En anglais

Reading the Odds Before an Eruption

Science · Volcanoes & Earthquakes · ages 12-14

Name ______________________ Date ____________

Which observation does not directly measure volcanic unrest?
- Measurements of ground swelling
- Counts of tourists at the visitor center
- Measurements of gas leaving the volcano
What is a recurrence interval?
- The average gap between past events of a similar kind
- The fixed waiting period before every future eruption begins
- The total time needed to evacuate every nearby community
A fault's slip rate can tell scientists the exact day an earthquake will happen.
Circle one: True False
These fictional model estimates show eruption chance over the same upcoming ten-year period (%). Which volcano has the higher estimate?
- Mount Cedar
- Mount Stone
- Both estimates are equal
A volcano's past eruptions had an average gap of 20 years. Its last eruption was 19 years ago. What follows from this information alone?
- An eruption must begin during the next calendar year
- An eruption cannot occur until another full year has passed
- The average cannot establish the next eruption date
A family knows its volcano could erupt. Its income depends on crops grown in soil formed from old volcanic ash. Which conclusion about its reason for staying is supported?
- The old ash shows that the farm now faces a lower eruption hazard
- The fertile soil supports crops and income
- The family's crop income would be easy to replace after moving
Two towns face the same estimated volcanic hazard. One has evacuation buses and repair funds. The other lacks both. What does this comparison show?
- Resources can affect evacuation and recovery
- Equal hazard estimates mean the towns face equal overall disaster risk
- Repair funds affect recovery, but transport is separate from disaster risk
Residents hesitate at a new evacuation warning after earlier evacuations were not followed by eruptions. Officials never explained the uncertainty. Which interpretation best fits the lesson?
- The earlier outcomes show that officials lacked enough evidence to justify evacuation
- The earlier outcomes show that residents should give the current warning less attention
- Residents may lose trust and hesitate at the next warning

Answer key

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

Reading the Odds Before an Eruption W1-mt_edaoZRkK6M-s1

Counts of tourists at the visitor center · Tourist counts measure visitors. Ground deformation and volcanic gas measurements can provide evidence about unrest.
The average gap between past events of a similar kind · A recurrence interval describes average gaps in past records. It does not set a fixed waiting time for future events.
False · Slip rate describes movement over time. It helps assess long-term hazard with other evidence, but does not give an exact earthquake date.
Mount Cedar · Mount Cedar's estimate is 38%, greater than Mount Stone's 12%. Neither value guarantees what will happen.
The average cannot establish the next eruption date · Individual eruption gaps can differ from their average. Nineteen elapsed years does not establish when the next eruption will happen.
The fertile soil supports crops and income · Fertile soil supports the family's livelihood. Old ash does not establish a lower future hazard, and the question gives no evidence that income would be easy to replace elsewhere.
Resources can affect evacuation and recovery · Equal physical hazard estimates do not establish equal community risk. Buses can help people leave safely, and repair funds can support recovery.
Residents may lose trust and hesitate at the next warning · Unexplained warnings may reduce trust. Earlier outcomes alone do not establish whether past evacuations were justified or how much danger the current warning concerns.