Disaster agents are events resulting from hazards overwhelming highly vulnerable communities, always leading to morbidity and mortality. Over the last decade, more than 300 disaster agents occur annually worldwide, impacting millions and costing billions. Experts use the duration, magnitude, area of impact, and disaster agents' speed to create an in-depth analysis. Earthquakes are among the disaster agents that have an adverse impact on the lives of individuals. Earthquakes cause huge damage to property and lives. The impact caused by earthquakes depends on the intensity of the occurrence. Weak earthquakes may go unnoticed without any feasible impact, while major ones are always overwhelming in nature. The impact of earthquakes is always devastating since their occurrence is quite unpredictable. A primer of earthquakes incorporates its natural science, vulnerability, an example of an earthquake event, response, and mitigation measures.
Natural Science of Earthquakes and Tsunami
An earthquake is an event where plate tectonics slip past one another, creating seismic waves that travel through the earth's rocks. A fault plane refers to the surface where the earth's blocks slip (Hua et al., 2020). Epicenter is the location directly above the fault plane, while the regions below the earth's surface where earthquakes start are referred to as the hypocentre (Hua et al., 2020). The earth is made up of about 25 plates, which are like conveyor belts. After being generated, a plate sinks like a conveyer belt to the neighboring plate. The earth also consists of four major layers: inner core, mantle, crust, and outer core. The thin skin on top of the earth comprises the crust and the mantle's top (Cummins et al., 2020). However, the skin is not consolidated together; rather, it comprises several fragments like a puzzle. Besides, the fragments move gently past one another, sliding and bumping into each other. A tectonic plate is a term used to refer to these pieces, and the edges between the plates are called tectonic boundaries. The slippage between tectonic plates causes earthquakes. Most of the earthquakes occur on the faults existing in the tectonic boundaries. Due to the rough edges of the plates, some get stuck while others keep moving. After the rest of the plates have moved quite a distance, the edges free on one of the slips leading to an earthquake.
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When the borders of faults are fixed together while the other plates are moving, the energy that could be used to slide the blocks are stored. The edges unstick when the force of the moving blocks overwhelms the friction of the rough surfaces (Takashimizu et al., 2020). The stored energy exudes outwards to all directions from the fault, forming a seismic wave. The movement of the seismic waves through the earth shapes it, and when it reaches the earth's surface, it shakes the ground and anything on it. Experts record earthquakes using a seismograph. The base of the seismograph shakes during an earthquake recording its intensity.
An earthquake that occurs under the water causes a series of great sea waves called a tsunami. Tsunamis are most frequent in Japan, and it has claimed the lives of several individuals in the region over the current periods (Cummins et al., 2020). A tsunami results from an earthquake if the earthquake is of adequate force and there is an intense movement of the earth that can lead to the sudden and substantial displacement of huge quantities of water. Unlike tidal waves, tsunami waves are long series of waves about 100 kilometers, which happen as far as one hour apart (Takashimizu et al., 2020). The waves can travel the entire ocean without losing energy, making it destructive when it reaches the land. The speed of a tsunami depends on the depth of the ocean. It can travel as fast as 800 kilometers per hour on deep oceans with a wavelength close to hundreds of miles (Cummins et al., 2020). A tsunami only becomes hazardous when it nears the land. It is due to the decreased wavelength, increased height, and intensification of currents as it enters the shallow water close to coastal shorelines.
Vulnerability of Earthquakes and Tsunami
Some of the frequent impacts of earthquakes include loss of lives, tsunami, liquefaction, damage to bridges and highways, fires, and structural damage to buildings. The intensity of impact depends mostly on where the earthquake occurs: highly developed or underdeveloped, densely or sparsely populated, where it is predominantly urban or rural, and the infrastructure's ability to endure shaking (Takashimizu et al., 2020). Building damage is associated with earthquakes and is greatest in areas of soft sediments. Besides, the damage is serious for multi-story buildings than the smaller structures. In most earthquake-prone areas, buildings are built to withstand most earthquakes. Fires are another impact of earthquakes since the earthquake leads to the destruction of electrical lines and fuel pipelines' rupture. The 1906 San Francisco earthquake led to the destruction of 25000 buildings, which were mainly fuelled by broken gas pipelines (Cummins et al., 2020). It was difficult to fight the fire during this earthquake since it ruptured the water mains too.
