Seismicity and Crustal Structure of the Southern Main Ethiopian Rift: New Evidence From Lake Abaya

Abstract

The Main Ethiopian Rift (MER) captures the transition from embryonic fault-controlled continental rifting in the south to more evolved magma-rich continental rifting in the north (e.g., .In the relatively mature central and northern MER, the locus of strain has largely shifted from 60 kmlong Miocene border faults to narrower (20 km-wide), Quaternary magmatic zones of short length-scale (1 km), small-offset faults (the Wonji Fault Belt, WFB:

Determination of Conrad and Curie point depth relationship with the variations in lithospheric structure, geothermal gradient and heat flow beneath the central main Ethiopian rift

“…(b) Lithosphere-asthenosphere boundary depth map of the central MER and surrounding regions obtained from our previous work ( Kassa et al., 2022 ). Focal depth values, less than 16 km (red circles), greater than 25 km (pink circles) and between 16 and 25 km (green circles), obtained from previous published seismic works ( Keir et al., 2006 ; Delvaux and Barth, 2010 ; Lapins et al., 2020 ; Ogden et al., 2021 ). Holocene (red triangles) and Pleistocene (black triangles) volcanoes are acquired from global volcanism programs ( https://volcano.si.edu ).…”

“…More than 200 focal depth values ( Keir et al., 2006 ; Delvaux and Barth, 2010 ; Lapins et al., 2020 ; Ogden et al., 2021 ) are employed to show correlation of the focal depth values with the CPD ( Figure 7 ) and Moho depth values ( Figure 11 a) beneath the MER including the CMER.…”

Gas emissions and sub-surface architecture of fault-controlled geothermal systems: a case study of the North Abaya geothermal area

“…2c, Section 4.1). Tectonic activity in this region has occurred through the Late Pleistocene-Holocene (Corti et al, 2013) and there is ongoing seismicity associated with this border fault swarm (Ogden et al, 2021).…”

“…Here, we bring together new remote sensing and gas emission data from the North Abaya geothermal area in the Main Ethiopian Rift (MER) which is a fault-controlled geothermal play that shows no surface volcanic edifice. North Abaya is consistently highlighted as one of Ethiopia's key geothermal prospects (Burnside et al, 2021), and although previous studies have investigated regional volcano-tectonic activity (Corti et al, 2013, Ogden et al, 2021 and documented surface geothermal manifestations (i.e., hot springs and fumaroles, Craig et al, 1977;Chernet, 2011;Minissale et al, 2017) there is no conceptual model to understand the heat source, fluid flow, gas emissions and geothermal potential of the resource. We show that despite a clear lack of surface volcanism, a deep magmatic source is required, and that large offset graben bounding faults play a key role in channelling gas and hydrothermal fluids toward the surface.…”

Gas Emissions and Subsurface Architecture of Fault‐Controlled Geothermal Systems: A Case Study of the North Abaya Geothermal Area

“…Here, we bring together new remote sensing and gas emission data from the North Abaya geothermal area in the MER, which is a fault‐controlled geothermal play that shows no surface volcanic edifice. North Abaya is consistently highlighted as one of Ethiopia's key geothermal prospects (Burnside et al., 2021), and although previous studies have investigated regional volcano‐tectonic activity (Corti et al., 2013; Ogden et al., 2021) and documented surface geothermal manifestations (i.e., hot springs and fumaroles, Craig et al., 1977; Chernet, 2011; Minissale et al., 2017) there is no conceptual model to understand the heat source, fluid flow, gas emissions and geothermal potential of the resource. We show that a large offset graben bounding fault plays a key role in channeling gas and hydrothermal fluids toward the surface, and while there is no evidence for volcanism along the fault, a deep magmatic heat source is still required.…”