Text #9021"Don't blame the Trojan Horse: Earthquakes toppled ancient cities" .
Around 1200 B.C., the great Bronze Age civilizations of the Eastern Mediterranean toppled like a string of dominos. One by one, over a period of 50 years, dozens of bustling centers of scholarship and industry, including Troy, Mycenae and Knossos, collapsed into rubble. Today, crushed skeletons and scattered debris are all that remain of the powerful cities. What force could wreak such widespread destruction?
Historians and archaeologists have long battled over this question, citing civil war, invasion and pestilence as possible causes. When Stanford geophysicist Amos Nur examines the evidence, he sees another possibility: The earth moved. A string of massive earthquakes could have knocked down one city-state after another, bringing the Bronze Age civilizations to a premature end. …
His findings suggest that earthquakes are episodic periods of greater earthquake activity are bracketed by periods of relative quiet. Large quakes may trigger other large quakes, in a domino effect that zips down a fault line, knocking down cities along the way.
[Nur’s] current work suggests that earthquakes may have played a large role in the collapse of at least 50 great cultural centers, including Troy, Mycenae and Knossos, at the end of the Bronze Age. He presented his data in July at a conference on the destruction of Bronze Age civilizations held at Cambridge University.
Because it took 50 years, from 1225 B.C. to 1175 B.C., for the major cultural centers to collapse, it is unlikely that the end of the Bronze Age was caused by a single historical event. However, a string of earthquakes could have destabilized society enough to wipe out the economic, social and political structures. “The end of the Bronze Age may actually have been a period of recovery following a string of severe earthquakes,” Nur said.
According to Nur, seismic records indicate that large earthquakes are temporally clustered. Short periods of very intense earthquake activity are preceded and followed by long interludes of relative quiet. Geologically, these episodes may be explained as follows: When a plate ruptures in one place, it strains another part of the plate boundary and may cause its collapse a short time later. This cascade of activity occurs until the entire plate boundary ruptures. This period of intense activity is followed by longer time periods when the whole plate is strained but doesn’t quite give. Eventually the strain builds up and the cycle begins again.
According to Nur, the cities destroyed at the end of the Bronze Age were located in regions that historically have experienced high seismic activity. He has calculated the intensities of recent earthquakes and shown that the modern-day regions that experience heavy damage overlap with the ancient ruins destroyed at the end of the Bronze Age. As Nur states, “Earthquakes have been happening in this region for thousands of years. There is no way that these places could have escaped severe ground shaking. It is impossible.”
It is not too hard to imagine how earthquakes might have caused the collapse of ancient societies. Given their limited technology, it would have been difficult for societies to rebuild their magnificent temples and houses. In the wake of such a catastrophe, skills like reading and writing could have disappeared if people were concerned with more important activities, like survival. “It probably took many years to recover from such an event,” Nur said. …
The traditional view is that strain is periodically released at each segment of the plate boundary. The evidence obtained from Nur’s analysis of the Eastern Mediterranean suggests that strain is released in episodes via a sequence of earthquakes. A tremor at one segment of the plate boundary appears to trigger a chain reaction of displacements along the rest of the fault. According to Nur, “The entire plate boundary gets unzipped by this sequence of large earthquakes.”