Safety and Disaster

 B

1. Name the major earthquake zones of the earth.

Ans: Nearly 95% of all earthquakes take place along one of the three types of tectonic plate boundaries, but earthquakes do occur along with all three types of plate boundaries. About 80% of all earthquakes strike around the Pacific Ocean basin because it is lined with convergent and transform boundaries. Called the Ring of Fire, this is also the location of most volcanoes around the planet. About 15% take place in the Mediterranean-Asiatic Belt, where convergence is causing the Indian Plate to run into the Eurasian Plate creating the largest mountain ranges in the world. The remaining 5% are scattered around other plate boundaries or are intraplate earthquakes.

2. What are seismic waves?

Ans: Seismic waves are caused by the sudden movement of materials within the Earth, such as slip along a fault during an earthquake. Volcanic eruptions, explosions, landslides, avalanches, and even rushing rivers can also cause seismic waves. Seismic waves travel through and around the Earth and can be recorded with seismometers.

3. Name two types of mitigation strategies for earthquakes?

Ans: Structural mitigation measures reduce the risk of building damage or collapse through carefully engineered actions to maintain the integrity of the building’s structural support system.  This can be accomplished by reinforcing key elements of a building.

Non-structural mitigation measures:

• Help protect people from injury
• Reduce the risk of damage to furniture,  utilities, and interior surfaces
• Prevent items from shifting and blocking exits.

4. Describe the types of floods?

Ans: 

The main types of floods

i. Flash floods are fast-moving waters that sweep everything in their path. They are caused by heavy rainfall or rapid snow thaw. Floods usually cover a relatively small area and occur with little to no notice, generally less than six hours. The rapid water torrents can move large objects such as cars, rocks, and trees.

ii. Coastal floods are caused by strong winds or storms that move towards a coast during high tide. When powerful waves breach the coast’s dune or dike, the area is usually flooded. Coastal areas with fewer defenses and lower elevations are the most affected. The best time to repair the breach is during low tide.

iii. River floods are characterized by gradual riverbank overflows caused by extensive rainfall over an extended period of time. The areas covered by river floods depend on the size of the river and the amount of rainfall. River floods rarely result in loss of lives but can cause immense economic damage.

iv. Urban floods occur when the drainage system in a city or town fails to absorb the water from heavy rain. The lack of natural drainage in an urban area can also contribute to flooding. Water flows out into the street, making driving very dangerous. Although water levels can be just a few inches deep, urban floods can cause significant structural damage.

v. Pluvial floods form in flat areas where the terrain can’t absorb the rainwater, causing puddles and ponds to appear. Pluvial flooding is similar to urban flooding, but it occurs mostly in rural areas. The agricultural activities and properties in areas where pluvial floods have occurred can be seriously affected.

5. What is an industrial fire?

Ans: An industrial fire is a type of industrial disaster involving a conflagration that occurs in an industrial setting. Industrial fires often, but not always, occur together with explosions. They are most likely to occur in facilities where there is a lot of flammable material present. Such material can include petroleum, petroleum products such as petrochemicals, or natural gas.

C. 

1. What are the effects of an earthquake?

Answer:

Ground Shaking: Ground shaking is a term used to describe the vibration of the ground during an earthquake. Ground shaking is caused by body waves and surface waves. 

Surface Faulting: Surface faulting is a displacement that reaches the earth's surface during slip along a fault. Commonly occurs with shallow earthquakes, those with an epicenter less than 20 km. Surface faulting also may accompany aseismic creep or natural or man-induced subsidence.

Ground Failure: Liquefaction is not a type of ground failure; it is a physical process that takes place during some earthquakes that may lead to ground failure. 

Flow Failure: Flow failures, consisting of liquefied soil or blocks of intact material riding on a layer of liquefied soil, are the most catastrophic type of ground failure caused by liquefaction.

Landslides: Past experience has shown that several types of landslides take place in conjunction with earthquakes. The most abundant types of earthquake-induced landslides are rockfalls and slides of rock fragments that form on steep slopes.

Tsunamis: Tsunamis are water waves that are caused by sudden vertical movement of a large area of the seafloor during an undersea earthquake.

