Hazard Assessment & Evacuation · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Reading the Odds Before an Eruption

Science · Volcanoes & Earthquakes · ages 12-14
Name ______________________   Date ____________

  1. Which of these is NOT something a volcano observatory watches to set an alert level?

    • Ground deformation
    • Number of tourists visiting
    • Gas emissions

  2. What is a 'recurrence interval'?

    • The average time between past eruptions or quakes
    • The exact date of the next eruption
    • The height of a volcano

  3. A fault's slip rate can tell scientists the exact day an earthquake will happen.

    Circle one:   True   False

  4. Look at the chart. Which volcano's past eruptions suggest a higher chance of erupting in the next 10 years?

    MountQuiet5MountOften65
    • Mount Often
    • Mount Quiet
    • Both are equally likely

  5. A volcano has erupted about every 20 years for two centuries and last erupted 19 years ago. What does this recurrence interval suggest?

    • It will never erupt again
    • It only matters for earthquakes, not eruptions
    • It may be due for another eruption soon

  6. Why might a family keep farming on the slopes of an active volcano instead of moving away?

    • They don't believe eruptions are dangerous
    • Volcanic ash breaks down into rich soil that grows better crops
    • Farming is only allowed near volcanoes

  7. Two neighborhoods sit near the same fault. The wealthier one evacuates quickly and rebuilds within a year. The poorer one struggles to leave and takes five years to rebuild. What does this gap show?

    • Money and resources shape who can evacuate and recover, not just distance from the hazard
    • The poorer neighborhood must be farther from the fault
    • The wealthier neighborhood was never actually at risk

  8. A city issues several evacuation warnings that turn out to be false alarms. What does this risk for the next real warning?

    • The volcano becomes less likely to erupt
    • Scientists will stop monitoring gas emissions
    • Fewer people may evacuate because they've stopped trusting the warnings
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Reading the Odds Before an Eruption W1-mt_edaoZRkK6M-s1

  1. Number of tourists visiting · Alert levels are set from ground movement, gas readings, and earthquake activity, not from how many people are visiting.
  2. The average time between past eruptions or quakes · A recurrence interval looks backward at how often eruptions or quakes have happened, which helps estimate the odds of the next one.
  3. False · Slip rate only shows how fast strain builds up over years, not the exact day it will release.
  4. Mount Often · Mount Often has a much shorter recurrence interval, so its bar for near-term risk is far taller than Mount Quiet's.
  5. It may be due for another eruption soon · Since eruptions have come roughly every 20 years and it's been 19, the pattern suggests the odds are rising.
  6. Volcanic ash breaks down into rich soil that grows better crops · Volcanic ash weathers into mineral-rich soil, which is why many farming communities settle near active volcanoes despite the risk.
  7. Money and resources shape who can evacuate and recover, not just distance from the hazard · Recovery speed often depends on money and resources, which means disaster risk falls unevenly across rich and poor communities.
  8. Fewer people may evacuate because they've stopped trusting the warnings · Repeated false alarms erode trust, so people may hesitate or ignore a warning even when it turns out to be real.
Worksheet · LightMySky