tivity on the carmel faul

5. Discussion
The purpose of the present study is to date large paleoseismic events along the CF
during the Quaternary using the ages of broken speleothems from Denya Cave.
Speleothems are dated using the uranium disequilibrium decay series. The use of the three
dimensional isochron was found to be the best method to determine the ages of speleoseismites.
The method reasonably generates age clusters, which are probably indicative of
seismic events that caused damage to Denya Cave speleothems. These age clusters are
based on statistically viable isochrons as well as structural and morphological criteria. A
comparison showed that some sample age clusters were similar to the ages determined in
other paleo-seismological studies in Israel (Table 4 and Fig. 29). The comparison
indicates that the breaks, which were identified in Denya Cave speleothems, are not
random and lends supportive evidence to the assumption that they represent seismic
events.
5.1 Seismic events recorded in Denya Cave speleothems
Analysis of U-Th ages of speleo-seismites in Denya Cave, using three dimensional
isochrons, yielded age clusters that are considered to represent nine seismic events during
the last 200kyr BP:
1. A seismic event at ~4.8(±0.8)ka is based on five pre and post seismite samples
from around the cave, among them DN-2, which is a type A speleo-seismite.
2. A seismic event at ~10.4(±0.69)ka is based on six pre and post seismite
samples from around the cave, where two are type A speleo-seismites (DN-7
and DN-17). This calculated age is considered accurate since it is based on 11
dated samples, of which four DN-7 post-seismite samples are considered to be
of the same age and two DN-9 pre-seismite samples that are likewise
considered to be of the same age.
3. A seismic event at ~20.8(±3.0)ka is based on eight seismite samples from
around the cave. Most of those are pre-seismite samples of type C speleoseismites.
This calculated age is based on 13 dated samples, of which four
DN-4 pre-seismite samples are considered to be of the same age and likewise
for two DN-6 pre-seismite samples. It is supported by DN-7 pre-seismite
sample, which is a type A speleo-seismite.
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