Liquefaction results from ground shaking during an earthquake, which weakens unconsolidated materials and rocks to the failure point. Solid sediments are then transformed into liquid masses that can flow by gravity. Earthquakes also lead to the loss of lives and displacement of communities. When this disaster event destroys buildings with people, several people are always injured, with others dying on the sport. Similarly, a tsunami can claim many people's lives and displace communities within the shores of an ocean in which it occurs (Takashimizu et al., 2020). Liquefaction can cause buildings that could have been undamaged to collapse. Apartment buildings that collapsed during the Niigata earthquake in 1964 were due to liquefaction. Previous experiences indicate that many types of landslides occur due to earthquakes. Some of the types of landslides induced by earthquakes include slides of rock fragments and rockfalls (Cummins et al., 2020). Earthquakes can induce some destructive forms of landslides, such as soil avalanches and rock avalanches. In the 1970 Peruvian earthquake, more than 18,000 people died due to a single rock avalanche's destructive impact. Hebgen Lake's earthquake in 1959 also had a similar but less destructive impact as 26 people died due to rock avalanches. Unlike earthquake whose destructive impact is only experienced within the vicinity of origin, tsunami leads to destruction both locally and other distant regions far from where tsunami originated.
Assessment of Earthquake Prone Areas in the US
California is the state that is more prone to earthquakes than other states in the US. It has several fault lines that generate earthquakes during any particular year. Some of these fault lines are found in densely populated areas, risking the lives of residents. The seismic movement in California is extensively acknowledged, and high-hazard regions include some huge sections of the state, such as Los Angeles, San Diego, and San Francisco Bay (Amezquita-Sanchez et al., 2017). Significant research has been focused on predicting the future occurrence of earthquakes in these areas and devise a system to prevent such occurrences. Other prone areas include the Coastal Pacific Northwest, which could affect Olympia, Salem, Eugene, Portland, Tacoma, and Seattle. The New Madrid Seismic Zone records about two hundred quakes annually, making it another prone area (Amezquita-Sanchez et al., 2017). A report compiled by seismologists on the East Coast reveals that the Charleston region is at high risk of experiencing destructive earthquakes within the next fifty years. Almost all the buildings were damaged in Charleston city’s 1886 earthquake, which spread to southern Virginia and central Ohio. Hawaii also experiences thousands of quakes annually due to its active volcano. Most of the damage caused by these quakes isis small, but others significantly impact people and the community. Alaska forms part of the most seismically active areas globally (Amezquita-Sanchez et al., 2017). Alaska-Aleutian Megathrust is an active fault line in this state, making everyone concerned with their safety in the region.
An Example of a Disastrous Event
On Friday, 11 March 2011, Japan experienced an undersea megathrust earthquake whose magnitude was 9.0, often referred to as the 2011 Tōhoku earthquake. The earthquake resulted from the collision of two of the tectonic plates along a subduction zone offshore of Japan. East of Japan, the Pacific plate plunges underneath the superseding Eurasia plate. Recent research on the cause of the 2011 Tōhoku earthquake found that the tremor fully released energy stored between the two tectonic layers built up for centuries. The subduction zone study found a slippery clay lining that enabled the two layers to slide an extraordinary gap of about fifty meters, which led to the massive earthquake and tsunami. The maximum height reached by the wave was 128 feet. A video recorded at Oarai indicated a massive whirlpool generated by the tsunami. Besides, the tsunami caused a malfunction in the cooling system of the Fukushima Nuclear Plant, which led to the release of radioactive materials and a level-7 nuclear meltdown.
The Great East Japan Earthquake was the most intense ever noticed earthquake in Japan and one of the five most disastrous earthquake events worldwide since 1900. The tsunami led to the destruction of infrastructure, nuclear accidents, and loss of life. A statement released by the Japanese National Police Agency indicated that more than 120,000 buildings were destroyed, 7,060 people were missing, 5,685 injured, and 15,538 deaths. According to the Japanese government, the damage caused by the tsunami was equivalent to approximately 199 billion US Dollars. More than 150,000 residents lost their homes. The impact of the tsunami was felt in other parts of the world other than Japan. The waves traveled across the Pacific, moving through Hawaii, Chile, and Alaska. Destroyed buildings during this event emitted several tons of ozone into the atmosphere. Japanese citizens were alerted to this disastrous event's potential occurrence via text messages sent to their cell phones. Some of the government's measures to prevent more deaths include stopping factory assembly lines and high-speed trains.
