The synergy between the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) and the Kenya National Data Centre (KE-NDC)

Josphat Kyalo Mulwa; Norbert Opiyo-Akech

Josphat Kyalo Mulwa University of Nairobi, Department of Geology, P.O. Box 30197-00100, Nairobi, Kenya https://orcid.org/0000-0001-7940-0397
Norbert Opiyo-Akech

Keywords: Chyulu hills Seismic event Characterization Seismic phases Focal depth

Abstract

The March 24, 2019 earthquake in the Chyulu hills area was one of the strongest earthquakes (mb 4.2) to occur in Kenya during the year 2019. Chyulu hills is an off-rift volcano located in the southwestern Kenya and has been seismically active. As part of the Kenya National Data Centre (KE-NDC) efforts to complement the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) to monitor compliance of the Comprehensive Nuclear Test-Ban Treaty (CTBT) by member states, we used seismic and infrasound data to evaluate the nature and characteristics of the Chyulu hills seismic event (whether anthropogenic or natural). In our analyses, we used body wave seismic phases (Pn, Sn), surface wave seismic phase (Lg) as well as the focal depth. In addition, we also used propagation velocity of the acoustic signal detected by the infrasound station I32KE. Our results show that the seismic event is a natural earthquake by virtue of its depth of focus i.e. 9.1 km. The infrasound station to source azimuth of 139.63^o further complements the epicentral location of the seismic event in the southwestern Kenya near Chyulu hills.