Quantifying Earthquake Effects on Ancient Arches, Example: The Kalat Nimrod Fortress, Dead Sea Fault Zone

ABSTRACT Deformed arches are often key elements of archaeoseismic studies; arches have been in use for more than three millennia and damage, particularly moved keystones, are clear indications of a seismogenic cause. We introduce a damage evaluation scheme that allows a straightforward determination of the degree of damage to an arch based on laser scan models and digital images. The scheme is applied to 90 arches of the Nimrod Castle, which is neighboring the Dead Sea fault and which was heavily damaged during the 1759 Lebanon earthquake. The analysis shows that the a priori assumption of a correlation between arch orientation and damage degree does not hold for the entire building. An exception is a large tower including a secret passage in which voussoirs have dropped along a more than 20 m long section.