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A seismometer is a tool that scientists use to measure earthquakes. These special instruments can feel even the smallest shakes in the ground that humans can't notice. Seismometers help us learn about earthquakes and keep people safe.
What is a seismometer?
A seismometer is a device that records the motion of the ground during an earthquake. Scientists place these tools in different spots around the world to track earth movements. Some seismometers are small enough to fit in your hand, while others are as big as a refrigerator!
What does a seismometer measure?
Seismometers measure how much the ground moves during an earthquake. They can detect three types of movement:
● Up and down motion
● Side to side motion
● Back and forth motion
These tools are so sensitive they can pick up tiny shakes from far away earthquakes or even large trucks driving by.
How does a seismometer work?
Most seismometers work using a simple idea. Inside the device is a heavy weight hanging from a spring. This weight tends to stay still because of inertia (the same reason you move forward in a car when it stops suddenly).
When an earthquake happens, the ground and the seismometer case move, but the heavy weight tries to stay in place. The difference between the moving case and the still weight is measured and turned into a signal. This signal can be drawn on paper as squiggly lines or sent to a computer.
Modern seismometers use electronics to sense these movements and can detect ground movements smaller than the width of a human hair!
Scientists use information from many seismometers to figure out how strong an earthquake was and where it started. This helps them warn people about future earthquakes and build safer buildings.
Fun Fact: Modern seismometers are so sensitive they can detect earthquakes happening on the opposite side of the planet and even recorded the impact of the Perseverance rover landing on Mars in 2021! These instruments can measure ground movements smaller than the width of a hydrogen atom.
What is the main purpose of a seismometer?
To predict when earthquakes will happenTo measure the motion of the ground during earthquakesTo prevent earthquakes from occurringTo create earthquakes in a laboratoryWhy are seismometers placed in different locations around the world?
To make them easier to maintainTo track earth movements globallyBecause they are too expensive to keep in one placeTo test which location works bestAccording to the passage, what makes the weight inside a seismometer stay relatively still during an earthquake?
MagnetismFrictionInertiaGravityWhich statement best summarizes the main idea of the passage?
Earthquakes are dangerous and unpredictable natural disastersSeismometers are complex machines that only scientists can understandSeismometers measure ground movement to help us learn about earthquakesModern technology has replaced traditional seismometersWhat is the primary reason seismometers are important, according to the passage?
They help scientists learn about earthquakes and keep people safeThey are valuable collectible scientific instrumentsThey provide jobs for many scientists around the worldThey are required by law in all scientific laboratoriesIn the passage, the word "sensitive" most nearly means:
EmotionalFragileAble to detect small changesExpensiveThe passage compares the size of some seismometers to:
A human hand and a refrigeratorA car and a truckA pencil and a computerA spring and a weightWhen the passage mentions "inertia," it is referring to:
The speed at which earthquakes travelThe tendency of an object to resist changes in motionThe electronic signal created by seismometersThe squiggly lines drawn on paper
