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geology pick and sand

What does a consulting geologist do?

Well, a few different things...

Geologic Hazards Assessment

Geologic hazards include landslides, earthquakes, fault movement, ground settlement, cracking and sliding related to earthquake shaking, volcanic eruptions and related hazards, erosion, sedimentation, and floods. All these hazards can potentially affect property and human lives. Many cities and counties now require some form of geologic hazards assessment for development, so these hazards may be avoided or remedied as part of the project design.

Critical facilities, such as hospitals or fire stations, must continue to function during natural disasters and are required to have a very careful geologic hazards evaluation. Hazard evaluations are also typically performed for other structures, such as schools, where the consequences of failure are very high.

Nolan Associates provides geologic hazards assessments for individual projects ranging from single-family residences to hospitals and dams. We also prepare area-wide geologic hazard evaluations for city and county general plans (seismic safety and geotechnical hazards components) and land management plans for conservation of open space. These studies are used to guide long-term planning decisions.

Landslide Evaluation and Repairslide photo

Once a landslide has taken place, it may come to rest in a stable configuration, or it may be capable of further movement. To repair things damaged by landsliding or to use property underlain by a landslide, it is necessary to determine whether the landslide is stable, and, if not, what means can be employed to make it stable. A landslide must be characterized in terms of width, length, depth, types of geologic materials involved, groundwater levels, and causative factors. This information provides a basis for design of stabilization measures. Nolan Associates provides landslide remediation services for private clients and public agencies.


Paleo (meaning old or ancient) Seismology (the study of earthquakes) is the study of prehistoric earthquakes by examining the records they have left in sedimentary layers. trench photoEarthquakes are produced by movement on faults-- cracks in the earth's crust--caused by the buildup of stress in the crust. When a fault slips, the release of stored energy results in waves traveling through the earth, which we experience as an earthquake. The fault movement offsets layers at the earth's surface. The most common method for studying prehistoric earthquakes is to excavate trenches across faults so that we can examine the way in which layers of different ages were offset by fault movement.fault photo The variation in offset of layers of different ages can be used to find when earthquakes have occurred in the past, how frequently they occur, and approximately how large they were. This type of work is done to aid public and private organizations in earthquake hazard assessment and earthquake preparedness planning. Most of this type of work is funded by research grants from the U.S. Geological Survey.


Hydrogeology is the study of the occurrence and movement of groundwater. The most common application of hydrogeology presently is in the study and treatment of groundwater contamination. Leaky underground fuel tanks, accidental spills of industrial solvents, concentrated discharge of sewage effluent, and other activities of man have the potential to contaminate groundwater that is used for drinking and agriculture. Hydrogeology is also used in water resource evaluation and management. In California, the growing population is placing increasing demands on surface and groundwater supplies. Nolan Associates participates in the evaluation of water use impacts on ground water availability and groundwater quality.

Engineering Geology

Engineering geology is application of geologic principals to engineering practice, to help insure that geologic factors are adequately accounted for in design, construction, operation, and maintenance of engineered structures. Engineering geology practice includes an understanding of the character and properties of geologic materials and processes as they relate to the construction of earthworks and foundations. It includes the recognition of geologic hazards as well as an appreciation of the role of groundwater, rock structure, and soil properties in engineering design.

Geologic Impacts Assessment lake photo

In California, the assessment of potential environmental impacts and the means for mitigating those impacts is required by the California Environmental Quality Act (CEQA) for many types of new development. Nolan Associates provides geologic impacts assessments as part of the CEQA certification process, generally as a subcontractor to an Environmental Impact Report preparer.



Nolan Associates Contact: na@nolangeology.com 3/9/09