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Systematic Seismic Events Discrimination Methods at the Kenya National Data Centre (N090)

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A Correction to this article was published on 03 June 2024

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Abstract

The International Data Centre (IDC) routinely applies event screening using a multi-technology approach in order to enable member states to characterize events as either natural or anthropogenic. Various event discriminants are presented in literature. At the Kenya National Data Centre (KE-NDC or N090), a systematic and step-by-step procedure of SEISMIC events discrimination is applied. Results from the discriminants adopted are obtained within a short time and the discriminants are relatively easy and fast to use. The discriminants used at KE-NDC (N090) are ranked in a hierarchy based on results obtained from one discriminant being applied in subsequent discriminants and ease of returning results within the shortest time possible to allow for events discrimination and dissemination of results. The discriminants applied and their hierarchy at KE-NDC include: (i) event location (epicenter/hypocenter parameters) (ii) hypocenter parameters based on events relocation using HYPOCENTER, (iii) magnitude determination, (iii) mb:Ms criteria and (iv) focal mechanism determination. Two seismic events are used as case examples to demonstrate how event discrimination is achieved based on the discriminants presented herein. The two seismic events are the 20190324 and 20200503 seismic events in southwestern and northern Kenya respectively. The choice of these two events is based on the fact that they were strong enough to be recorded by a number of global seismic stations and their magnitudes are comparable to the 2009, 2013 and 2016, but slightly lower than the 20170903 DPRK announced tests. Based on the discriminants used and presented herein, the two seismic events were categorized as being due to natural earthquakes.

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Data availability

All the data used in the current study is publicly available from the CTBTO to all CTBT member states. In addition, IRIS, NEIC and USGS data is also available to all scientists and an acknowledgement of the data source is critical.

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Acknowledgements

The support from the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) to CTBT member states for the establishment of National Data Centres and continuous support to national technical experts through trainings and capacity building in the CTBT’s verification regime is greatly appreciated. The author further expresses his profound gratitude to two anonymous reviewers for their careful reviews and constructive suggestions in improving the manuscript.

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Authors and Affiliations

  1. Department of Earth and Climate Sciences, University of Nairobi, Chiromo Campus, Riverside Drive, P.O. Box 30197-00100, Nairobi, Kenya

    Josphat K. Mulwa

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Contributions

The results of seismic event discrimination at KE-NDC were presented during the Comprehensive Nuclear Test-Ban Treaty (CTBT) Science and Technology Conference 2023 (SNT2023) which was held from 19 to 23 June 2023 at the Hofburg Imperial Palace in Vienna, Austria. The author’s contribution is outlined below: Josphat Kyalo Mulwa (JKM): JKM is the sole author of this paper and is involved in routine analysis of seismic events at the Kenya National Data Centre (KE-NDC). IMS data from four seismic stations is received on continuous basis at KE-NDC. Additional data was requested by JKM from the IDC in Vienna, and these together with the continuous data forms part of the data used in this and other studies at KE-NDC. Waveform data from non-IMS seismic stations is requested from either IRIS or FDSN in SAC format. The analysis of waveform data, application of the seismic event discriminants and the write-up of this paper were done solely by JKM. JKM presented the results of this work during the CTBT Science and Technology conference (SNT2023) in Vienna, Austria. Based on the SNT2023 presentation, JKM was called upon and requested by the Provisional Technical Secretariat (PTS) to prepare and submit a full paper for publication in Pure and Applied Geophysics (PAGEOPH) Journal Topical Issue on “Nuclear Explosion Monitoring and Verification: Scientific and Technological Advances”. On the basis of this call for papers, JKM has written this manuscript based on his expertise seismology and taking into consideration the mandate of the CTBTO and the obligations of CTBT member states.

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Correspondence to Josphat K. Mulwa.

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Mulwa, J.K. Systematic Seismic Events Discrimination Methods at the Kenya National Data Centre (N090). Pure Appl. Geophys. (2024). https://doi.org/10.1007/s00024-024-03458-4

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