The Collapse of Ancient Societies by Great Earthquakes

Abstract of talk by Amos Nur

Department of Geophysics, Stanford University, Stanford, CA 94305, USA. e- mail: nur[at]
Presented at the SIS Conference: Natural Catastrophes during Bronze Age Civilisations (11th-13th July 1997)

Although earthquakes have often been associated with inexplicable past societal disasters, their impact has thought to be only secondary for two reasons: Inconclusive archaeological interpretation of excavated destruction, and misconceptions about patterns of seismicity. However, a better understanding of the irregularities of the time-space patterns of large earthquakes suggest that earthquakes (and associated tsunamis) have probably been responsible for some of the great and enigmatic catastrophes in ancient times. The most relevant aspect of seismicity is the episodic time-space clustering of earthquakes such as during the eastern Mediterranean seismic crisis in the 4th century AD and the seismicity of the north Anatolian fault during our century. During these earthquake crises plate boundaries rupture by a series of large earthquakes that occur over a period of only 50 to 100 years or so, followed by hundreds or even thousands of years of relative inactivity. The extent of the destruction by such rare but powerful earthquake clusters must have been far greater than similar modem events due to poorer construction and the lack of any earthquake preparedness in ancient times. The destruction by very big earthquakes also made ancient societies so vulnerable because so much of the wealth and power w as concentrated and protected by so few. Thus the breaching by an earthquake of the elite's fortified cities must have often led to attacks by (1) external enemies during ongoing wars (e.g., Joshua and Jericho, Arab attack on Herod's Jerusalem in 31 BCE); (2) neighbours during ongoing conflicts (e.g., Mycenea's fall in 1200 BCE, Saul's battle ~1020 BCE); and (3) uprising of poor and often enslaved indigenous populations (e.g., Sparta and the Helots in 465 BCE, Hattusas ~1200 BCE?, Teotihuacan ~700 AD?). When the devastation was by a local earthquake, during a modest conflict, damage was probably limited and may have required a few tens of years to rebuild. But when severe ground shaking is widespread, and when it happened during a major military conflict, the devastation may have been so great that it took hundreds of years for a society to recover - going through a dark age period during which many of the technical skills (e.g., writing) are abandoned (e.g., the cessation of linear B), construction and repairs of monumental buildings ceased, and looting of building materials by surviving squatters was common. In contrast, we can imagine the pastoral countryside, especially away from the tsunami prone coastal areas, to have been much less affected (and perhaps even flourished a little as their tax burden to the ruling elite is reduced). During a regional seismic crisis an entire region must have been subjected to a series of devastations by earthquakes over a short period of time. The catastrophic collapse of the main Eastern Mediterranean civilizations at the end of the Bronze age may be a case in point, with the Sea People being mostly squatters and refugees.

AMOS NUR is the Wayne Loel Professor of Earth Sciences and Professor of Geophysics at Stanford University. Amos specializes in earthquake physics. For over twenty years, he has been investigating the temporal and spatial patterns of earthquakes throughout history to find clues useful for earthquake prediction. The longest and most complete record is in the Holy Land, where the Dead Sea seismic fault defines the Arabia - Africa plate boundary, as the San Andreas defines the N. American/Pacific plate boundary. Together with colleagues in archaeology, history, geology and geophysics at Stanford and Israel, Amos has organized an expedition to search for, and excavate and recover skeleton/s, artifacts, and Dead Sea scrolls buried 2000 years ago in the "Cave of Letters. in Israel's Judean desert by the devastating Dead Sea Earthquake of 31 BC. The first part of this expedition took place in March of this year. Amos is a winner of the Silver Apple Award for physical sciences at the National Educational Film Festival, 1991 for producing and directing a video on Earthquakes in the Holy Land. This has been shown extensively on a number of PBS stations around the country. Publications: Over 180 papers in refereed journals; and 3 books.