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Thursday, October 1 2020
11:00am - 12:00pm
Virtual seminar
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Dr. Joyce Shi Sim 

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On the Origin of Orphan Tremors & Intraplate Seismicity in Western Africa

The School of Earth and Atmospheric Sciences Presents Dr.Tolulope Olugboji, University of Rochester

On the Origin of Orphan Tremors & Intraplate Seismicity in Western Africa

On September 5-7, 2018, a series of puzzling tremors were reported in the capital city of Nigeria, Abuja. These events follow a growing list of earthquakes experienced in a stable intra-plate region not expected to be earthquake-prone. Due to the sparse distribution of stations in Western Africa, a single-station method for event detection is used. A search for a parent location in West-Africa is inconclusive. A match with a Japanese teleseismic earthquake coincident with multiple landslides is identified. It is highly unlikely that shaking on the continent is due to this event.

We consider other explanations: the possibility of a local amplification of earthquakes from regional tectonics, reactivation of local basement fractures by far-field tectonic stresses, and induced earthquakes triggered by groundwater extraction. Testing these explanations is made difficult by the absence of reliable seismological and complementary geodetic measurements.

In the second half of this talk, I describe strategies for addressing these shortcomings. I explain how we plan to develop and deploy a low-cost, low-power, real-time seismic network in West Africa. This network will provide local and regional earthquake monitoring, and enable other environmental and economic applications. The challenges of infrastructure require the application of new technologies.

With a reliable geophysical observatory combined with remote sensing techniques like InSAR, we can resolve this puzzle, which has important implications for understanding western Africa’s intraplate seismicity and its connection to regional tectonics,  local geology, and anthropogenic activity.


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