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Article |
University of Memphis
Center for Earthquake Research and Information
Memphis, Tennessee 38152
(J.-M.C.)
Hanyang University
Seismological Institute
Ahnsan, Kyoungi-do, 425–791
Korea
(S.G.K.)
Located between the very active Japan and Ryukyu subduction zones and the
northern China plate, the Korea Peninsula has been considered a part of the
stable Eurasia continent and is very quiet in seismic and tectonic activity.
Although there were many significant damaging earthquakes reported in
historical times, seismic hazard in Korea has long been overlooked. Modern
earthquake activity in the Korean Peninsula is very low and is not well
recorded, at least until 1998 when the modernization of the Korean National
Seismic Network was implemented. Thus, modern earthquake data are not adequate
for evaluating seismic hazard in the Korean Peninsula. On the other hand, the
historical earthquake catalog, which includes documented earthquake
information from around the Korean Peninsula and can be dated back to as early
as A.D. 2, provides the only available long-term database for the
investigation of temporal and spatial patterns of earthquake activity. The
importance of seismic hazard assessment has significantly increased in modern
times because of the recent construction of many critical facilities, such as
nuclear power plants, super-computer centers, large hospitals, and
high-technology centers, throughout the entire Korean Peninsula. Although
uncertainties on the historical earthquake locations and their magnitudes are
expected to be large, information obtained from this historical earthquake
catalog can at least provide a long-term scientific basis for an estimation of
seismic hazard in Korea. For the entire Korean Peninsula, seismic hazard is
evaluated in terms of the spatial distribution of seismicity and relative
seismic energy release over the 2000 years of the historical record. Results
from our preliminary analysis clearly demonstrate that seismic activity in the
Korean Peninsula can be categorized into four prominent seismic zones, inside
which seismic hazard is much higher than that in the surrounding regions.
These four seismic zones include: (1) the western Korean seismic zone
extending from Seoul to Pyongyang, which is characterized by a few
concentrated regions of high seismicity and a high relative seismic energy
release; (2) the eastern Korean seismic zone, which is characterized by a low
seismic rate but a high relative seismic energy release from a few large
historical events; (3) the northeastern Korean seismic zone, which is probably
related to the deep Japan subduction-zone earthquakes underneath northeast
China and has a very low seismicity but a very high relative energy release;
and (4) the southern Korean seismic zone, which is characterized by many
scattered patches of high seismicity and a few zones of high seismicity and
high relative seismic energy release from a few large historical events. Among
the three most seismically active regions near Pyongyang, Seoul, and Pusan,
the probability of occurrence for an earthquake of magnitude greater than 5.0
is estimated to be about 1%, 2%, and 3% per year, respectively. Since
significant damaging earthquakes (M 
7.0) have occurred in these
three regions in historical times, an effective assessment of seismic hazard
potential in the Pyongyang, Seoul, and Pusan regions cannot be overlooked.
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