Two Different Maps, Two Different Acts
Owners conflate them and they are separate. The Alquist-Priolo Earthquake Fault Zoning Act concerns surface fault rupture and prohibits structures for human occupancy over or within fifty feet of the trace of a known active fault.
The Seismic Hazards Mapping Act is companion legislation addressing hazards beyond fault rupture, particularly ground failure from liquefaction and earthquake-triggered landslides. Toward the bay it is the second of those that is more often the live question. The full position is on our page covering the debris and the ground.
How Do I Find out Which Applies to Me?
Why That Statement Is Worth Finding
It answers in one page what would otherwise take enquiries to the city, and it is a document you already own rather than one you have to commission.
It also matters for a sale in the other direction. A buyer will receive the same disclosure, so anything you establish now is something they will see anyway. Knowing it first means you are not learning it from their diligence.
What If I Inherited the Property and Have No File?
We publish no hazard zone determinations, ground condition assessments or geologic conclusions for individual north San Jose parcels. The city, the State Geologist's mapping and a registered geologist hold those.
The Air District Rule Does Not Vary With the Ground
Worth being clear about, because the two constraints sit on entirely different axes. The demolition notification requirement and the survey obligation apply identically across all nine counties the Air District regulates, whatever the parcel is mapped as.
So an owner here has the same testing decision as an owner anywhere else in the valley, and a separate question about what the ground permits to be built back.
Mixed Stock, Mixed Answers
Housing across this side of the city spans a wide range of eras, from the older settlement at the bay edge through to comparatively recent construction. That means the build year is a poor guide at neighbourhood level and a good one at parcel level.
It is worth establishing yours rather than reasoning from what is nearby, because it bears on both what a survey is likely to find and whether the framing can be kept.
North San Jose in Context
Where post-war tract housing dominates, see our page about east San Jose. Where fault mapping rather than ground failure is the live question, see our page for south San Jose and the Almaden foothills.
The Acts and Sections That Govern the Ground
Alquist-Priolo sits at Public Resources Code sections 2621 to 2630 and prohibits occupancy structures within 50 feet of a known active fault trace, exempting work under 50 per cent of structure value. The companion Seismic Hazards Mapping Act covers liquefaction and earthquake-triggered landslides.
Both sets of zones appear on the disclosure given under Civil Code section 1103.2. The Air District requirements at 10 working days and section 11-2-303.8 apply identically across all 9 counties.
North San Jose Questions
Where Is My Hazard Disclosure?
In your purchase file if you bought the property. It identifies both fault zones and seismic hazard zones and it costs nothing to look.
Is Liquefaction Mapping the Same as a Fault Zone?
No. They come from two different Acts and they have different consequences. Both appear on the same disclosure statement.
Will You Buy Near the Bay Margin?
Yes, across north San Jose, Berryessa and Alviso. Ground conditions affect the figure and they do not stop us buying.