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Earthquakes have taken millions of lives in the past. Millions of lives could be taken in the future if we don’t take action. Did you know that earthquakes occur many times a day. It’s hard to believe but it's actually true. Although these small earthquakes don’t cause any damage, large earthquakes can occur anytime and I am sure that some people aren’t prepared for a big earthquake. For this inquiry, the natural hazard I have chosen is an earthquake. I chose this natural hazard because I’ve always wanted to know how the ground shakes and what causes it to shake. My fertile question for this inquiry is what should be done to mitigate the negative effects of an earthquake? I will also talk about the different effects of an earthquake and how we can mitigate them.
What is an earthquake?
An earthquake is an event in which the surface of the earth suddenly starts to shake, tremble or rock. The shaking of the ground can be quite weak and it can also be really violent. Earthquakes are really dangerous and really common, earthquakes occur many times in a day, and thousands occur each year. We don't feel most of them because they are really small.
The earth's crust is divided into many pieces called tectonic plates. There are seven major tectonic plates and eight minor tectonic plates. The tectonic plates fit together like puzzle pieces, but they don’t stick together. The tectonic plates float on the earth’s mantle, a thick layer of hot moving rock. The tectonic plates are always moving slowly, and friction causes them to get stuck at their edge, and the friction builds up. When there is too much friction it becomes really violent and when the stress on the edge overcomes the friction an earthquake occurs. It releases energy in the form of waves that travel through the earth's crust which is what causes the shaking in the ground which we experience.
https://www.youtube.com/watch?v=AcH2GP-59ro
https://www.phivolcs.dost.gov.ph/index.php/earthquake/introduction-to-earthquake
https://www.amnh.org/explore/ology/earth/plates-on-the-move2
https://www.usgs.gov/faqs/what-earthquake-and-what-causes-them-happen
The effects
Earthquakes can be really dangerous. The effects of an earthquake can also be dangerous. There are many different effects of an earthquake, but the main ones I am going to talk about are ground shaking, tsunami, liquefaction and landslides. These are probably the worst effects on an earthquake, and many deaths are caused by these effects.
The most common effect of an earthquake is ground shaking. The shaking is caused by seismic waves traveling through the earth, the seismic waves can be relatively soft in small earthquakes and extremely powerful in large earthquakes. In the Alaskan earthquake on march 27, 1964, strong ground shaking lasted as long as seven minutes which caused a lot of damage. Powerful seismic waves can cause the ground to shake a lot which can result in buildings being damaged or destroyed. People inside buildings or near it during strong earthquakes are at great risk because if buildings collapse a lot of people could die or be really injured.
This image shows the seismic waves traveling through the earth. There is the mantle, the shadow zone, outer core and the inner core. The different coloured lines show where the waves are passing through.
Earthquakes can cause small or extremely large tsunamis. Tsunamis are a major threat to many parts of the world, particularly those located in the pacific ocean basin. Tsunamis are a series of extremely long waves that can travel extremely long distances in a short amount of time. Tsunamis are caused by the seafloor moving vertically during an earthquake. Tsunamis can travel at really high speeds, they can reach speeds of up to more than 700km/h in deep ocean, which is as fast as some jet planes. They can also reach heights of more than 27 meters when they are near the coast. Big tsunamis can cause lots of damage to structures and can also kill many people.
Strong seismic waves can cause liquefaction. Liquefaction occurs due to strong shaking causing loosely packed, waterlogged sediments near the ground surface to lose its strength. The strong vibration in the ground increases the water pressure between soil grain, which then transforms soil into mud. Liquefaction beneath houses or other structures can cause significant damage. After an earthquake stops all the wet mud gets left behind from liquefaction, which then becomes a big problem. Liquefaction can cause roads to be covered in mud and footpaths, then you can not go anywhere until the mud is cleaned.
