Landslide Investigation

Malibu, CA

Background: Earth forensics was hired by consulting firm to investigate potential causes of a landslide that occurred on December 2010 in Malibu, CA. A hydrogeological evaluation was performed to provide information on the local groundwater conditions as they pertain to the subject property, geophysical borehole data for the site and precipitation rates near the time of the landslide event at the subject site.

Scope of Work: The scope of our work included the following:
- Manually measure groundwater levels and install groundwater level loggers in onsite wells.
- Analysis of the collected data to provide information on the localized hydrogeology.
- Conduct geophysical surveys of the existing inclinometers.
- Research the local precipitation rates prior to the onsite landslide event of January 2011.

Results: Earth Forensics Inc. collected and analyzed groundwater data for the area of concern. The groundwater data was utilized to compile a groundwater contour map that was used to determine the flow direction and gradient. The groundwater level data was also utilized to calculate the hydraulic conductivity of the geologic materials at the subject site. The general groundwater flow direction was determined to be to the south-southwest and that two distinctive groundwater flow gradients are present at the subject site. North of the fault zone, the flow gradient is much lower than in the area south of the fault zone.

The groundwater level data was also utilized to calculate the hydraulic conductivity of the geologic materials at the subject site. EF also completed an analysis of the precipitation events that occurred prior to the onsite landslide event of January 2011. The analysis revealed that the rainfall during this time period was not an extraordinary event.

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For Landslide Investigations, Earth Forensics gathers data and provides statistical analysis of hydrogeological and hydrometeorological effects on the causation of landslides/earth movement. These earth movements include rock falls, rotational slumps, translational block slides, debris flows, sea cliff erosion, and complex earth movement.  Landslide evaluations involve: 

- Hydrometeorologic services (PDF) - Hydrogeological evaluations - Review of topographic maps, stereoscopic aerial photography - Historical aerial photography/satellite imagery interpretation - Installation of groundwater monitoring wells - Record, literature and air photograph research - 3D Geologic modeling - Forensic investigation of post-development distress - 3D geological models of landslide and geology - Evaluation of geologic hazards - Drone photography - Expert opinion reports on causation of landslide/earth movement

For more information on how our team can help you, please contact us at: Phone: 714.296.4055 Email: contact@earthforensics.com