Best answer: The dead volcanic terrain area formed by magmatism in the earth’s crust or accompanied by volcanic eruption, where volcanic activity has occurred, and the surface uplifted due to the movement of the earth’s crust plate, and there is still uncooled magma under the ground, will continuously release a large amount of heat energy. Because the heat of such heat sources is concentrated, as long as there are porous water-bearing rock formations nearby, they will not only be heated to become hot water at high temperature, but also boil to steam, mostly sulfate springs.
1. In the extinct volcanic terrain area formed by magmatism in the earth’s crust, or accompanied by volcanic eruption and volcanic activity, because of the uplift of the earth’s crust plate movement, there are still uncooled magma under the ground, which will continuously release a large amount of heat energy. Because of the heat concentration of such heat sources, as long as there are pores in the nearby water-bearing rock stratum, it will not only be heated to become hot water at high temperature, but also boil to steam in most cases, mostly sulfate springs.
2. Formed by the infiltration and circulation of surface water. That is to say, when the rain drops to the surface and penetrates downward, it goes deep into the aquifer in the crust to form groundwater (sandstone, conglomerate, volcanic rock and these good aquifers). Groundwater is heated by the geothermal heat below to become hot water, and most of the deep hot water contains gas, which is mainly carbon dioxide. When the temperature of hot water rises, if there is a dense and impervious rock layer on it to block the way, the pressure will become higher and higher, so that the hot water and steam are in a high pressure state, and they will surge up as soon as there are cracks. The closer the hot water rises, the pressure will gradually decrease. As the pressure gradually decreases, the contained gas will gradually expand, thus reducing the density of hot water. These expanded vapors are more conducive to the rise of hot water. The rising hot water repeatedly circulates with the cold water heated later due to the different density (hydrostatic pressure difference) to generate convection. When the resistance of the open fissure is small, it rises along the fissure and gushes out of the ground, and the hot water can continuously surge up and finally flow out of the ground to form a hot spring. With the cooperation of high mountains and deep valleys, the ground water at the valley bottom may be higher than that at high mountains, and the medium groundwater level is lower. Therefore, the valley bottom may be the place where the hydrostatic pressure difference is the largest, and the possibility of hot water upwelling from the valley bottom is the greatest. Most hot springs occur on the riverbed in the valley.