The Morphological Change by Slope Erosional Processes in the Dokdo Seamount Ji Hyun Kang* Hyo Hyun Sung** Chan Hong Park*** Chang Hwan Kim**** Eui Young Jeong***** 0 2 14 40 submarine gully Abstract The purpose of this study is to analyze landform characteristics and geomorphic processes in Dokdo seamount. For geomorphic analysis, bathymetry data were collected by multi-beam echosounder and the seismic survey was also conducted. Through the detailed analysis of depth, slope, aspect and erosional landform, Dokdo Seamount is characterized by a flat or gently sloping top of 2 or less and seamount slope with 14~40 gradient. There are protrusion of landform around the Dokdo on top of the Dokdo seamount. It is inferred that the features are formed by collapsed debris deposits or remained bedrocks by differential erosion in the past. The massmovement topography including slump and slide is shown on seamount slope with 14~40 gradient. In addition, gullies with various length are developed on the Dokdo seamount slope. Slope erosional processes occur more actively along the submarine gullies on the Dokdo seamount. It is inferred that the massmovement processes on the slope of Dokdo seamount are related to earthquake activities and evolution of submarine volcano. Consequently, slope of the Dokdo seamount has retreated by erosional processes of mass-movement and submarine gullies. : Dokdo seamount, guyot, slope erosional processes, massmovement, submarine gully (Research Fellow, National Institute of Environmental Research), kjh31-orion@hanmail.net (Professor, Dept. of Social Studies, Ewha Womans University), hhsung@ewha.ac.kr (Research Fellow, Korea Ocean Research & Development Institute), chpark@kordi.re.kr (Research Fellow, Korea Ocean Research & Development Institute), kimch@kordi.re.kr (Research Fellow, Korea Ocean Research & Development Institute), eyjeong@kordi.re.kr 791
E131 40 E132 05 N37 05 N37 25 1 Multi beam Echo Sounder 2005 3D Map Multibeam single beam Echo Sounder DGPS X Y Z ArcView 3 2 Sufer8 Surfer8 3D 3D ArcView 3 2 TIN 5m 5m GRID 792
Yolin Disturbance Kim et al., 1987 2000 1986 1987 Won and Lee 1988 Shon and Park 1994 2003 7 Shon and Park 1994 2003 8 2000 2005 Shon and Park 1994 K-Ar 2 7 0 1Ma 2 5 0 1Ma 2000 K-Ar 2 7 2 4Ma 2 4 2 3Ma 2 2 2 1Ma 793
tablemount guyot Hess 1946 Guyot Guyot 2002 200 300m Ingle 1992 Menard 1963 1984 Menard 1984 Smoot 1995 Shon and Park 1994 2005 2007 2 a Shon and Park 1994 b 2007 b c d Volcanian Eruption e f Shon and Park 1994 2003 2005 2 5km 1 5km 2008 6km 794
Guyot 2100m 200 300m E-W 11km N-S 10km 800m 30km 0 200m 15 07 3 4 0 2 7 86 2 5 13 92 5 15 36 02 15 40 38 24 40 3 95 2 2 5 38 24 15 40 5 15 15 35 2001 15 35 5 15 40 3 95 795
5 6 200m 0 2 100m 7 796
1998 0 200m 8 Type IA 8 Type IF 797
1998 798
30m 9 Maltman 1994 Smoot 1995 Hampton et al. 1996 Lee et al. 2002 30 40 3D gully 799
10 3D 10 A B C D 10 11 800
2007 2005 12 10 B 13 10 C 12 2005 13 14 10 D 801
15 A 16 15 B 17 15 18 802
1400m Alves et al. 2003 4 4 submarine gully setting 1. Erosional processes setting 2. Slope-related processes setting 3. Canyonrelated processes setting 4. Hemipelagic processes 19 Setting 1 803
