Earthquake Evidence & Hazard Risk — Drills · Grade 9 Science

Chapter: Earth’s Interior & Plate Tectonics

What these drills covers

By the end of Earthquake Evidence & Hazard Risk you should be able to:

8 questions, written answer, multiple choice and numeric, each with a worked explanation.

Vocabulary used: epicenter, intensity, vulnerability.

Problem 1

Distinguish magnitude and intensity.
Answer and explanation

Magnitude characterizes source size; intensity describes local shaking effects.

Problem 2

Which increases exposure?
  1. Moving development away from a hazard area
  2. Adding more homes in a hazard area
  3. Strengthening building connections
  4. Improving warning communication
Answer and explanation

Adding more homes in a hazard area

More people and property are situated where the hazard can affect them.

Problem 3

Hazard and risk differ because risk also accounts for
  1. magnitude only
  2. exposure and vulnerability of people and buildings
  3. depth only
  4. the date
Answer and explanation

exposure and vulnerability of people and buildings

The same hazard poses different risk depending on who and what is exposed.

Problem 4

An event with a 1-in-100 chance per year has what percentage chance in any single year?
Answer and explanation

1 %

1/100 = 1 percent per year.

Problem 5

Buildings on loose saturated sediment typically suffer more damage because the ground
  1. is colder
  2. amplifies shaking and can lose strength
  3. is harder
  4. blocks waves
Answer and explanation

amplifies shaking and can lose strength

Soft sediment increases shaking amplitude and can liquefy.

Problem 6

A '100-year flood' means a flood of that size
  1. happens exactly every 100 years
  2. has about a 1 percent chance in any year
  3. happened 100 years ago
  4. cannot happen twice
Answer and explanation

has about a 1 percent chance in any year

It is a probability per year, not a schedule, so two can occur in consecutive years.

Problem 7

Explain why earthquake deaths vary enormously between countries for similar magnitudes.
Answer and explanation

Magnitude measures the energy released, while deaths depend on what that energy encounters: building construction and enforcement of codes, population density, time of day, ground conditions, and the speed of emergency response. A well-prepared area can experience a large earthquake with few deaths, while a poorly constructed one can suffer heavily from a smaller event.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

Name two measures that reduce earthquake risk without reducing the hazard.
Answer and explanation

Building codes requiring structures to flex and stay standing, and land-use planning that keeps critical buildings off unstable ground. Neither changes how often or how strongly the ground shakes — the hazard is fixed by geology — but both reduce the harm that shaking causes, which is what risk measures.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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