Ground subsidence along the San Francisco Bay shoreline
Satellite radar mapping published in Science Advances showed substantial stretches of the San Francisco Bay shoreline — much of it built on artificial fill and young bay mud — that subside at rates locally near 10 mm per year. This subsidence compounds sea-level-rise inundation risk for shoreline infrastructure.
What is documented here
Large stretches of the San Francisco Bay shoreline are reclaimed land: artificial fill placed over soft, compressible bay mud during the last 150 years. Peer-reviewed satellite radar mapping in Science Advances showed parts of that filled shoreline sink at rates locally near 10 millimeters per year. That is slow enough to stay invisible on any given day, and fast enough to matter over the life of a foundation, a runway, or a levee.
The headline finding of the study was compounding: shoreline subsidence adds to sea-level rise, so inundation projections that assume stable ground understate the exposure of filled areas. For the built environment, the more immediate issue is differential settlement. Fill thickness and consolidation history change over short distances, so one end of a structure can sink faster than the other.
Does a specific parcel sit on fill, and what did that fill do recently? That is a screening question the public Sentinel-1 archive can answer per site. Dense urban development along the Bay provides abundant stable radar reflectors, which makes this one of the most measurable coastal environments anywhere.
What the satellite archive holds here
The public Sentinel-1 radar archive, sampled at a representative point in this region. These numbers describe measurement availability — how often the satellites pass, and over what period — not ground movement. We compute movement per site, after the feasibility check.
- Radar acquisitions
- 172
- Revisit
- ~12 days
- Observed span
- 2022-01 → 2026-07
- Satellite tracks
- 3
Coverage stats as of 2026-07-14 · full Sentinel-1 archive extends back to 2015
What satellite radar can — and cannot — tell you
It can
- — Reconstruct a millimeter-scale movement history for stable radar reflectors (rooftops, pavement, rock, bare ground) on a specific site, from archive data
- — Show if the movement slows, stays steady, or accelerates — the trend shape that matters for decisions
- — Give you a dated record of what the ground did before a purchase, a design, or a dispute
It cannot
- — Measure surfaces that change between passes: dense vegetation, active construction, water
- — Replace geotechnical instrumentation, borings, or engineering judgment — it shows you where to look, not how to design
- — Tell you why the ground moves — it documents that it moves and how fast, as an input to the engineer who determines why
The honest economics: a commissioned InSAR study typically costs $10,000–30,000 and takes weeks. A self-serve report on one site costs $749, one time. The feasibility check before it is free — if the satellites cannot measure the site reliably, you pay nothing, and we say so.
Common questions
Which parts of the Bay shoreline are subsiding?
Published radar mapping found the fastest settlement on artificial fill and young bay mud — reclaimed shoreline areas around the Bay — with rates locally near 10 mm per year. Areas on older, consolidated ground are comparatively stable. Behavior varies over short distances with fill thickness and age.
Why does slow settlement matter for due diligence?
Consolidation settlement of fill often continues for decades after placement. A parcel that sinks steadily — or unevenly — affects foundation design, utility connections, and long-term flood exposure. A buyer wants that fact documented before the purchase, not discovered after.
Can radar tell if consolidation slows?
At screening grade, yes: a multi-year movement time series shows if the movement slows (typical consolidation), stays steady, or accelerates. That trend shape — not the absolute rate alone — is usually the signal that matters for filled ground.
Check a site in the California region
Draw your site, and you get a free feasibility report from the Sentinel-1 radar archive in about one minute. It tells you how many passes cover the site, how often, over what period — and if the satellites can measure it at all. If they cannot, the report says so.
Check your site freeTelluric readings come from satellite radar and are screening-grade: use them to decide where to inspect. They do not replace geotechnical instrumentation or engineering judgment. Read the methodology.