The continental plate in the eastern part of Asia is composed of various volcanoes and tectonic movements. Most of the volcanic rocks in this region are composed of alkali basalts with signs of continental contamination. There are various models that explain the region’s magmatic evolution. The two most common models used to explain the movements refers to the surficial processes and the other one refers to the deeper processes associated with the Pacific ocean plate. These two processes are antithetic and may hay happen subsequently. The volcanism can be traced by tomographic imaging that can be directly associated to the subducted oceanic lithosphere presence in the transition zone that is found beneath the East Asian continent (Richard and Iwamori, 2010). The Pacific slab that penetrates beneath the countries Korea, Japan and China is one of the widely accepted communities in the mantle transition zone in Earth Science. The intra-plate volcanoes in this part of Eastern Asia do not have hotspot origins. The existence of the Pacific slab in the tectonic plates of the East Asia is in the zone of broad deformation. The deep subduction of the slabs is influencing the volcanic and seismic activities in the region (Kim et al, 2015).
There are many Cenozoic volcanoes that are found along the East Asia. The Changbai is one of the most active volcanic zones along the continent. The Changbai intraplate volcano also referred to as Tianchi volcano is found in the boundaries of Korea and China. There have been various researches and models that used multidisciplinary approaches in the investigation of the mantle and crust structures. There have been various soundings detected from this area such as high-conductivity layers, seismic explosion movement, and magma chambers. Changbai volcano is likened to Hawaii, which is called as hotspot due to the presence of the many active volcanoes. However, the seismic stations along the north eastern part of Asia are not yet fully digitally established. Thus, the mantle and crust seismic structure under this region is not fully well established. There are around 19 stations with portable seismic networks that are developed along the region of Changbai. There were waveform data that were gathered and used for the estimation of the depth distribution along the area (Zhao et al, 2008).
Mt. Changbai volcano is found between the Songliao Basin and Japan Sea covers about 12,000 km2 area. It is characterized by the presence of three main eruptive cones and the elevation of the mountain decreases from the crater going into its surroundings. The central part of the Changbai is composed of Tianchi, In the southwest part is the Wangtina’e and in the southwest part is the Namphothe. There is a large crater lake found at the main peak of Tianchi that was formed through the various eruptions that happened in the past. The Tianchi is also composed of the trachytes in the cone, the lava plateau, and at the summit is the pantellerites. The Wangtian’e volcano is composed of platforms of basalt-trachybasalt in the early stage, the trachyandesite-trachyte in the middle stage, and the pantellerite out crops ar the late stage. The peak of the Namphothe is composed of trachytes along the cone of the volcano and in the surrounding parts are the pantellerites. There are also around 81 smaller volcanic cones that is found in the large pumice area of the peak. Figure 1 shows the geological map of the Mt. Changbai. Changbai also serves as water sources of the rivers Tumen, Yalu, and Songhua. The scenery on the mountain is also very lovely composed of natural features such as hot springs, waterfalls, and tundra regions (Liu et al, 2015).
Figure 1. Mt Changbai (Liu et al, 2015)
The Changbai Mountains have a volcanic zone that is found in the eastern part of the NE China continent. The volcanic zone in this part has been active ever since the Cenozoic time. It is also part of the Pacific volcanic belt that separates the West Pacific plate from the Japanese back-arc extensional region. During the early era of Cezonoic time, the north east part of China was still in an extensional environment. In the Miocene, the Japan sea opening happened as a result of the northeastern China intra-plate extension. Thus, the genesis of the Tianchi volcano zone in the Changbai evolved. Along the volcanic one, there are several volcanoes that are found in this area. There were various crustal uplifts that occurred along the Changbai Mountains from the Pliocene towards the time of the Pleistocene. Some of the notable large volcanoes include Tianchi, Xitudingzi, Wangtian’e, Nanbaotai, and many more (Wang et al, 2003). The Chanbaishan is one of the active strato-volcanoes that is found at around 1200 km from the Eastern Japan convergent boundary. There have been historic records for several eruptions for this volcano, where the most recent one happened in the year 1903. The largest explosion of the volcano happened in 1946, called the Millennium eruption. This eruption produced large amount of pyroclastic flows and big amount of fallen ash (Hong et al. , 2015). Mt Changbai is considered as one of the most active and dangerous volcanoes both in the local and global consideration. Although there has been no record of eruption for the volcano for the last 100 years, there is high potential for its eruption consistent with the cycle of volcanic eruptions. The Tianchi-centered volcanic field of the Mt Changbai comprised of the Cenozoic basalts coming from the volcanic eruptions during the early Palogene and late Quaternary (Wang et al, 2003).