Strong earthquakes can cause landslides by direct rupture and continued shaking. Seismic activity has long been a major contributor to landslides around the world. When plate tectonics shift, the soil beneath them shifts as well. When earthquakes strike places with steep slopes, the soil often slips, resulting in landslides. Furthermore, earthquake-induced ashen debris flows can cause widespread soil movement. Landslides can easily damage structures in their path and as well as block roads and railway lines, and they can take hilltop houses with them.
https://topex.ucsd.edu/es10/es10.1997/lectures/lecture20/.
https://www.youtube.com/watch?v=ILlyfwDwJVs
https://www.usgs.gov/faqs/what-liquefaction
https://people.uwec.edu/jolhm/eh2/rogge/causes.htm
https://topex.ucsd.edu/ure20/.
Ways to prevent deaths and inquiries
The average annual deaths from natural disasters in the United States are shown in this graph. As shown in this graph, earthquakes cause far more deaths than any other natural hazard, making earthquakes the deadliest natural hazard with 20,000 deaths per year. Volcanoes are responsible for 540 deaths per year, floods for 88, tornadoes for 68, and hurricanes for 45. This demonstrates the devastating nature of earthquakes.
All families that live in high risk zones should prepare an emergency plan. Planning on what to do in emergencies can be really helpful, because when there is an emergency you don't have to think about what you need to do. An emergency plan for earthquakes should include what should be done if there is an earthquake, and where you can be safe. You should create safe zones in each part of your house or your workplace. A safe zone would be where there is strong furniture like a sturdy table or desk and also where there aren’t things hanging on the wall. You should also practice drop cover hold. Drop to the ground, take cover under a sturdy table or desk and hold and hold onto one of the legs of the furniture. These are some things your emergency plan should include.
If you live in an area where earthquakes often occur, you need to make sure that your house would be a safe place during an earthquake. You need to make sure that no heavy objects fall, because that could cause damage and inquiries. You should secure large furniture like bookshelves and shelves to the wall to avoid them from falling. Any objects that are hanging on the wall should be secured, and none of the heavy objects should not be hung over beds and couches and other places where you often spend time.
https://www.waikatoregioncdemg.govt.nz/.
https://www.earthquakeauthority.com/Blog/2020/How-to-Protect-Your-Home-before-an-Earthquake
Ways to prevent damage to properties
Many big buildings and houses are damaged or destroyed due to big earthquakes. Each year earthquakes cause billions of dollars worth of damage worldwide. We need to take action so we can prevent further damage, and I have some solutions for this problem. I think the main solutions are base isolation, seismic dampers, and building houses with earthquake resistant materials.
Base isolation was invented during the 1970s in New Zealand by Bill Robinson. Between the building's foundations and the structure above, flexible bearings or pads constructed of layers of rubber and lead are placed. These base isolators move and stretch under pressure, absorbing the kinetic energy of seismic waves and much of the pressure of an earthquake decreasing swaying and shaking. This is good because the isolators allow structures to move elastically, which makes them much safer in an earthquake.
Seismic dampers are used in lots of countries and I think they do a good job in earthquakes. A seismic damper is a mechanical device that works by absorbing the kinetic energy of seismic waves. Seismic are mainly used for building but they can also be used in homes. I think this is the best method to prevent damage to property because it’s a bit cheaper than installing base isolation, and it’s much more common.
Building all new houses in risk zones with earthquake resistant materials is really efficient. Every new house in areas where earthquakes are common should either be timber framed or steel framed. That is because they are both seismically safe and steel frames are also fire resistant.
Base isolation is a bit more expensive than seismic dampers. Base isolation generally costs around $10,000 for each unit. Seismic dampers cost around $6,500.
The building code should be changed in all high risk zones in New Zealand. They should add that all new houses and buildings should have enough seismic dampers installed. I think that the government should subsidize 40% of the cost of each seismic damper for the next five year.
In conclusion, seismic dampers should be implemented and an emergency plan should be followed to mitigate the negative effects of an earthquake. I am sure if we follow this plan, not only we will be safer in the future but our future generation will also be safe. We don’t want any more lives being taken and cities being destroyed because of earthquakes. If we want to stop this we must take action now.
https://www.sciencelearn.org.nz/resources/1022-base-isolation-and-seismic-dampers
https://www.buildmagazine.org.nz/assets/Uploads/Build-186-23-Shorts-Residential-base-isolators.pdf?
https://www.hindawi.com/journals/tswj/2014/189106/
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