Geophysical modeling of one of the world’s most important fossil sites reveals the history of the site where early humankind evolved.

The field studies of this project were carried out by Gerard Schuster, Sherif Hanafy and doctoral student Kai Lu.

Olduvai George is located in north Tanzania, almost 6 hours’ drive distance from Arusha and 2 hours from Karato. The project was carried out over four trips.

Recent Submissions

  • Robust Imaging Methodology for Challenging Environments: Wave Equation Dispersion Inversion of Surface Waves

    Li, Jing; Schuster, Gerard T.; Zeng, Zhaofa (Society of Exploration Geophysicists, 2017-12-22)
    A robust imaging technology is reviewed that provide subsurface information in challenging environments: wave-equation dispersion inversion (WD) of surface waves for the shear velocity model. We demonstrate the benefits and liabilities of the method with synthetic seismograms and field data. The benefits of WD are that 1) there is no layered medium assumption, as there is in conventional inversion of dispersion curves, so that the 2D or 3D S-velocity model can be reliably obtained with seismic surveys over rugged topography, and 2) WD mostly avoids getting stuck in local minima. The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic media and the inversion of dispersion curves associated with Love wave. The liability is that is almost as expensive as FWI and only recovers the Vs distribution to a depth no deeper than about 1/2~1/3 wavelength.
  • Opportunities and pitfalls in surface-wave interpretation

    Schuster, Gerard T.; Li, Jing; Lu, Kai; Metwally, Ahmed Mohsen Hassan; AlTheyab, Abdullah; Hanafy, Sherif (Society of Exploration Geophysicists, 2017-01-21)
    Many explorationists think of surface waves as the most damaging noise in land seismic data. Thus, much effort is spent in designing geophone arrays and filtering methods that attenuate these noisy events. It is now becoming apparent that surface waves can be a valuable ally in characterizing the near-surface geology. This review aims to find out how the interpreter can exploit some of the many opportunities available in surface waves recorded in land seismic data. For example, the dispersion curves associated with surface waves can be inverted to give the S-wave velocity tomogram, the common-offset gathers can reveal the presence of near-surface faults or velocity anomalies, and back-scattered surface waves can be migrated to detect the location of near-surface faults. However, the main limitation of surface waves is that they are typically sensitive to S-wave velocity variations no deeper than approximately half to one-third the dominant wavelength. For many exploration surveys, this limits the depth of investigation to be no deeper than approximately 0.5-1.0 km.
  • Wave-equation dispersion inversion

    Li, Jing; Feng, Zongcai; Schuster, Gerard T. (Oxford University Press (OUP), 2016-12-08)
    We present the theory for wave-equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. The dispersion curves are obtained from Rayleigh waves recorded by vertical-component geophones. Similar to wave-equation traveltime tomography, the complicated surface wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the phase-velocity and frequency domains. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2-D or 3-D S-wave velocity models. This procedure, denoted as wave-equation dispersion inversion (WD), does not require the assumption of a layered model and is significantly less prone to the cycle-skipping problems of full waveform inversion. The synthetic and field data examples demonstrate that WD can approximately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic data and the inversion of dispersion curves associated with Love waves.
  • Data: Olduvai Gorge Project Trip # 2

    Schuster, Gerard T.; Hanafy, Sherif M.; Lu, Kai (2016)
  • Data: Olduvai Gorge Project Trip # 4

    Hanafy, Sherif M.; Lu, Kai (2016)
  • Data: Olduvai Gorge Project Trip # 3

    Hanafy, Sherif M.; Lu, Kai (2016)
  • Data: Olduvai Gorge Project Trip # 1

    Schuster, Gerard T.; Hanafy, Sherif M.; Lu, Kai (2016)