Geosciences Journal

The Association of Korean Geoscience Societies (한국지질과학협의회)
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The offshore Uljin, Korea, earthquake sequence of April 2006: seismogenesis in the western margin of the Ulleung Basin

Kang, Tae-Seob;Shin, Jin-Soo

  • Published : 20060000
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Abstract

An unusual earthquake sequence comprising 11events with magnitude range of ML 2.0 to 3.2 ocurred of the east-ern coast of the southern Korean Peninsula in April 2006. Sincethere is no obvious mainshock in this sequence unlike a typicalmainshock-aftershock sequence, the seismicity patern shows thecharacteristics of swarm behavior. Focal mechanism of the largestevent (ML 3.2) on Hypocenter relocations of nine events improve the epicenter loca-tions that fal within an area with a radius of about 0.7 km whiledepths are les well constrained with ranges of 1.6 km to 13.0 km.We propose that a swarm behavior of the sequence is closelyrelated to the marginal geometry of the Ulleung Basin and theregional stress regime. The fact that epicenters of the April 2006sequence are at the same transitional zone of continental to riftedcontinental crust as that of the 29 May 2004, Mw 5.1, earthquakeindicates that the Uleung Fault is seismically active.

Keywords

References

  1. Chang, S.-J. and Baag, C.-E., 2005, Crustal structure in southern Korea from joint analysis of teleseismic receiver functions and surface-wave dispersion. Bulletin of the Seismological Society of America, 95, 1516−1534, doi:10.1785/0120040080
  2. Chang, S.-J. and Baag, C.-E., 2006, Crustal structure in southern Korea from joint analysis of regional broadband waveforms and travel times. Bulletin of the Seismological Society of America, 96, 856−870, doi:10.1785/0120040165
  3. Cho, H.-M., Kim, H.-J., Jou, H.-T., Hong, J.-K. and Baag, C.-E., 2004, Transition from rifted continental to oceanic crust at the southeastern Korean margin in the East Sea (Japan Sea). Geophysical Research Letters, 31, L07606, doi:10.1029/2003GL019107
  4. Chough, S.K., Lee, H.J. and Yoon, S.H., 2000, Marine Geology of Korean Seas. 2nd ed., Elsevier, Amsterdam, p. 313
  5. Kang, T.-S. and Baag, C.-E., 2004, The 29 May 2004, $M_{w}$=5.1, off-shore Uljin earthquake, Korea. Geosciences Journal, 8, 115−123 https://doi.org/10.1007/BF02910274
  6. Lay, T. and Wallace, T.C., 1995, Modern Global Seismology. Academic Press, San Diego, p. 521
  7. Park, S.-C. and Mori, J., 2005, Source parameters of the May 29, 2004 South Korea earthquake ($M_{L}$ 5.2). Earth, Planets and Space, 57, 471−475 https://doi.org/10.1186/BF03352581
  8. Snoke, J.A., Munsey, J.W., Teague, A.G. and Bollinger, G.A., 1984, A program for focal mechanism determination by combined use of polarity and SV-P amplitude data. Earthquake Notes (Abstract), 55, 15
  9. Waldhauser, F. and Ellsworth, W.L., 2000, A double-difference earthquake location algorithm: method and application to the northern Hayward fault, California. Bulletin of the Seismological Society of America, 90, 1353−1368 https://doi.org/10.1785/0120000006