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Oklahoma Earthquakes FAQs

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Oklahoma Earthquakes FAQs

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5 km is a "fixed depth". Sometimes data are too poor to compute a reliable depth for an earthquake. In such cases, the depth is assigned to be 5 km. In Oklahoma, reliable depths tend to average 5 km or close to it. For example, if we made a histogram of the reliable depths in this area, we'd expect to see a peak around 5 km. Thus, if there are not enough data, or data are too poor, 5 km is a reasonable guess. 

The USGS is responsible for monitoring earthquakes all over the world. Some of their information comes from contributing networks within the region of the earthquake occurrence. Please see their information on reporting here:

The Oklahoma Geological Survey is one of these contributing networks. The OGS uses a denser seismic network within Oklahoma and has the capability of reporting lower magnitude earthquakes, if time and resources permit.

That really depends on the safe room or storm shelter. One should check with a structural engineer or the vendor to ensure that a structure would truly be safe during an earthquake. The greatest challenge to relying on such structures such as these is that earthquakes occur without warning and by trying to reach a safe room or storm shelter, you could be placing yourself in greater danger. Please see our information on Preparedness about how to prepare for and what to do during an earthquake.

Induced earthquakes are more accurately described as triggered earthquakes. This means that there is a naturally occurring fault inside the Earth that is "close" to having an earthquake and when a perturbation occurs in the subsurface from man's activities or other earthquakes, an earthquake occurs. This means that because most of what is being released is the natural energy stored within the Earth on an existing fault system, it is often not possible to readily distinguish a naturally occurring earthquake from a triggered earthquake. Often, we have to turn to more complex analysis and compare human activities with earthquake occurrence to identify such cases. In some cases, there may be some early indications that earthquakes may be triggered, such as very shallow earthquakes (about 6,000 feet) or other considerations. Some have tried to use strength of shaking, but this is very dependent on a number of factors, and one is depth, but there may be other subtle differences that the scientific community will be able to identify in the future.

Yes, the number of earthquakes felt since 2009 is unusual. The frequency of earthquakes has increased in Oklahoma. However, the majority of these earthquakes align with the natural stresses in Oklahoma and appear to be occurring on previously known and unknown faults, therefore, these earthquakes do not appear to be inconsistent with what might be called normal seismicity for Oklahoma.

Some people in Oklahoma recall that, in the past, Oklahoma had more earthquakes than another state, but they were so small they could not be felt. However, there is no scientific evidence to support that. In recent years, the media has reported on the large increase of earthquakes, but they are only showing events that are M3.0 and above. This leads some people to wonder if we are having more earthquakes of all intensities or if it is just that many of the earthquakes that we are having are stronger than they have been in the past.

Oklahoma has a recorded seismic history dating back to 1882. However, the Oklahoma Geological Survey has only been operating a seismic network since 1978. Ultimately, we are having more earthquakes of all intensities.

Oklahoma Earthquakes Magnitude 0.0 and Greater (1979-June 11, 2014)
Oklahoma Earthquakes Magnitude 0.0 and Greater (1979-June 11, 2014)
Oklahoma Earthquakes Magnitude 3.0 and Greater (1979-June 11, 2014)
Oklahoma Earthquakes Magnitude 3.0 and Greater (1979-June 11, 2014)

Please contact the Oklahoma Geological Survey expressing your interest in housing an OGS temporary or permanent seismic station. We will keep your information on file and contact you when and if we have the equipment and interest in placing one on your property.

Another option is to look into the Quake-Catcher-Network.

QCN is a volunteer hosted real-time strong-motion seismic network utilizing sensors in and attached to internet-connected computers.

The Raspberry Shake is a personal seismograph that you can purchase and install in your home with relative ease. The OGS uses these handheld seismographs in an educational project called BLOSSM

The increase of magnitude of 3.0 and greater earthquakes indicates a greater possibility of having a magnitude 4.0 or greater event in the future. This arises from the Gutenberg-Richter law which expresses the relationship between magnitude and frequency of earthquakes in a given region and time period. Simply stated, for every 10 magnitude 2.0 earthquakes we have we can expect a magnitude 3.0 earthquake. So, for every 100 magnitude 2.0 earthquakes we have we can expect 10 magnitude 3.0 earthquakes and one magnitude 4.0 earthquake. This relationship holds worldwide and does not vary significantly from region to region or over time.

Furthermore the energy released by a small event (M2.0) is nowhere near comparable to the energy released by a larger event (M5.0). Each whole number step in the magnitude scale corresponds to the release of about 31.6 times more energy than the amount associated with the preceding whole number value. For instance, a magnitude 2.0 earthquake releases 31.6 times more energy than a magnitude 1.0 earthquake, while a magnitude 3.0 earthquake releases about 1000 times (31.6x31.6) more energy than a magnitude 1.0 and a magnitude 5.0 earthquake releases 1,000,000 times (31.6x31.6x31.6x31.6) more energy than a magnitude 1.0.

Earthquake Magnitude and Energy Release
Earthquake Magnitude and Energy Release

The USGS and the Oklahoma Geological Survey sometimes differ on reported magnitudes. Both the USGS and OGS estimates magnitude based off of ground motion recordings at different sites. So the OGS only uses stations within or near Oklahoma and the USGS can use stations over a much larger area to calculate magnitude. In addition there are many different ways to calculate magnitude and each make different assumptions and provide different results. There is no single magnitude for any earthquake as there are always multiple estimates, but they generally agree quite well. Magnitude can be expected to have an uncertainty of approximately +/- 0.2 magnitude units.

The USGS, generally, only reports Oklahoma earthquakes larger than magnitude 2.5.

With the rate of seismicity currently occurring in the State of Oklahoma, and our limited resources, the Oklahoma Geological Survey is unable to locate all earthquakes. At a minimum, OGS is working hard to locate all events above a magnitude 2.5 and people may be experiencing smaller events that are not getting located at this time. In time, our seismic team will reexamine our catalogs and locate these smaller events.

If you feel an earthquake, you can report this to the OGS by completing a brief form

Our Preliminary Earthquake Information list gets updated as earthquakes are located. If there is a delay, it is either because we do not have an analyst working (during evenings or weekends) or there is a lull in seismic activity.

Earthquakes produce two types of seismic waves through  the earth. P waves move the earth's surface mainly up and down, and S waves move it mainly side to side. The P waves travel faster so they arrive first.

As the P waves arrive at your location, they cause the ground surface around you, and your floor, to vibrate up and down, just like a loudspeaker cone. The movement is too tiny to be seen, but just large enough to cause a low frequency sound. These sounds are often described as a boom or rumble. To persons who experienced the Oklahoma City bombing, the earthquake sounds are similar to the air blast sounds from that atrocity. Many check to see if their furnace exploded, or go outside to look for an explosion. The sounds are frequently described as "like a sonic boom, only somehow different".

Persons near an Oklahoma earthquake epicenter may hear and/or feel the P wave, and shortly after (only a second or so) may feel and/or hear the S wave. So you may have any of the following:
        1. sound only
        2. vibration only
        3. sound and vibration
        4. sound followed by vibration
        5. vibration followed by sound
        6. sound and vibration followed by vibration

or any other possible combination. 1., 2., 3., and 4. are the most common.

An earthquake swarm is a series of earthquakes, specific to an area, that happen over a period of time. They generally last days, weeks, or months. Earthquake swarms are different from the typical foreshock, main shock, and aftershock associated with earthquake occurence because no single main shock can be distinguished within the series.