Geophysical Investigations AHA (Activity Hazard Analysis / Job Hazard Analysis)
Updated 2026-06-23
A Geophysical Investigations AHA (Activity Hazard Analysis / Job Hazard Analysis) is the plan that keeps the crew performing geophysical investigations safe in the terrain and access, around the equipment and its energy sources, and from the traffic and environmental hazards. Geophysical investigations use surface geophysical methods to characterize the subsurface non-invasively — combining the terrain and access hazard, the equipment and energy-source hazard, and the traffic and environmental hazard. This guide walks through building a Geophysical Investigations AHA that names the terrain/access, equipment/energy-source, and traffic/environmental hazards and assigns the terrain, equipment, and traffic controls that hold up in the field.
Why geophysical investigations needs its own AHA
Geophysical investigations use surface (non-invasive) geophysical methods — ground-penetrating radar (GPR), seismic surveys, electrical resistivity, electromagnetic (EM) surveys, magnetics, and gravity — to characterize the subsurface (soil, rock, groundwater, buried objects, utilities, voids) without drilling, by measuring physical properties from the surface. The defining feature is that geophysical crews traverse the site on foot (or with towed/vehicle-mounted equipment) carrying and operating survey equipment, some of which has energy sources (seismic sources, electrical currents), across the site terrain and near traffic. The hazards combine the terrain and access (traversing the whole site on foot to run the geophysical lines/grids — often uneven, undeveloped terrain — the terrain (slip/trip/fall) and access hazards, like site surveys), the equipment and energy-source (the geophysical equipment and its energy sources — seismic sources (sledgehammers, weight drops, or explosive/mechanical sources), electrical-resistivity currents (electrode currents), and towed/mounted equipment — the equipment and energy-source hazards), the traffic and environmental (surveying near roads and on active sites (traffic), and the outdoor environment (weather, biological)), and the ergonomic. The terrain/access and the equipment/energy-source justify a dedicated AHA.
Breaking geophysical investigations into steps
The steps for a Geophysical Investigations AHA follow the survey:
- Plan the geophysical survey and identify site hazards
- Traverse the terrain to run the lines/grids
- Set up and operate the geophysical equipment
- Manage the energy sources (seismic, electrical)
- Manage the traffic where near roads
- Manage the terrain, equipment, and traffic hazards
- Collect and record the data
- Complete
Each step carries a hazard, and the terrain/access, the equipment/energy-source, and the traffic/environmental are where the most significant risks concentrate.
The hazards step by step
Terrain and access
Traversing the whole site on foot to run the geophysical lines/grids — often uneven, undeveloped terrain — the terrain (slip/trip/fall) and access hazards, like site surveys. The controls are careful traverse of the terrain (footing, sturdy footwear), surveying the route for hazards, awareness of holes/obstructions, not traversing hazardous terrain alone, and the terrain controls. The terrain/access is a defining hazard — geophysical crews cover the whole site on foot. (These follow the walking-working-surface fundamentals.)
Equipment and energy-source
The geophysical equipment and its energy sources — seismic sources (sledgehammers, weight drops, or explosive/ mechanical sources), electrical-resistivity currents (electrode currents), and towed/mounted equipment — the equipment and energy-source hazards. The controls are safe operation of the geophysical equipment, managing seismic sources (struck-by/impact from sledgehammers/weight drops, and special controls where explosive sources are used), managing electrical-resistivity currents (electrode currents can shock — controlled current, clearance during energizing), safe towing/mounting, and the equipment/energy controls. The equipment/energy-source is a defining hazard — geophysical energy sources (seismic, electrical) carry their own hazards. (These follow the equipment-energy fundamentals.)
Traffic and environmental
Surveying near roads and on active sites (traffic), and the outdoor environment (weather, biological). The controls are high-visibility PPE and traffic control where near roads, awareness of site traffic/equipment, weather-appropriate protection, biological-hazard awareness, and the traffic/environmental controls. The traffic/environmental is a defining hazard. (These follow the traffic-control and environmental-exposure fundamentals.)
Ergonomic
Carrying and operating the equipment (repetitive, carrying) brings the ergonomic hazard. The controls are safe carrying/handling, and the ergonomic controls. (These follow the ergonomic fundamentals.)
A simple Geophysical Investigations AHA structure
| Step | Hazard | Control | Standard |
|---|---|---|---|
| Plan | Site hazards | Plan geophysical survey, identify site hazards | project |
| Traverse | Slip / trip / fall | Careful traverse, sturdy footwear, hazard awareness | OSHA 1926.25 |
| Operate equipment | Equipment | Safe operation of geophysical equipment | project |
| Manage energy sources | Impact / shock | Manage seismic sources, electrical currents | project |
| Manage traffic | Struck-by | High-visibility PPE, traffic control near roads | OSHA 1926.201 |
| Collect data | Environmental | Weather/biological protection, record data | project |
Terrain safety and equipment/energy-source control
A Geophysical Investigations AHA centers on terrain safety and equipment/energy-source control. The terrain safety addresses traversing the whole site on foot — controlled by careful traverse of the terrain, sturdy footwear, surveying the route for hazards, and awareness of holes/obstructions. The equipment/energy-source control addresses the geophysical equipment and its energy sources — controlled by safe operation, managing the seismic sources (impact from sledgehammers/weight drops, special controls for explosive sources), and managing the electrical-resistivity currents (electrode currents can shock — controlled current, clearance during energizing). And the traffic and environment get high-visibility and environmental controls. An AHA built on terrain safety and equipment/energy-source control, with traffic controls, addresses the hazards that define geophysical investigations.
