Gradual and smooth movement along a fault is considered as:
2024
Gradual and smooth movement along a fault is considered as:
Answer: C. Seismic slip — Concept: Movement on a fault is classified by how the elastic stress stored in the rock is released across the fault plane. When the two rock masses move past…
- A.
Seismic jerk
- B.
Epicenter
- C.
Seismic slip
- D.
Fault rupture
Show answer & explanation
Correct answer: C
Concept: Movement on a fault is classified by how the elastic stress stored in the rock is released across the fault plane. When the two rock masses move past each other continuously, the stress is released about as fast as it builds up, so the motion stays slow and steady; when friction locks the fault, stress accumulates until the rock fails all at once. Seismology therefore keeps two different families of words here: some name a manner of movement, others name a place on the fault.
Applying it to this item:
The stem describes movement that is gradual and relatively smooth, that is, the continuous-release regime rather than the locked-then-failing one.
The passage names that regime outright: "When movement along faults occurs gradually and relatively smoothly, it is called creep or seismic slip and may be undetectable to the casual observer."
Because the movement is continuous, strain is released about as fast as it accumulates instead of building towards one large release, so a creeping stretch of fault usually produces no shaking that a casual observer would feel, which is why the passage adds that it may go unnoticed.
So the term the passage attaches to gradual, smooth movement along a fault is seismic slip, equivalently called creep.
Cross-check - how each term is used:
Term | What it names | Kind of term |
|---|---|---|
Seismic jerk | The all-at-once release that follows a period of friction-locked stress build-up | Manner of movement (episodic) |
Epicenter | The point on the fault that the passage ties to where the first movement of an earthquake occurs | Location |
Seismic slip | Gradual, relatively smooth movement along a fault; the passage also calls it creep | Manner of movement (continuous) |
Fault rupture | The failure of rock across the fault plane at the moment the fault gives way | Event of failure |
Note: In standard seismology the point where rupture begins is the focus (or hypocentre), while the epicentre is the point on the Earth's surface directly above it. This item follows the passage's own wording.
Among the four terms offered, only seismic slip names continuous, gradual movement along a fault, and the passage states that equivalence in so many words.