2015 Nepal earthquake: seismic performance and reconstruction of stone masonry buildings

[@willschneider8608]

I have a question. Are the houses that are made of 18 inch by 10 inch granite blocks earthquake proof? They are very stable, unlike rubble stone, which tends to brittle. Also, do granite blocks (or even limestone blocks for that matter) need vertical and horizontal seismic bands for more stability?

[@RohitKumarAdhikari]

Hi Will, Many thanks for your query. Of course dressed granite blocks, termed as dry-stone masonry when no mortar is used, is better than random rubble stone in mud. This is for their much better interlocking as well as frictional resistance in shear. For such reasons, such dry stone masonry as well as dressed stone masonry with mud or cement mortar have also been traditionally used in residential as well as school construction in Nepal as well as other countries in the Himalaya. Including seismic bands will certainly improve their so called box-like global behaviour. Moreover, more of such bands e.g. lintel leve, roof level, window sill level or even intermediate ties, improve the seismic resistance by improving the shear resistance as well as mobilising maximum capacity of masonry structure. Please refer to NBC 203: 2015, for example. Hence, whether the seismic bands are needed or not depends on multiple factors: type of structure, seismic hazard at the site, acceptable risk, local policy, seismic design code in the country. Best wishes, Rohit

[@medea27]

It's important to note that - as Rohit says during his presentation - there's no such thing as _'earthquake proof'_ & there's _no single solution_ to ensure a building is more resistant to earthquake damage. Every earthquake is different... it can literally move a mountain & rip cracks in the ground that a building can fall into.... so it's impossible for any human-made construction to be 'quake-proof.' Your house could survive a magnitude 6.5 only to be knocked down by a smaller 5.0 because the epicenter is closer & the frequency of shaking is different. That's why a qualified engineer is so important because the best solution for your home might be different to your neighbour's home based on the rock in the foundations, the number of storeys, etc.... lots of different factors to consider in addition to the stonework. It's also crucial to install any seismic solutions like bands correctly, because they can't do their job otherwise. It's upsetting & frustrating to hear that the Nepalese have been moving into homes where the seismic bands & structural elements aren't installed properly, because that's almost as bad as not having anything at all.