Lebanon's earthquakes, when's the next?

So Lebanon’s in an earthquake zone is it?

Well, err, yes. Dr Ata Elias’ address to the British Lebanese Business Group last week, richly if rather frighteningly peppered with pictures demonstrated numerous proofs of the fact. And as an introduction, citizens of Beirut felt a tremor as recently as the evening before Dr Elias' speech.

Dr. Elias is in the American University of Beirut Geology department and his specialist interest is earthquakes. No armchair geologist he, he’s gone out with digging equipment and dug-up small sections of two out of the three main faults (the other’s under water, just off the coast) affecting Lebanon, most notably the one where Africa meets the Arabian Peninsula (the thick red line on the map), then taken photographs of it. Yes, really, there’s an obvious boundary between the two - unbelievers, please see the picture below. Now, we can’t feel it, but Africa and the Arabian Peninsula are moving, very slowly but at different speeds and in different directions, so something has to give from time to time. Hence the Lebanese mountains with sea-shells embedded in them, clearly visible at two thousand metres up. 

According to Dr. Elias, no-one, it seems, can predict when that “something” is going to give, but the result is an earthquake.  More, when the giving is on an underwater fault, then a further consequence is a tsunami. Apparently, the sea retreated approximately three kilometres in 551 AD before surging back in to destroy much of Beirut and, according to contemporary accounts, “drown” Tripoli. What can be done is to calculate the average time between major events at a fault. For two of the faults it seems that if nature ran like clockwork, we could expect an event sooner rather than later. But of course nature doesn’t.  The energy of a quake can’t be predicted either.

Just what are the risks then? It isn’t a question of if but when a magnitude 7 plus earthquake will happen. Much of Beirut is built on sand, which behaves in a very strange way when mixed with water, say from a tsunami; it becomes quicksand and just sucks in anything on top of it.

So, if we can’t predict when, nor how big a ‘quake is going to be, what can we do? Well, we can plan for the consequences, engineers and architects need to structure buildings to be able to withstand the shock, architects and builders need to design in escape routes to high ground for locations, like beaches, near the coast, by teaching people at work, at home and in school what to do during a shock and by local government training the emergency services in coping with the aftermath.

Chile does this very well, Haiti did not; two recent earthquakes occurred in those two countries, the one in Chile, though a thousand times stronger, hardly made the news, while the devastation in Haiti, with a thousand times more deaths, dominated our TV screens for days. Yes, readiness can change the effect by the ridiculously large factor of a million! Where is Lebanon? The good news is that a law was passed in the last decade laying our standards for buildings, and there’s a sign on the AUB beach saying that if the sea retreats, get to high ground immediately. Other than that, the feeling is that Lebanon is a long long way from Chile’s readiness.

Dr. Elias is passionate that his mission is to discover all he can about earthquakes and promote awareness about them and their consequences in the region. If you get a chance, listen to what he has to say and, if you are an engineer, town planner or just buying your own home take note and act.