Earthquake in Florida
An earthquake is a tremor or sudden shake of the earth's surface that occurs when two tectonic plates - massive slabs of rocks beneath the oceans and lands - suddenly slide against one another.
Earthquakes are the third most common natural disaster but cause the most fatalities. There are different types of earthquakes: tectonic, explosion, volcanic, and collapse earthquakes. A majority of earthquakes occur "naturally" from the continuous movement of the tectonic plates, but human activities like mining and fracking can also induce these events. However, earthquakes from these activities rarely have great magnitudes.
The National Earthquake Information Center (NEIC) identifies approximately 55 earthquakes of varying magnitudes every day. The Valdivian or Great Chilean Earthquake in May 1960 is the worst recorded earthquake in history, with a 9.5 magnitude. This earthquake triggered a tsunami that tore across the Pacific and hit coastal communities in Japan, the Philippines, New Zealand, and Hawai'i. The result was thousands of injuries, fatalities, and massive economic damage. An example of an induced earthquake is the Oklahoma Earthquake in September 2016 with a 5.8 magnitude which is believed to be caused by fracking with wastewater injections.
A reliable prediction method for earthquakes is yet to be developed. Scientists can only calculate the probability of an earthquake occurring. In the meantime, efforts are being made to mitigate the hazards and damages with better-engineered buildings, new earthquake detection methods, better-prepared authorities, and dissemination of information through earthquake alerts and warnings.
The Science Behind Earthquakes
The earth has four layers: the inner core, the outer core, the mantle, and the crust. The outermost layer, the crust, makes up 1% of the earth's mass. However, the earth's crust is not one solid mass but several massive pieces of rock that lie beneath oceans and dry land. These pieces fit snugly like puzzle pieces and are constantly moving - albeit very slowly - due to the currents of the semi-molten mantle.
Why Do Earthquakes Occur?
Earthquakes usually occur when the most active tectonic plates meet and release pressure. When two tectonic plates push against one another, tension or energy increases around the sticking point and causes stress in the earth's crust. The pressure accumulates until the plates are forced to let go, slip, or crumble, and the accumulated energy is released as shock or seismic waves so powerful it causes an earthquake.
The surface where the plates slip is called the fault or fault plane, and the location where the earthquake originates within the earth is the hypocenter. The point directly above the hypocenter (on the earth's surface) is called the epicenter of an earthquake. The closer the hypocenter is to the earth's surface, the more intense the quake is likely to be.
How Do Earthquakes Happen?
When pressure builds as tectonic plates push against one another, there are different ways that the plates can move depending on the types of plate boundaries. Divergent boundaries occur when the plates move away from one another, and the space between the two plates fills with molten rock forming a new surface. This movement mostly occurs in mid-ocean ridges and often triggers low-magnitude quakes.
On the other hand, convergent boundaries cause most earthquakes and are more intense. A convergent boundary is when two plates collide, resulting in either subduction, where the thinner and more flexible plate moves underneath the stronger, more rigid plate, or two plates of equal strength crumble and move upwards, forming mountain ranges. In subduction, the lower plate crumbles or melts, and sometimes, magma can rise to the surface, creating volcanoes.
Lastly, tectonic plates can also slip against one another in what is known as a transform or lateral fault. This occurs when two plates slide against one another while moving in opposite directions without moving up or down. While there is no production or destruction of crust in a transform fault, this movement can also cause high-magnitude quakes like convergent boundary earthquakes or offset mid-ocean ridges like divergent boundary earthquakes.
These three types of boundary movements can also cause tsunamis, although convergent boundaries cause the majority of tsunamis. For instance, the Valdivian Earthquake of 1960, the largest earthquake ever recorded, was a convergent earthquake and triggered a tsunami as high as 80 feet.
How Earthquakes Are Measured
Scientists use seismographs to measure earthquakes and use different scales to interpret the recorded data and determine the magnitude or intensity of the earthquake. Scales like the Richter Scale calculate the magnitude of earthquakes based on the largest recorded seismic wave detected by the seismograph.
