What is an Earthquake?
An earthquake is a sudden strong shaking of the ground. They happen more frequently along active and major fault lines. However, earthquakes can still be experienced in areas in which they are less common as well. The violent shaking can lead to property damage, injuries, and shifting of the landscape. Major earthquakes can leave communities without necessary shelter or supplies for an extended amount of time depending on their severity.
- The USGS offers information for kids to help them learn more about the science behind earthquakes: http://earthquake.usgs.gov/learn/kids/eqscience.php. Weather Wiz Kids also offers a resource: http://www.weatherwizkids.com/weather-earthquake.htm.
- Adults can learn more about earthquakes from the New Mexico Bureau of Geology and Mineral Resources: http://tremor.nmt.edu/faq/what.html
Why Do Earthquakes Happen?
When tectonic plates (the pieces of the earth’s hard outer surface) move against each other, they cause a detectable shaking. These plates move because they are floating on top of the planet’s liquid mantle, which also moves.
- UPSeis offers additional information about the causes of earthquakes: http://www.geo.mtu.edu/UPSeis/why.html. The Incorporated Research Institutions for Seismology also offer a good source of information: https://www.iris.edu/hq/inclass/fact-sheet/why_do_earthquakes_happen.
- The Rice Space Institute similarly offers further information: http://earth.rice.edu/mtpe/geo/geosphere/hot/3earthquakes.html.
The Richter Scale
What exactly is the difference between an earthquake that makes the dishes rattle and one that brings down skyscrapers like those that we see in movies? The answer to that can be found by understanding the Richter scale. The scale is a base 10 logarithmic scale meaning each level is 10 times greater than the next. This means that an earthquake with a magnitude of 3 is 10 times more intense than one with a magnitude of 2 and a magnitude of 4 is 100 times more intense than 2.
- Less than 3.5: Often goes unnoticed, but still picked up by seismic recording devices.
- 5 – 5.4: These are usually felt, but they rarely cause much damage.
- 5.5 – 5.9: Can cause slight damage to well-constructed buildings and more severe damage to buildings that are not built or maintained to withstand earthquakes.
- 6 – 6.9: Destructive in populated area.
- 7 – 7.9: Widely destructive.
- 8+: These are known as great earthquakes and can cause severe damage to very large areas.
To learn more about the Richter scale, you can visit the Nevada Seismological Laboratory at http://crack.seismo.unr.edu/ftp/pub/louie/class/100/magnitude.html or the Missouri Department of Natural Resources at http://dnr.mo.gov/geology/geosrv/geores/richt_mercali_relation.htm.
When we discuss earthquakes, the subject of the epicenter usually comes up. We want to know where the earthquake started as well as where it was the most violent. When we talk about earthquake epicenters, our attention is on the earth’s surface directly above the focus of an earthquake.
How do scientists determine where that focus is? They utilize the waves given off by earthquakes and use those to triangulate the source. Sometimes they make an original estimate based on immediate data and then later update it to be more accurate by combining information from several sources.
- To learn more about what triangulation is, you can visit the Qualitative Reasoning Group at Northwestern University: http://www.qrg.northwestern.edu/projects/vss/docs/navigation/1-what-is-triangulation.html.
- If you would like to find out about the different ways that scientists utilize triangulation to determine the center of an earthquake, visit Earthguide, a part of the Geosciences Research Division at Scripps Institution of Oceanography: http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/swf_earthquake_triangulation/p_activity_eqtriangulation.html.
Do you know everything there is to know about earthquakes? Here are a few facts to add to your personal knowledge:
- Earthquakes can strike at any time of the year, regardless of if it is day or night.
- Smaller earthquakes often follow larger ones.
- California has earthquakes that cause damage more frequently than in the other states.
- Not all faults are identified before an earthquake occurs.
- The biggest recorded earthquake was a 9.5 on the Richter scale. It occurred in Chile in 1960.
- The equipment used to measure an earthquake is called a seismometer.
- Alaska has the most earthquakes out of all of the US states.
- Most earthquakes are less than 50 miles deep.
