Seismic triggering of unstable slopes in northern Israel

Hillel Wust-Bloch, Daniel Wachs

Research output: Contribution to journalArticlepeer-review

Abstract

Landslides in Israel inflicted severe damage to life and property during the earthquakes of 1837 and 1927 (M 6.5 and 6.2, respectively). In the Galilee, landslides occurred mainly in the chalks and marls of the Zefat Formation. The aim of this study was to investigate slope stability in general, and slope stability during earthquakes in particular. Investigations were conducted at the conducted at the Gush Halav site in the Galilee, just east of the village of Jish. Field studies, including engineering-geological mapping of the slopes, were conducted over a period of three years. Downhill slope movement and groundwater level variations were continuously monitored during the same period, with the intent of assessing the influence of groundwater on slope stability. At the Gush Halav site, the annual average downhill slope movement ranges between 10 and 20 mm, while the highest annual variation of groundwater levels reaches 120 cm. The main failure planes are located below the groundwater level throughout the year. No connection was found between the variation of groundwater levels and the downhill slope movements. The results of field measurements show that the slopes are unstable and therefore likely to slide during future earthquakes. Observations of past slope failure triggered by earthquakes in the region indicate that an earthquake with a magnitude of 6.0 can trigger landslides at distances of up to 120 km from the epicenter. This study suggests that other unstable slopes in Israel which are composed of the same rock units could slide during a future earthquake which has a magnitude of 6.0 and an epicenter located along the Dead Sea fault between the Dead Sea and the Hula Valley.

Original languageEnglish
Pages (from-to)103-109
Number of pages7
JournalIsrael Journal of Earth Sciences
Volume49
Issue number2
DOIs
StatePublished - 2000

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