North Carolina Earthquake

Earthquakes are caused by intense movements of tectonic plates (giant slabs of rocks that make up the earth's outermost layer). This natural disaster can strike without warning and can happen anywhere in the world. About 81 percent of major earthquakes occur in a volcanic area called the "Ring of Fire" along the rim of the Pacific Ocean. Other regions vulnerable to earthquakes include the Alpide belt that extends along the southern margin of Eurasia through the Himalayas, Java, and Sumatra; and the Mid-Atlantic Ridge that runs along the floor of the Atlantic Ocean.

Earthquakes range in size from those that are too small to be felt to those that are violent enough to cause deaths and destroy buildings, bridges, roads, electric poles, etc. This natural disaster can trigger environmental hazards such as fires, tsunamis, landslides, soil liquefaction, and even volcanic eruptions that can cause enormous loss of life and property damage.

Science Behind Earthquakes

The earth is made up of four major layers, which are the crust, mantle, inner core, and outer core. The crust is composed of tectonic plates, which are huge irregularly-shaped slabs of solid rock that make up the continental and oceanic lithosphere. These rocks are constantly slowly moving, colliding, moving away, or slipping past one another on a surface called the fault or fault line. As these plates slide against each other, they get stuck at their edges because of friction. This builds up pressure and causes energy to form along the edges of the fault. Eventually, the force of movement overcomes the friction and releases the stored-up energy in the form of waves that travel through the earth's crust. These waves are called seismic waves, and they cause the shaking that people feel during an earthquake.

The size of an earthquake usually depends on where it occurs and the depth of the hypocenter. The hypocenter is the point below the earth's surface where an earthquake starts, while the place directly above it (at the ground surface) is called the epicenter. The more shallow the hypocenter of the earthquake, the greater the shaking of the ground. Unlike shallow earthquakes, seismic waves from deep earthquakes have to travel farther to the earth's surface, and they end up losing their power along the way.

Earthquakes may have foreshocks, smaller earthquakes that occur in the same location as the larger earthquake that follows. Scientists have, however, found it difficult to predict whether an earthquake is a foreshock until the larger earthquake occurs. This large earthquake is called the mainshock. Sometimes, mainshocks are followed by aftershocks, smaller earthquakes that happen after the main earthquake takes place. Aftershocks can continue for weeks, months, or years, depending on the size of the mainshock.

Earthquake Size and Intensity

The severity of an earthquake is expressed in both size and intensity. The size of the earthquake is called its magnitude. It is the amount of seismic energy released at the hypocenter of an earthquake. The magnitude of earthquakes was initially measured with the Richter Scale, a mathematical formula invented by Charles Richter.

However, the Moment Magnitude scale (Mw) replaced Richter Scale because it only works for certain frequency and distance ranges. Mw accurately measures a wide range of earthquake sizes across the world, including magnitude 8 and greater earthquakes. The different categories of earthquake magnitude can be seen as follows;

• Magnitude 2.5 or less: Minor earthquakes; not felt but can be reported by a seismograph.
• Magnitude 2.5 - 5.4: Minor earthquakes; are often felt but cause minor damages.
• Magnitude 5.5 - 6.0: Moderate earthquakes that cause slight damage to buildings and other structures.
• Magnitude 6.1 - 6.9: Strong earthquakes that may cause significant damage in overpopulated areas.
• Magnitude 7.0 - 7.9: Major earthquakes that cause serious damage.
• Magnitude 8.0 or greater: Great earthquakes that cause enormous loss of life and property damage in areas several 100 kilometers across.

Intensity is the observed effects of an earthquake, such as ground shaking. The intensity of shaking varies and usually depends on your location during the earthquake. The Modified Mercalli Intensity Scale is used to measure the intensity of an earthquake. It has twelve levels designated by Roman numerals I – XII (one through twelve), ranging from slight shaking to catastrophic destruction. The lower numbers on the intensity scale represent how much people can feel an earthquake. The higher numbers on the scale are based on observed structural damage.

Earthquake Consequences

Earthquakes can have direct consequences, such as damage to structures from ground shaking and rupture. They can also produce secondary effects such as triggering fires, landslides, soil liquefaction, tsunamis, floods, and even volcanic eruptions.