There has been a series of volcanic eruptions that occurred along the Changbai mountain Tianchi volcanic zone. There was a single parental magma that had evolved through the various cogenetic magmatic processes. There is the formation of the pantellerite, trachyte, and basalt that have been distributed along the zone, from the volcanoes of the Wantian’e, Xitudingzi, and Tianchi going towards the Nanbaotai Volcano found in Korea. The West Pacific plate subduction has affected the Tianchi volcanic zone’s volcanic activities. The stress at this point of time was compression at sub-latitudinal and shearing and not extension. There are uplifting that happened along the crust during the various volcanic eruptions. Due to the West Pacific plate subduction, the geotectonic background of the volcanic zone is restricted, where there were no formation of island-arc volcanoes and orogenic andesites. Furthermore, the pallenterite formation is associated with the deep crustal structures found along the Tianchi volcanic zone. It was formed by differentiation and crystallization of the magma from the trachyte chamber. Thus, the volcanic eruption along the Tianzi volcanic zone of the Changbai is more of intra-continental and not active or intraplate continental margin (Wang et al, 2003). The Japan sea is generally is thought to be formed via the continental margin breakdown caused by the tension increase, or through the extension of the back-arc basin. Specifically, the Western Pacific Plate experienced subduction under the continental margin thereby causing the extension in the lithosphere and breakdown of the continental margin. The process of the continental breakdown intensified as the subduction continues, resulting to increasing distances in block separations and the subduction zone retreat. The Japan sea is then created through this process. The back-arc basin extension also paved way to the continental tectonic changes, from extensional to compressional, derived from gradual weakening of the continental drift volcanic activities. Thus, the fault in Songliao-Jizhong is associated also with the expansion of the Japan sea. However, during the intense period, the Songliao-Jizhong fault has closed and contracted, that marked the volcanic cessation (Liu et al, 2015).
The strong motions of the ground are the ones that induce dynamic stress changes. This movement also disturbs the volcano’s magma chambers and evokes volcanic activities. In North Korea, the underground nuclear explosions that they have tested in the years 2006, 20099, and 2013 have been studied if these strong forces affect the volcanic activities. Various studies claim that there is correlation between the earthquakes and volcanic eruptions. The nuclear tests done about 116 km away from the Bakdusan is considered to be close enough to trigger various volcanic activities. Based on the tests, large UNEs that produce seismic waves that are very strong can trigger volcanic eruption. The earthquakes are triggered at a certain dynamic stress of about 0.01-1 MPa. Volcanic eruption is triggered by bubbles that nucleate at various changes of pressure. The explosions in North Korea, therefore, can produce large changes in the pressure, causing bubble nucleation, and potentially trigger volcanic eruption (Hong et al, 2015).
References:
Hong, TK., Choi, E., Park, S. and Shin JS. (2015). “Prediction of ground motion and dynamic
stress change in Baekdusan (Changbaishan) volcano caused by a north Korean nuclear explosion”. Scientific Reports . Vol 6
Kim, YH, Lee, C., and Kim S. (2015). “Tectonics and Volcanism in East Asia: Insights from
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Liu, J., Chen, S., Guo, Z., He, H., You, H., Kim, H., Sung, G., and Kim, H. (2015). “Geological
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Zhao, D., Tian, Y., Lei, J., Liu, L. and Zheng, S. (2008). “Seismic image and origin of the
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