Update: For the latest on the earthquakes which have struck Iran in April 2013 click here
The Middle East may not possess the same reputation for seismic disasters as some other parts of the world, but that is of little comfort to the people of north-west Iran, over 300 of whom were killed when a twin earthquake struck the country's mountainous region earlier this year. Destroying villages and injuring many thousands, the two six-plus magnitude quakes - striking the same location north-east of the city of Tabriz and spaced just 11 minutes apart - were among the worst to hit Iran since 2003, when an earthquake killed 25,000 people in the city of Bam.
Yet, if one Tel Aviv-based scientist is right, then Iran, which straddles a major fault line and has an unenviable reputation for seismic activity, is not the only part of the Middle East with a reason to fear for the safety of its towns and cities. Research conducted by Dr Shmulik Marco, an academic at the department of geophysics and planetary sciences at Tel Aviv University, has suggested that a seven-plus magnitude earthquake would imperil one of the region's most sacred places, encompassing such cities as Ramallah, Bethlehem and Jerusalem, raising fears of mass casualties and the destruction of holy sites.
"We fear that a major earthquake in the Holy Land is imminent," says Marco, whose research led him to conclude that following four major earthquakes in the region some 300 to 400 years apart in roughly the first millennium, the last 1,000 years of quiescence are a matter of grave concern for all in the Holy Land.
"Earthquakes are generated at the boundary between any two of the earth's tectonic plates that move relative to each other," explains Marco, who used a combination of scientific and historical research to deduce that the Holy Land is due an earthquake of potentially epic proportions.
"The friction does not allow smooth motion, so when the plate driving forces overcome the friction, the boundary ruptures as the plates move suddenly. This sudden rupture shakes the region and we call it an earthquake. The longer the plates move without rupturing, the more stress accumulates … Consequently, long periods of quiescence indicate that large stresses have been built up. The stresses will have to be released - sooner rather than later - in the next big earthquake."
Based on the translations of documents written in Latin, Greek and Arabic, and sourced from a number of religious institutions, Marco managed to ascertain that the region was pummeled by several major earthquakes in the years 31BC, AD363, AD749 and AD1033, and though this 300- to 400-year trend ended there, it was a pattern that sat uneasily with Marco himself.
"We know that earthquakes happen where they have happened before, so their location shouldn't come as any surprise. In our research we wanted to ask whether there was any pattern to their occurrence and what we could learn from past earthquakes. From that we wanted to learn about two things: first, about the phenomena itself, and second, assess the hazard or risk to human life.
"For [geologists], earthquakes are just like the noise or [heart]beat of the earth, just like a doctor who uses a stethoscope to listen to your body. And, from my geological observations where I examined the fine laminated sediments which had been disrupted by earthquakes near the Dead Sea Fault in the past, I managed to corroborate the historical accounts, which made it clear to me that all of us in the region should be worried."
The four major earthquakes occurred along the Jordan Valley - itself part of the Jordan Rift Valley - and were accounted for in the many ancient letters and reports, which the Tel Aviv-based geologist used to piece together his clues. Written by monks and clergy, in monasteries and churches, and even by hermits in the desert, the documents, many in the form of correspondence to Europe requesting funding for church repairs, were deciphered by an international team of historians whose assistance, says Marco, proved crucial to his findings.
"These documents were dated, and in order to read them, I needed the expertise of historians, which enabled me to [substantiate] my geological records. But, the historical records are not like reading today's newspapers. They used different calendars, were in different languages, and many terms that we use today were different to how they were used 1,000 years ago. So, it took a lot of detective work, and you had to cross-check and understand what the background was, what the political situation was like and you always wondered whether you had the whole record put into writing."
Marco's theory may be compelling, but other experts advise caution. Dr Roger Musson, head of seismic hazard and archives at the British Geological Survey, says that while the view from Tel Aviv carries weight, in many seismological circles other theories demand equal billing.
"Earthquakes do not go like clockwork, so if you calculate the average time between major earthquakes from the catalogue and then extrapolate that into the future, you will get into trouble," asserts Musson, flagging up one counter-theory.
"What tends to happen is that earthquakes go in clusters. So, you get a hot period when you have a number of large earthquakes following each other in short intervals and then a cold period when they stop and you can wait 1,000 years or 2,000 years before you get another hot period - so that seems definitely to apply to the Dead Sea Fault."
Musson, citing a recent study by seismologists in Strasbourg, who, after delving into prehistoric times, found "clear evidence" for the clustering of seismic activity along the Dead Sea Fault, disputes Marco's certainty that a major earthquake in the region is imminent.
"The fact that we haven't had a major earthquake in, let's say the Jordan Valley since the 11th century, indicates that the cluster that ended in AD1033 has stopped and we're now waiting for the next cluster," explains the Edinburgh-based seismologist, who also raises the possibility that "some of the energy that would go to being stored up for large earthquakes on the Dead Sea Fault is actually being dissipated in non-ridged deformation off the coast" as another plausible explanation for the millennium-long quiescence period.
"It's much harder to anticipate how long the waiting period is between clusters than it is the waiting period between earthquakes when you're in a cluster. So, that's a bit of good news, because it means it's wrong to say that the next major earthquake is imminent, because it may not be. It could happen tomorrow - that's possible - but on [the] other hand it would be seismologically quite possible for it not to happen for another 100 years."
The last sizeable seismic shift to hit the region was 85 years ago, when a 6.25 magnitude tremor killed 500 people and damaged much of Jerusalem's Old City after it struck in the northern Dead Sea area on July 11, 1927. The interior of Government House, the official residence of the High Commissioner, Lord Plumer, in Jerusalem was seriously damaged. And, such was the quake's intensity that a tremor was felt as far away as Cairo. The "Safed earthquake" of 1837 was even more pronounced, with some estimates putting the magnitude as high as 6.8. With its epicentre in the Jordan Rift Valley, the New Year's Day quake destroyed Safed and severely damaged many of the villages in the surrounding area, claiming more than 4,000 lives.
But, as Marco's theory stands, such sub-seven quakes have little bearing on substantially reducing the seismic strain, which he asserts will "sooner rather than later" wreak havoc.
"The 1,000-year-long quiescence at the Jordan Valley is longer than previous quiescence periods … but many people think that the occurrence of small earthquakes reduces the stress and defers the 'big one'. However, it takes over 30 magnitude-five earthquakes to account for one magnitude-six or 30 magnitude-six earthquakes for one magnitude seven and so on. There aren't enough small earthquakes in the region to replace the large ones."
Alasdair Soussi is a freelance journalist, covering the Middle East and Scottish politics.