• Ground shaking: When earthquakes occur, they produce seismic waves that radiate in all directions and cause the ground to vibrate at different rates or frequencies. The severity of ground shaking usually depends on the magnitude of the earthquake. High-magnitude earthquakes can lead to the collapse of buildings, bridges, roads, electric poles, and other structures. Such earthquakes can also be very dangerous to humans and can lead to massive loss of lives.

• Surface faulting or rupture: This occurs when an earthquake movement along a fault breaks through the earth's surface and pushes the ground apart. Surface rupture can happen suddenly during an earthquake or after the disaster. It can cause severe damage to buildings, roads, bridges, railways, pipelines, canals, storm drains, and gas lines.

• Liquefaction: This arises when water-logged sediments lose their strength and turn into liquid due to strong shaking of the ground. Liquefaction causes buildings, roads, bridges, and pipelines to collapse or sink into the ground.

• Landslides: Earthquakes can cause large rocks or debris to roll down a slope and cause destruction. Landslides can lead to significant loss of life and property damage. They can destroy buildings, block roads, and disrupt water or gas lines.

• Tsunamis: These are a series of long waves that arise when an earthquake strikes beneath the ocean floor. Large tsunamis are dangerous to buildings and other structures along the coast. They can cause devastating loss of life and mass injuries. While earthquake-induced tsunamis can arise in many parts of the world, they are common within the Pacific Ocean basin.

• Fires: When the ground shakes or ruptures during an earthquake, they damage gas lines and electric poles, which can trigger a fire. Earthquakes can also cause flammable substances, such as household chemicals, to spill and ignite fires in homes. Fires are one of the most dangerous secondary impacts of an earthquake. They can lead to death and the destruction of property.

• Floods: High-magnitude earthquakes can cause dams or levees to rupture, thereby sending waters into surrounding areas and causing severe flooding. Floods can sweep people off their feet and damage buildings and other structures.

Large tectonic earthquakes can trigger volcanic eruptions. However, this can only happen when the volcano is already on the brink of erupting. According to the U.S. Geological Survey (USGS), an earthquake can cause magma from a volcano to release dissolved gases, thereby increasing the pressure and possibly leading to an eruption. For this to occur, the agency noted that there must be enough magma within a volcano and significant pressure within the magma storage area.

North Carolina Earthquake Threat Profile

The state of North Carolina is located in the southeastern region of the U.S. It shares borders with Virginia to the north, South Carolina and Georgia to the south, Tennessee to the west, and the Atlantic Ocean to the east. With an area of 53,819 square miles (139,391 square km) and a population of 10.5 million people, North Carolina is the 28th largest and ninth-most populous of the 50 states in the U.S.

North Carolina lies within an intraplate zone that experiences relatively few earthquakes. There are earthquake source zones that could generate ground motion of sufficient strength to cause structural damage in the state. These include the Eastern Tennessee Seismic Zone, Charleston, South Carolina Seismic Zone, and Central Virginia Seismic Zone.

Although North Carolina has had its share of earthquakes since 1735, large seismic activities are not common. This contrasts states like California, South Carolina, and Washington, which have many active fault lines where large and destructive earthquakes occur frequently. Most earthquakes reported in North Carolina are small and usually range between 2.0 and 3.0 on the Richter scale. The state has, however, experienced a few strong earthquakes over the years. Some of the historical earthquakes in North Carolina can be seen below.

Preparing for Earthquakes in North Carolina

Since earthquakes occur suddenly and without warning, it is important to prepare ahead of time to prevent serious injury or loss of life from the disaster. Consider the following safety tips when preparing for an earthquake:

Assess Your Risk

Although an earthquake strikes suddenly and without warning, it is possible to know the earthquake risk in your area. Your earthquake risk is the potential building damage and the number of people that might be injured or killed if an earthquake strikes a fault line. The amount of shaking usually depends on several factors, including magnitude, location, the type of soil under your building, the type of building you live in, etc.

