Earthquakes in Syria and Turkey are common, but the magnitude 7.8 that
shook the region on 6 February at 4:17am local time is clearly
impressive. To find earthquakes this strong on this particular fault, we would have to go back to the year 1114.
Read also: The Geology Behind the Deadly Earthquakes in Turkey
What is the name of the Türkiye earthquake(s)?
Kahramanmaraş Earthquake Sequence
When did the Kahramanmaraş Earthquake Sequence occur?
On February 06, 2023, at 1:17 UTC, a magnitude 7.8 earthquake struck south-central Türkiye near the Syrian border. The earthquake was relatively shallow. A magnitude 6.7 aftershock followed 11 minutes later followed by a magnitude 7.5 aftershock about 9 hours after that. Aftershock earthquakes in the sequence extend for 402 km (200 mi) from the Mediterranean coast inland to Malatya, Türkiye.
Where were these earthquakes felt?
The earthquakes were felt by people throughout Türkiye, Syria, and surrounding countries, including Israel, Jordan, Egypt, Armenia, Georgia, and Iraq.
How much damage did the earthquakes cause?
The USGS PAGER loss estimation indicated that economic and fatality losses would be high, with widespread and extensive damage. Earthquakes of this magnitude in this region could lead to tens of thousands of deaths and billions of dollars worth of damage and economic losses. As of the end of March 2023, the death toll was over 57,000. (Reliefweb)
Why was there so much damage?
The population in this region typically resides in structures that are extremely vulnerable to earthquake shaking, although some more resilient structures exist. The vulnerable buildings were older low- to mid-rise concrete frames constructed with infill or unreinforced masonry.
Were there other geologic hazards triggered by the earthquakes?
Yes, there were both landslides and liquefaction across a significant area. While aerial reconnaissance and on-the-ground investigations can authoritatively map out these locations, the USGS Ground Failure Report provides an estimate of where they're most likely to have occurred.
How long did the shaking last?
Scientists are able to estimate the time it took for the earthquake to complete its rupture. In the case of the M7.8 earthquake, this time was about 85 seconds. The duration and intensity of shaking felt by individuals depends on many different factors, most importantly how far away they are from the fault. During the M7.8 earthquake, some people experienced intense shaking for 30 seconds or more.
How long was the fault rupture?
The M7.8 earthquake caused shifting along nearly 354 km (220 mi) of the East Anatolian fault. The M7.5 earthquake ruptured roughly 161km (100 mi) of the Çardak fault. In some places, the shift was at much as 3 m (10 ft) along the East Anatolian fault and as much as 9 m (30 ft) along the Çardak fault. Both earthquakes occurred on mostly vertical strike-slip faults, meaning that the earthquakes caused a horizontal shift along the affected faults.
Why do earthquakes occur in this region?
Plate boundaries are where many of the world's earthquakes occur. The East Anatolian Fault system where the Kahramanmaraş Earthquake Sequence occurred, is near a triple plate junction where the Anatolian, Arabian, and African plates come together.
When was the last large earthquake in the region?
The last large earthquake in the East Anatolian fault zone was a magnitude 6.7 earthquake in January 2020, about 225 km (140 mi) northeast of the M7.8 epicenter. Prior to this earthquake sequence, there had been no magnitude 7 or larger earthquakes in the East Anatolia fault zone since 1822 and 1138. The last time Türkiye experienced an earthquake of similar size, was the M7.8 Erzincan earthquake on the North Anatolian Fault in 1939.
Why are there different magnitudes listed for the same quake? For example, USGS has the largest quake listed at M7.8, while it is being reported locally as M7.7.
USGS measures an earthquake’s size by its moment magnitude, not the Richter scale, which is no longer used. The moment magnitude is a measurement of the amount of ground that slips within the area of the fault on which an earthquake occurs. There are also other scales that are used globally to measure the size of an earthquake, will results varying slightly. It's worth noting that sometimes the preliminary magnitude will change after scientists have reviewed the initial data.
Can the magnitude, location, and time an earthquake occurs be predicted?
