Natural and environmental hazard

    Hello, how about your work today? how about your study today?
    I'm fine,but a small earthquake was happened yesterday. I think some natural hazards like earthquake are occur on the earth anytime. Today I will talk about the geologic hazards on the earth.  
   A geologic hazard is a natural geologic event that can endanger human lives and threaten human property. Earthquakes, geomagnetic storms, landslides, sinkholes, tsunamis, and volcanoes are all types of geologic hazards.
   Earthquakes occur all over the world and often occur without significant warning. These geohazards can have far-reaching affects on humans and on the surface of the Earth. Small, localized earthquakes may cause no noticeable damage and may not even be felt by people living in the affected area. In contrast, a large earthquake may cause destruction over a wide area and be felt thousands of miles away.Earthquakes can also occur within plates, although plate-boundary earthquakes are much more common. Less than 10 percent of all earthquakes occur within plate interiors. As plates continue to move and plate boundaries change over geologic time, weakened boundary regions become part of the interiors of the plates. These zones of weakness within the continents can cause earthquakes in response to stresses that originate at the edges of the plate or in the deeper crust. The New Madrid earthquakes of 1811-1812 and the 1886 Charleston earthquake occurred within the North American plate.While we can't prevent earthquakes or even accurately predict when they will occur,but what we should to know is how to be prepared for an earthquake and what to do if one occurs.
    A landslide is the movement of soil, rock, or other earth materials, downhill in response to gravity. Landslides include rock falls and topples, debris flows and debris avalanches, earthflows, mudflows, creep, and lateral spread of rock or soil. Landslides constitute a major geologic hazard, they are widespread, occurring in all 50 States, and they cause more than $2 billion in damages and more than 25 fatalities on average each year.One of the largest landslides in the world is in the 20th century occurred at Mount St. Helens, Washington, in 1980. A moderate earthquake caused roughly 1.7 cubic miles of rocks and mud to break free and slide down the side of the volcano, releasing pent-up pressure to produce the major eruption of May 18.
  A volcano is a vent at the Earth's surface through which magma and associated gases erupt, and also the cone built by eruptions. A volcano that is currently erupting or showing signs of unrest (earthquakes, gas emissions) is considered active. A volcano that is not currently active but which could become active again is considered dormant. Extinct volcanoes are those considered unlikely to erupt again. Volcanic eruptions are one of Earth's most dramatic and violent agents of change. They pose significant geologic hazards because their eruptions and associated activities can affect large areas and go on for extended periods of time. Many kinds of volcanic activity can endanger the lives of people and property, and the affects of these activities are felt both close to and far away from the volcano. Explosive eruptions can spread lava, gas and other materials over a wide area, and may drastically alter the landscape. Slow eruptions or flows can also alter landscapes, while associated earthquakes, atmospheric effects, landslides, and floods all may damage or destroy property and threaten human lives.
   Tsunamis are large, destructive waves that are caused by the sudden movement of a large area of the sea floor. Most tsunamis are caused by earthquakes, some are caused by submarine landslides, a few are caused by submarine volcanic eruptions and on rare occasions they are caused by a large meteorite impact in the ocean.The Krakatau volcanic eruption of 1883 generated giant waves reaching heights of 125 feet above sea level, killing thousands of people and wiping out numerous coastal villages. Locally generated tsunamis may reach a shoreline with only a few minutes warning, while distant events may allow several hours warning. In addition, many coastal areas have tsunami alert systems that sound sirens or provide information through local media. While we can't prevent tsunamis, we can take steps to lessen their impact. Those who live in or visit tsunami-prone areas should know the warning signs of an approaching tsunami, and what to do when a tsunami is imminent.
  We live on the earth which has too many natural and environmental hazards, and here I just have talked some. Also, hazards like flood, Glossary of Terms and Sinkholes can't be looked down upon.
   We can't change the natural hazard, but we can change the man-made hazard what we do on the earth. Before we protect our lives, we should protect the Earth. If we save the food and water, if we protect the rare species of animals, plants and other living things, the earth will be better, we will be live longer.