This module will discuss EARTHQUAKES and TSUNAMI Facts.
- Earthquake and Tsunami facts
- What they are
- How they are classified
- The dangers associated with them
- How to determine your RISK Level of them
What are Earthquakes & Tsunamis?
The Earth is made up of several layers surrounding an inner core. [See picture to the right.] The outermost shell, the “Crust” and the “Upper Mantle” are made up of huge irregularly shaped slabs of rock called the “Tectonic Plates”. These plates can range in thickness from 40 miles to 125 miles thick and be bigger than entire continents.
There are 15 major Tectonic plates and dozens of minor ones. These Tectonic Plates float on the Lower Mantle and move around at a speed anywhere from one inch to five inches per year or approximately a mile every 13,000 years.
As these Tectonic Plates move around they start running into each other. Where these plates run into each other is typically called a “Fault Line”. This is where Earthquakes tendto happen – along Fault Lines. One of the most famous Fault Lines is the San Andreas Fault in California. This Fault Line is 650 miles in length and runs from San Francisco all the way down to the Mexican border.
When these plates run into each other, sometimes one Tectonic Plate just moves under the other Tectonic Plate. However, sometimes they press up against each other and neither plate wants to move. When this happens pressure starts building up between the two plates. Eventually the pressure is released in the form of seismic wave.
Sometimes pressure can be released anywhere within the Tectonic Plate, away from the edges, due to internal stresses associated within the plate. Read: You don’t need to be on top of a Fault Line to be impacted by an Earthquake. Earthquakes can happen anywhere and have been reported in all 50 states of the USA.
Predicting when and where an Earthquake is going to happen is not possible – at least not yet. Scientists can give very broad estimates, but nothing that a planned evacuation can be based upon. Therefore, Earthquakes happen with little or no warning.
Earthquakes are killers. The deadliest Earthquake on record was the 1556 Shaanxi Earthquake in China. That Earthquake killed 830,000 people. More recently, the 1976 Tangshan Earthquake in China killed 779,000 people and even more recent, The 2004 Indian Ocean Earthquake is responsible for killing 280,000 people.
When the interaction of the Tectonic plates happens out in the ocean, close to a shoreline, the energy released may cause a Tsunami. Being that Tsunamis are closely related to Earthquakes, let’s take some time here to discuss what they are and how they can be formed.
Some Tsunami facts: A Tsunami is a set of waves generated by a disruption in the ocean floor. This disruption may be caused by an Earthquake, Underwater Landslides, Volcanoes and Meteor impacts.
The wave sizes of Tsunamis can range in size: from small ripples to wave heights in excess of 100 feet. These waves can travel across an entire ocean at speeds up to 500mph.
“More than 80% of the world’s Tsunamis were caused by earthquakes and over 70% were observed in the Pacific Ocean. Tsunamis have been reported in the Pacific Ocean, Atlantic Ocean, Indian Ocean, Mediterranean Sea and the Caribbean Sea. However, Tsunamis can happen at any time in any large body of water. ” Tsunami Glossary 2013 http://unesdoc.unesco.org/images/0018/001882/188226E.pdf
The immediate impact from a Tsunami will be the coastline that is in the direction the Tsunami is traveling. But the actual wave impact can travel far inland as it moves into bays, harbors and river systems that are located in the impacted area.
As with Earthquakes, you cannot predict when Tsunamis will occur. However, once a Tsunami has been generated, a network of buoys and sensors located throughout the Pacific, Atlantic and Indian Oceans are constantly being monitored and the data is being coordinated through several multi-national governmental organizations. The map below shows the distribution of these sensors.
When the data indicates the potential for a Tsunami to make landfall, the organizations (NOAA in the USA) will issue Tsunami Watches or Warnings as necessary. The amount of time associated with these warnings and alerts is dependent upon where the actual incident occurred in relationship to the area that will be impacted.
Tsunamis are killers. The 2004 Indian Ocean Earthquake killed over 230,000 people. The Tsunami generated by the 2011 Great East Japan Earthquake killed almost 16,000 people.
Earthquakes & Tsunamis.
Before we discuss the classification system for Earthquakes, there is one more term we need to discuss: Epicenter. The epicenter is the point on the Earth’s surface that is directly above the focus point where the fault ruptures or where the event originates. It is important to know this location because this is usually where (in most cases) the greatest amount of damage will occur. This is the shortest distance from the event to the surface of the Earth. Look at it as “Ground Zero”.
Earthquake magnitude is measured by two systems: The Richter Scale and The Moment Magnitude Scale.
The Richter Scale was developed by Charles Richter back in 1934 and used a formula based upon the largest wave recorded on a seismometer. The scale was originally developed for California, but other scales were also developed that used Richter’s scales methodology. However, over the years, several inaccuracies were uncovered in the Richter Scale, especially for the larger magnitude earthquakes.
The Moment Magnitude Scale was developed to overcome the Richter Scale’s inaccuracies and is the scale used most today. However many people still refer to an Earthquakes magnitude by the Richter Scale, even if the Moment Magnitude Scale is actually being used. The workings of this scale are rather technical, so we are just going to focus on the main points.
