Earthquakes occur when large pieces of subterranean rock suddenly slide past one another along what is known as a fault. The slipping of these large rocks across a fault plane generates a substantial amount of energy that is released in the form of seismic waves. The movement of these waves through the Earth’s surface is what causes the shaking associated with earthquakes. Typically, a large, main earthquake known as a mainshock is followed by a number of smaller earthquakes. These smaller earthquakes, known as aftershocks, can occur hours, days, or even months after the main earthquake. It is important to note that although all earthquakes share a similar mechanism and general characteristics, their magnitude and severity can vary drastically. Some earthquakes can be so weak that their occurrence goes unnoticed while others can generate shaking so violent that it can destroy entire cities.
Capable of happening at any time, earthquakes can devastate entire areas in a matter of minutes. Violent shaking produced by earthquakes can topple buildings, damage utilities and roadways, and trigger other natural hazards like landslides and ground liquefaction. There are also a number of common hazards typically associated with the aftermath of an earthquake. These hazards can include fires caused by broken gas lines and damaged electrical wiring, hazardous materials spills, and dam failures. Overall, the damage caused by earthquakes can be truly devastating. Entire regions can be crippled by seismic events and the recovery process can sometimes take months to years.
Threatening all 50 states to varying degrees, the areas in the country at highest risk from earthquakes are those situated near or overlying seismic zones. For example, the Pacific Northwest is bordered by the Cascadia Subduction Zone, a 600-mile-long fault plane stretching from Northern California to British Columbia. As a result, a major portion of the Pacific Northwest is at significant risk from a magnitude 9.0 or greater earthquake. Other areas of the country at significant risk from earthquakes include California, the Southern United States, and portions of the East Coast. With major population centers and large portions of the county at significant risk from earthquakes, officials immediately recognized a need for research targeted at better understanding this natural phenomenon. Currently, the US Geological Survey (USGS) functions as the leader of earthquake research in the United States and operates the Earthquake Hazards Program.
Tasked with a number of duties, the USGS Earthquake Hazards Program monitors and reports seismic events, identifies earthquake risks, impacts, and hazards, and researches the cause and effect of earthquakes. The efforts put forth by the USGS have drastically increased the understanding of earthquakes. Communities across the country have utilized this knowledge to better prepare for the occurrence of this natural phenomenon and further increase their resiliency.
Despite the efforts of the Earthquake Hazards Program, scientists still cannot predict the occurrence of seismic events and do not expect to learn how to make accurate predictions anytime in the foreseeable future. At this time, no recognized organization or individual has accurately predicted the date, time, location, or magnitude of a major earthquake. As a result, a major emphasis has been placed on the mitigation of earthquake hazards to improve public safety as well as the development of earthquake sensing technologies and early warning systems.
Although accurate earthquake predictions cannot be made at this time, the USGS has developed an earthquake early warning system known as ShakeAlertTM. This system, currently being tested in California, consists of approximately 400 high-quality ground monitors that sense compression waves generated by earthquakes and then transmit data to an earthquake alert center. This center then sends alerts to mobile devices and people, alerting them as to when shaking is expected to arrive at their location. The few seconds to minutes allowed by this system give individuals time to take action to protect life and property from destructive shaking. Review the ShakeAlertTM Factsheet produced by the USGS to learn more about this life-saving system.
Before an Earthquake
There are a number of proactive measures you can take prior to an earthquake to both decrease the chances of being injured and prevent damage incurred by the event. These measures involve preparing both your home and family. One of the first steps you can take to prepare for an earthquake is to prepare your home.
Begin preparing your home for an earthquake by mitigating the simplest hazards first. Most often, this involves identifying objects that could fall or slide during an earthquake. These objects pose the highest risk to individuals during an earthquake. Secure cabinet doors with strong latches, hold shelved items in place with removable putty, and secure refrigerators, large appliances, and furniture to walls. After you have mitigated falling hazards, you can then consider taking more extensive action to further prepare your home.
Many homes damaged during an earthquake fail for similar reasons. Homeowners who identify weaknesses and mitigate them prior to an earthquake can drastically reduce damage to their homes incurred by seismic events. Common weaknesses include inadequate foundations, unreinforced masonry, and soft first stories. Although it may seem labor intensive and rather expensive to retrofit your home, repairing major structural damage caused by seismic events can be far more expensive and difficult in the immediate aftermath of an earthquake. In certain cases, earthquake damages can be so extensive that your home may have to be demolished. To learn more about retrofitting your home for a seismic event, you can consult a structural engineer. You can also review FEMA’s Earthquake Safety Guide for Homeowners for more suggestions on how to retrofit your home before an earthquake.
It is also important that individuals living in areas at risk from earthquakes have an emergency communication plans as well as a disaster supplies kit. Having a family emergency communications plan will ensure that all your family members know what to do during and in the immediate aftermath of an earthquake. In addition to composing this plan and having it readily accessible to all family members, it is important that you practice utilizing this plan on an annual basis. Practicing your plan will allow you to utilize your plan and make any necessary changes prior to a disaster. As well as having an emergency communications plan, individuals living in earthquake-prone areas should also have a well-stocked disaster supplies kit.
Having a well-stocked disaster supplies kit will ensure that you and your family have enough supplies to survive in the immediate aftermath of an earthquake. It is also advised that everyone in the household keep a pair of sturdy shoes and a flashlight secured to their bedpost. Having these items easily accessible will ensure that all family members are able to exit your home safely in the event that an earthquake occurs at night. Additionally, it is recommended that individuals living in areas at risk from earthquakes build both work and car disaster supplies kits. Visit Ready.gov to learn more about how you can prepare for an earthquake.