Understanding your earthquake risk helps you to know how to prepare when a disaster strikes. You can use the USGS National Seismic Hazard Map to learn about the earthquake hazard in your area. You can also stay informed by contacting your local emergency management or geological survey office. Understanding your risks helps you to know how to protect yourself and your property when an earthquake occurs.

Create a Family Emergency Plan

Develop an emergency plan in advance. The plan must provide for how you and your family will communicate during an earthquake. Plan for a meeting point in case you get separated during the disaster. You can ask an out-of-state relative or friend to be the family contact. Make sure each family member knows your contact person's name, address, and phone number. Also, do not forget to include your pets in your emergency plan.

Gather Emergency Supplies

You should have a supply kit ahead of time which should contain essential items such as non-perishable foods, water, medicines, a flashlight, a fire extinguisher, a whistle, a first aid kit, clothing, a battery-powered radio, extra batteries, and extra cash. Store the supply kit where you can easily access it during an earthquake.

Get an earthquake insurance policy: A standard home insurance policy does not cover damages from earthquakes. You should get separate earthquake insurance to minimize your financial hardship when the disaster occurs.

Prepare Your Home

• Anchor heavy furniture or objects to the wall, including bookcases, china cabinets, refrigerators, and televisions. This is to prevent them from falling during an earthquake.

• Do not hang heavy items such as pictures and mirrors over beds, couches, and anywhere people sit.

• Keep heavy objects away from doors and escape routes.

• Place heavy and breakable objects such as china, bottled foods, and glass in lower cabinets. Use strong latches or bolts to keep cabinet doors from flying open during an earthquake.

• Ensure everyone knows how to turn off the gas, water, and electricity.

• Fasten overhead lighting fixtures to ceilings.

• Secure stoves, water heaters, and other appliances that could move enough to rupture gas or electrical lines.

• Store all flammable products on lower shelves or cabinets with latches.

• Check electrical wiring and gas connections and ensure they are in good condition. This is to prevent the risk of fire in your home.

• Call a professional to check if your home is securely anchored to its foundation. Get expert advice and strengthening tips for exterior features, including decks, porches, sliding glass doors, garage doors, etc.

• Know your area's seismic building standards and land use codes before you begin any construction.

• Learn first aid and CPR (cardiopulmonary resuscitation) from your local Red Cross chapter or any other organization within your community.

• Practice Drop, Cover, and Hold On with your family members.

Prepare Your Vehicle

• Pack your car emergency kit and store it in your trunk. The kit should contain essential supplies such as local maps, a first aid kit, bottled water, an emergency flasher, a white distress flag, blankets, toiletries, extra clothes, sturdy shoes, a rubber hose, a tire repair kit, jumper cables, pump, flares, tools like screwdrivers, can opener, pliers, wire, and duct tape.

• Avoid carrying spare gas in the trunk of your car. Instead, keep your vehicle's gas tank full in case you may need to evacuate.

• Maintain your car and car parts and ensure they are in good working condition.

• Listen to the radio, television, and other media for emergency updates.

Prepare Your Pets

• Create an emergency plan for your pet. The plan should provide for how you will collect your pets and keep them safe during and after an earthquake.

• Gather your pet supply kit, which should contain items like pet food, water, crates or sturdy carriers, litter box, pet towels, blankets, pet shampoo, conditioner, pet first aid kit, medicines, pet toys and treats, leash, collar, ID tag, pet life jacket, paw protectors, and pictures of you and your pet. Your pet supply kit should also contain your pet paperwork, including copies of your pet's vaccinations, adoption papers, medical records, microchip and registration information, and other important documents.

• Find a shelter for your pet ahead of time. You can find an animal shelter or ask your friends or relatives that live outside your immediate area to take care of your pets during the emergency.

• Make sure your pet is tagged or microchipped to make finding them easier if you get separated from them during an earthquake.

• Place a "pet inside" sticker at the entry doors of your home. This will notify rescuers about the number of pets in your home that needs assistance.

Get Earthquake Warnings and Alerts in North Carolina

The National Weather Service (NWS) and the USGS use ground-motion sensors to detect earthquakes that have already started and to predict their size, location, and impact. Once the sensor detects fast-moving but non-destructive primary waves (P-waves), it quickly sends alerts to warn people before the slower but more destructive secondary waves (S-waves) arrive.

