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Deep Talks about Earthquake


In this blog post I firstly will mention some technical aspects. Then in following parts I will be touching to the points of time periods after earthquake. The article has a definition, types of hazards, human actions and the importance of precautions.


Society should know some important things about earthquake reality. You'll always find a lot of dirty and wrong information on websites. They will always confuse you and maybe make you anxious. As Master Structural Engineer that finish his studies on earthquake topic

I will try to keep things as clear as possible for you.


Enjoy your read.


So as a roadmap before we start reading, WHAT DO WE NEED TO KNOW ?

  • A simple definition

  • What causes earthquakes ? - Why this thing even happening ?

  • How to be prepared for the REALITY? - People tend to believe it is something extraordinary, therefore I find it very useful to clarify as REALITY

  • What to do during and after earthquake event?

  • What is magnitude scale , how do you decide big or small earthquakes?

  • Impact on buildings

Let's dive deeper. You'll be more informed about this reality in the end of this blog post.



A different Definition about Earthquake


The tremors that occur due to the movement of the plates that make up the earth's crust relative to each other are called earthquakes. The majority of earthquakes in the world coincide with the regions where the plates forming the earth's crust converge, diverge or are tangent to each other. From these regions, the Pacific Seismic Belt includes the coasts of South America from Chile to the north, Central America, Mexico, the Aleutian Islands from the south of Alaska, Japan, the Philippines, New Guinea, the South Pacific Islands and New Zealand. The Alpine-Himalayan Earthquake Belt, starts from Indonesia and reaches the Atlantic Ocean through the Himalayas and the Mediterranean. The Atlantic Belt extends along the plate boundary in the middle of the Atlantic Ocean.


Many cities and metropolitan areas are situated in areas affected by at least one natural hazard. Some of these areas are vulnerable to multiple hazards, including extreme events that could or have resulted in a large number of casualties and high repair costs.


According to FEMA (2000), the US economic losses arising from earthquake effects on structures are about $4.4 billion dollars a year, whereas the hurricane losses add up to $5.4 billion dollars a year. In the past few decades, countless structures were severely damaged or completely destroyed due to devastating earthquakes (e.g., Northridge 1994, Kobe 1995, Izmit 1999, and Haiti 2010) or catastrophic hurricanes (e.g., Katrina 2005, Rita 2005, Sandy 2012).


This damage was largely caused by designs that misestimated the structural response, in terms of displacements, drift ratios, and internal stresses, produced by different extreme loading events.


Regions prone to both seismic and wind/hurricane hazards are scattered all around the globe. The design of structural systems in such areas is particularly challenging and is customarily tackled by designing for the worst effect of the different hazards acting separately. In modern design codes and standards, the effect of multiple hazards is accounted for by considering amplification factors for loads to include variabilities coming from the randomness of events and lack of knowledge and/or scarcity of information on previous events.




What Causes Earthquakes?


Earthquakes happen as a result of the movement and collision of tectonic plates in the Earth's crust. The Earth's outer shell is made up of several large plates that float on the semi-liquid mantle below. These plates are in constant motion, sliding past each other, colliding with each other, or moving apart. When the movement of these plates is sudden and dramatic, it can cause the ground to shake and vibrations to travel through the Earth's crust, resulting in an earthquake.






In some cases, earthquakes can also be caused by human activities, such as underground nuclear testing, the construction of large dams, or the extraction of oil and gas. These earthquakes are known as "induced earthquakes."

It is important to note that earthquakes are a natural part of the Earth's geological processes and have been occurring for billions of years. While it is not possible to completely prevent earthquakes, steps can be taken to reduce their impact and help communities prepare for them.


Types of Earthquakes


Tectonic Earthquakes:

These are the most common type of earthquake and are caused by the movement of tectonic plates. When two plates collide or move apart, stress builds up in the Earth's crust. When the stress becomes too great, it is suddenly released, causing the ground to shake.


Volcanic earthquakes:

These earthquakes occur when magma rises to the surface and creates volcanic eruptions. The shaking of the ground during a volcanic eruption is caused by the release of energy from the movement of magma and ash.


