physics

Subsidence crater

Subsidence crater is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Subsidence crater rather than just read about it. In short: A subsidence crater is a hole or depression left on the surface of an area which has had an underground (usually nuclear) explosion. Many such craters are commonly present at bomb testing areas; one notable example is the Nevada Test Site, which was historically used for nuclear weapons testing over a period of 41 years.

Key takeaways

Subsidence crater belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Subsidence crater to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Subsidence crater from memory before moving on to harder problems.

Reference excerpt

A subsidence crater is a hole or depression left on the surface of an area which has had an underground (usually nuclear) explosion. Many such craters are commonly present at bomb testing areas; one notable example is the Nevada Test Site, which was historically used for nuclear weapons testing over a period of 41 years. Subsidence craters are created as the roof of the cavity caused by the explosion collapses. This causes the surface to depress into a sink (which subsidence craters are sometimes called; see sink hole). It is possible for further collapse to occur from the sink into the explosion chamber. When this collapse reaches the surface, and the chamber is exposed atmospherically to the surface, it is referred to as a chimney. It is at the point that a chimney is formed through which radioactive fallout may reach the surface. At the Nevada Test Site, depths of 100 to 500 meters (330 to 1,640 ft) were used for tests.

When the material above the explosion is solid rock, then a mound may be formed by broken rock that has a greater volume. This type of mound has been called "retarc", "crater" spelled backwards. When a drilling oil well encounters high-pressured gas which cannot be contained either by the weight of the drilling mud or by blow-out preventers, the resulting violent eruption can create a large crater which can swallow a drilling rig. This phenomenon is called "cratering" in oil field slang. An example is the Darvaza gas crater near Darvaza, Turkmenistan.

Gallery

See also Underground nuclear weapons testing Explosion crater Chagan (nuclear test) Sedan (nuclear test) Camouflet Glory hole (mining), specifically the subsidence crater produced by underground block caving. Subsidence (atmosphere) - the similar phenomenon observed in the air, upon cooling. Caldera

References

External links DOE Image of NTS's many subsidence craters Crater at DOE site Low-Yield Earth-Penetrating Nuclear Weapons at FAS site

Illustrations

Worked examples

Example 1 — a first encounter with Subsidence crater

Start with the simplest possible case. Write down what Subsidence crater claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Subsidence crater before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Subsidence crater ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Subsidence crater

In research: Subsidence crater appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Subsidence crater in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Subsidence crater is common in secondary-school and first-year university syllabi. It links to neighbouring topics Explosion craters, Nuclear weapons testing, Underground nuclear weapons testing, so understanding it makes those chapters shorter.
In everyday life: Look for Subsidence crater outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Subsidence crater in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Subsidence crater means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Subsidence crater out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Subsidence crater in simple terms?

Why does Subsidence crater matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Subsidence crater?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Subsidence crater.