Geomorphology of the underwater caldera of the Changbaishan Tianchi volcano using 3D virtual visualization

Based on high-precision multibeam underwater terrain data, 3D virtual visualization technology is adopted to reconstruct the Changbaishan Tianchi Volcano Crater, China, because this technology can intuitively show the shape of underwater calderas. Results indicate that the current terrain of the lakebed at the Tianchi Caldera mainly formed by a combination of one volcanic explosion, eruption and collapse in the periods of the Tianwen Peak and the Millennium Eruption, and it is also associated with the orographic uplift caused by the subsequent and frequent activities of the magma chamber. Two boccas at different periods are observed at the lakebed of the Tianchi Caldera: the large bocca located in the centre of the caldera that probably formed 5,000-4,000 years ago during the eruption period and the small bocca located in the west of the large bocca that probably formed in the Millennium Eruption period. The eruption resulted in the collapse of the magma cave, thus forming a semi-annular dike and two lava domes along the topographic slope, which extends along the lakebed with the direction of 30 degrees-45 degrees NE. The southern and northeastern feet of the collapsed crater slid downward and accumulated, with the southern foot of the crater touching the southern end of the ridged dike.