2. Write five safety measures one should take during an earthquake.

Ans: i. If you are in your homes, offices, malls or any other building do rush out immediately. Often panic can cause stampede and disarray. Being calm in such calamities is paramount.

ii. Do turn off electrical appliances and gas connections. The easiest way to do so is simply by switching the mains off.

iii. If you are unable to go out in the open then do take shelter under a sturdy table or a sturdy bed. Also, cover your face and head with your arms.

iv. Also stay away from upright furniture and bookcases. In fact, it’s advisable to bolt bookcases to wall studs, installing strong latches on cupboards, and strapping other such things like water purifier,s etc. to the walls especially if you are living in an earthquake-prone zone.

v. Lastly, if you are driving then stop immediately and remain in your car till the shaking stops. But don’t stop under trees, buildings or near walls. However, if you find this to be the case then run out and go into an open space.

3. What are the major causes of flood?

Ans: Here are eight of the most common causes of flooding, both natural and human-induced. And the consequences of flooding can be savage.

i. Heavy Rains

The simplest explanation for flooding is heavy rains. No matter where you live, you are surrounded by infrastructure and systems designed to move rainwater into appropriate basins and reservoirs. In most cases, the infrastructure does its job, and you never have to think about where the rain goes when it runs off. When it rains heavily, however, those systems are overwhelmed, and that water doesn’t drain nearly as quickly as it needs to. In short, the drainage systems back up, and the water rises — sometimes into homes. This typically happens only in cases of sustained heavy rains over a long period.

ii. Overflowing Rivers

You do not necessarily need to have heavy rains to experience flooding in your area. For example, if you live along a river and areas upstream from you experience heavy rains, it could lead to a serious overflow where you live. Most larger rivers include a series of dams to help manage large amounts of rainfall, and most river systems are managed by government authorities.Sometimes, however, those authorities have to make tough decisions about how to operate dams. They often can manage the water and prevent flooding altogether — but not always.

iii. Broken Dams

Much of America’s infrastructure was built in the 20th century, so it is getting old. When heavy rains come, and water levels rise, aging dams can fail and unleash torrents of water on unsuspecting households. This is part of what happened after Hurricane Katrina hit New Orleans in 2005. Levees failed and made the flooding far worse than it would have been otherwise. While we have come to depend on 20th-century architecture, and much of it does its job well, there is always a possibility that a structure will fail.

iv. Urban Drainage Basins

Many of our cities are made of mostly concrete and other impermeable material. When you have an urban drainage basin that is made of concrete, there is no ground for water to sink into. So, when those drainage basins fill up, it is going to mean flooding for low-lying areas.

This is mostly the case in large urban areas — think Houston and Los Angeles. When heavy rains strike, the basins used to drain them cannot always handle the load.

v. Storm Surges and Tsunamis

Rain is not always the culprit when it comes to flooding. Storm surges related to hurricanes and other storms can lead to significant flooding, as can tsunamis that are sometimes caused by underwater earthquakes. Given modern technology, we often know about storm surges and tsunamis before they arrive, but this is not always the case. For example, in 2004, an earthquake off the coast of Indonesia created a tsunami that gave little warning before coming ashore.

vi. Channels with Steep Sides

Flooding often occurs when there is fast runoff into lakes, rivers and other reservoirs. This is often the case with rivers and other channels that feature steep sides. It is a similar issue to having a lack of vegetation, which is explained in more detail below.

vii. A Lack of Vegetation

Vegetation can help slow runoff and prevent flooding. When there is a lack of vegetation, however, there is little to stop water from running off. This can be a bit of a conundrum after a drought. While area residents likely welcome the rain, the lack of vegetation after the drought can cause flash flooding. This does not always happen given that basins and reservoirs are close to empty, but it can occur in cases of extreme rains following long periods of drought.

viii. Melting Snow and Ice

A winter of heavy snow and other precipitation can lead to a spring of flooding. After all, that snow and ice have to go somewhere when they melt. Most mountainous areas experience relatively consistent snowfall totals from year to year, but an unusually heavy winter of precipitation can spell bad news for low-lying areas around the mountains when spring hits.

5. What are the major causes of fire?

Ans: 1. candles 2. cooking 3. electricals 4. Heating 5. smoking. Elaborate yourself