However, this scale does not provide detailed information on the earthquake's intensity, i.e., earthquake depth, the effect of the quake on the surface, or how energy was released across different areas. Scientists use the Mercalli or Modified Mercalli Scale for a broader understanding of the earthquake's magnitude and intensity. Based on human reports, the amount of shaking, and damages across different locations, the Mercalli Intensity Scale provides more data on what the earthquake actually did when it hit.
Recently, scientists have used the Moment Magnitude Scale to determine how an earthquake releases energy, how far a fault moved, and the force required to move it. Factors from all these scales help paint a fuller picture of the magnitude, intensity, and effects of earthquakes.
Earthquake Consequences
The effects of an earthquake depend on the magnitude of the earthquake and its intensity on the surface. Out of the 500,000 detectable earthquakes estimated to occur in the world every year, only 100,000 can be felt. And only 100 of those cause damage. Therefore, most recorded earthquakes have few consequences.
The earthquakes that cause damage range above four or five on the magnitude or intensity scale. These earthquakes can lead to injuries, deaths, and damages as a result of primary and secondary effects such as:
Collapsing buildings and bridges: Seismic waves, especially s-waves and surface waves, can shake the ground and everything on it. In addition to falling objects, high-magnitude earthquakes can topple houses from their foundations and damage bridges and other structures like dams, railways, and roads. The collapse or damage of these structures can lead to injuries and deaths, not to mention homelessness and the economic loss that individuals and businesses will face.
Exploding gas lines and fires: Earthquakes in loosely-packed, less solid, or waterlogged sediments can lead to liquefaction of the surface. When this occurs under buildings, it can break or pull gas lines from their connections and potentially cause explosions or fires if an ignition source is present.
Burst water and sewer pipes: Earthquakes can also burst water pipes, making it hard to fight fires.
Illnesses and diseases: Waterborne diseases can be a secondary effect of earthquakes due to poor sanitation from burst sewer pipes and overwhelmed medical aid. For example, the cholera outbreak that followed the Haiti 2010 earthquake.
Damaged electricity cables: Earthquakes can bring down electricity poles, and liquefaction can significantly damage buried electricity cables. This can pose a hazard to humans and may also lead to explosions or fires when there is a gas leak.
Landslides: Many landslides are caused by earthquakes. Earthquake-induced landslides in mountainous areas can cause catastrophic damage to lives, homes, and communities.
Tsunamis: Earthquakes are the major causes of tsunamis globally. Whether from land or underneath the ocean floor, earthquakes can trigger tsunamis that send violent waves to surrounding areas.
Aftershocks: Aftershocks are lower-intensity earthquakes that occur after the largest shock of a fault. These account for up to 40 percent of earthquake damages and can occur days, weeks, months, or years after the mainshock.
Volcanic eruptions: Earthquakes can trigger volcanic eruptions, just as the movement of magma can trigger earthquakes.
Land and sea level change: When the earth settles after a quake, the moving tectonic plates often leave their mark in rising sea levels and changes in ground level. Affected areas along the coast can lose significant land because of the rising water, and inland areas can have uplifts or down drops, changing the landscape.
It is worth noting that the extent of these consequences can also depend on some other factors like location, time of day/year, emergency communication and response system, population, planning, climate, and building style. So, an earthquake in the desert is not as dangerous as one in a densely-populated city on a winter night. However, if this city has built earthquake-resistant structures and has a good emergency communication and response system, the damages can be mitigated.
Florida Earthquake Threat Profile
Located in the southeast region of the U.S., Florida has a population of approximately 22 million people and rarely has earthquakes because it is not located near any plate boundary or active faults. However, earthquakes are not entirely uncommon in Florida. It is only that the recorded earthquakes often have low magnitude, and the epicenters of the earthquakes have been in the neighboring states or as far as Cuba or the Gulf of Mexico.