Collapse earthquakes:

These earthquakes occur when underground mines or underground structures such as tunnels or caverns collapse. The collapse of these underground structures can cause the ground to shake and generate seismic waves.


Landslide earthquakes:

These earthquakes are caused by the movement of large masses of rock, soil, or other material down a slope. The shaking of the ground during a landslide earthquake is caused by the movement of the material and the displacement of the ground.






Can we prevent the losses that occur from earthquakes?


There is no way to completely prevent the losses that occur from earthquakes, as they are a natural hazard. However, thanks to science, there are steps that can be taken to reduce the impact of earthquakes.


  1. Building Codes and Standarts: Adopting strict building codes and standards can help to ensure that new structures are designed and constructed to withstand earthquakes.

  2. Retrofitting: Older buildings that do not meet current building codes can be retrofitted, or strengthened, to reduce the risk of damage or collapse in the event of an earthquake.

  3. Public awareness and education: Raising public awareness about earthquakes and providing education on what to do during and after an earthquake can help reduce the impact of earthquakes on communities.

  4. Emergency preparedness planning: Developing and practicing emergency preparedness plans can help individuals, families, and communities respond effectively to earthquakes and reduce the impact of their aftermath.

  5. Investment in early warning systems: Investment in early warning systems can provide critical seconds of warning before an earthquake strikes, allowing people to take protective actions.

  6. Regular earthquake drills and exercises: Regular earthquake drills and exercises can help people become familiar with what to do during an earthquake and increase their chances of survival.


= About Building Codes =


Building codes are sets of standards and guidelines that specify the minimum requirements for the design, construction, and maintenance of buildings. There are several international, national, and regional building codes that address earthquake safety, including:


  1. International Building Code (IBC): The International Building Code is a model building code developed by the International Code Council (ICC) and is widely used in the United States.

  2. Eurocode 8: Eurocode 8 is a set of European standards for the design of buildings and other structures to resist earthquakes.

  3. Uniform Building Code (UBC): The Uniform Building Code was a model building code widely used in the United States until it was replaced by the International Building Code.

  4. Seismic codes of specific countries: Many countries have their own seismic codes, such as the Japan Society of Civil Engineers Standard for Earthquake-resistant design of buildings (JSCE), or the Seismic Design Category of the National Building Code of Canada, New Zealand Society for Earthquake Engineering (NZSEE) Seismic design standards ,Australian Earthquake Loading Standard, Chinese seismic design codes, including GB 50011 and GB 50010, Indian Standards for seismic design, including IS 1893 Mexican Building Code (Norma Técnica de Edificación


These codes specify requirements for the design and construction of buildings to ensure they are able to resist earthquakes and protect the safety of the occupants. This can include requirements for the materials used in construction, the size and strength of structural elements, and the methods used to fasten components together.



=MAGNITUDE SCALE=


The magnitude scale is a numerical system used by seismologists to measure the amount of seismic energy released by an earthquake.


The most widely used scale is the Richter scale. Richter magnitude scale, which was developed in 1935 by Charles Richter which assigns a number to the earthquake based on the amplitude of the waves recorded on a seismograph. This scale is logarithmic, meaning that an increase of one unit corresponds to a tenfold increase in the amplitude of the waves and a 32-fold increase in energy released.


Therefore, an earthquake with a magnitude of 7.0 releases 32 times more energy than an earthquake with a magnitude of 6.0. The magnitude of an earthquake is an important indicator of its potential to cause damage and disruption, but other factors such as distance from the epicenter, local geology, and building construction can also affect its impact.


  • Earthquakes with a magnitude of 2.5 or less are usually not felt by human beings, but can be detected by sensitive seismographs.

  • Earthquakes with a magnitude of 2.5 to 5.4 are often felt, but typically cause little to no damage.These are generally happening as aftershock earthquakes.

  • Earthquakes with a magnitude of 5.5 to 6.0 can cause minor damage to buildings and other structures.

  • Earthquakes with a magnitude of 6.1 to 6.9 can cause moderate to severe damage, depending on the proximity to populated areas.

