Week 29 · Theme 4, Unit 4 Shifting Surfaces, Concept 4.3 Volcanoes (B) and Unit Project “Forces That Shape the Earth” · 3 lessons
2
Predicting eruptions and staying safe
Discovery Education Science P4: Term 2, Unit 4, pp. 179–195
GoalDescribe the signs scientists watch to predict an eruption and the steps that keep people safe.
New words
monitor · to watch and measure something over timeevacuate · to leave a dangerous place and go somewhere safeemergency kit · a bag with the things you need in an emergency
Explanation
Scientists cannot say the exact day a volcano will erupt, but they can see warning signs. Before an eruption, magma moves under the ground. It causes many small earthquakes. The ground may swell, like a slowly filling balloon. The gases that come out may change, and the ground and water nearby may get hotter. Scientists monitor these signs all the time with instruments that sense shaking, tilting, heat and gas, and with pictures from satellites. When the signs get stronger, they warn the authorities. People can then evacuate along planned routes, carry an emergency kit with water, food, a torch and masks for ash, and listen to the official messages. Preparing early, and following the plan, keeps people safe.
Warning sign
What may be happening
many small earthquakes
magma is moving
ground swelling
magma is pushing up
changing gases
magma is nearer the surface
hotter ground
heat is rising
Worked examples
Reading data. A scientist counts small earthquakes near a volcano each day. The numbers are 2, 3, 2, 7, 15 and 28. The numbers jump on the last three days, which is a warning sign. From the 1st to the 6th day it rose by 28 − 2 = 26.
siren→listen to news→take the emergency kit→walk the safe route
A safety plan. Hana’s class makes a plan for a pretend town. First a siren sounds. Next people check the radio for news. They pick up their emergency kits. They walk the marked route to the safe place.
An emergency kit. Mina packs water, tinned food, a torch, a radio, masks and a first-aid kit. She does not pack toys that need plugs. She thinks about what is needed for the first day.
Class activity
Make a plan. With a grown-up, make an emergency plan for a pretend home near a volcano, or for another event such as a storm. Draw a map of the exit routes and the safe place. List six things for an emergency kit, with a reason for each. Practise with your family for two minutes: how fast can you find the kit? This is practice only, not a scary game.
Practice
1
Name two warning signs that a volcano may erupt.
Any two: many small earthquakes, the ground swelling, changing gases, hotter ground.
2
Why do scientists monitor a volcano all the time?
To spot changes early and warn people in time.
3
There were 4 small earthquakes on Monday and 12 on Tuesday. How many more on Tuesday?