1998 19 IIIA 19 Setting 2 19 IIC 19 Setting 3 V 19 Setting 4 19 IIA 1998 Yoon and Choungh 1995 Chough et al. 2000 20 Baag et al. 1998 20 B 300m Lee et al. 2002 20 15 804
A Lelikov et al. 2006 B 1905 2007 Baag et al. 1998 1997 2007 30m 40m 2 15 40 5 15 15 40 gully 15 40 805
300 2002 The Sea 7 4 267-285 2001 2000 K-Ar Sr 36 313-324 1987 23 67-82 2007 40 2 153-170 2008 2000 2005 1998 2 2003 36 6 527-536 Alves, T. M., Gawthorpe, R. L., Hunt, D. W., and Monteiro, J. H., 2003, Cenozoic tectonosedimentary evolution of the western Iberian margin, Marine Geology, 195, 75-108. Baag, C. E., Chang, S. J., and Shin, J. S., 1998, Evaluation of seismic hazard in southern part of Korea, Proceedings of 2nd International Symposium on Seismic Hazards and Ground Motion in the Region of Moderate Seismicity, 31-50. Chough, S. K., Lee, H. J., and Yoon, S. H., 2000, Marine Geology of Korean Seas, 2nd Edition, Elsevier, Amsterdam. Hampton, M. A., Lee, H. J., and Locat, J., 1996, Submarine landslides, Reviews of Geophysics, 34, 33-59. Hess, H. H., 1946, Drowned ancient islands of the Pacific Basin, American Journal of Science, 244, 772-791. Ingle, J. C., 1992, Subsidence of the Japan sea; stratigraphic evidence from ODP site and onshore sections, Proceeding ODP, Sci. Results, 128, 1197-1218. Kim, Y. K., Lee, D. S., and Lee, K. H., 1987, Fractional crystallization of the vilcanic rocks from Dok Island, Korea. Journal of the Geological Society of Korea, 23, 67-82. Lee, S. H., Chough, S. K., Back, G. G., and Kim, Y. B., 2002, Chirp(2-7-kHz) echo characters of the South Korea Plateau, East Sea: styles of mass movement and sediment gravity flow, Marine Geology, 184, 227-247. Lelikov, E. P., Tsoy, I. B., Vashchenkova, N.G., Terekhov, E. P., Sedin, V. T., and Nabiallin, A. A., 2006, Geology and basic types of rocks of the Japan sea floor, Dalnauka, Vladivostok. Maltman, A., 1994, Introduction and overview, in Maltman, A.(ed.), The Geological Deformation of Sediments, Chapman and Hall, London. Menard, H. W. and Ladd, H. S., 1963, Oceanic Islands, 806
Seamounts, Guyots and Atolls, The Sea, 3, 365-385. Menard, H. W., 1984, Origin of Guyots: The Beagle to Seabeam, Journal of Geophysical Research, 89(B13), 11117-11123. Shon, Y. K. and Park, K. H., 1994, Geology and evolution of Tok Island, Journal of the Geological Society of Korea, 30(3), 242-261. Smoot, N. C., 1995, Mass wasting and subaerial weathering in guyot formation: the Hawaiian and Canary Ridge as examples, Geomorphology, 14, 29-41. Won, J. K. and Lee, M. W., 1988, The study on petrology for the Quaternary alkali volcanic rock of the Korean peninsula, Journal of the Geological Society of Korea, 20, 296-305. Yoon, S. H. and Chough, S. K., 1995, Regional strike slip in the eastern continental margin of Korea and its tectonic implications for the evolution of Ulleng Basin, East Sea(Sea of Japan), Geological Society of America Bulletin. 107, 83-97. 120-750 11-1 hhsung@ewha.ac.kr 02-3277-2668 Correspondence: Hyo Hyun Sung, Dept. of Social Studies, Ewha Womans Univ., #11-1, Daehyundong, Seodaemun-gu, Seoul, 120-750, Korea (email: hhsung@ewha.ac.kr, phone: 82-2-3277-2668) 807