Geologic Hazard Review

Is my property located within a Geologic Hazard Zone?

Geologic hazard maps

What does the County Geologic Ordinance require?

The Santa Clara County Geologic Ordinance (Sections C12-600 through C12-624) establishes minimum requirements for the geologic evaluation of land, based on proposed land uses and geologic hazard zones. The ordinance defines types of geologic reports and establishes requirements for reports. It contains procedures for determining whether a geologic report is required, review of reports, the recording of acknowledgment statements, and requires disclosure to a potential buyer if a property is located within a geologic hazard zone.

What is a geologic hazard?

A geologic hazard is a natural condition that presents the potential for ground deformation to occur. Examples of geologic hazards include faults, landslides, liquefaction, compressible soils hazards and dike failure hazards.  Maps depicting geologic hazard zones are on file with the Planning Office and may be accessed through an interactive map (County Geologic Hazards Zones).

When is geological review required?

When construction is proposed on property located within a geologic hazard zone, a site-specific geologic investigation must be performed. A geologic report, prepared and signed by a certified engineering geologist, must be submitted for review by the county geologist, prior to approval of the application.

Why is geologic review required?

As a matter of public safety, geologic review is required for a proposed development if the property is located within a geologic hazard zone, or if the proposed development will create or increase the risk of damage to be caused by a geologic hazard. (Section C12-607).

What are the types of geologic reports?

There are three types of geologic reports: in-depth geologic report, feasibility geologic report, and geologic letter report. A geologic report must address the risk of damage or injury posed by any geologic hazard found to threaten the proposed improvements and include mitigations of any identified geologic hazards. A feasibility report is normally required for subdivisions located within geologic hazard zones. A letter report is required for relatively simple situations, where geologic conditions do not necessitate in-depth investigation. An in-depth investigation (such as trenching or drilling) is usually necessary where geologic circumstances are more complex or the hazard is considered high. Section C12-608 provides details and requirements for each type of report.

What is a plan-review letter?

A plan-review letter is a letter signed by the project consulting engineering geologist and/or soils engineer indicating that he/she has reviewed the construction plans for the proposed project and found them to be in conformance with the recommendations presented in the approved geologic report. (Section C12-605.26).

What is a construction-observation letter?

A construction observation letter is a letter authored and signed by the consulting engineering geologist and/or soils engineer indicating that he/she has observed the relevant portions of construction and found them to be in conformance with the recommendations presented in the approved geologic report.

What is the timing for the submittal, review and decision on a geologic report, plan-review letter and construction-observation letter?

Depending on the nature of the proposed project, a geologic report may be required before an application is deemed complete. Sometimes, a geologic report may be required prior to final action, or prior to the issuance of a building or grading permit. For some projects, a plan-review letter is required prior to the issuance of a building or grading permit, to ensure that the plans follow the requirements of the approved geologic report. A construction-observation letter may be required to be submitted prior to final inspection and/or release of bonds, to ensure that construction proceeded according to the approved plans and the recommendations presented in the geologic report. Section C12-613 provides details about the timing related to specific projects.


Fees are charged for the County Geologist's review of a geologic report. Different fees are charged for review of an in-depth report and a geologic letter report. Fees are not charged for the review of a plan-review letter or construction-observation letter.

What are the public disclosure requirements?

In addition to the requirements found in state law, section C12-624 of the Geologic Ordinance requires that the seller of real property located partially or wholly within a County Geologic Hazard Zone shall disclose in a written statement to the buyer that the property is located within such zone(s).

For additional information, please contact:

County of Santa Clara
Planning Office
70 West Hedding Street, East Wing
San Jose, CA 95110

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