No. For an earthquake prediction to be accurate, you need to know which fault, how big, and when exactly it will occur. This is impossible. Stating vague predictions that an active fault zone will fail is pure speculation. Sometimes a guess is close enough that it may seem accurate, but it is simply coincidence. Although no one can predict earthquakes, the USGS sometimes puts out statistical-based aftershock forecasts. These statements describe the likelihood of the size and number of potential aftershocks that could follow a mainshock.
Why can’t we predict earthquakes?
To successfully predict an earthquake, there needs to be some form of precursor or signal that scientists can rely on to know that a big earthquake is about to happen. There have been countless supposed precursors explored throughout history: earthquake patterns, tidal forces, animal behavior, radon gas emission, earthquake lights, and various electromagnetic signals. However, after being analyzed and tested, none of them have been shown to reliably predict future earthquakes.
Will prediction ever be possible?
Some seismologists are skeptical that earthquake prediction will become a reality. For example, over 40 years ago, Charles Richter was asked by an interviewer if he thought prediction would ever be possible. He replied, “I don’t know, nothing is less predictable than the development of an active scientific field.” That statement still holds today.
Can seismologists forecast earthquakes, especially aftershocks?
Yes. Scientists can use historical data and previous research to determine the likelihood of future earthquakes following a large-magnitude earthquake. Smaller earthquakes, known as aftershocks, tend to follow over the days, weeks, months, or even years after a mainshock. Because aftershocks follow certain patterns, scientists can typically forecast how many and how large aftershocks might be. For example, the frequency of aftershocks decreases over time at an expected rate. Similarly, there is a known relationship between the magnitudes of aftershocks, themselves. Namely, there are typically 10 times as many smaller earthquakes as larger ones. For instance, you’ll see 10 times more magnitude 4 earthquakes than magnitude 5’s, or 10 times more magnitude 3’s than 4’s. Seismologists use these expected trends to issue aftershock forecasts that help support response and recovery efforts and to inform people of likely continued earthquake activity.
What is the difference between prediction and forecasting?
Although the two words seem similar, seismologists use “forecast” to refer to the probability that another earthquake might occur based on historical data and previous research. It is not the same as a “prediction” that pinpoints the exact location, timing, and magnitude of a future earthquake. For example, a forecast would be, “There is a 90% chance that no aftershocks will be of the same magnitude as the mainshock.” Whereas a prediction would be “There will be a magnitude 6.5 earthquake within 161 km (100 mi) of Los Angeles this week.”
Can the moon influence earthquakes? What about the sun? Or other planets?
The sun and moon both affect tides in our oceans and tidal stresses in the Earth, itself. Studies have shown that, although not very common, earthquake rates do sometimes fluctuate due to tidal stresses. However, since solar and lunar tides happen every day and vary seasonally, they are not useful predictors of earthquakes. Any tidal stress that might be related to other planets is incredibly small compared to the gravitational influence of the moon or sun, even if all the planets are aligned.
Is it possible for humans to induce earthquakes through programs like the now-defunct High-frequency Active Auroral Research Program (HAARP)?
There is no plausible mechanism for triggering an earthquake with a manmade device/weapon in these settings. The idea of a HAARP earthquake-generating weapon is purely science fiction.
Could a similar earthquake sequence happen in the United States?
There have been numerous parallels drawn between the San Andreas fault system in California and the East Anatolian fault system in Türkiye. Both the East Anatolian and the San Andreas Faults are shallow strike-slip fault systems that are known to be capable of generating infrequent, yet large earthquakes. The San Andreas fault produced two roughly comparable earthquakes during historical times: the 1857 Fort Tejon earthquake, estimated to be magnitude 7.8-7.9, and the great 1906 San Francisco earthquake estimated at a magnitude 7.9. However, the San Andreas Fault is not the only place in the U.S. where such an earthquake sequence could take place – it's also possible along the Cascadia subduction zone, the Alaska-Aleutian Islands subduction zone, and the New Madrid seismic zone, for example.
What is earthquake early warning?
Earthquake early warning is not a prediction. Instead, it is a tool that detects the start of an earthquake and sends a warning to people and systems before they begin to feel strong shaking. It’s like how the flash of lightning can act as a warning of impending thunder. The lightning has already happened, and the sound of thunder takes longer to reach you than the light. If you are far enough from the epicenter of an earthquake, it is possible to be warned in advance that an earthquake has occurred and that shaking is on its way.
The above post is reprinted from USGS.