During an Earthquake
An earthquake can strike at any time. As a result, individuals living in earthquake-prone areas should know what to do if an earthquake strikes no matter where they are. Earthquakes commonly occur when people are in their homes, at work, outside, or in their vehicles.
If you are inside when an earthquake strikes, do not attempt to run to other rooms or outside. In most cases, you can decrease your chances of sustaining an injury if you:
Immediately drop to the ground on your hands and knees. Not only are you less likely to be knocked over by an earthquake in this position, but you are also less likely to be struck by falling objects. Additionally, this stable position allows you to move to cover if necessary.
Cover your head and neck with your arms to better protect yourself from falling objects. If it is safe to do so, seek shelter under a sturdy table or desk. To further decrease your chances of being injured by falling debris, attempt to cover your entire body with shelter. If you cannot find a table or desk to cover your neck or head, drop to the floor near an interior wall or low-lying furniture. Stay away from any glass or windows that could shatter as well as ceiling and light fixtures that could fall during intense shaking.
Make sure that you hold onto your shelter until the shaking stops. Strong earthquakes can move large tables and desks and you want to ensure that you remain protected throughout the duration of the quake.
Taking these three simple actions will drastically decrease the chances of you being injured by falling objects and even building collapse during an earthquake. It is also important to remember that doorways in modern homes are not stronger than any other part of a home. Additionally, doorways do not protect against the biggest hazard during an earthquake, falling objects. Consequently, it is not advised that you stand in a doorway during an earthquake.
If you are outside during an earthquake, immediately move away from any buildings, utility wires, streetlights, and fuel or gas lines. One of the most dangerous places to be during an earthquake is near the exterior walls of a building. Shaking from earthquakes can cause windows to break and facades and other architectural details to fall from buildings. Even if you are outside, it is still important to remember to get down low so that intense shaking doesn’t knock you to the ground.
If you are in your vehicle when an earthquake strikes, stop as quickly and safely as possible. Pull your vehicle to the curb or side of the road, keeping in mind that utility poles, electrical lines, and overpasses can collapse during earthquakes. When you have safely pulled over, make sure to set the parking brake and turn on the radio to listen for emergency broadcasts. While a car may violently shake during an earthquake, it is a safe place to stay as it adequately shelters you from any falling debris. If a power line falls on your car, do not attempt to exit your vehicle. Call 911 and stay inside the vehicle until a trained technician advises you that it is safe to do so. Visit ShakeOut.org for more information on what to do during an earthquake.
After an Earthquake
Once the shaking from an earthquake has subsided, pause for a minute, check yourself and your family members for injuries and look around to identify any hazards that pose an immediate risk to your safety. If you feel it is unsafe to remain in your home, identify a clear escape route and calmly exit your home. Once you are outside, seek an open area, making sure to avoid downed power lines and other hazards. If you feel it is unsafe to remain in or reenter your home seek refuge at the nearest public shelter. If instead, you chose to remain at your residence, be aware that a number of hazards could be present in the immediate aftermath of an earthquake
A major hazard typically present after an earthquake is fire. Frequently resulting from damaged electrical wiring and severed gas lines, fires can quickly grow in size and cause considerable damage in addition to that caused by the earthquake. As a result, it is crucial that you immediately contact emergency services and, if it is safe to do so, attempt to put out small fires. As well as being a possible fuel source for fires, gas leaks also pose a major health risk. If you smell natural gas or see a broken gas pipe, shut off the main gas valve to your home immediately and contact the gas company as soon as possible.
In addition to fires and gas leaks, it also important to keep in mind that aftershocks are quite common in the minutes, hours, and days immediately following an earthquake. These subsequent earthquakes often compound damage caused by the main earthquake, further damaging weakened structures and utilities. If an aftershock does occur, be prepared to drop, cover, and hold on.
Earthquakes in Klamath County
As confirmed by both the Federal Emergency Management Agency and the USGS, Klamath County is considered to be a high-risk area for earthquakes. Like many counties in Oregon, the full destructive potential that earthquakes pose to Klamath County was not fully understood until recently. Recent earthquakes and scientific studies have revealed the true destructive potential that a major earthquake can have on the county.
Two of the most notable earthquakes to strike Klamath County occurred on September 20, 1993. These earthquakes, centered near the community of Rocky Point, resulted in 2 fatalities and caused widespread damage to more than 1,000 buildings in Klamath Falls. In total, the earthquake caused damage in excess of $10 million and damage to the Klamath County Courthouse was so extensive that it was considered to be a total loss. Of the 2 fatalities that occurred as a result of the September 20th Earthquakes, one was the result of a heart attack and the other was a consequence of a landslide along U.S. Highway 97 near Modoc Point.
Currently, Klamath County is most likely to be impacted by earthquakes resulting from shallow crustal events within the North American plate. Historically, earthquakes generated by shallow crustal events have been most damaging to Oregon and geologists believe that these events can produce earthquakes up to about magnitude 6.5. In addition to earthquakes generated by shallow crustal events, Klamath County is also susceptible to an earthquake generated by the Cascadia Subduction Zone. This type of earthquake, expected to be a magnitude 9.0 or greater, poses the greatest danger to both the county and the state. To view earthquake hazards in your area, visit the Statewide Geohazard Viewer produced by the Oregon Department of Geology and Mineral Industries.