From the field: what actually goes wrong
In fourteen years across federal, heavy civil, and industrial projects, geophysical investigations characterize the subsurface non-invasively from the surface, so unlike subsurface drilling they do not penetrate the ground — which means their hazards are the field-survey hazards (terrain, traffic, environment) plus the specific hazards of the geophysical energy sources. The terrain and access hazard is a primary concern, and it mirrors site surveys — geophysical crews traverse the whole site on foot to run the survey lines and grids, over often uneven and undeveloped terrain, so slip, trip, and fall hazards are constant, controlled by careful traverse, sturdy footwear, surveying the route for hazards, and not traversing hazardous terrain alone. The geophysical crew, like the survey crew, covers the whole site on foot.
The equipment/energy-source and the traffic/environmental are the other defining hazards. On the projects I have run, the distinctive hazard of geophysical work (versus plain surveying) is the energy sources some geophysical methods use: seismic surveys use a seismic source to generate the waves, which is often a sledgehammer struck against a plate or a weight drop (an impact and struck-by hazard) and occasionally explosive or mechanical sources (which carry their own serious controls); and electrical-resistivity surveys inject electrical current into the ground through electrodes, which can shock, so controlled current and clearance during energizing matter. So safe operation of the geophysical equipment, managing the seismic sources (impact hazards from sledgehammers and weight drops, and special controls where explosive sources are used), and managing the electrical-resistivity currents are the controls. The energy sources are what make geophysical work more than just walking with an instrument. The traffic and environmental hazard is that geophysical surveys often run near roads and on active sites (traffic), and in the outdoor environment (weather, biological hazards), controlled by high-visibility PPE and traffic control near roads, awareness of site traffic, and weather and biological-hazard protection. The ergonomic carrying rounds it out. This is closely related to GPR and site surveys. The AHA built on terrain safety and equipment/energy-source control is the one that protects the geophysical crew.
The bottom line
A Geophysical Investigations AHA names the terrain/access, the equipment/energy-source, and the traffic/ environmental hazards with specific controls — careful traverse for the whole-site terrain, managing the geophysical energy sources (seismic impact sources and electrical-resistivity currents), and high-visibility PPE with traffic control near roads. The terrain safety and the equipment/energy-source control are the defining concerns. The AHA that manages both is the one that protects the crew.
Frequently asked questions
What energy-source hazards apply to geophysical work?
Some geophysical methods use energy sources: seismic surveys use a seismic source (often a sledgehammer struck against a plate or a weight drop — an impact/struck-by hazard, occasionally explosive/mechanical sources with their own controls), and electrical-resistivity surveys inject electrical current into the ground through electrodes (which can shock). Controls are safe operation of the geophysical equipment, managing seismic sources (impact from sledgehammers/weight drops, special controls for explosive sources), managing electrical-resistivity currents (controlled current, clearance during energizing), and the equipment/energy controls.
Why is the terrain a defining hazard?
Geophysical crews traverse the whole site on foot to run the survey lines and grids, over often uneven and undeveloped terrain, so slip, trip, and fall hazards are constant (mirroring site surveys). Controls are careful traverse of the terrain (footing, sturdy footwear), surveying the route for hazards, awareness of holes/obstructions, not traversing hazardous terrain alone, and the terrain controls.
What traffic and environmental hazards apply?
Geophysical surveys often run near roads and on active sites (traffic), and in the outdoor environment (weather, biological hazards). Controls are high-visibility PPE and traffic control where near roads, awareness of site traffic/equipment, weather-appropriate protection, biological-hazard awareness, and the traffic/environmental controls.
What are geophysical investigations?
Geophysical investigations use surface (non-invasive) geophysical methods — ground-penetrating radar, seismic surveys, electrical resistivity, electromagnetic surveys, magnetics, and gravity — to characterize the subsurface without drilling, by measuring physical properties from the surface. Because crews traverse the site on foot with equipment that has energy sources (seismic, electrical), near traffic and in the outdoor environment, those hazards apply.
Related AHAs and JHAs
- Magnetic Investigations - Gas Line Detection AHA — a specific geophysical detection method
- Performing Ground Penetrating Radar AHA — the GPR geophysical method
- Geotechnical Investigations AHA — the invasive subsurface investigation
- Utility Locating and Ground Disturbance JHA — related subsurface-detection work
Written by Mustafa Tok, CSP, ASP, CHST — OSHA Authorized Outreach Trainer with 14+ years of international construction safety experience across federal, heavy civil, and industrial projects.