---
title: "Ground Subsidence — AP Enviro Definition & Exam Guide"
description: "Ground subsidence is the sinking of land caused by removing subsurface material or fluids, a key mining impact in AP Enviro Unit 5 tied to subsurface mining and groundwater pumping."
canonical: "https://fiveable.me/ap-enviro/key-terms/ground-subsidence"
type: "key-term"
subject: "AP Environmental Science"
unit: "Unit 5"
---

# Ground Subsidence — AP Enviro Definition & Exam Guide

## Definition

Ground subsidence is the sinking or settling of the land surface (including sinkhole formation) that happens when subsurface materials or fluids are removed, most often from subsurface mining or over-pumping groundwater. In AP Enviro, it's a core ecological impact of mining in Topic 5.9.

## What It Is

Ground subsidence is what happens when you take material out from underneath the land and the surface above it [sinks](/ap-enviro/unit-1/hydrologic-cycle/study-guide/Mnp6Jfh7MANP2YtOhxCb "fv-autolink"), settles, or collapses. Think of it like pulling support beams out of a building. When subsurface mining hollows out [coal](/ap-enviro/key-terms/coal "fv-autolink") seams or ore deposits, or when humans pump out groundwater or oil faster than it can be replaced, the empty space underground can't hold the weight above it. The result ranges from slow, gradual sinking over decades to sudden, dramatic collapses called sinkholes.

In the [AP Enviro](/ap-enviro "fv-autolink") CED, subsidence shows up in Topic 5.9 (Impacts of Mining) as one of the ecological costs of resource extraction. The CED's logic chain matters here. As easily accessible ores and coal reserves get depleted (EK EIN-2.K.1), operations are pushed toward expensive subsurface mining (EK EIN-2.L.2), and subsurface mining means tunnels and voids underground. Those voids are exactly what cause subsidence. Abandoned coal mines collapsing under towns is the classic example.

## Why It Matters

Ground subsidence lives in [Unit 5](/ap-enviro/unit-5 "fv-autolink") (Land and Water Use), Topic 5.9, supporting learning objectives AP Enviro 5.9.A (describe natural resource extraction through mining) and AP Enviro 5.9.B (describe its ecological and economic impacts). The exam loves cause-and-effect chains, and subsidence is the payoff of a chain the CED builds explicitly. Lower ore grades force more intensive extraction, depleted surface reserves force subsurface mining, and subsurface mining leaves voids that make the land sink. Subsidence is also a great example of an impact that's both ecological (destroyed [habitat](/ap-enviro/key-terms/habitat "fv-autolink"), altered drainage, damaged wetlands) and economic (cracked foundations, broken roads and pipelines, lost property value), which is exactly the dual framing 5.9.B asks for.

## Connections

### Subsurface mining (Unit 5)

This is the most direct cause-and-effect pair on the exam. [Subsurface mining](/ap-enviro/unit-5/impacts-mining/study-guide/FQ3xs647jJqAbjtrqIzc "fv-autolink") digs tunnels to reach deep coal and ore (EK EIN-2.L.2), and those tunnels become voids that can collapse, sinking the land above. If a question gives you subsurface mining, subsidence should be on your shortlist of impacts.

### Groundwater depletion and irrigation (Unit 5)

Subsidence isn't only a mining problem. When [aquifers](/ap-enviro/key-terms/aquifers "fv-autolink") are over-pumped for irrigation or drinking water, the sediment layers that water once held open compact and the land sinks, often permanently. California's Central Valley has dropped many feet this way. Same mechanism, different fluid.

### Fossil fuel extraction and fracking (Units 5-6)

Pulling oil and gas out of the ground also removes subsurface fluids, which can trigger subsidence above the wells. The 2022 FRQ on [hydraulic fracturing](/ap-enviro/key-terms/hydraulic-fracturing "fv-autolink") shows how the exam frames extraction technologies around their environmental consequences, and subsidence fits that consequence list.

### [Acid mine drainage (Unit 5)](/ap-enviro/key-terms/acid-mine-drainage)

Subsidence and acid mine drainage are the two signature legacies of subsurface coal mining, and they often appear together in 5.9 questions. Subsidence is the physical damage (sinking land), while acid mine drainage is the chemical damage (acidic, metal-laden water leaching from mines).

## On the AP Exam

Subsidence usually shows up in multiple-choice stems asking you to identify a consequence of subsurface mining or groundwater over-extraction, or to match a mining method with its environmental impact. On FRQs, it's a ready-made answer when you're asked to "describe an environmental impact" of mining, drilling, or aquifer depletion. No released FRQ has used the term verbatim, but the 2022 FRQ on hydraulic fracturing is exactly the kind of extraction-impact prompt where subsidence earns a point. The move that scores: don't just name it. State the mechanism (removal of subsurface material or fluid creates voids or compaction) and then the consequence (land sinks, structures and habitats are damaged).

## Ground subsidence vs Sinkholes

A sinkhole is one specific, sudden form of ground subsidence, not a separate phenomenon. Subsidence is the umbrella term covering everything from slow regional sinking (like an over-pumped aquifer compacting over decades) to abrupt collapse into an underground void (a sinkhole). On the exam, use "subsidence" for the general impact and "sinkhole" only when describing a sudden collapse.

## Key Takeaways

- Ground subsidence is the sinking or settling of the land surface caused by removing subsurface materials or fluids, and it can be gradual or sudden (sinkholes).
- In AP Enviro, subsidence is tested as an impact of mining in Topic 5.9, especially subsurface mining, which leaves underground voids that can collapse.
- The CED's logic chain explains why it happens more over time, as accessible reserves are depleted, extraction moves to deeper subsurface mining, which increases subsidence risk.
- Subsidence is also caused by over-pumping groundwater and extracting oil and gas, so it connects mining, irrigation, and fossil fuel topics across Unit 5.
- Aquifer compaction from groundwater withdrawal is often permanent, meaning the aquifer loses storage capacity even if pumping stops.
- On FRQs, always pair the term with its mechanism. Say that removing subsurface material creates voids or compaction, which causes the land above to sink and damages structures and habitats.

## FAQs

### What is ground subsidence in AP Environmental Science?

Ground subsidence is the sinking or settling of the land surface caused by the removal of subsurface materials or fluids, such as coal from subsurface mines or water from over-pumped aquifers. It appears in Topic 5.9 (Impacts of Mining) in Unit 5.

### Is ground subsidence only caused by mining?

No. Mining is the cause emphasized in Topic 5.9, but over-pumping groundwater and extracting oil and gas also cause subsidence by removing the fluids that support sediment layers. California's Central Valley has sunk dramatically from groundwater withdrawal alone.

### What's the difference between subsidence and a sinkhole?

A sinkhole is one type of subsidence, the sudden-collapse version. Subsidence is the broader term that also includes slow, regional sinking, like land gradually dropping over a compacting aquifer or an old mine.

### Does the land come back up if you stop pumping groundwater?

Usually not. When fine sediment layers in an aquifer compact, the change is largely permanent, so the land stays sunken and the aquifer permanently loses storage capacity. That irreversibility is a strong point to make on an FRQ.

### Why does subsurface mining cause more subsidence than surface mining?

Subsurface mining digs tunnels and removes material from underneath intact land, leaving voids that can collapse under the weight above. Surface mining strips the overburden from the top, so its main impacts are erosion and habitat destruction rather than collapse (EK EIN-2.K.2).

## Related Study Guides

- [5.9 Impacts of Mining](/ap-enviro/unit-5/impacts-mining/study-guide/FQ3xs647jJqAbjtrqIzc)

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