Research on "Magma Chamber" of Changbai Mountain Volcanoes by Means of Seismic Tomography
Guo Lucan; Ma Shizhuang; Zhang Yushen(Institute of Geophysics,SSB) (Institute of Geophysics ,Academia Sinica)
Some geological evidences show that there exists some possibility of eruption risk at Changbai Mountal Volcanoes region. A scientific project of "The research of eruption risk of Changbai Mountain Volcanoes region " was established in 1994. At the first stage,there are two win to detect "Magma Chamber" of Changbai Mountain Volcanoes by Seismic Tomography: 1) Calculating the 3-dimension distribution of S wave velocity: there are 3-Profile across Tian-chi Volcano, according to the RG5. 5 model by Dr. Zhang Yushen, shows a "Magma Chamber" located at the depth between 38-65 km, the horizontal extension is 100 -300 km. 2) Using the convolution back projection method of honging to reconstruct the spatial distribution of surface-wave quality factor Q values in this region shows that there is a lower Q-value distribution Q = 155-165, it is 40% lower than the average Q-value Q = 250 in China region, this may be the second evidence for "Magma Chamber" of Changbai Mountain VolCanoes. At the end of this paper, the eruption risk of Changbai Mountain Volcanoes region has been discussed. We try to infer that these volcanoes is a dormant volcano group.