---
title: "Define fault"
subject: "Engineering Geology I"
chapter: 5
key: "semester_3/engineering_geology_i:define-fault"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/define-fault
site: BCT Engineering
---

# Define fault

Engineering Geology I · Chapter 5: Structural Geology

- Asked in: 2066 Bhadra (old course), 1 marks
- Video: [Classification of Faults](https://www.youtube.com/watch?v=qlk7IfYMufs) — GeoScience Videos
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/define-fault
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-5

## Question

Define fault.

## Short answer

A fault is a fracture in the rock mass along which the two blocks have moved relative to each other, parallel to the fracture surface. Displacement can range from millimeters to hundreds of kilometers.

## Answer

A **fault** is a fracture in the rock mass along which the two blocks have moved relative to each other, parallel to the fracture surface. The displacement may be a few millimetres to hundreds of kilometres.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is a fault?
   A. A fracture with no displacement
   B. A fracture along which the two blocks have moved relative to each other
   C. A bend in rock layers
   D. An erosion surface between strata
   Answer: B. Fault means a fracture with relative displacement parallel to the surface. (Key point: Definition)

2. How does a fault differ from a joint?
   A. A fault has no displacement
   B. A joint always shows large displacement
   C. A fault shows displacement; a joint has none or negligible
   D. They are the same
   Answer: C. The key difference is displacement. (Key point: Joint vs fault)

3. What is the possible displacement on a fault?
   A. Only a few millimetres
   B. Only metres
   C. Always exactly zero
   D. A few millimetres to hundreds of kilometres
   Answer: D. Fault displacement ranges widely. (Key point: Range of displacement)