At least 34 people have died in earthquakes in Iran

A 6.3 earthquake and one with a magnitude of 7.8 hit Western Iran in the course of just a week. These are largely rural areas, with a lot of mud brick buildings that tend to collapse when the earth shakes. It's hard to say how many casualties there are, in total. Scientifically speaking, the earthquakes were also fairly interesting, writes Chris Rowan at Highly Allochthonous. They happened in different — in fact, totally opposite — ways, with the smaller one happening as plates crashed into one another and the larger caused by tectonic plates moving away from each other. This was along the same plate boundary. How's that work? Rowan has the details.


    1. Maggie’s link does actually mention that the 34 dead (now 35 per your link) were in Pakistan, though the epicenter was in a sparsely-populated part of Iran near the border.

  1. Because I’ve been pulling the “I’m an academic geologist” card in boingboing comments for years now, I thought I might mention that this sort of structural geology and tectonics – relating specifically to convergent tectonic plates – is my research interest. 

    Not the earthquakes aspect of this, though, aside from their usefulness in determining where deep faults etc. are, so I can’t really comment on the earthquake. The article at Highly Allochtonous is great (the blog is consistently excellent) at linking all these things together.

    A good tl;dr addition might be that one reason this is particularly interesting is that while this situation of divergent and convergent earthquakes at the same plate boundary is not actually uncommon, what is more uncommon is the scale of the divergent earthquake here. Often all the major earthquakes will be in accordance to the plate boundary, and the others are caused by shallower features that don’t have as much energy. You’ll have to read the article to find out what’s different here though.

    1. “I’m an academic geologist” – in which case, feel free to provide an authoritative expansion (or contradiction!) of my own armchair-geologist comment below, about Tehran being the world’s worst seismic risk.

  2. This is a real  wake-up call for Iran: Tehran is possibly the world’s worst seismic risk, a city of  8 million people on a series of active faults, with a history of earthquakes in the MS 7.1 to 7.6 order every 300-500 years.

    The last major earthquake  they had was in 1830, MS7.1 (MMI =VIII). Given the size of the city and the low quality of their buildings, a similar earthquake would kill tens-to-hundreds of thousands. The next one could be smaller; it could be bigger; it could be three centuries away; or it could be happening right now and you’ll hear about it in a few minutes.

    I’d love to say that they’ve ‘dodged a bullet’ but that simply isn’t true: this latest earthquake is some distance away and it’s unlikely to have relieved strain on the crust at Tehran; equally, it’s unlikely to have transferred load ‘down the line’, as  the faults and geological structures  of Northern and Central Iran  are extraordinarily numerous. Load transfers are not something we can model with any degree of confidence on structures that complex.

    Hopefully yesterday’s event will concentrate their minds on disaster planning, resilient infrastructure, and a programme of building surveys and structural reinforcement. However, the 1968 earthquake at Dasht-e Bayaz killed about 10,000 people and almost nothing was done – and that event was in an agricultural province with no major cities. 

    Let’s *not* talk about their nuclear facilities. It’s not a reassuring thought, but they are probably the only fully earthquake-resistant structures in the entire country. 

  3. Maggie: ‘the larger caused by tectonic plates moving away from each other.’

    I don’t read it like that. Both ‘quakes are the product of collision. The larger ‘quake was caused by extension within the Arabian Plate – either by the pull of the lower part of descending slab as it is subducted under Iran; or by stretching of the upper part of the Arabian Plate as it flexes downwards and begins to be subducted.

  4. I heard that very little phone photos or video was emerging from the Iran side, which could mean the same thing as low population, but two villages destroyed, and that one of the Iran quakes was only about 100 km from the country’s sole nuclear power plant, the coastal Buschehr.

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