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| Titel |
Seismic investigation of a South Korean warship sinking and two North Korean nuclear explosions |
| VerfasserIn |
Tae-Kyung Hong, Seunggu Rhee |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050234
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| Zusammenfassung |
| A South Korean warship sank on 26 March 2010. The
incident was recorded as an M1.5 event at local seismic
stations. We analyze three local seismic records and
investigate the source properties. The S-wave amplitudes
are found to be comparable to the P-wave amplitudes.
Seismic waves coupled from shock waves are observed,
which allows us to constrain the epicentral distance and
explosional-source feature. The coupled shock waves have
a dominant frequency of ~32 Hz. The shock waves and high
P/S amplitude ratios suggest an underwater explosion. The
spectral contents of P waves allows us to constrain the
source depth in the water. It appears that an explosive
source was detonated at a depth of ~30 m in the water.
Two North Korean nuclear explosion (UNE) tests were
conducted in 2006 and 2009. The UNEs were well recorded
by dense regional seismic networks in Korea, Japan and
China. We examine the regional waveform features
observed in the continental margin. We compare the
waveforms and spectral contents between UNEs and
earthquakes. The P, S and P/S ratios fluctuate
significantly depending on the raypaths. Crustal phases
(Pg, Lg) are attenuated along raypaths with undulated
Moho depths. On the other hand, mantle-lid phases (Pn,
Sn) are strengthened along the raypaths. The North Korean
UNEs are well discriminated from regional earthquakes
around the Korean peninsula using P/S amplitude ratios.
Strong overshooting feature is observed in P spectra. It
is observed that the 2009 UNE is about 5 times larger
than the 2006 UNE. |
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