COVER to COVER
Moving Land
How Earthquakes Form and Affect Our Planet
Written by Kizzi Roberts
COVER to COVER
Moving Land
How Earthquakes Form and Affect Our Planet
Written by Kizzi Roberts
Introduction to Earthquakes
On April 18, 1906, a large earthquake hit San Francisco The ground shook hard The earthquake didn’t last long, but it caused a lot of damage Buildings collapsed Fires broke out Eighty percent of the city was nearly destroyed It was the deadliest earthquake in US history Back then, people knew an earthquake caused the ground to shake They knew earthquakes made cracks in the ground, but they didn’t know why
When the Earth Moves
The Earth is made of several layers These layers are grouped into three parts The inside layer is called the core It’s the center of the Earth The middle layer is called the mantle The outer layer is called the crust The crust is Earth’s surface where we live
Tectonic Plates
Earth’s crust is not a solid layer The crust is made of sections called tectonic plates Tectonic plates rest on the mantle The mantle is made of molten rock called magma Tectonic plates are always moving in different ways They can collide or separate, or they can slide next to each other Each movement causes something to happen on Earth’s crust Sometimes a volcano forms Sometimes an earthquake occurs Sometimes a deep trench opens, and sometimes new crust is made
Earthquakes and Volcanoes
When plates separate or collide, sometimes a pathway between the mantle and the crust opens This pathway allows hot magma to rise Once magma reaches Earth’s surface, it is called lava
This is how a volcano is made Volcanoes usually form along the edges of plates But they can also form in the middle of a plate In some areas of the mantle, a column of superhot magma rises This area is called a hot spot
A hot spot doesn’t move like tectonic plates As plates pass over a hot spot, the Earth’s crust weakens Magma pushes through the crust and creates volcanoes When this happens under the ocean, islands can form The Hawaiian Islands are actually a chain of volcanoes
Do earthquakes cause volcanoes to erupt? Sometimes! The earthquake must be powerful. It must happen near the volcano, and the volcano must be close to erupting anyway.
Earthquakes in the News
Earthquakes are always happening around the world
Some earthquakes are mild and don’t cause damage
Stronger earthquakes cause great damage across cities or regions There have been several memorable earthquakes throughout history Let’s learn about a few
Scientists detect about 55 earthquakes every day. That means over 20,000 earthquakes happen around the world every year!
The Great Earthquakes
Powerful earthquakes cause damage by themselves But sometimes they trigger landslides or tsunamis When this happens, even more damage is done The largest earthquake ever recorded was in 1960 in Southern Chile Tsunamis then caused damage in Hawaii, Japan, and the Philippines The West Coast of the United States suffered too
On March 27, 1964, an earthquake shook Alaska. It lasted almost five minutes. It was the most powerful earthquake in the history of the United States In 2001, an earthquake hit a desert in Peru This earthquake caused massive landslides, and big cracks formed in the ground
Tsunamis
Earthquakes can occur under the ocean Volcanoes can erupt underwater too When one plate in the ocean slides under another, this can displace water This means if one plate drops and the other rises, water pushes up In both cases, the water moves extremely fast It can create dangerous, giant waves This event is known as a tsunami (soo-NAH-mee)
In 2004, a major earthquake hit the Indian Ocean The earthquake caused a tsunami The tsunami hit many countries, including Indonesia, India, Myanmar, Sri Lanka, and Thailand
Scientists can’t always predict when an earthquake will trigger a tsunami In 2004, tsunami warning systems failed As a result, many people didn’t know the tsunami was coming Some people survived by following the animals Animals like elephants, buffalo, and flamingos seemed to sense something They fled from low areas to higher ground People who witnessed that behavior also ran to higher ground Scientists don’t know if these animals really knew what was happening, but their actions saved lives
The Ring of Fire
Most earthquakes have something in common: they usually occur along the Ring of Fire The Ring of Fire is also called the CircumPacific Belt It stretches for 25,000 miles and follows a path along the edges of the Pacific Ocean It is where many of Earth’s tectonic plates meet
Mount St. Helens in Washington
The Ring of Fire is named for the active volcanoes found there More than 75 percent of Earth’s volcanoes are found on this path About 90 percent of earthquakes happen somewhere along the Ring of Fire This includes many of the most powerful earthquakes in history
Because of this, the Ring of Fire is a good place for scientists to study earthquakes
Digging Deep
The science of earthquakes is called seismology Scientists who study earthquakes are called seismologists Scientists use seismometers to study earthquakes A seismometer is an instrument that measures the ground shaking during an earthquake The instrument used to record the shaking is called a seismograph Seismographs are attached to the ground, so they move when the ground moves Old seismographs used a pen and paper to record the size of an earthquake Today, seismographs record data on computers They tell how much the ground moves during an earthquake
Magnitude
The size of an earthquake is called its magnitude The magnitude is a number that tells how much energy is released during an earthquake
An earthquake measuring above a 6 magnitude is a strong earthquake
Each number is ten times stronger than the previous number For example, a 7 magnitude earthquake is ten times stronger than a 6 magnitude
Earthquakes measuring above an 8 magnitude are really powerful
They usually cause a lot of damage Remember the largest earthquake in history happened near Chile? It had a magnitude of over 9!