One of the last felt earthquakes in Florida was the 2020 Caribbean Earthquake, with a 7.7 magnitude. This event only caused shaking in southern Florida and the east coast, especially Miami-Dade County, Palm Beach County, and the Florida Keys. Shaking buildings were evacuated, but there was no collapse, and only a few structural damages were reported.
According to Florida's Department of Environmental Protection, there were 24 reported seismic activities in Florida between 1727 and 2016, but only five were confirmed earthquakes. There are even fewer instances of a high-magnitude earthquake's epicenter being located in Florida, the closest being a 4.0 magnitude earthquake recorded in the Florida panhandle in September 2020.
Preparing for Earthquakes in Florida
Although earthquakes are less frequent in Florida, especially compared to the more common natural disasters like hurricanes, tornadoes, tropical storms, and flooding, it is important to take necessary measures against earthquake hazards along with precautions being taken against other natural disasters or emergencies. Preparing yourself, your family, and your workplace for earthquakes is the best plan one can make and the best protection against avoidable injuries, property damages, and incurred financial loss.
The steps for preparing for earthquakes can be divided into three: home hazards, supplies, and personal preparedness or emergency plans.
Prepare for Home Hazards
This entails preparing the household for earthquake scenarios and protecting your home, family, and pets by identifying earthquake hazards in the home. Preparing against home hazards involves:
Bracing heavy furniture that can topple during a quake and securing other heavy items.
Keeping the breakables on low shelves.
Moving the heavy mirrors or picture frames away from the bed.
Learning or teaching the responsible members of the household how to turn off the water, electricity, and gas.
Correcting possible hazards that could be caused by heaters pulling away from pipes or appliances moving enough to rupture electrical and gas lines.
Identifying safe spots in each room with the family and having impromptu earthquake drills on the drop, cover, and_ hold on_ safety actions.
Learn basic first aid and CPR with household.
Get an earthquake insurance policy.
Consider fixing structural problems that can make the building collapse during an earthquake.
Get Emergency Supplies
Having an emergency supply kit is important to provide yourself - and others - the basic care and first aid while the community recovers from the effect of the quake. The supply kit should be enough for a few people to survive on for a few days as long as nobody suffers a serious injury, in which case urgent medical care is needed. Essential earthquake supplies include:
First-aid kit and manual.
Whistle.
Flashlight and batteries.
Battery-powered radio (and batteries).
A power bank and USB cable.
Fire extinguisher.
Water, preferably commercially bottled water or water in an airtight storage container and purifying tablets.
Food, preferably the non-perishable kind, in cans or sealed packs. Remember to pack formulas for infants, food for pets, and those with allergies.
Special needs items like inhalers, EpiPens, medications, diapers, and other specific items unique to your family's needs.
Clothes in case of an emergency during the winter.
Cash, cards, and copies of important documents and identification.
Some of these items are already available, and you can slowly stock up on the rest while noting the expiry dates, if any, for restocking. It is also important to choose the best place in the house, car, or workplace to keep the emergency supply, usually a close, common area with the least earthquake hazards.
Make Personal Preparations
With the addition of emergency supplies and a prepared household, making personal preparations can give you a better sense of control over the out-of-control situation. Five things to do before an earthquake are:
Subscribe to an earthquake shake alert for your location
Decide where to meet with loved ones or designate out-of-state contacts for everyone to check in with after an earthquake.
Learn or make an earthquake plan for your workplace, car, home, or school
Practice safety actions
Have an emergency earthquake kit.
Earthquake Warnings and Alerts
An earthquake warning system detects the primary waves of an earthquake. Then, the system calculates its intensity and magnitude and sends alerts to locations likely to feel the more destructive secondary waves. Depending on how close one is to an earthquake's epicenter, an earthquake early warning system can give people a few seconds of notice before an earthquake hits. The further away one is from the epicenter, the more time it takes before the earthquake reaches the location.