Individual Preparation and Response to Earthquakes
The possibility of an individual surviving an earthquake and reduce the risk of injury depends on an individual’s planning, preparation, and practice what they will do if such a disaster event happens (Schmidt, 2018). Individuals living in earthquake-prone zones have to devise means to protect themselves and their loved ones from the impact of earthquakes and tsunami. First, an individual should learn the safe spots. Several injuries and deaths recorded during an earthquake result from collapsing of materials and heavy falling equipment like heating units and bookcases. Therefore, it would be essential to know some of the safe places in each home's room. Staying away from walls may increase safety during such events (Schmidt, 2018). An individual can also create an evacuation plan for themselves and the family. Adequate preparation would help an individual to avoid more uncertainties associated with the event. Developing an emergency supply kit and first aid kits helps individuals avoid potential injuries associated with earthquakes. Besides, a person should check for hazards in the home and fix potential problems. Identifying safe places indoors and outdoors such as under sturdy furniture, against the wall, and in open places would safeguard an individual from falling objects that can create more harm. Also, a person should store some of the valuable documents in a waterproof and fireproof bag (Schmidt, 2018). It is important to develop an emergency communication plan to reunite and communicate with other family members after the disaster event.
After an earthquake, an individual can respond by moving to a safe location. The person should carry their emergency supply kit. Check for injuries and use a first aid kit where possible. Check for hazards such as gas leaks, damaged electrical wiring, fire hazards, and spills, among others. For serious injuries, it is advisable to seek medical help. Once you are in a safe place, use the emergency communication plan you developed during the preparation stage to reconnect and communicate with other family members.
Community Response to Earthquakes
A community should work together to create a community action plan for earthquakes. The plan's core purpose is to ensure every member of the community is aware of possible disasters that the earthquake can cause (Sumasto et al., 2019). The community should tell the members of possible threats, enlighten them on safe places for evacuation, and guide them on emergency kits' inclusion criteria. The plan should also indicate clear communication channels to be used during the disaster. In response to the impact of earthquakes and tsunamis, communities should identify and serve specific health needs of vulnerable individuals such as people with disabilities, expectant mothers, children, and the elderly (Semenov et al., 2018). Besides, a community can train health workers to identify trauma and provide psychological support to vulnerable people. With public officials' help, a community can also build a temporary structure to provide immediate care for the injured.
Conclusion
In conclusion, if not properly managed, an earthquake can negatively impact both individuals and communities. An earthquake is an event where plate tectonics slip past one another, creating seismic waves that travel through the earth's rocks. An earthquake that occurs under the water causes a series of great sea waves called a tsunami. Impacts of earthquakes include loss of lives, tsunami, liquefaction, initiation of slope failures, damage to bridges and highways, fires, and structural damage to buildings. Some of the areas prone to earthquakes in the US include California, Alaska, Charleston, and the New Madrid Seismic Zone. The 2011 Tōhoku earthquake is an example of an earthquake that claimed the lives of more than 15,000 people and caused massive destruction of properties. Individuals and communal preparation and response to earthquakes help to reduce the impact after the occurrence.
OUTLINE
Title : 2011 Tōhoku Earthquake and Tsunami (JAPAN 2011 EARTHQUAKE)
Introduction
Definition and history of disaster events
Overview of earthquakes as a disaster event
Thesis statement: A primer of earthquakes incorporates its natural science, vulnerability, an example of an earthquake event, response, and mitigation measures.
Natural Science of Earthquakes and Tsunamis
An earthquake is an event where plate tectonics slip past one another, creating seismic waves that travel through the earth's rocks.
The slippage between tectonic plates causes earthquakes.
The movement of the seismic waves through the earth shapes it, and when it reaches the earth's surface, it shakes the ground and anything on it.
An earthquake that occurs under the water causes a series of great sea waves called a tsunami.
