Multiple Lapse Time Window Analysis of the Korean Peninsula Considering Focal Depth

Abstract

The recent Multiple Lapse Time Window (MLTW) analysis of Korean Peninsula event showed that the focal depth was far greater influence factor than the velocity structure of the model, applying the analysis of the direct simulation Monte Carlo (DSMC) method. Thus, using the events with focal depth of about 10 km, this study considered 330 paths connecting 41 events and 71 stations, and re-examined uniform and depth-dependent velocity models previously studied. As a result, the residual of misfit function greatly decrease from analytic model to DSMC model, reflecting variation of the focal depth from 0 to 10 km. On the other hand, the difference of residuals for each velocity model were relatively small.

Separation of Intrinsic and Scattering Attenuation Using Single Event Source in South Korea

“…In spite of the large difference in the Q values according to the depth, only a few of the previously reported MLTWA studies have considered between the shallow crust and the upper-mantle source (Badi et al, 2009). Recently, our review on MLTWA, where the focal depth range was narrowed around 10 km in South Korea (hereafter S. Korea), showed remarkably different attenuation values (Chung and Asep, 2013) compared to those of the other studies Chung, 2014) that used various focal depths.…”

“…These DSMC analyses, however, assumed all events to be at a 10 km focal depth, in spite of the uninformed depths for numerous events. Chung and Asep (2013) reexamined S. Korea using events with ∼10 km focal depth and reported the highest Q i and Q S values among the previous studies.…”

“…Using DSMC code to the theoretical values of MLTWA, the current study selected the data from the review study (Chung and Asep, 2013) that used a focal depth of about 10 km to compare the results of the studies between each single event and averaged multiple events. In addition, the current study attempted to fit the observations of the radiation pattern to the expanded version of DSMC (E-DSMC), by inserting the focal mechanism algorithm to the code of DSMC method.…”

Direct simulation Monte Carlo method with a focal mechanism algorithm

“…The small magnitude of event 5 is attributed to larger M sum of DSMC-2 than that of DSMC-1, in spite of the second-most numerous recorded stations. In Figure 7, the Q s -1 values for DSMC-2 are low compared with those for DSMC-1 and Chung and Asep's (2013) results, which were also performed by DSMC-1. However, the Q s -1 values are consistent with the Q s -1 values obtained by Lee et al (2010) in Kyeongsang Basin.…”

“…Our data are based on the study by Chung and Asep (2013), which used 41 events during the period of 1999 -2009. Each event of depth and magnitude ranges from 6.1 to 16.9 km and from 2.0 to 4.8, respectively, which were recorded by 3 to 18 stations operated by the Korea Meteorological Agency (KMA) and the Korea Institute of Geoscience and Mineral Resources (KIGAM).…”