Noise based tomography around the Asal Rift, Djibouti

Passive seismic methods have become increasingly important for investigating crustal structures in tectonically active regions. The Asal Rift, located in central Djibouti, is characterized by pronounced lithospheric thinning resulting from extensional processes accommodated by major normal faults and a high geothermal flux associated with mantle upwelling beneath the region.

In this study, we evaluate the contribution of passive seismology to the assessment of the geothermal potential of the Asal Rift. The dataset comes from a network of 31 short-period and broadband seismic stations deployed between 2009 and 2011 as part of the Dynamics of Rifting in Asal (DORA) Project. We performed ambient seismic noise cross-correlations, applied Frequency–Time Analysis to extract Rayleigh-wave dispersion curves within the 1–5 s period band and constructed group velocity maps of the region. From those group velocity maps we constructed a 3D shear-wave velocity model around the rift.  

The results reveal a significant decrease in seismic velocities within the rift zone, where several geothermal development projects are ongoing. These findings are interpreted as thermal anomalies that provide valuable insights for guiding future geothermal exploration and improving the understanding of crustal dynamics in the Asal Rift. Updated results will be presented at the meeting.