  • Earthquakes with a magnitude of 7.0 or higher are considered major earthquakes and can cause widespread damage, loss of life, and significant disruption to infrastructure.

But the question is, do we only understand the effect of earthquake with magnidute scale ??


Of course NO! It's important to note that while the magnitude of an earthquake can provide some indication of its potential impact, other factors such as the depth of the earthquake, the type of soil and rock underlying an area, and the proximity of population centers can also have a significant impact on the level of damage and loss of life.



=DEPTH OF THE EARTHQUAKE=


The depth of an earthquake can also have a significant impact on the level of damage and loss of life it causes as much as magnitude scale of the earthquake.


In general, shallow earthquakes (those with a depth of less than 70 kilometers) are more likely to cause damage and casualties than deeper earthquakes.


This is because shallow earthquakes release their energy closer to the Earth's surface, which can cause more intense shaking and greater damage to buildings and infrastructure. In addition, shallow earthquakes are more likely to generate aftershocks, which can cause further damage and complicate rescue and recovery efforts.





In contrast, deeper earthquakes (those with a depth of more than 70 kilometers) typically cause less damage and fewer casualties. This is because the seismic energy is dissipated over a larger area and is less intense at the Earth's surface. However, deeper earthquakes can still have significant impacts, particularly if they occur in populated areas or areas with poor building construction practices.



First 30 Minutes of Earthquake : IMMEDIATE ACTIONS



  1. Drop, cover, and hold on: If you are inside a building, immediately drop to the ground, take cover under a sturdy piece of furniture (such as a table or desk), and hold on until the shaking stops. If you are unable to take cover, cover your head and neck with your arms. In this moments, the couches will be lifesaver for you. You can hide behind the couch and have the necessary position as it is stated.

  2. Stay inside: This is very big mistake that in certain cases people are trying to run away while earthquake is happening. Do not attempt to exit the building during the earthquake, as there may be falling debris or other hazards.

  3. Stay away from windows and objects that could fall: Glass materials are tend to explode during big energy releases. Move away from windows, mirrors, and other objects that could shatter or fall during the earthquake. In addition to this the edges of the buildings might be dangerous. The reason why is if the bulding didn't projected and reinforced well the edges might fall first.

  4. If Possible Turn off gas and other utilities: When this major movement happens, the pipes lose the connection and the problem of natural gas release can occur. If you smell gas or suspect a gas leak, turn off the gas supply at the main valve, and do not turn it back on until it has been inspected by a professional. Turn off other utilities, such as electricity and water, if there is damage to the building. If you can't reach to the source close all the electronic devices you have around. A little spark can trigger everything.

  5. Check for injuries and damage: Once the shaking has stopped, check yourself and others for injuries, and assess the damage to the building. If you are injured or require medical assistance, call for help immediately.

  6. Evacuate if necessary: After checking yourself try to approach in evacuation level. If you are in a coastal area and there is a possibility of a tsunami, or if there is significant damage to the building that makes it unsafe, evacuate the building and move to higher ground if necessary. You'll have shock state , do not make yourself to tired. You might feel very strong at the certain moment but this is the reaction of survival psyhocology.



First 60 Minutes of Earthquake : FOLLOW-UP ACTIONS


  1. Check for injuries and damage after the evacuation or during the waiting period under the debris: Assess yourself and others for injuries and seek medical attention if necessary. Check your surroundings for damage to buildings, roads, bridges, and other infrastructure. If you were not fast or lucky enough to evacuate the building check out the tunnels under the ruins. Try to reach out to your earthquake bag. Find yourself water and food sources. NEVER drink tap water after an earthquake event.

  2. Gather emergency supplies: Make sure you have access to essential supplies such as water, food, first aid kit, and medications. If you were not fast or lucky enough to evacuate the building try to reach to your earthquake bag. Find yourself water and food sources. NEVER drink tap water after an earthquake event.

  3. Check for aftershocks: Be aware that earthquakes can be followed by aftershocks ( most probably it will be followed ), which may cause further damage or injury. Be prepared to drop, cover, and hold on if another earthquake occurs. If you have your safe triangle that protects you don't leave that place until you have a contact by professionals.

