GeoHazards Division

The GeoHazards Division of GEO-HAZ Consulting handles basic geologic mapping, photogeology and remote sensing, and the assessment and mitigation of a wide spectrum of existing and potential geologic hazards.

Earthquake Hazards

Analysis of earthquake hazards is our specialty. We have over two decades of experience in documenting hazards from surface faulting, ground shaking, and ground failure. GEO-HAZ scientists have pioneered many of the standard techniques of modern fault-zone trenching technology, age dating of large prehistoric earthquakes, and application of paleoseismic data to seismic hazard analysis.

We provide deterministic or probabilistic seismic hazard analyses of both sites and regions. From our digital library of earthquake strong motion records we can provide design earthquake response spectra for any combination of local ground conditions and earthquake shaking. We have particular experience in analyzing seismic hazards to dams and critical facilities such as waste disposal sites.

Through our GIS Division, we exploit the power of Geographic Information Systems for predicting the spatial patterns of earthquake hazards. Several state-of-the-art techniques have been developed at GEO-HAZ for predicting sites of future earthquake-induced landslides.

Slope Stability Hazards

At GEO-HAZ, we realize that slopes fail due to the unique (and predictable) spatial coincidence of steep slopes, weak rocks, and temporarily abundant water. Identification of past failures (landslides) forms the basis for quantitative analysis of future failures. Our past landslide inventories, performed for agencies such as the U.S. Forest Service, have covered hundreds of thousand of acres. GEO- HAZ developed a classification of landslide activity that was later adopted for use by the U.S. Forest Service- Intermountain Region.

We assess slope stability via computer programs such as STABLE 5M and CRSP 4.0. These sophisticated programs permit us to simulate the effects of development disturbance and remedial actions on slope stability. Sites of future high failure potential are identified via GIS modeling using the DeGraff and Newmark approaches.

Multi-Hazards Assessment

Many development sites are subject to multiple hazardous processes, such as landslides, debris flows, rockfalls, erosion, and the earthquake aggravation of all the above. Our Multi-Hazards/GIS Assessment Package involves documenting all physical land use constraints resulting from natural forces or conditions at a particular site. Remediation can then be planned in a holistic rather than a piecemeal fashion, in the context of existing or planned development. In our experience, using the Multi-Hazards/GIS package ensures that development will be placed in harmony with ongoing earth processes, with minimum esthetic and maintenance costs.

Supporting Services

We provide these support services on an as-needed basis:

• geologic mapping (by Certified Professional Geologists).
• soil survey (by Certified Soil Scientists).
• surface and groundwater hydrology (by Certified Professional Groundwater Scientists).
• cultural resource surveys/archaeology (by qualified Archaeologists).

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