The Tongonan springs are located between the "Bao Fault" and the "East Fault". There are more than one hundred boiling springs that occur at the intersections of major faults and subsidiary fractures and joints in andesite and sedimentary rocks. One-meter temperature probe-hole survey on the geothermal ground indicates tremendous heat underneath the area.

The temperature of thermal waters from six major boiling springs ranges from B8' to 100°C. Their total estimated heat discharge is 801,000 kilo-calories per minute (total mass discharge is 10,400 liters per minute and the maximum temperature of river water fed to the springs is 23“C) or the equivalent of about 55,900 kilowatts.

Field observations and partial chemical analysis of water samples indicate that most of the hot spring waters are fed from the surface or are meteoric water and little comes from depth. Evidences indicate that the heat is of magmatic origin.