I was in a motel in Albuquerque when the devastating magnitude 7.9 earthquake struck Sichuan, China on 12 May. However, thanks to the Internet I was in touch with events and a few hours after the event I downloaded the map below (from the website of US Geological Survey Earthguake Hazards Program). This captures all earthquakes above magntiude 2.5 on the Richter scale in the previous 7 days. The only magntiude 7 quake in that week was the one in Sichuan (marked by a large orange square). Already there had been a magnitude 5 aftershock, shown by the superimposed red square, the red colour denting an event less than one hour before I captured the map.
Earthquakes on 12 May 2008.
After seeking out some other basic information on this event, I wrote some quotes for the British media, disseminated by the excellent Science Media Centre. I explained how the quake had been both large and relatively shallow (which probably accounted for the violence of the ground motion and the extent of the damage) and explained that the quake was a consequence India's plate tectonic collision with Asia, which is squeezing Tibet eastwards over the Sichuan Basin. On the next day, I was pleased to find that some of my material had been used by The Times. 'So, Tibet fights back' posted one wag in the on-line comments section.
That made me smile, but the earthquake was, of course, a terrible tragedy. The official death toll has now exceeded 65,000, making it a close rival to the cyclone that recently hit the Irrawaddy delta in Burma. Fortunately, the Chinese rescue and relief effort seems a good deal more effective than what the Burmese government has managed to do, even though hampered by contunuig aftershocks - smaller than the initial quake, but big enough to collapse already-damaged buildings.
Today's map shows yet another in a the long series of aftershocks in the same region.
Earthquakes on 27 May 2008.
[Map courtesy of United States Geological Survey]
What really depresses me though is the disproportionate loss of life among school children. This is such a common story in many parts of the world; schools are built with inadequate resilience to earthquake shaking, not through ignorance but through corruption. I discussed this in my book Teach Yourself Volcanoes, Earthquakes and Tsunamis, which forms the basis of the Open University's Volcanoes, Earthquakes and Tsunamis short course:
School buildings have often proved unstable in earthquakes. They are built at the public expense, usually as a result of competitive tendering with the construction firm that offered the cheapest deal being given the contract. Without conscientious enforcement of seismic building codes tragedy can ensue, as at San Giuliana di Puglia in 2002 where poor-quality masonry walls and a heavy reinforced concrete roof contributed to the collapse of the school. Following this event, the Italian government ordered an evaluation of the seismic vulnerability of all public buildings, such as schools and hospitals. Similar lessons were learned in Venezuela when two schools, built in contravention of the local seismic building code, collapsed as a result of a M7.0 earthquake on 9 July 1997 killing 46 students. In Algeria a M6.8 quake on 21 May 2003 left 122 schools in need of rebuilding. School-house tragedy was avoided in this case because the quake happened after the end of the school day, though 2287 other people died. However a M6.4 earthquake in eastern Turkey on 1 May 2003 brought down the roof of a school dormitory, killing many children as they slept. A subsequent survey found that none of the local schools accorded with the 1998 Turkish Seismic Code, and the blame for this was placed on lack of resources to supervise building works, and on poorly-trained architects and engineers. A similar story is likely to emerge concerning the collapse of school buildings during the Kashmir earthquake of 2005.
The same lessons keep being learned, and then ignored. In the next edition, I can foresee that I'll be adding in a damning comment about Chinese flouting of building codes.
Take it further
Teach Yourself Volcanoes, Earthquakes and Tsunamis by David Rothery
published by Hodder Education