April 16, 2013

expert reaction to the Iran earthquake

A 7.8 magnitude earthquake struck Iran, close to the Pakistani border. 

Dr John Macdonald, Reader in Structural Dynamics at the Earthquake Engineering Research Centre, University of Bristol, said:

“The earthquake was very large in magnitude – typically about 2 earthquakes of this magnitude would occur each year worldwide.  But since it was quite deep (about 80km, contrary to some reports) and in a sparsely populated area, the number of casualties will hopefully be low.  In contrast, the Bam earthquake of 2003, although much smaller in magnitude (total amount of energy released) was shallow (10km) and close to the city (only about 10km away), leading to major damage and loss of life.

“Iran has a reasonable seismic design code for buildings, but I believe a major problem is the lack of compliance with that code.  In particular, I understand a high proportion of the population, especially in rural areas, live in buildings made of unreinforced mud bricks, which are vulnerable to earthquakes.  Another potential problem is earthquake-triggered landslides blocking roads into the affected area, which would obviously hamper rescue activities, and disruption to other infrastructure such as power and water supplies, as well as to communications.”

Dr Brian Baptie, Head of Earthquake Seismology at British Geological Survey, said:

“This earthquake occurred in the great belt of earthquakes that stretches through the Middle East into Central Asia that results from the collision of the northwards moving Arabian and Indian tectonic plates with Eurasian tectonic plate to the North.  Given the depth, the earthquake was probably a result of normal faulting within the Arabian plate as it is subducted under the Eurasian plate along the Makran coast of Iran and Pakistan.  The earthquake is located approximately 380 km ESE of the magnitude 6.6 Bam earthquake that killed over 31,000 people on 26 December 2003.”

Dr David Rothery, Chair of the Open University’s Volcanoes, Earthquakes and Tsunamis course at The Open University, said:

“This morning’s earthquake in Iran was strong (magnitude 7.8) but fortunately its source was quite deep, about 80 km.  Although the ground probably shook for the best part of a minute, the intensity of the shaking was less than it would have been for a shallower earthquake of the same magnitude.

“The area where the quake struck is mountainous and damage can be expected from landslides as well as because of poorly-constructed buildings.  It can add about 20% to initial construction costs to make a modern building resilient to earthquakes so that it will not collapse when the ground shakes. 

“This quake was in an earthquake-prone part of the world, as a consequence of the northward collision of both Arabia and India into Asia.”