Summary, Draft 2

In the article, “How Volcanic Ash Strengthens a Roof Against Powerful Projectiles,” Williams (2019) proposes that having a layer of volcanic ash on the rooftops of building can increase protection from volcanic projectiles. He mentions that a study by scientists from the Earth Observatory of Singapore (EOS) and the University of Canterbury (UC) was conducted to measure the ability of ash to cushion volcanic projectile impacts shot by a high-pressure air cannon, in which tests show that having a five centimeters ash layer tripled the strength of the roof to withstand projectiles. He notes that while a thicker layer helps, it increases the risk of the roof collapsing. He states that scientists also believed that buildings would be more damaged when struck by multiple projectiles compared to one. However, the tests proved otherwise, provided that the roof is protected with a 5cm layer of tephra. Nonetheless, he remarks that this method should be done on an individual basis by ensuring the shelter benefits from the tephra on its roof, and still withstand its weight. Therefore, he concludes buildings with reinforced concrete roofs are found to be ideal.