Table of Contents
Housing in Volcanic Zones
The first thing that people think about volcanic damage is fire damage because of lava. Mudslide damage, floods, and ashes are the most damaging in buildings. Volcanic eruptions of one of the most potent and damaging natural calamities. It also triggers a Domino effect of other disasters. Dust and ashes in the sky can collapse on the roofs. One of the most important things to do is to protect the roof from ash compilation. Flat roofs are usually avoided because it leads to a buildup of ashes. Similarly, heavily stooped roofs are also avoided because ash is corrosive.
Building Design in Volcano Zones
The roof is meant to be smooth with a slick surface so the Ash slides from it. Reinforcing the structure with titanium makes it durable, robust, and is used for lateral support. The house is supported on stilts. These design solutions do not offer entire volcanic resistance. Volcanoes instigate earthquakes and tsunamis. These solutions do not complete protection, but protect the home on some level. Experts suggest the use of extra roof support and avoiding flat roofs or roofs with complicated designs. Concrete reinforced buildings are protected from storms and other disasters. Use of timber is supposed to be avoided.
Effect of Volcanoes on Buildings
Volcanoes result in slow-moving Lava whose temperature goes up to 1292 °F to 2192 °F (700 °C to 1200 °C). Volcanic eruption leads to poisonous gases and strong storms. The distance of a building from a volcano doesn’t determine the degree of damage that it does. A building’s proximity to lava and the pyroclastic flow zones determines the level of damage a volcano might inflict on the building.
According to national geographic, pyroclastic is the rapid flow of lava, volcanic ash, and gasses running down in fickle ways. They’re hazardous because they can’t be stopped, even by water, and consume everything that comes in their way. Lava moves at a slow speed which buys people the time to escape, but, pyroclastic flows are rapid and go up to 200 miles per second.
Usually, buildings with stilts can withstand lava. Since ash is heavier than snow, it can damage the paint, flooring, drainage systems, and other structural support systems of the building, like HVAC. If the interiors aren’t maintained, it increases health risks. Volcanic eruptions also give rise to extreme storms and fierce winds that may fling boulders through the air and crush buildings that aren’t constructed properly. Fire, earthquakes, tsunamis, mudslides are some of the after-effects of the eruption.
Use of Lava Rocks
Using lava rocks for building construction makes it durable towards the lava. The downside to this is the complicated technicality and cost of construction. Buildings in Hawaii historically used lava locks for construction. Although this can be a great technique, the difference in composition of these rocks can be a hurdle in accomplishing quality construction. Some rocks are heavy and robust, while some are flimsy and quite crushable. This technique is not cost-efficient. Reinforced cement would be the best option for buildings in volcanic regions.
Techniques and Materials for Earthquake Resistant Homes
Earthquakes are one of the most dangerous, impactful, and damaging disasters of all time. The aftershocks are sustained by the neighboring places. Structures built with stacked bricks and mortar and weak. In such houses, the weight is carried from the roof to the walls, all the way to the foundation. When such houses are subjected to seismic forces, it is very easy for them to crumble down. Concrete blocks or unreinforced bricks put the structure in a great degree of danger. Concrete and wood are earthquake resistant.
Base isolation techniques permit the foundation to move without moving the entire structure. In this technique, isolation pads made from lead, steel, and rubber reduce the damage. Another technique is called damping, which involves the installation of shock absorbers that reduce the magnitude of earthquake vibrations. The most popular technique is called Base Isolation Technique. In this, the structure floats on a lead rubber bearing. A structural engineer ensures the seismic improvements in the buildings. The impact of the earthquake is beyond control. The necessary measures can be taken to ensure minimal damage. The walls, partitions, and slabs are thin and light.
Housing in Flood Prone Areas
Floods have been the reason for loss of human lives, loss of cattle lives, degradation of public utilities, damage of crops, and migration of the inhabitants. According to the National Commission of Floods, around 400 lakh hectares of land in India are under the flood-prone zone. Around 320 lakh hectares can be provided protection, which constitutes 80% of the total flood-prone zone. Structural measures can be taken to prohibit water from entering the habitations.
Categories Of Damage
According to an export group appointed by the Ministry of Urban Development, the government of India, there are five categories of flood damage. G1 stands for very low damage, where there are fine cracks in the plaster and about 10% of the total surface of walls is subjected to falling. G2 stands for Low damage, where the cracks are around 6m wide and about 50% of the total surface area of the walls is subjected to fall.
G3 stands for moderate damage where there are large and deep cracks in the walls. This leads to damage to the walls, electrical fittings, and loss of belongings. G4 stands for high damage where there is significant damage and loss of property. The property may experience collapse, sinking, and the lighter parts of the buildings may even float away. G5 stands for very high damage.
Curbing Effects of Flood
Embankments near river channels, river damming, raising the level of villages above flood level can n all help in the prevention of floods. Proper planning of stormwater drainage system and including it in the master plans reduces the chances of urban flooding. Soil testing matters in determining the soil’s capacity to absorb water.
Houses built by filling small water bodies with sand have more chances of sinking. Houses built on slopes by removing the soil have higher chances of landslides during months. Houses are built away from any source of water, or away from areas where the course of water bodies has changed during previous floods.
Before constructing buildings in the flood-prone zones, maps are produced which show the flood-prone zones and contours at an interval of 0.3m or 0.5m. The frequencies of flooding in each area are also mentioned in these maps. The degree of submersion or accumulation of water is also marked on these maps.
Precautions through Construction such Natural Calamities
Houses are raised and built on elevated platforms to avoid floods. Houses are built on stilts. Kutcha houses made of mud, clay, or brick or stone walls with mud mortar are very easily damaged by rain. Water seeps into them through roofs or directly through walls. The upper surface of the roofs can be plastered with water-proof mud plaster and also can be made fire-resistant if applied on the internal side.
150-200 mm thick black polythene of heavy gauge sheets can be laid at mid-thickness or upper quarter thickness of the clay layer as an alternative. The drainage of the roof should be ensured, and the lower portion of the wall next to the fall of water should be made a pucca. Water-proof mud, lime, or cement plaster is used for plastering the top of parapets. 500 mm of roof projection protects the wall from saturation.
Another method to protect walls is using burnt bricks externally and sundried bricks internally. This wall will be one and a half brick thick. The minimum plinth should be 450 mm above ground level, and a DPC (Damp Proof Course) should be laid at the plinth level on all the walls.