During this time, persons can move to safe spots and practice safety actions or halt potentially dangerous actions like cooking or delicate surgeries. This also helps industries and emergency responders initiate safety procedures and prepare for emergencies. Early warning services usually send earthquake alerts for significant quakes from magnitude 4 or from intensity MMI 3.0 and above, and alerts can be received and distributed through different platforms. The warning/advisory usually warns recipients of imminent shakes and tells them to protect themselves. The public alert or emergency notification system in Florida can also issue earthquake warnings, although earthquakes are rare.
What to Do During an Earthquake in Florida
When you receive an earthquake alert or find yourself in the middle of an earthquake, remember to keep calm and protect yourself by practicing the following safety actions depending on the situation:
If indoors, stay indoors until the shaking stops. Immediately drop down, cover your head and neck, and hold on to something steady. You can take cover under sturdy furniture (desk, bench, or table), against an inside wall, or inside a doorway near the center of the building.
Grab the emergency kit and keep it close.
For persons using walkers or canes, use the walker or cane to get yourself down to the floor and get cover. Persons using wheelchairs and walkers with seats can remain seated, lock the brakes, cover their head and neck, and hold on.
If outdoors, stay away from buildings, poles, trees, and anything that can fall.
If in bed, cover your head with a pillow and hold on, except if under a heavy light fixture or anything that can fall. Then move to a safer spot, preferably by crawling and keeping one hand over your head and neck, protecting vital organs.
Stay away from windows, outside walls, and anything glass.
Stay away from furniture or fixtures that can fall.
If in a car, stop and pull safely to the side of the road and stay in the car. Avoid stopping on or under a bridge or overpass. Also, avoid stopping near trees, utility wires, and buildings.
Additional safety tips for earthquakes include:
Avoid elevators; use the stairs.
Do not enter any damaged building when the shaking stops; there can be aftershocks.
You can use purses, books, or cushions to cover the head and neck if nearby.
Stay away from the kitchen unless entirely necessary.
Do not rush into or out of a building during an earthquake. Avoid the doorways.
Put off all fires immediately after the alert or after feeling the first quake as a safety measure for earthquakes.
Note that fire alarms or sprinklers may turn on and electricity may go out. Do not panic and seek refuge from the most pressing danger; quakes do not last long, and evacuation can happen after.
What to Do After an Earthquake in Florida
There can still be hazards after an earthquake, and affected persons must remain careful. The following are tips for things to do after an earthquake.
Check yourself and others for injury and apply first aid when necessary.
Use an extinguisher to put out any small fires, if possible.
Use mobile phones to call 911 for serious injuries or emergencies, as telephone lines may be down.
Check supplies and plan accordingly. Only use emergency food and water supplies after the home supply is exhausted or cut off.
Use a flashlight, not a candle, to check the earthquake's damage to your surroundings, as there may be a gas leak. Leave immediately if the building looks like it will collapse.
Check gas, water, and electricity lines and if there is any damage, switch off electrical power or shut off any damaged valves. In the case of a gas leak, open all doors and windows and leave the building.
Wear sturdy boots or shoes as protection against debris and broken glasses.
Stay away from damaged buildings and areas.
Use the battery-powered radio for emergency updates and save the phone battery.
Avoid beaches and be on the lookout for tsunami warnings. Head inland to higher ground if a tsunami warning is issued.
Chimneys can fall, so be careful when stepping out or making fires.
Prepare for aftershocks.
Take pictures and videos for insurance.
Check in with the emergency contact when possible or plan to reunite.
If trapped, do not light a match and keep your nose and mouth covered with a piece of clothing or handkerchief to avoid inhaling dangerous amounts of dust. Use a whistle or tap on a pipe or wall to help rescuers locate you, and only shout as a last resort. Lastly, avoid moving too much and use a mobile phone to contact emergency services.
