Aftershocks ‘unlikely’ after Tuesday’s EP temblor

RIYADH: There would probably not be any aftershocks in the wake of the earthquake that hit the Eastern Province on Tuesday night, according to the National Center for Earthquakes and Volcanoes (NCEV).
Hani Zahran, director of the earthquake center, said Thursday that the earthquake was felt in the eastern part of Riyadh on Tuesday, but was weak. This means aftershocks are unlikely, he said.
A bulletin released by the Saudi Geological Survey (SGS) said the magnitude-3.7 quake struck at 9:25 p.m. on Oct. 20, 2015, with the epicenter traced at 133 kilometers southwest of Hofuf, Eastern Province, or east of Riyadh. Although the quake falls under "light" or "weak" category, it had a shallow depth of 2.5 km and thus was felt as far as the capital.
A Riyadh resident said earthquakes are unusual in the Kingdom. “It could be a reminder from God that we have to behave and take care of the environment,” he said.
Another person said that he had never experienced an earthquake in his lifetime. However, records show that the Kingdom has previously been hit by these natural events except that most are minor.
SGS records show that Tuesday’s quake was the 11th to strike within or close to the kingdom this year and the fourth in that same area about 160 km southwest of Hofuf.
The first one was on March 10, followed by another on May 10 and a third on August 17. All four were measured at magnitudes ranging from 3.3 to 3.7, which are classified as “minor” in the Richter Scale. All occurred at shallow depths from 2 km to 12 km.
The other quakes for the year occurred on Sept. 3, 24 km from Mintaqat, Tabuk; Sept. 2, 42 km from Al-Uqdah, Jazan; Aug. 5., 79 km from Salwa, Eastern Province; July 28, in the Red Sea 105 km southwest of Umluj, Tabuk; June 25, 220 km west of Jazan; May 7, 267 km southwest of An Nimas in Asir region; and January 12, 101 km west of Umluj, Tabuk.
Stronger earthquakes that hit the kingdom included two that took place in Jazan two years ago. One was measured at 4.6 magnitude at a depth of 10 km, while the other had a magnitude 4.4 at the same depth.
Four years earlier, a 4.6 magnitude earthquake hit Jazan at a depth of 10 km. Earlier, 14 other earthquakes were registered in Jazan and Tabuk, with magnitudes ranging from 4.1 to 5, at an average depth of 10 km.
In the Richter Scale, magnitude 3-3.9 quakes “are often felt by people, but very rarely cause damage. Shaking of indoor objects can be noticeable.”
Magnitude 4-4.9 quakes cause noticeable shaking of indoor objects and rattling noises and are felt by most people in the affected area but generally cause none to minimal damage.
Quakes of 5-5.9 magnitude are felt by everyone and can cause damage of varying severity to poorly constructed buildings, but at most, none to slight damage to all other buildings.
Seimologists say that the earthquakes are caused by the movement of the earth’s tectonic plates. The Arabian tectonic plate is currently drifting away from Africa and colliding with Eurasia at a rate of 2 cm a year.