  4. Follow instructions from local authorities: Follow instructions from emergency services and local authorities. Be aware of evacuation orders, road closures, and other instructions that may affect your safety.

  5. Stay away from damaged areas: Stay away from damaged areas, buildings, and infrastructure until they have been assessed and deemed safe by authorities. People tend to make this mistake. Sometimes help actions can harm more. It can harm you or the others. If you don't have license for search and rescue please wait for the certain commands.


Why the Earthquake Bag is Important?


An earthquake bag, also known as a go-bag or emergency kit, is a collection of essential supplies and items that you may need in the event of an earthquake or other disaster.


In the event of an earthquake or other disaster, you may not have immediate access to food, water, or other essential supplies. An earthquake bag ensures that you have these supplies readily available. An earthquake bag can help increase your safety and survival in the aftermath of an earthquake by providing you with essential items such as a first aid kit, flashlight, and emergency blanket. It can also provide comfort and convenience in the aftermath of an earthquake. For example, having a change of clothes and a toothbrush can help you feel more comfortable and prepared.

Knowing that you have an earthquake bag with essential supplies and items can provide peace of mind, especially in earthquake-prone areas.




What the Earthquake Bag must have?





  1. Water: Pack at least one gallon of water per person per day, for a minimum of three days. Water will be the fundamental thing that keeping you alive.

  2. Non-perishable food: Pack non-perishable, easy-to-prepare foods such as canned goods, energy bars, and dry goods like pasta and cereal. Food will keep you alive.

  3. First aid kit: Include a well-stocked first aid kit that contains items such as bandages, antiseptic, and pain relievers. This will be so crucial if you get any damage from the hazardous event. First 30-60 minutes you have to close your wounds before it get any more serious situation.

  4. Flashlight and extra batteries: Make sure you have a reliable flashlight with extra batteries to help navigate in the dark.

  5. Radio: Include a battery-operated or hand-cranked radio so you can stay informed of emergency updates.

  6. Medications: Include a supply of any prescription or over-the-counter medications that you or your family members may need. Supplementary pills can keep your body in power.

  7. Warm clothing and blankets: Pack warm clothing and blankets to stay warm in case you have to spend the night outdoors. If the hazard happens in winter time, danger of frost will be very problematic.

  8. Cash: In the region which earthquake happened ATM machines or credit card systems are will most probably not working. Include some cash and coins in case.

  9. Important documents: Make copies of important documents such as passports, birth certificates, and insurance policies, and store them in a waterproof bag. You'll most likely need them for administrative steps after the hazard.



=The Impact of Earthquake on Buildings=


Structural damage: Earthquakes can cause significant damage to the structural integrity of buildings, including cracking and collapse of walls, columns, and beams. This can compromise the safety of the building and its occupants.


Non-structural damage: Earthquakes can also cause non-structural damage to buildings, such as damage to ceilings, partitions, and finishes. This type of damage can be expensive to repair, but is typically not life-threatening. The image below shows us an example of non-structural damage.


Foundation damage: Earthquakes can cause damage to the foundation of buildings, including cracking and settling. This can compromise the stability of the building and require extensive repairs.




Soil liquefaction: In areas with loose or saturated soils, earthquakes can cause soil liquefaction, which is when the soil loses its ability to support the weight of buildings and other structures. This can cause buildings to sink, tilt, or even collapse.




In conclusion


A structural engineer can assess the building to determine its level of seismic resistance. This typically involves an inspection of the building's foundation, framing, and other structural elements to identify any weaknesses or vulnerabilities.


Based on the assessment, the engineer can make recommendations for improving the building's seismic resistance.


Also in some areas, buildings can be certified as being seismic-resistant by a third-party organization. If the building has been certified as being seismic-resistant, it is likely to have undergone rigorous testing and evaluation to ensure its resistance to seismic events.





Dear friends , I'm hoping that you are more informed about earthquake after this informative blog post. Please feel free to reach me out if you'll have any further question.


Best Regards.

-MSc Structural Engineer M. Ayberk Yavuz



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