If you do want to learn more about these Earthquake Magnitude Scales, please click on this link: http://www.geo.mtu.edu/UPSeis/intensity.html
Here are the important things you should know about the scale:
These are “Logarithmic Scales” used to report on the magnitude of the earthquake. That means that as the numbers go up, each number indicates a magnitude factor that is 10X more powerful than previous number (the lower number).
- A reading of 3 is 10X more powerful than 2.
- A reading of 6 is 10X more powerful than 5, etc.
Tsunamis Classifications are a little difficult to nail down.
Some people classify Tsunamis based upon its cause.
- Caused by an Earthquake: A Tectonic Hazard.
- Caused by a Landslide: A Mass Movement Hazard.
- If looking at just the water damage that a Tsunami can cause – it could be classified as a Hydrological Hazard.
Some classify Tsunamis according to intensity. This intensity was determined by Hm (the maximum height of the Tsunami Wave) with an epicenter that was located between 10 and 300km from the coast line of impact. https://answers.yahoo.com/question/index?qid=20070730150043AAxz3IZ
- -1: Hm less than 0.5m, 1ft 8”: Minor Tsunami
- 0: Hm =1 m, 3ft 3”: No Damages
- 1: Hm = 2 m, 6ft 6”: Damages (ships broken and dragged to the coast).
- 2: Hm = 4 to 6 m, 13ft to 20ft: Habitations destroyed; Human Deaths likely.
- 3: Hm = 10 to 20 m, 33ft to 66ft: Damage will be observed in a 400 km, 250 mile radius area.
- 4: Hm = More than 30m, Greater than 99ft: Damage will be observed in a 500 km, 310 mile radius.
One of the most recent Earthquake & Tsunami events was the 2011 Great East Japan Earthquake. Here are some details that we know from this event:
Source of information: World Nuclear Assoication. Fukushima Accident. Updated: February 2015
- Event Date: March 11, 2011 @ 2:46pm
- Event Type: Earthquake & Tsunami
- Earthquake Magnitude: 9.0
- Resulting in a Tsunami of 39-meters ( 128 feet ) high at Miyako City and traveled inland as far as 6-miles.
- Flooded an area of approximately 217 square miles.
- Warning time given to the residents: 1-minute.
- Duration: The earthquake lasted for 3-minutes.
- Death Toll: Over 19,000 people died.
- Over 1,000,000 buildings were either destroyed or partially collapsed.
The Fukushima Daiichi Nuclear Power Plant with 4 Nuclear Reactors:
Was hit by a 15-meter (50 feet) Tsunami flooded the entire site; disabling 12 of the 13 back-up generators that would be used to cool the reactors. Within an hour, Units 1,2 & 3 lost the ability to maintain proper reactor cooling and water circulation and melted in the first 3-days. Unit 4 became a problem on Day 5. The accident was rated a 7 on the INES Scale. This scale will be discussed in detail in the Nuclear Accident Module. But for now, a 7 A Major Accident, is the worst case scenario. Over 100,000 people had to be evacuated from the area due to the meltdown.
On this day – Japan was hit with 4 Major disasters:
- A massive 9.0 Earthquake.
- A Tsunami 128 feet high.
- A Flood that covered 217 square miles.
- A Nuclear Meltdown of 4 Nuclear Units.
Two years after the quake…
300,000 people were still living in temporary housing.
Side Note: The 2011 Great East Japan Earthquake was NOT the largest or deadliest Earthquake/Tsunami to happen in this century. That record goes to the 2004 Banda-Aceh Earthquake and Tsunami. A magnitude 9.1 Earthquake resulting in the deaths of 230,000 people. Live Science http://www.livescience.com/39110-japan-2011-earthquake-tsunami-facts.html
The Dangers associated with Earthquakes:
Falling Debris: During and after the quake.
If you are inside a structure or outside of a structure, falling debris is going to be an issue. Items located on shelves, walls, ceilings, etc., may come lose and fall on top of you. If the earthquake is strong enough, the structure itself may collapse on top of you.
If you are outside, structural components like (broken glass from windows), chimneys, utility poles, etc., may fall on you. If the Earthquake is strong enough, entire structures may even come down and fall on top of you.
Flooding: Caused by a dam or levees breaches along rivers giving way. If you are located near a low lying coastal area, Tsunamis can cause enormous amounts of danger.
Nuclear Plants – Radioactive Catastrophes and Potential Nuclear Melt Downs: This was a new danger that was added to the list and became very evident in the 2011 Great East Japan Earthquake.
Fires: There is a good chance that fires will break out caused by broken gas lines and power lines. There may be a good chance that water lines will also be broken which will make firefighting very difficult.
Fallen Power Lines: Can cause electrocution, especially if they are associated with broken water mains.
Rock Slides and Landslides: If you are located near hillsides or mountains.
