Journals Information
Universal Journal of Geoscience(CEASE PUBLICATION) Vol. 8(2), pp. 25 - 32
DOI: 10.13189/ujg.2020.080201
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Earthquakes Occurrence on the East African Coast and Their Implication on Stress Drop along the Davie Ridge of the East African Rift System (EARS)
Josphat K. Mulwa *
Department of Geology, University of Nairobi, Kenya
ABSTRACT
The Davie Ridge (also known as Davie fracture zone), considered as the seaward extension of eastern branch (Kenya Rift Valley) of the East African Rift System [1,2], is a 2200 km-long prominent relic fracture zone that cuts across the West Somali Basin [3-5]. It ranges between 30 and 120 km wide, with a west-facing scarp along the lower half of its length [2,6]. Earthquakes as deep as 40 km have been recorded below the Davie Ridge. However, recent seismic data shows that Mw 4.0 -5.0 earthquakes at crustal depths (10≤d≤30 km) are common. Since early 2018-2019, the Davie ridge has been characterized by high frequency of 4.4≤Mw≤5.4 earthquakes occurrence. The purpose of the present research is to evaluate the stress drop along the Davie ridge using an empirical exponential relationship developed for Mw and fault parameters (length, width and rupture area) for the East African region and compare the results to those obtained from conventional body wave inversion. The results of this study show that, using empirical exponential relation, the stress drop, 
, and the corresponding fault (rupture) area, S2, ranges between 0.49-0.78 MPa and 15.7-32.5 km2 respectively. Fault rupture area and stress drop results based on body wave inversion and empirical exponential equations for Mw < 6.0 are very similar. For Mw≥ 6.0, however, the fault rupture area is under-estimated and this tends to over-estimate the stress drop. Empirical exponential relations offer a rapid estimate of fault parameters and stress drop for Mw ≤ 6.0 earthquakes.
KEYWORDS
Earthquakes, Davie Ridge, Empirical Exponential Relation, Fault Parameters, Stress Drop
Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Josphat K. Mulwa , "Earthquakes Occurrence on the East African Coast and Their Implication on Stress Drop along the Davie Ridge of the East African Rift System (EARS)," Universal Journal of Geoscience(CEASE PUBLICATION), Vol. 8, No. 2, pp. 25 - 32, 2020. DOI: 10.13189/ujg.2020.080201.
(b). APA Format:
Josphat K. Mulwa (2020). Earthquakes Occurrence on the East African Coast and Their Implication on Stress Drop along the Davie Ridge of the East African Rift System (EARS). Universal Journal of Geoscience(CEASE PUBLICATION), 8(2), 25 - 32. DOI: 10.13189/ujg.2020.080201.