Aftershocks
After an earthquake ends, people may still feel the ground shake This is called an aftershock Aftershocks may happen hours, days, or even months after the main earthquake Aftershocks happen because the energy from the earthquake can pass to other rocks These rocks can break and release more energy, causing the ground to shake
As days pass, the aftershocks lessen Even though aftershocks are usually not as strong, they can still cause harm and damage
Out of This World
Do earthquakes happen on other planets? Scientists sent seismometers to the moon and to Mars to find out They recorded the ground shaking on both surfaces
But these events aren’t called earthquakes When the ground shakes on Mars, it’s called a marsquake On the moon, it’s a moonquake!
Conclusion
Today, scientists know a lot about earthquakes, but there is still much to learn The more scientists learn about earthquakes, the more questions they have For example, is a magnitude 10 earthquake possible?
Scientists say a magnitude 10 earthquake is not likely Specific plates would have to move in certain ways at the same time for that to happen However, scientists continue to study earthquakes so people can be more aware of when to expect an earthquake and how to protect themselves so many lives can be saved in the future
GLOSSARY
aftershock - when the ground continues to shake after an earthquake Aftershocks happen because the energy from the earthquake can pass to other rocks These rocks can break and release more energy
core - the center of the Earth The inner core is solid, and the outer core is made of hot liquid rock Both parts of the core are made mostly of iron and nickel
crust - the thin outer layer of the earth This is where we live displace - when something is moved from its original place, usually by force
hot spot - an area of the earth’s mantle where a column of hot magma rises This often leads to volcanoes erupting lava - hot liquid rock when magma reaches the Earth’s surface Lava usually comes up through a volcano
magma - hot molten rock located beneath the earth’s surface magnitude - a measurement that tells the strength of an earthquake, or how much energy is released during an earthquake
mantle - the middle layer of the Earth It sits between the crust and the core
seismologist - a scientist who studies earthquakes
seismograph - an instrument used to record earthquake activity It reports how much shaking occurs during an earthquake
seismometer - the instrument used to measure the ground shaking during an earthquake
tectonic plates - large sections of the Earth’s crust that can move and interact, causing earthquakes
tsunami - a giant wave caused by the displacement of water, often triggered by tectonic plates moving under the ocean
This book is dedicated to young readers everywhere. May you thrive in your wondrous reading journeys.
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Reading Partners Cover to Cover
Moving Land: How Earthquakes Form and Affect Our Planet by Kizzi
Roberts
©2025. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form by any means electronic, mechanical, or photocopying, recording or otherwise without the permission of the author.
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ISBN: 979-8-89138-731-7
Printed in the United States
COVER to COVER
About this Book
If you’ve ever felt the ground shake, you may have experienced an earthquake. Earthquakes occur in many places around the world. Some earthquakes are mild, while others cause great damage. What causes earthquakes to happen? How do scientists study them? Can quakes happen on other planets? Uncover the answers to these questions and more!
About Reading Partners
Reading Partners is a national early literacy nonprofit that partners with schools, community-based organizations, volunteers, and families to provide individualized tutoring and other evidence-based literacy support for students striving to read at grade level. The Reading Partners Cover to Cover series is for readers of all levels with a focus on instructional practices rooted in the science of reading. The stories in the series include and celebrate a broad range of affirming characters and experiences. The Reading Partners team recognizes that learning to read is a civil right, and we aim to ensure students have the resources necessary to foster lifelong literacy skills and confidence to actualize their limitless potential. We envision a future where every reader has the skills they need to read a book from cover to cover and then reach for another!