Service
Non-intrusive subsurface imaging that fills the ground between boreholes — resistivity, seismic and radar methods selected for the site and integrated into the geotechnical investigation.
Overview
Boreholes give certainty at a point. Geophysics gives continuity between those points, which is what allows a consultant to interpolate ground conditions across a site with confidence instead of assumption. Used together, the two methods cost less and reveal more than either does alone.
Geophysical survey is delivered through Horema's network of specialist geophysicists. Methods are selected and applied according to site conditions and project requirements, with Horema coordinating survey design, field execution and integration of results into the ground investigation.
That integration is the point of the service. A resistivity section or a seismic velocity profile is of limited value in isolation; calibrated against borehole logs and laboratory results, it becomes a continuous model of the ground that the design team can actually use.
Methods & standards
ASTM D6431 · 2D and 3D inversion
Continuous resistivity sections mapping lithological boundaries, cavities and karstic features, made ground, and the fresh/saline groundwater interface that governs durability design on coastal sites.
ASTM D5777
P-wave velocity layering used to define depth to bedrock or competent ground and to assess rippability and excavatability ahead of earthworks and cut design.
Shear wave velocity profiling · Vs30
Shear wave velocity profiles giving small-strain stiffness and the Vs30 value used for seismic site classification under the Egyptian Code and international equivalents.
ASTM D6432
High-resolution shallow imaging for utility detection, pavement layer thickness, reinforcement location, voids and near-surface anomalies before excavation or coring.
ASTM D7400 · ASTM D4428
Direct in-borehole measurement of compression and shear wave velocities where dynamic soil properties are required for machine foundations or detailed seismic analysis.
ASTM G57 (Wenner array)
Soil resistivity profiling supporting earthing system design and buried-metal corrosion assessment across industrial, airport and utility infrastructure.
Joint interpretation with intrusive data
Geophysical sections tied to borehole logs and laboratory results so that velocity and resistivity contrasts are interpreted as real stratigraphic boundaries rather than modelling artefacts.
Where it applies
What you receive
Common questions
Geophysics is most valuable where the ground varies between boreholes or where the site is too large to characterise economically by drilling alone — corridors, masterplans, karstic limestone and reclamation areas. It does not replace boreholes: intrusive data is still required to calibrate the geophysical model and to obtain samples. The efficient scope usually pairs a reduced borehole grid with continuous geophysical coverage between them.
Electrical resistivity tomography is the primary method for mapping cavities, karstic features and dissolution zones, because air- or clay-filled voids contrast strongly with intact limestone. Microgravity and GPR can supplement it depending on depth and target size, and the method mix is selected against the specific site conditions.
MASW measures shear wave velocity with depth, giving small-strain stiffness and the Vs30 value used to assign a seismic site class under the Egyptian Code ECP 201 and international codes. It is non-intrusive and well suited to sites where seismic design parameters are needed without deep borehole geophysics.
Survey is delivered through Horema's network of specialist geophysicists, with methods selected and applied according to site conditions and project requirements. Horema coordinates the survey design, the field execution and the integration of results into the wider ground investigation.
Where we have done it
Send us the site location, the structures planned and your programme — our team will scope the investigation and testing required.
