Geo-Hazardous of AlUla Ancient City, Saudi Arabia

AlUla, is a city in the Medina Region in north-western Saudi Arabia. The city lies within the governorate of Ula, one of seven in the Medina Region, covering an area of 29,261 square kilometres. The city is 110 km southwest of Tayma and 300 km north of Medina. The city (municipality) covers 2,391 square kilometres. The population of the city is 5,426.

The walled city of AlUla was founded in the 6th century BC.It was located along "Incense Road", the network of routes that facilitated the trading luxury items through Arabia, Egypt and India. AlUla stands on the site of the Biblical city of Dedan but was founded with the ancient North Arabian Kingdom of Lihyan, which ruled from the 5th to 2nd century BC. The older history of the oasis has been divided into several phases. The Dedanite kingdom spans the seventh and sixth centuries BC. It is thought that around the turn of the fifth century BC the kingdom became hereditary. In the 20th century the new town centre was established beside the old town and eventually the people left the old buildings. The last family left in 1983. Both the ruins of the town and the site of the Liyhanite settlement now lie within the limits of the modern town. AlUla has the potential to be one of the most important archaeological destinations for tourists from around the world. AlUla’s Hegra archaeological site (Al-Hijr / Mada’in Salih) was the first world heritage property to be inscribed in Saudi Arabia. A major integrated archaeological survey of AlUla valley and beyond was launched by the royal commission for AlUla (RCU). AlUla is a unique and extraordinary landscape because of the distinct geological eras packed together in one region. The earliest of the geologic ages which formed the rocks during the Precambrian Arabian shield rocks, marked by different layers of sedimentary rock. Second, the area’s underlying sandstone created during the Cambrian period and tectonic activity has helped further shape its dramatic geology, creating volcanic landscapes, basalt plateaus and sandstone massifs. These geological features enable the area to act as a water catchment basin allowing the valley to flow southwards towards AlUla’s settlements. Trilobite trace fossils discovered in sandstone date to at least 252 million years ago. The soft and porous rock, perfect for carving, also acts as an aquifer that can store the vital fresh water resources required to sustain life in an arid environment. Following that the black basalt layer formed by volcanic eruptions creates the dramatic plateaus called the Harrat. The desert of AlUla is famous for its several geological rock formations, formed over millions of years by wind and water, to form natural shapes untouched by human hands. geological and geophysical studies show that Geohazards in the area may include weathering and erosion processes, rock falling or sliding, and collapse of the carved architectonic structures.