An earthquake warning is issued through the Integrated Public Alert and Warning System (IPAWS), which is an advanced notification system that allows public safety officials to alert and warn the public about a disaster. The IPAWS uses the Emergency Alert System (EAS), Wireless Emergency Alerts (WEA), the National Oceanic and Atmospheric Administration (NOAA) Weather Radio, and other public alerting systems from a single interface.

Earthquake warnings are usually distributed over the Wireless Emergency Alerts system to cell phones in the form of text messages. The alert informs residents of North Carolina about an incoming earthquake within the next few seconds or minutes. If you live on the coast, you may also receive a Tsunami Warning if the earthquake occurred beneath the sea floor. The notice given within seconds or minutes allows you to immediately take safety precautions such as Drop, Cover, and Hold On.

What to Do During an Earthquake in North Carolina

Consider the following safety tips if an earthquake happens when you are at home:

• If inside your home, you should drop, cover, and hold. Drop down to your hands and knees, find cover under a table, desk, or other sturdy furniture, and hold on until the shaking stops.

• Make sure you hold on to the sturdy furniture with one hand and be ready to move with it if it moves.

• If there is no sturdy table or desk nearby, move to a structurally sound interior wall and cover your head and neck with your arms. Stay away from windows, glass, and outside doors.

• If you are using a wheelchair or walker with a seat, be sure to lock your wheels and remain seated until the shaking stops.

• If you are in bed, hold on and cover your head and neck with a pillow. Move to the nearest safe spot if you are under a heavy light fixture that could fall.

• If you are in the kitchen when an earthquake strikes, move away from the stove, water heater, refrigerator, and overhead cupboards.

• Stay indoors until the shaking stops, and you are sure it is safe to exit.

• Get out of your house immediately if you smell gas. This is because the house may catch fire.

• Never use the elevators because they may shut down during an earthquake.

• Minimize your movements during an earthquake and stay as safe as possible.

If You Are in a Vehicle During an Earthquake

• Pull over to a clear location as quickly as possible.

• Turn off your car engine and put your emergency brake on. Your emergency brake prevents your car from rolling forward or backward during the earthquake.

• Make sure you stay inside the car with your seatbelt fastened until the earthquake stops.

• Avoid parking under bridges, overpasses, or near trees, signs, or buildings that can collapse and fall on your vehicle.

• Do not get out of your car if downed power lines fall across it. Wait for help instead.

• If you need assistance, signal and/or turn your hazard lights on. You can also place a HELP sign on your window if possible.

• Stay below window level in your car.

• If you are on a bus, stay in your seat and take cover in a safe place. If you cannot take cover, sit in a crouched position and protect your head and neck from falling debris.

• Avoid driving through a flooded area since your car can be swept away in six inches of fast-flowing water.

• Get out of your car immediately if you smell gas, and stay away because it could catch fire or even explode.

• Listen to your car radio for updates and follow emergency instructions.

If Outdoors During an Earthquake

• Find an open area and drop to the ground. Stay there until the shaking stops.

• Stay away from buildings, trees, walls, and power lines that may fall on you.

• If you are on a sidewalk near buildings, use a doorway for shelter and protect yourself from falling bricks, glass, and other debris.

• If you are hiking in a mountainous area, watch out for landslides, falling rocks, trees, and other debris.

What to Do After an Earthquake in North Carolina

After an earthquake, there can be serious hazards and damage to structures, including buildings, electric poles, gas and water lines, etc. If away from home, you should return only when local authorities say it is safe. Consider the following safety tips when returning home after an earthquake:

Reunite With Loved Ones

• Follow your emergency earthquake plan to communicate and reunite with your family members.

• Make sure you check yourself for injuries and get first aid (if necessary) before helping injured or trapped people.

• Pay close attention to children and pets and keep them under your direct control.

• Check how your loved ones are handling stress following an earthquake.

• Move away from damaged buildings, chimneys, trees, broken glass, and other debris.

Get Help for Injuries

• Pay attention to children, the elderly, people with disabilities, and those needing special assistance.

• If you are trapped, cover your mouth with your shirt for protection and use a whistle to signal for help.

