Is there lava under the natural hot springs?

it has always been common knowledge that hot springs are in the mountains or near volcanoes. But this is not absolute, all natural hot springs do not necessarily have lava underground!

Three types of hot springs are analyzed:

1. Underground heat source type (natural hot springs that naturally gush out)

1. Rainfall-originated hot springs

These hot springs are formed near the foothills of volcanoes. Mountains formed by volcanic eruption, for example, Changbai Mountain in the northeast of China also belong to this type.

the formation process of this type of hot spring: when the rain falls to the surface, it penetrates downward into the easily permeable stratum such as volcanic ash. However, the impermeable layer and impermeable layer of lava and clay layer form the slope of the mountain. Groundwater is stored near the foothills at high temperature under the heat conduction of high-temperature magma and gushes out of the surface under pressure.

2 underground heat source of granite and hot spring of magma water

Can there be hot springs without volcanoes on the surface? There is such an incredible place.

Hot springs gushing out in China are almost of this type. Most of them are underground or where there is hot granite on the surface.

I don't know much about the formation process of this kind of hot springs, but suppose there is magma underground, which is located near the plate structure. According to the pressure and friction, the strata are heated, and the seawater and minerals contained in the strata are concentrated. The heat sources of many hot springs are not very clear. It can be considered that the magma that failed to be sprayed was slowly cooled and formed granite underground. Because it takes millions of years for granite to cool down, there is still residual heat, so it is presumed to be a heat source.

second, the aquifer type (mainly hot springs developed in plain areas)

is a stratum formed by unconsolidated geological accumulation in the new period. Hot springs in the coastal areas of China, especially in Tianjin, Beijing, Shanghai and Fuzhou, belong to this type of hot springs.

the stratum is accumulated over 1m. It is composed of gravel layer, gravel layer and clay layer. Gravel layer and gravel layer have strong water permeability, and groundwater flows, just like when sprinkling water on a sand pit where children play.

Try to find this kind of stratum in the deep underground, and extract the groundwater heated by the heat inside the earth. Generally speaking, it is possible to develop geothermal hot springs under this stratum with a thickness of about 1m m.

III. Fissure-type hot springs (mainly hot springs developed in the mountains and surrounding areas)

Most of China is in hilly areas, and 8%-9% of the underground is in rock plate areas, which are basically impermeable.

However, there are spaces where groundwater can penetrate in faults and rock cracks, and the development of such groundwater is called fissure water hot spring.

☆ The hot springs recently developed in the suburbs of the city are hot springs with water layers in deep underground. Due to the influence of high pressure in the deep underground and the heat released from the earth, the temperature near 1m underground is 4-5℃. Of course, if the correct investigation method and precise drilling technology are used, high-temperature and mineral-rich groundwater can be developed in the deep underground.