JEDDAH – The regions of Saudi Arabia most prone to earthquakes are Tabuk, Jizan and Najran, seismologists have said. Jeddah, they say, is not vulnerable.
Experts on seismic activity were speaking at a recent conference in Jeddah to present the English-language “Arabian Journal of Geosciences,”published by King Saud University and King Abdul Aziz City for Science and Technology along with the Saudi Society for Geosciences.
“In Saudi Arabia the regions that see most seismic activity are Tabuk, which experienced a destructive quake in 1995, and areas down towards Jizan and Yemen,” said Professor Abdullah Al-Amri, director of the Seismic Studies Center in Jeddah and president of the Saudi Society for Geosciences.
“Jeddah is protected in a very unusual manner, in that the Red Sea experiences a lot of earthquakes but we don’t feel them because Jeddah is built on a thick layer of wet salt deposits which absorb quakes, much like a tire tube absorbs shocks. This goes all the way down to the coast of Jizan,” Al-Amri said.
Saudi Arabia is located on the Arabian Shield, and the Arabian plate between Saudi Arabia and Africa is bounded by the Red Sea rift. “The rift is moving from north to south, with the northern section spreading at a rate of 8 mm per year, the central part at about 10 mm, while the southern section toward Jizan and Yemen moves at a rate of 14mm per year,” Al-Amri said. “Considerable magma activity helps plates expand north-eastwards, which explains way the southern and northern zones of the Red Sea are more vulnerable than the central part.”
Three active fault lines meet in the southern part of the Red Sea, one heading toward the Indian Ocean, the other moving along the Red Sea, and the third going toward Somalia. “The three fault lines intersect at one point resulting in a lot of seismic activity,” Al-Amri said.
“The Arabian plate is moving northeast and the Red Sea is spreading,” said Dr. Zohair A. Nawab, President of the Saudi Geological Survey. “There is a large fault from the Red Sea to the Gulf of Aqaba, Turkey to the Gulf of Aden and to other areas.”
“There is a collision in the northeastern area where the Zagrous mountains are, but in the Arabian Peninsula it is very mild.
“Saudi Arabia is very lucky. It’s not like Japan where one plate slips under the other, producing large earthquakes,” said Dr. M.J. Roobol, a King Saud University consultant at the National Saudi Earthquake and Volcano Survey Center. “But we should build according to international earthquake standards as a precaution.”
Since the 1995 Tabuk earthquake the government has taken steps to build to international earthquake standards in vulnerable areas.
“We monitor seismic activity in the Haqal region, and Jizan and the areas bordering Yemen,” said Nawab. “The seismic source is deep magma at the center of volcanic activity, but it’s different to that found in Japan and western United States.” The active zone is described by experts as “mild”.
“Two years ago,” said Al-Amri, “we introduced international earthquake building standards. We divided Saudi Arabia into 25 zones, each zone having its specific building code covering not only seismic activity but other criteria as well.”
Experts reassured those who fear a tsunami in Jeddah. “A tsunami needs a great distance to build up a sizeable wave, but in Red Sea it’s not possible,” Nawab said. – SG