Ground Debris: As mentioned in the Tornado Module… There is a very good chanced that there will be ground debris after the Earthquake. This debris can be very sharp and can cause cuts and puncture wounds. Depending upon the debris, some of it may contain hazards chemicals that can poison you. If you want to help – fine. But don’t get hurt, because you just added to the number of people who now need assistance. So, do the right thing – but be careful and know what you are doing.
Contamination and Disruption in Underground Water Wells: For those of us who have well water systems, earthquakes can cause shifts in the ground that may change water flows. These shifts can change the feed waters to your well which can cause cross contamination from these new sources, or even may shut off the feed water completely, causing a well to dry up.
The Dangers associated with Tsunamis:
Drowning: The force of the Tsunami is enormous. Drowning will be cause for the largest amount of deaths.
Floating Debris: There is going to be much debris, even large structures like ships, cars and buildings in the tsunami wave and this debris can crush you and tear you apart like if it was a giant blender. This debris will also impact the foundations of structures weakening them and may even cause them to fall over.
Erosion: The strong Tsunami currents can lead to erosion of foundations of building, bridges and seawalls, which can cause them to be unsafe or to collapse.
Nuclear Plants – Radioactive Catastrophes and Potential Nuclear Melt Downs: This was a new danger that was added to the list and became very evident in the 2011 Great East Japan Earthquake. This same danger was reported for Earthquakes.
Ground Debris: As mentioned in the Earthquake and Tornado Module… There is a very good chanced that there will be ground debris after the Tsunami. This debris can be very sharp and can cause cuts and puncture wounds. Depending upon the debris, some of it may contain hazards chemicals that can poison you. If you want to help – fine. But don’t get hurt, because you just added to the number of people who now need assistance. So, do the right thing – but be careful and know what you are doing.
There are many steps that you can take to protect yourself and family members from Earthquakes and Tsunamis. Because there are so many things you can do, they will all be covered in the next lesson.
So, we are going to move onto determining your risk level for Earthquakes and Tsunamis.
Earthquake Risk Assessment:
Make sure to have your Risk Assessment Chart out so that you can record your Risks for Earthquakes and Tsunamis.
FEMA has a great website that helps you determine your Earthquake Risk: https://www.fema.gov/earthquake/your-earthquake-risk
Side Note: This page has a lot of good information on it. It will be well worth your time to review it.
So, let’s determine your Risk for Earthquakes in your location.
Just follow the listed sequence below when you are ready to begin.
- Click on the Blue “Earthquake Hazard Maps” link.
- The Top Section is “How to read the Maps”. Review the color codes that will determine your Risk Factor.
- Scroll down the page to where the Maps are located. And Locate your Map.
- The First Map is for the Eastern United State.
- The Second Map is for the Western United States.
- The Third Map is for Alaska.
- The Fourth Map is for Hawaii.
- And the Final Map is for Puerto Rico.
- Find your State and locate your county on the appropriate map.
- Determine the Color and Letter Code for your specific location.
- Pull out your Chart: Risk Assessment: Probability of a Natural Disaster Occurring.
- Use this Table For Your Risk Assessment for Earthquakes:
If you determine your location falls into the “A” Zone of the Map. Check the 1 – Very Low Box.
- If you determine your location falls into the “C” Zone of the Map. Check the 3 – Moderate Box.
- If you determine your location falls into any of the “D” Zones. Check the 4-High Box.
Now, you have to admit – that was pretty easy.
Tsunami Risk Assessment:
OK, so now we are going to determine your risk for a Tsunami.
- Find your approximate location on the map below. Note: If you have trouble reading the map, just click on the Blue Button: Tsunami Threat Zones
2) Determine the Color Code for your location.
3) Pull out your Chart: Risk Assessment: Probability of a Natural Disaster Occurring.
4) Use this Table For Your Risk Assessment for Tsunamis:
5) If you are located on a coast line and you are within 25 miles of the coast – Add 1 number to your risk score.
- If you are located in the State of Oregon and you are within 25 miles of the coast line. Add 1 to your Risk Score. The map indicates that you are an Orange Color a “4”. But if you are within 25 miles of the coastline Add 1 to your risk factor and record your risk as a 5.
- If you are located in Florida and you are within 25 miles of the coast line. Add 1 to your Risk Score. The map indicates that you are a Yellow Color a “2” . But if you are within 25 miles of the coastline Add 1 to your risk factor and record your risk as a 3.
Again, Pretty easy…
Now you should have the following Disaster Types Assessed for your location:
Your half way done! Congratulations!
This is what you should be taking away from this module:
- Earthquake and Tsunami facts.
- What an Earthquake is.
- What a Tsunami is.
- What causes Earthquakes.
- What causes Tsunamis
- Both Earthquakes and Tsunamis are very difficult to predict and come with little warning.
- Both Earthquakes and Tsunamis can cause huge amounts of damage.
- Both Earthquakes and Tsunamis are killers.
- How to determine the Risk of an Earthquake for your location.
- How to determine the risk of a Tsunami for your location.
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