Validation of gravity data from the geopotential field model for subsurface investigation of the Cameroon Volcanic Line (Western Africa)

Jean Marcel,Oumarou Sanda,Philippe Njandjock Nouck,Eliézer Manguelle-Dicoum,Jean Marcel Abate Essi

doi:10.1186/s40623-018-0812-x

Abstract

Belonging to the Cameroon Volcanic Line (CVL), the western part of Cameroon is an active volcanic zone with volcanic eruptions and deadly gas emissions. The volcanic flows generally cover areas and bury structural features like faults. Terrestrial gravity surveys can hardly cover entirely this mountainous area due to difficult accessibility. The present work aims to evaluate gravity data derived from the geopotential field model, EGM2008 to investigate the subsurface of the CVL. The methodology involves upward continuation, horizontal gradient, maxima of horizontal gradient–upward continuation combination and Euler deconvolution techniques. The lineaments map inferred from this geopotential field model confirms several known lineaments and reveals new ones covered by lava flows. The known lineaments are interpreted as faults or geological contacts such as the Foumban fault and the Pan-African Belt–Congo craton contact. The lineaments highlighted coupled with the numerous maar lakes identified in this volcanic sector attest of the vulnerability of the CVL where special attention should be given for geohazard prevention.

Highlights

The Cameroon Volcanic Line (CVL), called the Cameroon Line (Ngako et al 1991) or Cameroon Hot Line (Nkono et al 2014), is made up of an alignment of mountains trending N30° and is divided into two parts: an oceanic part with volcanic islands of Gulf of Guinea and a continental part characterized by volcanic eruptions of Mount Cameroon and deadly gas emissions from lakes Monoun in 1984 and Nyos in 1986, respectively (Fig. 1)
Poudjom-Djomani (1993) and Marcel et al (2010) have used these terrestrial gravity data to investigate the internal structure of the CVL and suggested a general asthenospheric uplift
The findings of this study provide an opportunity for more research on the CVL

Summary

Introduction

The Cameroon Volcanic Line (CVL), called the Cameroon Line (Ngako et al 1991) or Cameroon Hot Line (Nkono et al 2014), is made up of an alignment of mountains trending N30° and is divided into two parts: an oceanic part with volcanic islands of Gulf of Guinea and a continental part characterized by volcanic eruptions of Mount Cameroon and deadly gas emissions from lakes Monoun in 1984 and Nyos in 1986, respectively (Fig. 1). Several geological and geophysical studies have been carried out along the CVL to understand its structure, origin and evolution. Poudjom-Djomani (1993) and Marcel et al (2010) have used these terrestrial gravity data to investigate the internal structure of the CVL and suggested a general asthenospheric uplift. Marcel et al (2016) used gravity data derived from EGM2008 to investigate the depth of Moho discontinuity under the CVL and found values ranging from 19 to 34 km. Moreau et al (1987) and Nkono et al (2014) used remote sensing and deduced the general trend of the CVL From seismic data, Koch et al (2012) interpreted lattice-preferred orientation frozen into the Congo Craton and subcontinental lithosphere related to relict plate motion and deformation. Moreau et al (1987) and Nkono et al (2014) used remote sensing and deduced the general trend of the CVL

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