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Two King Saud University researchers are immersed in a two-year study observing the earthquake belt and assessing potential reaction to seismic activity in eastern Saudi Arabia, including the cities of Khobar and Dammam.
Two KSU geology professors, Seismic Studies Center Director Abdullah M. Al-Amri and Dr. Mohammed Fnais, hope to present a plan and method of action that would prepare the area should an earthquake occur.
The researchers said Dammam and Khobar are among the financial and commercial Saudi cities that have grown economically at a faster rate than the rest of the country, and although there is no known seismic source in that immediate area, there are several nearby that could cause damage and destruction.
A 10-kilometer-deep sedimentation basin beneath the Arab Gulf near the Zagros Mountains in Iran is one of the best-known active seismic belts. Wide-ranging seismic recordings of the western side of the Arab Gulf have shown tremors in the Zagros area, and readings of seismic waves near the surface of the Earth show they continue to disperse at the separation surface between the basement rocks and surface sediments.
Low-amplitude waves (less than 1 second) die out quickly, but waves of greater amplitude resist attenuation even over long distances. Because of that, Drs. Al-Amri and Fnais believe strong earthquakes in the Zagros Mountains would be felt in eastern Saudi Arabia, and they warn that terrain displacements from swaves of 1-10 seconds amplitude could affect large structures such as high-rise buildings and long bridges.
Although eastern Saudi Arabia is seismically calm, it is adjacent to one of the most active seismic belts. Dammam is approximately 300 km from the clash point of the Arabian and Eurasian plates. According to the plate tectonics theory, the Earth's surface is made up of a series of large plates that travel a few centimeters per year. Earthquakes, volcanoes and formation of mountains occur where the plates border each other.
The belt along which these plates clash stretches across the Zagros Mountains and is considered one of the greatest sources of earthquakes. Magnitude 5 (on the Richter Scale) earthquakes are common along this belt, and Magnitude 6 earthquakes occur there several times a year. Magnitude 7 quakes occur about once a decade.
Doctors Al-Amri and Fnais want to learn whether these seismic events are a source of danger to eastern Saudi Arabia.
They say that although the probability of earthquakes there is slim, the threat to the population, buildings and infrastructures in Dammam and Khobar is high. They also point out that the mechanism of these events is not well understood and might be linked sometimes to the excessive production of hydro-carbon (oil, gas) or can be the result of clashes of the Arabian and Eurasian plates.
In the latter case, the quakes could be devastating, the two researchers warned.
Based on all of the above, the two researchers propose a comprehensive program to accurately assess the zone of possible earthquakes and the reaction of the ground in the eastern province.
“We will adopt the probability method to assess seismic dangers, and we will use the modeling method to produce maps that will be useful to engineers and decision makers to design infrastructures that resist earthquakes,” they said. “The understanding of earthquake risks and dangers is a pressing and important need, especially in the areas of facilities for oil production, in the eastern part of the kingdom, on the Arab Gulf.”
KSU’s Seismic Studies Center was founded in 1985.