• Call 911 if you or anyone around you needs urgent medical attention.

Check the Utilities for Damage

• Be careful of downed power lines when returning home. This is to avoid the risk of electrocution.

• Examine your house for structural damage before entering. Never enter a damaged building. If you are already in a damaged building, go outside and move away from the building.

• Check gas, water, and electric lines for damage. Turn the utility off at the source if there is any damage.

• If you smell gas, get out of your house immediately and call the fire department.

• Do not use matches, candles, or lighters inside your home.

• Take pictures of your damaged home and belongings for insurance purposes.

• Be sure to check for other hazards in your home and control them. These include toxic fumes, spilled chemicals, and other flammable liquids.

Clean Up Your Home

• Inspect your home, including the walls, floors, windows, doors, and staircases, for cracks or possible collapse.

• Wear protective clothing when cleaning. These include rubber gloves, sturdy shoes, facemasks, long pants, and a long-sleeved shirt.

• Throw out spoilt food and ensure your water supply is safe to use.

• Never try to remove heavy debris by yourself. Work with a partner when cleaning.

• Keep children, pets, and people with asthma and other lung conditions away when cleaning.

Prepare for Post-Earthquake Hazards and Disasters

• Expect and prepare for potential aftershocks, landslides, or even a tsunami if you live in a coastal area. When you feel an aftershock, drop down, cover yourself, and hold on to something sturdy.

• If you live on the coast where tsunamis occur, go inland or move to higher ground immediately after the shaking stops.

• Avoid contact with floodwaters because they can contain sewage, chemicals, broken glass, plastics, and other debris.

• Continue listening to the radio, television, and other media for emergency updates.

If You Are in a Vehicle After an Earthquake

• Get out of your car once the shaking stops, and assess your surroundings.

• Check yourself and other occupants in the car for injuries.

• Listen to emergency updates on the radio and ensure it is safe before driving again. Remember that it might be safer to stay where you are, especially if there are obstructions on the roads.

• Use extreme caution when driving after an earthquake, as traffic lights may stop working.

• Be aware that earthquakes might have aftershocks. These can be dangerous and can easily dislodge concrete from damaged buildings and other structures. It is best to pull over if you notice any shaking or tremors again.

• Avoid passing through bridges, ramps, and roadways when driving back home. This is because they may have sustained damage during the earthquake.

• Watch out for road obstructions, including fallen trees and downed power lines.

• Since the traffic lights will be out, stay alert for panicked or distracted drivers around you.

• Be careful of potential landslides on the road if driving in a mountainous or rocky area.

• If your car is trapped under a pile of debris, use your phone and call for help. If you do not have a phone with you, wait for the shaking to stop, and honk your horn until someone comes to rescue you. If your horn is not working, you can use your keys to jam your car to get the attention of rescuers.

• Call 911 if you are badly injured or in serious danger.

Get Disaster Relief for Earthquake Survivors

Earthquake survivors in North Carolina can use the different federal and state disaster resources available in the state. FEMA's Individuals and Households Program provides financial assistance to repair the structural parts of damaged homes (walls, doors, windows, ceilings, floors, utilities, etc.).

The program also assists survivors with uninsured, disaster-related expenses, including medical expenses, household items, vehicles, educational materials, clothing, funeral and burial costs, and other necessary expenses related to the earthquake. You can apply on FEMA's website or call 800-621-3362. To be eligible for this disaster assistance, your area must have been declared a federal disaster by the president.

North Carolina also has the Earthquake Homeowner Recovery Program. This program provides survivors with assistance to repair, reconstruct, or replace their homes after an earthquake. You can apply for the program even if you have received funds from other sources, including from the SBA or private banks.

Homeowners, renters, and businesses may also apply for a low-interest disaster loan from the U.S. Small Business Administration (SBA). This is to compensate for losses that are not fully covered by insurance. You must be in an SBA-declared disaster area to qualify for this disaster assistance. Check the agency's Disaster Declarations website to find disaster areas by state and territory. If you meet the eligibility criteria, you can apply by using the SBA Disaster Assistance Application or by calling the agency's Customer Service Center at 800-659-2955 for more information on SBA disaster assistance.