Authors: Y. Finzi, N. Ganz, O. Dor, M. Davis, O. Volk, S. Langer, R. Arrowsmith , M. Tsesarsky
Published in: Journal of Geophysical Research
Plain Language Summary:
Rock pillars and precariously balanced rocks in the Negev desert, Israel, were used to re-evaluate the maximum seismic ground shaking that could have occurred during their life-span.
Our work documented dozens of fragile geologic features which formed thousands of years ago and have withstood the ground shaking induced by many regional earthquakes. Within a study area of approximately 3000 km2, we were able to document and analyze enough fragile structures to evaluate the long-term seismic activity of several faults in the Negev and along the southern Dead Sea Transform. Slender rock pillars were shown to have natural frequencies within the range of seismic waves, making them very sensitive to resonance motion induced by large distant earthquakes.
Our analysis and database provides new constraints on shaking intensity induced by historic earthquakes and significant implications for national hazard assessments. In particular it indicates that the Arava Faults, which is the main seismic source in the region, has not experienced earthquake magnitudes larger than M7 in the past 10,000 years. Expanding our study area can help resolve fundamental knowledge gaps regarding the magnitude of ancient earthquakes, and can improve regional and site-specific seismic hazard analyses in Israel and Jordan.