Earthquake Catalog from a Year+ of Seismic Monitoring on Bioko Island, Equatorial Guinea

Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Equatorial Guinea’s Bioko Island is located in the Atlantic Ocean off the west coast of Cameroon. It is a volcanic island and the first off-shore expression of the Cameroon Volcanic Line. It is home to three shield volcanoes: Pico de Basile, Pico Biao and Gran Caldera de Luba. Eruptive history is only known for Pico de Basile which erupted within the past 100 years and steam vents were observed as recently as 2012. There is no permanent seismic monitoring; the closest seismic stations are in Cameroon and have not reported data since 2015.

In Nov. 2017 Drexel University researchers, supported by the Bioko Biodiversity Protection Program (BBPP) and the Universidad Nacional de Guinea Ecuatorial (UNGE), installed 4 broadband seismometers. Two more stations were installed in March of 2019. Preliminary earthquake detection and location was completed using an automated STA/LTA algorithm. S wave arrivals were added manually. Initial locations use the global IASP91 model and events were relocated using a local model. Events cluster into two areas: those near Bioko Island and those near Cameroon. Between 12-Dec-2017 and 17-Feb-2018, 77 events were recorded. Local magnitudes range between 0.16 and 2.61. Of these events, 49 are located near Cameroon and 28 are near Bioko. Most of the depths are upper to mid-crust. Analysis of the entire data set yields 458 events with 367 near Bioko Island and 91 near Cameroon. The range in local magnitude is -0.28 – 3.86. Our preliminary results show seismicity associated with Bioko Island as well as Cameroon. Locations match well with events recorded by a regional network in Cameroon.

Stations were serviced in Feb. and Nov. 2018 and March 2019. Failures have been due to water infiltration, vandalism and heavy cloud cover. Enclosures were redesigned after the Feb. 2018 service. All stations were upgraded to the new design in Nov. 2018 and solar panels were upgraded (20 to 35 watt) in March 2019. The next anticipated service is in March 2020.

Presenting Author: Amanda C. Lough

Authors