The water level of the Dead Sea has been dropping rapidly for the past 50 years or so. This drop in water level is due to the development of agriculture north of the Dead Sea. (reasons why)
Right now (in 2017), the Dead Sea is dropping a over 1 meter (~3 + feet) per year.
As the Dead Sea level has dropped, much of what was formerly underwater has been exposed and subject to erosion. Because the Dead Sea bottom sediments are relatively soft, they erode quickly leaving many gullies and sinkholes on the shores. These gullies and sinkholes give Geologists direct access to sediments deposited thousands of years ago.
The exposed sediments contain a wealth of information about the climate and earthquake history of the region and have been studied by Geologists.
Three sites on the Western shores of the Dead Sea have been studied in detail. These sites are Ein Gedi, Nahal Ze’elim and Ein Feshka. (map)
In each case, the Geologists first went in and examined samples of burnt pieces of wood found in the section to engage in Carbon Dating. The Carbon Dating gives us our first crude understanding of the age of the sediments from the top to the bottom of the outcrop. After doing carbon dating, we find anchor earthquakes.
Anchor earthquakes are historically documented earthquakes that deformed the sediments in the Dead Sea. The historical documentation means we know the date when the earthquakes occurred. Three very useful anchor earthquakes in the outcrops are the Josephus quake of early spring in 31 BC, an earthquake on May 2, 1212 AD, and an earthquake in January 1293 AD. If these anchor earthquakes are successfully identified in a section, we have a precise indication of time at the top of the deformed layer.
In the case of the Jerusalem Quake Seismite of ~31 AD Earthquake , the anchor earthquake is the Josephus earthquake of early Spring in 31 BC. This earthquake can be observed throughout the Dead Sea including at the three well studied sites of Ein Feshka, Ein Gedi, and Nahal Ze’elim. The Jerusalem Quake seismite is also present at all three sites.
so, the challenge is to use what we know about the date of the Crucifixion (Easter between 26 and 36 AD) with what we can read from the sediments to determine if the earthquake in the sediments corresponds to the “earthquake of the crucifixion” … or something else.
and this leads to a discussion of Varves