An article on the subject is published this month in the journal Geology
Avi Blizovsky
Fallen ceiling in Sorek Cave - evidence of a devastating earthquake. Under the ceiling you can see stalactites that were once active as well as sentinels growing on the ceiling since its fall. The dating of the stalactites refers to the date before the fall, while the dating of the sentinels is after it. The earthquake was determined by both dates. (Photo: Alyssa Kagan.)
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Researchers at the Hebrew University have developed a method for determining the time of occurrence of destructive earthquakes according to stalactite caves. The only evidence of devastating earthquakes far from the Syrian-African rift is the extensive destruction left behind in caves.
An article on the subject is published this month in the journal Geology. The article is based on the graduate work of Elisa Kagan from the Institute of Earth Sciences at the Hebrew University and a report by the Geological Institute.
In stalactite caves, a record of environmental conditions such as climate and groundwater seepage is kept. The researchers have so far examined the Sorek Cave in the Avshalom Reserve in Beit Shemesh, known as the "Stone Cave" as well as a cave next to it. The two caves are about 40 km from the Dead Sea rift, which is considered responsible for the devastating earthquakes.
The researchers measured the earthquakes at 7.5 or higher on the Richter magnitude scale and found at least 13 destructive earthquakes in the last 200 thousand years. No evidence of noises of this magnitude was found in the research caves in the last 4,000 years. The researchers conclude that the prehistoric noises were stronger than anything recorded so far in human history.
Kagan measured the directions of dozens of stalactites and stalagmites that fell and discovered that their fall was not random but occurred in two main directions: north-south and east-west. Under the guidance of Prof. Amots Agnon from the Institute of Earth Sciences at the Hebrew University, Kagan showed that the fall of the stalactites and sentinels was apparently caused by abnormal ground accelerations during destructive earthquakes, especially noises whose epicenters were in the Dead Sea region.
Kagan chose avalanches of stalactites and stalactites that grew stalactites after the earthquake. The later sentinels will be dated under the guidance of Dr. Mira Bar-Matios and Dr. Avner Ayalon, experts from the Geological Institute for climate reconstruction from stalactite caves.
The scientists are continuing the research in other caves in Israel as part of Kagan's doctoral thesis.
Earth scientist - natural phenomena
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