x Abu Dhabi, UAESaturday 22 July 2017

UAE fault line unlikely, quake experts say

Researchers in Abu Dhabi say they are unlikely to include the 'West Coast Fault Line' in their earthquake zone map because there is little evidence to prove it exists.

ABU DHABI // A Dh100 million government project to map earthquake risk will probably not include a fault line that is said to run from Abu Dhabi to Ras Al Khaimah - because many experts say it does not exist.

Newspapers have mentioned the "West Coast Fault Line" for years but scientists presenting information about the project yesterday said there is no physical proof of the geological feature - and no evidence of seismic activity in the area.

Previous scientific studies that highlighted the fault as an active seismic source produced "unacceptably high hazard risk assessments", overestimating the likelihood of earthquakes here, said Zoran Milutinovic, a professor at the Institute of Earthquake Engineering and Engineering Seismology in Macedonia.

Mr Milutinovic said the project's researchers need to decide whether the fault line is real before they finalise seismic zoning maps that will show colour-coded earthquake risk.

"I don't really see any evidence to indicate there is a major fault along the coast," said Mohammed Ali, a member of the project's steering committee and an associate professor in geophysics at the Petroleum Institute in Abu Dhabi.

The one-year-old project is overseen by Abu Dhabi Municipality and the Department of Municipal Affairs.

Officials plan to use the seismic zoning maps to amend a new emirate-wide building code, set to launch in January, said Fatma Amer, a consultant for the Department of Municipal Affairs.

Chapter 16 of the code will set minimum requirements for engineers to make buildings earthquake-ready, depending on the seismic risk of the zone.

"That is the most important thing we are looking at," said Yousuf Al Marzooqi, director of the municipality's Spatial Data Division. "This will define for us which areas we really need to be careful in when we design buildings."

The maps will also mark the areas with the least seismic risk, appropriate for developments such as nuclear power plants. The risk of earthquakes here is low, Mr Al Marzooqi said.

The closest major collision of tectonic plates is across the Gulf, in Iran, according to Mr Ali.

"Fortunately, Abu Dhabi is far away from the collision zone, although the Northern Emirates are closer," he said. There are also some smaller fault lines in the Dibba area.

Contrary to popular belief, tall buildings such as the Burj Khalifa are not particularly vulnerable when an earthquake occurs, said SK Ghosh, an earthquake engineer consultant for the project based in the US.

"The taller the building, the less force it attracts in an earthquake," Mr Ghosh said. For architects and engineers designing very tall structures, wind is a more important stress factor.

The project's team is mainly focused on the risk of aftershocks from distant quakes, as well as the effect of seismic activity on artificial terrain, such as man-made islands. There is little knowledge of how these areas behave in earthquakes, Mr Al Marzooqi said.

Researchers are still gathering data for the project, compiling figures from 62 seismic sensors across the country. The sensors measure any movement in the ground, whether it is caused by an earthquake or a lorry rumbling down the street, Mr Al Marzooqi said.

To produce an accurate map of risk, the researchers will use that data as well as their knowledge of the region's plate tectonics, Mr Ali said.

The project's main phase will last another year, but officials will continue to monitor the seismic sensors for five to 10 years, updating the zoning maps appropriately.

vnereim@thenational.ae