The 12 February 2013 nuclear test conducted by the Democratic People’s Republic of Korea stands out among other nuclear tests because it produced unusually large transversal motions. Previous studies found various percentages of isotropic components of the seismic moment tensor (MT), which opens up an important question about the reliability of the methods and assumptions we routinely use to recover the seismic MT in the point source approximation. Of particular interest is the data noise model that can be utilized to represent the uncertainty associated with the recorded data. If the noise is not accounted for, this may result in a range of unwanted effects such as overfitting waveform data, and, in turn, it may lead to erroneous conclusions. We thus scrutinize the analyses of the seismic MT of this explosion by performing a thorough analysis of the source depth and time utilizing newly developed Earth structure models to invert seismograms at regional distances at different frequency bands. In addition, we estimate the solution uncertainty within a hierarchical Bayesian framework that allows accounting for noise in the data. Our results show that the resulting MT of this event contains an expectedly large isotropic component (about 70%) and a dip-slip faulting.
Using recordings of a mine collapse event (Mw 4.2) in South Korea in January 2015, we demonstrated that the phase and amplitude information of impulse response functions (IRFs) can be effectively retrieved using seismic interferometry. This event is equivalent to a single downward force at shallow depth. Using quantitative metrics, we compared three different seismic interferometry techniques—deconvolution, coherency, and cross correlation—to extract the IRFs between two distant stations with ambient seismic noise data. The azimuthal dependency of the source distribution of the ambient noise was also evaluated. We found that deconvolution is the best method for extracting IRFs from ambient seismic noise within the period band of 2–10 s. The coherency method is also effective if appropriate spectral normalization or whitening schemes are applied during the data processing.
This study investigated the phenolics (TP) and phytochemical contents and
radical-scavenging activity of ethanol extracts of Dendropanax
morbiferus parts (leaf, stem, and root). The contents of
chlorogenic acid (CA) and rutin (RT) and radical-scavenging activity of all
extracts by parts were in the order of leaf, stem and root. In the case of leaf,
the TP contents were 2.15-2.52 mg/g when extracted with hot water and ethanol
concentration (30-70%), and there was no difference depending on
extraction solvents and times. However, 95% alcohol extracts showed the
lowest content of TP (extraction time: 2-4 h). Particularly, CA and RT contents
of 70% ethanolic extract for 2 h were the highest as 12.33 mg/g and 14.01
mg/g, respectively, in which DPPH and ABTS radical scavenging activities were
also highest (85% and 110%), respectively.
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