Changbai Mountain Volcanic Group

　　The Changbai Mountain Volcanic Group Changbai Mountain is part of the ancient Xia continent and is a well-known dormant volcano. About 600 million years ago, this area was an ocean. From ancient times to the Mesozoic era, after the Earth underwent the Caledonian, Variscan, Yanshan, and Himalayan movements, the seawater finally retreated from this ancient land that had undergone many changes. The crust in the Changbai Mountain area underwent a series of fractures and uplifts, and basalt magma flowing from underground erupted in large quantities along the cracks in the crust, thus marking the beginning of Changbai Mountain's volcanic activity.

　　There are more than 100 volcanoes distributed around Changbai Mountain. The largest crater is about 2,600 meters above sea level, with a diameter of 4.5 kilometers, shaped like a funnel and over 800 meters deep. Its landscape is unique and rarely seen in China.

　　The smaller cones nearby are about 1,000 meters above sea level. Most of their craters are overflow vents, shaped like chairs or crescents, with flat summits. Famous ones include West Emaodingzi, East Emaodingzi, West Tudingzi, East Tudingzi, West Ma'anshan, East Ma'anshan, Chifeng, and Laofangzi Xiaoshan. These numerous small volcanoes surround Changbai Mountain, forming a spectacular volcanic group.

　　The Tianchi volcano of Changbai Mountain is currently the most well-preserved Cenozoic polygenetic composite volcano in China. The massive eruption of Tianchi volcano between 1199 and 1201 was the largest eruption event in the past 2,000 years globally, with volcanic ash falling as far as the Sea of Japan and northern Japan. Changbai Mountain is a dormant active volcano. Although it has been dormant for 300 years, it is not uncommon for volcanoes around the world to erupt again after hundreds of years of dormancy. Geophysical exploration indicates signs of a crustal magma chamber beneath Tianchi of Changbai Mountain, posing a risk of future eruptions. The eruption would be of a certain type, and the presence of 2 billion tons of water in Tianchi could make the eruption even more destructive.

　　Since the Quaternary period, the Longgang Volcanic Group in the western foothills of Changbai Mountain, covering nearly 2,000 square kilometers in Jingyu–Huinan, features over 160 low and densely distributed volcanic cones, showing characteristics of high-density, multi-center eruptions of a certain type. It mainly consists of basaltic volcanic slag, volcanic bombs, volcaniclastic rocks, and a small amount of lava. The Longgang Volcano is one of the few Quaternary volcanoes in China that still shows signs of recent eruptive activity. Changbai Mountain has experienced multiple eruptions as well as long periods of dormancy. Since becoming active in the 16th century, it has erupted three times—in August 1597, April 1688, and April 1702. The last eruption was about 300 years ago. The materials ejected from the Changbai Mountain eruptions accumulated around the craters, causing the mountain to rise into towering peaks and form concentric volcanic cones. The summits are covered with grayish-white pumice and volcanic ash, along with perennial snow, making the mountain appear as a snow-capped peak from afar—hence the name Changbai Mountain, meaning "Everwhite Mountain."

　　In 1997, the key project of China’s Ninth Five-Year Plan, “Monitoring and Research on Several Active Volcanoes in China,” was launched. The China Earthquake Administration began monitoring and research in the Tianchi volcanic area of Changbai Mountain. After several years of study, experts concluded that Changbai Mountain is a dormant active volcano. Although it has been dormant for 300 years, it is not uncommon for volcanoes around the world to erupt again after centuries of dormancy. Geophysical exploration indicates signs of a crustal magma chamber beneath Tianchi of Changbai Mountain, posing a risk of future eruptions. The eruption would be of a certain type, and the presence of 2 billion tons of water in Tianchi could make the eruption even more destructive. During the Ninth Five-Year Plan period, the China Earthquake Administration and the Jilin Provincial Earthquake Administration established a volcano monitoring station at Tianchi, including a digital seismic monitoring network, fixed deformation observation system, GPS mobile observation network, and geochemical observation network. The implementation of the Ninth Five-Year Plan project ended the unmonitored status of the Tianchi volcano. Based on current observations, no signs of volcanic reactivation have been detected, and people can safely enjoy the abundant resources and beautiful landscapes bestowed by nature at Tianchi of Changbai Mountain.