• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.5
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• pp.285-290
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• 2013

Both full linear and shallow water edge waves are compared to get a better understanding of edge wave behavior. By using method of separation of variables, we are able to get solution of full linear edge wave presented by Ursell (1952) without derivation. The shallow water edge waves show dispersive features despite being derived from shallow water equations. When bottom slope is mild enough, shallow water edge wave tends to linear edge wave and has some advantages of manipulation. Solution of edge wave generated by a moving landslide of Gaussian shape is constructed by an expansion of shallow water normal modes. Numerical results are presented and discussed on their main features.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.451-454
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• 2008

Potential tsunamis which may occur near Ryukyu Islands were simulated. Propagation characteristics of the potential tsunamis over the southwestern sea and the influence of tsunamis on the southwestern coast of Korean Peninsula were analyzed. The shallow water area in the east sea of China and the deep water Okinawa Trough play an important role in wave transformation and propagation of the potential tsunamis. The propagation characteristics of the potential tsunamis generated near Ryukyu Islands can be described as in followings : In the first stage after generation, the tsunamis propagate with high speed both northeastward and southwestward along the Okinawa Trough. As a result the waves are elongated and the tsunami height is significantly reduced. The elongated crest of tsunamis spans the whole distance of the Okinawa Trough and lines up toward the edge of the continental shelf of East China Sea. Then, the tsunamis are propagating towards the southeast coast of China. Thus, the influence of tsunamis on the Korean coasts becomes weak.

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.293-308
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• 2003

New results about the crustal structure down to a depth of 60 km beneath North Korea were obtained using the seismic tomography method. About 1013 P- and S-wave travel times from local earthquakes recorded by the Korean stations and the vicinity were used in the research. All earthquakes were relocated on the basis of an algorithm proposed in this study. Parameterization of the velocity structure is realized with a set of nodes distributed in the study volume according to the ray density. 120 nodes located at four depth levels were used to obtain the resulting P- and S-wave velocity structures. As a result, it is found that P- and S-wave velocity anomalies of the Rangnim Massif at depth of 8 km are high and low, respectively, whereas those of the Pyongnam Basin are low up to 24 km. It indicates that the Rangnim Massif contains Archean-early Lower Proterozoic Massif foldings with many faults and fractures which may be saturated with underground water and/or hot springs. On the other hand, the Pyongyang-Sariwon in the Pyongnam Basin is an intraplatform depression which was filled with sediments for the motion of the Upper Proterozoic, Silurian and Upper Paleozoic, and Lower Mesozoic origin. In particular, the high P- and S-wave velocity anomalies are observed at depth of 8, 16, and 24 km beneath Mt. Backdu, indicating that they may be the shallow conduits of the solidified magma bodies, while the low P-and S-wave velocity anomalies at depth of 38 km must be related with the magma chamber of low velocity bodies with partial melting. We also found the Moho discontinuities beneath the Origin Basin including Sari won to be about 55 km deep, whereas those of Mt. Backdu is found to be about 38 km. The high ratio of P-wave velocity/S-wave velocity at Moho suggests that there must be a partial melting body near the boundary of the crust and mantle. Consequently we may well consider Mt. Backdu as a dormant volcano which is holding the intermediate magma chamber near the Moho discontinuity. This study also brought interesting and important findings that there exist some materials with very high P- and S-wave velocity annomoalies at depth of about 40 km near Mt. Myohyang area at the edge of the Rangnim Massif shield.