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On the Origin of Orphan Tremors & Intraplate Seismicity in Western Africa
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  • Tolulope Morayo Olugboji,
  • Yingping Lu,
  • Adekunle Abraham Adepelumi,
  • Folarin Kolawole,
  • Manoochehr Shirzaei
Tolulope Morayo Olugboji
University of Rochester, University of Rochester, University of Rochester

Corresponding Author:[email protected]

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Yingping Lu
University of Rochester, University of Rochester, University of Rochester
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Adekunle Abraham Adepelumi
OAU, Ife, Nigeria, OAU, Ife, Nigeria, OAU, Ife, Nigeria
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Folarin Kolawole
University of Oklahoma, University of Oklahoma, University of Oklahoma
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Manoochehr Shirzaei
Virginia Tech, Virginia Tech
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On September 5-7, 2018, a series of tremors were reported in Nigeria's capital city, Abuja. These events followed a growing list of tremors felt in the stable intra-plate region, where earthquakes are not expected. Here, we review available seismological, geological, and geodetic data that may shed light on the origin of these tremors. First, we investigate the seismic records for parent location of the orphan tremors using a technique suitable when a single-seismic station is available such as the Western Africa region, which has a sparse seismic network. We find no evidence of the reported tremors within the seismic record of Western Africa. Next, we consider the possibility of a local amplification of earthquakes from regional tectonics, reactivation of local basement fractures by far-field tectonic stresses, landward continuation of oceanic fracture zones, or induced earthquakes triggered by groundwater extraction. Our assessments pose important implications for understanding Western Africa's intraplate seismicity and its potential connection to tectonic inheritance, active regional tectonics, and anthropogenic stress perturbation.