Whilst we wait for further news about the damage caused by Tuesday’s earthquake in Balochistan in Pakistan the press reports give a valuable insight into the negative perceptions associated with earth structures.
The BBC report (posted 25/09/2013) summarised the details of the 7.7 magnitude earthquake, and soon went on under the sub-heading “mud houses” to note that in some towns and villages in the region some 90% of houses had been destroyed.
“Most of the homes in the area are made from mud brick and easily collapsed when the tremors struck on Tuesday”
“Most people live in easily-collapsible mud homes, and many are feared to be trapped under the rubble.”
Whilst there are practical and physical limits to the use of earth as a building material, and its resistance to seismic damage these ‘practicalities’ are often overwhelmed by the negative perception of the materials fragility. This is shown by the negative reporting of earth buildings and earthquake damage. For example the December 2003 earthquake in Kerman province in Iran (which was a 6.6 magnitude earthquake) killed more than 26,000 and injured more than 30,000 and caused substantial damage to the modern and historic city of Bam. The outcry against earth building here was aided by the dramatic ‘before’ and ‘after’ photographs of destruction to the historic town. In reality much of the damage in Bam was to ‘new’ conservation materials, and to the modern structures built from materials of the contemporary construction industry (concrete and fired brick), but not necessarily built with skilled and expert knowledge, or that didn’t follow building regulations and standards.
In which case the issue isn’t the ‘mud houses’ but the ‘houses’ in general and the global pattern in which local building knowledge has been eroded by the commodification and industrialisation of construction. There are countless archaeological and historical examples of local knowledge of seismic resistance for earth structures from around the world, and these include the use of timber ring-beams, or incorporation of textiles to add tensile strength, and (perhaps most significantly) repair after previous seismic events.
The subject of seismic damage to earth buildings has been the focus of almost 40 years of research particularly in Peru, USA, New Zealand, Iran and others. Solutions are now widely known – but translating research into practical applications for new builds (and national, regional and local guidance and regulation) still seems an issue.
Perhaps those interconnected issues of erosion of local knowledge, commodification of building materials, and the introduction of ‘best practice’ for seismic resistance might have been a more interesting perspective on the reasons for the destruction on Tuesday rather than just blaming the ‘mud houses’.
Link to BBC report: http://www.bbc.co.uk/news/world-asia-24222760
and lots more on perceptions of earth buildings here:
Cooke, L, 2010. Conservation Approaches to Earthen Architecture in Archaeological Contexts. British Archaeological Reports International Series S2147. Oxford: Archaeopress.