws this natural water from 750m underground.
Onsensui99 and the Shirasu Plateau
Onsensui99 is sourced from 750m underground in Tarumizu City, Kagoshima Prefecture.
Its characteristics are:
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Natural alkaline hot spring water with a pH of 9.9
-
Ultra-soft water with a hardness of 1.7 mg/L
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Mellow taste
If you want to know more about its drinkability, please refer to this article:
→ [Why is Onsensui99 easy to drink?]
Also, the taste of water is discussed in detail in the following article:
The rich life nurtured by the Shirasu Plateau
The Shirasu Plateau has supported not only groundwater but also local agriculture and livelihoods.
Abundant groundwater is also used for agricultural purposes, supporting the lives of many people.
The Shirasu Plateau is an indispensable presence when discussing Kagoshima's nature and water culture.
Frequently Asked Questions
What is the Shirasu Plateau?
It is a plateau formed from pyroclastic flow deposits, widespread in Southern Kyushu.
What is Shirasu?
It is a pyroclastic flow deposit mixed with volcanic ash, pumice, and other materials.
Why is the Shirasu Plateau called a natural filter?
Because it is permeable to water, allowing rainwater to naturally filter as it permeates underground.
Why does Kagoshima have so many spring water sources?
Because groundwater accumulated in the Shirasu Plateau emerges as spring water.
Is there a relationship between Onsensui99 and the Shirasu Plateau?
The Shirasu Plateau extends around Tarumizu City, Kagoshima Prefecture, where Onsensui99 is sourced, fostering a rich groundwater environment.
Summary
The Shirasu Plateau is a unique landform in Southern Kyushu, formed by a massive eruption approximately 20,000 to 30,000 years ago.
The Shirasu layer, composed of volcanic ash and pumice, is permeable to water, allowing rainwater to permeate underground over long periods.
As a result, Kagoshima has been blessed with abundant groundwater and spring water.
Tarumizu City, where Onsensui99 is sourced, is also one of the areas that benefit from this natural environment.
Behind the deliciousness of Kagoshima's water lies the presence of the great landform known as the Shirasu Plateau.
