Summary
Traveltime, surface-wave, and resistivity tomograms are used to track the buried Qademah fault located near King Abdullah Economic City (KAEC), Saudi Arabia. The fault location is confirmed by the 1) resistivity tomogram obtained from an electrical resistivity experiment, 2) the refraction traveltime tomogram, 3) the reflection image computed from 2D seismic data set recorded at the northern part of the fault, and 4) the surface-wave tomogram.
Introduction
The western side of the Kingdom of Saudi Arabia (KSA) is one of the fastest growing parts of the country, where a new city (King Abdullah Economic City (KAEC)) and a new university (King Abdullah University of Science and Technology (KAUST)) were established a few years ago. The population of KAEC is expected to be more than a million people by 2040 and the city will have one of the largest ports in the Red Sea.
Due to its expected growth, it is important to assess KAEC's earthquake hazard and proper building codes. For a complete seismic hazard assessment, paleoseismologists need to dig trenches across known faults and date the colluvial wedges to find the size and recurrence intervals of past earthquakes (McCalpin, 1996). However, paleoseismologists need to first know the locations of the faults, especially if these faults are buried. If a large earthquake (magnitude 6.0 or larger) were to occur along a near-surface hidden fault then this will likely destroy almost any man-made structure above the fault. Hence, the area above an active fault should be free of any buildings, especially hospitals, schools, and residential housing.
In this paper I present the results of using geophysical methods to track a hidden fault that intersects the King Abdullah Economic City (KAEC) in Saudi Arabia. This fault is known as Qademah Fault, and is shown on the geologic maps as an inferred fault (Roobol and Kadi, 2008), where surface geology suggests that a hidden fault runs in a north-south direction (Figure 1a). However, the exact location of the fault and its starting and ending points are not well-known. Hanafy (2012) used seismic refraction traveltime tomography, reflection, and resistivity to locate the Qademah fault around the northern part of the KAEC. In this paper, we track the fault to the southern end of KAEC using a variety of geophysical methods.