Vulnerability of Earthquakes and Tsunami
The intensity of impact depends mostly on where the earthquake occurs: highly developed or underdeveloped, densely or sparsely populated, predominantly urban or rural, and the infrastructure's ability to endure shaking.
Some of the frequent impacts of earthquakes include loss of lives, tsunami, liquefaction, damage to bridges and highways, fires, and structural damage to buildings.
Fire results from the destruction of electrical lines and fuel pipelines.
Liquefaction results from ground shaking during an earthquake, which weakens unconsolidated materials.
Earthquakes and tsunamis lead to the loss of lives and displacement of communities.
Earthquake Prone Areas in the United States
California has several fault lines making it the most prone region to the earthquake.
Coastal Pacific Northwest could affect Olympia, Salem, Eugene, Portland, Tacoma, and Seattle.
Charleston region spreading to Southern Virginia and Central Ohio.
Hawaii
Alaska
Example of a disastrous event
2011 Tōhoku earthquake and tsunami.
Cause: a collision of two of the earth's tectonic plates along a subduction zone offshore of Japan.
More than 120,000 buildings were destroyed.
Injuries and deaths: 7,060 people missing, 5,685 injured, and 15,538 deaths.
The waves traveled across the Pacific, reaching Chile, Hawaii, and Alaska.
Individual preparation and Response to Earthquakes
Preparation
Learn the safe spots
Create an evacuation plan
Develop an emergency supply kit
Check for hazards
. Identifying safe places both indoors and outdoors
Develop an emergency communication plan
Response
Move to a safe location
Check for injuries
Check for hazards such as gas leaks, damaged electrical wiring, fire hazards, and spills.
Seek medical help for serious injuries
Use the emergency communication plan to reconnect with the family members.
Community response to earthquakes
Teach members of possible threats
Advice members on safe places for evacuation
Guide members on things to include in emergency kits
Indicating clear communication channels to be used during the disaster
Training health workers to identify trauma and provide psychological support to the vulnerable people
Building a temporary structure to provide immediate care for the injured
Conclusion
If not properly and timely managed, earthquakes can have a disastrous impact on both individuals and communities.
References
Amezquita-Sanchez, J. P., Valtierra-Rodriguez, M., & Adeli, H. (2017). Current efforts for prediction and assessment of natural disasters: Earthquakes, tsunamis, volcanic eruptions, hurricanes, tornados, and floods. Scientia Iranica , 24 (6), 2645-2664. https://dx.doi.org/10.24200/sci.2017.4589
Cummins, P. R., Pranantyo, I. R., Pownall, J. M., Griffin, J. D., Meilano, I., & Zhao, S. (2020). Earthquakes and tsunamis caused by low-angle normal faulting in the Banda Sea, Indonesia. Nature Geoscience , 13 (4), 312-318. https://doi.org/10.1038/s41561-020-0545-x
Hua, Y., Zhao, D., Toyokuni, G., & Xu, Y. (2020). Tomography of the source zone of the great 2011 Tohoku earthquake. Nature communications , 11 (1), 1-7. https://doi.org/10.1038/s41467-020-14745-8
Kozák, J., & Čermák, V. (2010). The illustrated history of natural disasters (p. p55). Dordrecht: Springer.
Schmidt, J. (2018). Notes on national earthquake education programs in Israel. Procedia Engineering , 212 , 1265-1272. https://doi.org/10.1016/j.proeng.2018.01.163
Semenov, R. M., Kashkovsky, V. V., & Lopatin, M. N. (2018). Model of tectonic earthquake preparation and occurrence and its precursors in conditions of crustal stretching. Geodynamics & Tectonophysics , 9 (1), 165-175. https://doi.org/10.5800/GT-2018-9-1-0343.
Sumasto, H., Wisnu, N. T., Ngestiningrum, A. H., Sugito, B. H., & Najib, M. (2019). Trauma healing during the earthquake disaster emergency response phase in Lombok, Indonesia. Indian J. Forensic Med. Toxicol. , 13 , 1745-8.
Takashimizu, Y., Kawakami, G., & Urabe, A. (2020). Tsunamis caused by offshore active faults and their deposits. Earth-Science Reviews , 103380. https://doi.org/10.1016/j.earscirev.2020.103380
