EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Effect of Combining Catalogs with Different Completeness

Myunghyun Noh
Myunghyun Noh
  • Korea Institute of Nuclear Safety, Department of Nuclear Safety Research, Daejon, Korea, Republic of (

In most seismic studies, we prefer the earthquake catalog that covers a larger region and/or a longer period. We usually combine two or more catalogs to achieve this goal. When combining catalogs, however, care must be taken because their completeness is not identical so that unexpected flaws may be caused.

We tested the effect of combining inhomogeneous catalogs using the catalog of Korea Meteorological Administration (KMA). In fact, KMA provides a single catalog containing the earthquakes occurred in and around the whole Korean Peninsula. Like the other seismic networks, however, the configuration of the KMA seismic network is not uniform over its target monitoring region, so is the earthquake detection capability. The network is denser in the land than in the off-shore. Moreover, there are no seismic information available from North Korea. Based on these, we divided the KMA catalog into three sub-catalogs; SL, NL, and AO catalogs. The SL catalog contains the earthquakes occurred in the land of South Korea while the NL catalog contains those in the land of North Korea. The AO catalog contains all earthquakes occurred in the off-shore surrounding the peninsula.

The completeness of a catalog is expressed in terms of mc, the minimum magnitude above which no earthquakes are missing. We used the Chi-square algorithm by Noh (2017) to estimate the mc. It turned out, as expected, that the mc of the SL is the smallest among the three. Those of NL and AO are comparable. The mc of the catalog combining the SL and AO is larger than those of individual catalogs before combining. The mc is largest when combining all the three. If one needs more complete catalog, he or she had better divide the catalog into smaller ones based on the spatiotemporal detectability of the seismic network. Or, one may combine several catalogs to cover a larger region or a longer period at the expense of catalog completeness.

How to cite: Noh, M.: Effect of Combining Catalogs with Different Completeness, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1749,, 2019

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Presentation version 1 – uploaded on 22 Apr 2020
  • CC1: Comment on EGU2020-1749, Angela Stallone, 04 May 2020

    Have you compared the Chi-square algorithm by Noh (2017) with other methods for the estimation of magnitude of completeness?

    • AC1: Reply to CC1, Myunghyun Noh, 06 May 2020

      Sorry for the late response. It was a national holiday.

      The comparison of performance of the Chi-square algorithm with that of the other methods is discussed in the Noh (2017), which is given in the reference section of my poster.

      • CC2: Reply to AC1, Angela Stallone, 09 May 2020

        Thank you, I will check it!