Rozlišení vzdálených záznamů přirozených zemětřesení a explozí na příkladu severokorejských jaderných testů
| Title in English | Teleseismic records discrimination of natural earthquakes and explosions on the example of the North Korean nuclear tests |
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| Authors | |
| Year of publication | 2017 |
| Type | Article in Periodical |
| Magazine / Source | Geologické výzkumy na Moravě a ve Slezsku |
| MU Faculty or unit | |
| Citation | |
| Field | Seismology, vulcanology, and Earth structure |
| Keywords | seismic monitoring; CTBTO; nuclear explosions; discrimination methods |
| Description | North Korea is only one country conducting nuclear explosions after year 2000. In the period 2006–2016, there are five nuclear explosions conducted at the nuclear test site Punggye-ri in the NE part of the North Korea. Body wave magnitude mb of last event reaches value 5.3 according U.S. National Earthquake Information Centre NEIC and NDC Brno. It shows, that the last event is strongest explosion up to now. Many seismic stations registered signal related to North Korean nuclear tests, including broadband seismic stations operated by IPE (Institute of Physics of the Earth). One of these stations, station VRAC, is part of the International Monitoring System CTBTO focused on the verification of the compliance with the Comprehensive Nuclear-Test-Ban Treaty. Not only detection and location of events is sufficient for such verification, the discrimination between records of natural earthquakes and explosions is necessary as well. Considering huge amount of data (more than 37.000 event located in the International Data Centre CTBTO during year 2016), the routinely used discrimination methods have to be simple and self-acting. First discrimination can be simply based on location and hypocentre depth evaluation. Other broadly used method is focused on comparison of Ms:mb magnitudes. Third method discussed in this article is method of quantification of complexity (ratio of coda to signal energy). The North Korean nuclear tests show higher Ms values (regarding to mb) than it is expected for nuclear explosions. On the contrary, the preliminary computed values of complexity are typically low for the North Korean nuclear tests, but their calculation strongly depends on the signal to noise ratio. Thus, combination both methods (Ms:mb magnitudes and complexity evaluation) seems to be more appropriate for discrimination of events like the North Korean explosions rather than individually applied criterions. |
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