Assessment of the effect of earthquake activity on regional vegetation — High-resolution pollen study of the Ein Feshka section, Holocene Dead Sea

Abstract

Possible effects of seismic activity in the Dead Sea basin on the regional vegetation distribution are presented in this paper. The palynology was investigated in high resolution at the Holocene outcrop near the Ein Feshkha oasis. Pollen samples were collected from three intervals (A, B, D), with thicknesses of 5–15 cm, containing 1–2 seismites each, and from one undisturbed layer (interval C). All four intervals are from the same Ein Feshkha outcrop section, but from different depths. In two of the intervals (B, C) the main pollen indicators (e.g. Olea, Pinus, Asteroideae, Cichorioideae) show no significant aberrations from the typical pollen fluctuations. Interval A, deposited during the late Byzantine period, shows a decline of Olea percentages immediately after the sedimentation of a breccia layer (interpreted as a seismite). While this decrease in olive percentages predominantly reflects an aridification crisis at the end of the Byzantine period, damage to olive orchards due to earthquake (root damages, collapses of the crowns) and/or the abandonment of cultivated land as a consequence of an earthquake cannot be ruled out. Nevertheless, minor anthropogenic indicators like Vitis or Juglans, which show low abundances in the pollen diagram of Ein Feshkha, as well as other trees and herbs, are not affected by the late Byzantine earthquake. Interval D, deposited during the Hellenistic–Roman period, shows a slight decrease of Olea and an increase of Cichorioideae after the deposition of a seismite. Our hypothesis that earthquakes might have affected vegetation dynamics in intervals A and D is supported by cluster analysis. While the data of this study do not support the use of pollen as a reliable paleoseismic tool in the lacustrine environment of the Dead Sea, some small effects of earthquakes on pollen fluctuations cannot be excluded.