For more earthquake facts, visit Emporia State University: https://www.emporia.edu/dotAsset/f8d91047-3d2a-4bcd-b3f2-012a62a85346.pdf or San Diego County: http://www.sandiegocounty.gov/oes/disaster_preparedness/oes_jl_earthquakes.html.
To learn about some common earthquake myths (such as California falling into the ocean), visit California State University, San Marcos: http://www.csusm.edu/em/procedures/earthquake_myths.html.
Earthquakes are not preventable, but there are still some things that we can do to minimize their impact when they occur.
- Have your building assessed to see if it can withstand an earthquake.
- Remove and repair potential hazards in your home and office.
- Create a disaster kit that includes water, food that does not require cooking, a fire extinguisher, tools for shutting off utilities to the building, medical supplies, necessary medicines, vital documents, a flashlight, a radio, dry shoes, and dry clothing.
- Make a disaster plan that accounts for pets, tsunami evacuations, evacuating to a safe area, and making contact with family members.
- Learn how to shut off the main gas, water, and electricity for your building.
- Locate nearby areas to evacuate to that are above tsunami level and away from tall buildings and trees.
For more tips and advice, visit:
- The University of California, Berkeley Seismological Laboratory: http://seismo.berkeley.edu/outreach/be_prepared.html
- The University of Missouri Extension: http://extension.missouri.edu/p/G1905
- The Federal Emergency Management Agency: http://www.fema.gov/media-library/assets/documents/34326
- The Centers for Disease Control and Prevention: http://emergency.cdc.gov/disasters/earthquakes/prepared.asp
During an Earthquake
Drop and Cover! Earthquakes give little warning and time to react.
- If you are indoors, move away from potentially dangerous objects, drop to the ground, get under a secure object such as a table, and hold onto it.
- If you are outdoors, move away from tall buildings, power lines, and other hazards.
- If you are in a vehicle, pull to the side of the road and remain inside of the vehicle.
- If none of the above applies, remember that one of the most important things is to protect your head as much as possible.
To learn more about what to do during an earthquake, visit:
- Ready.gov: https://www.ready.gov/earthquakes
- The United States Department of Labor, Occupational Safety & Health Administration: https://www.osha.gov/dts/earthquakes/preparedness.html
- The University of Dallas: http://udallas.edu/offices/cso/ef.php
After an Earthquake
After an earthquake is the time to assess for damages. Be careful because additional smaller after-shock earthquakes may occur during this period.
- Check for injuries. Assist anyone in immediate danger.
- Check for wires shorting out as well as breaks in water and gas lines. Shut off utilities as needed.
- Stay away from damaged areas.
- Evacuate the building if it may be damaged. If you hear creaking noises, leave the building until it has settled and/or been inspected.
- Bring your earthquake kit with you when evacuating, and leave a note somewhere safe and visible in case others come to look for you.
To learn more about what to do, visit:
- Be Prepared California: http://www.bepreparedcalifornia.ca.gov/beinformed/naturaldisasters/earthquakes/Pages/Earthquakes.aspx
- The Red Cross: http://www.redcross.org/prepare/disaster/tsunami
Resources for Parents and Educators
Taking care of children during an earthquake can be an added struggle, but with a little preparation on everyone’s part, the whole family can make it through safely.
Teach young children the basics of moving away from items that may topple as well as dropping and getting beneath a solid piece of furniture. Let them practice and learn about earthquakes in a safe environment so that they are ready for the real thing.
Infants should be held to your chest while you drop and get beneath a safe object.
To learn more, visit:
- Shake Out: http://www.shakeout.org/downloads/Earthquake_Safety_YoungChildren_Infants.pdf
- Earthquake Country: http://earthquakecountry.org/step5/
- The Central United States Earthquake Consortium: http://www.cusec.org/earthquake-safety/what-to-do-in-an-earthquake/70.html
Additional Earthquake Information
- National Geographic discusses the destruction left behind by earthquakes: http://environment.nationalgeographic.com/environment/natural-disasters/earthquake-profile/.
- The Earth Research Institute offers quizzes, videos and more to test your earthquake knowledge: http://projects.eri.ucsb.edu/understanding/.
- Find out where the latest earthquakes have been with Volcano discovery: https://earthquakes.volcanodiscovery.com/.