Earthquakes, Tsunamis & Landslides, Oh My!
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Questions 1 & 2
Earthquakes are caused by the boundaries of the Earth's tectonic plates colliding or sliding past one another. The section where two plates meet and move is called a fault. Sometimes, the plates get stuck on jagged edges. When the energy overcomes the friction caused, all of the energy is released and causes earthquakes.
Questions 4
Waves of energy caused by earthquakes are called seismic waves. They ripple like water on a pond when a stone is dropped in. They often reach the surface of the planet where everything starts to shake. This is why cities or towns that are located near faults are more likely to feel earthquakes than those in the center of a tectonic plate. These earthquakes are always followed by aftershocks starting from the same epicenter.
Questions 3, 5, 6
A seismograph is an instrument that records the seismic waves produced an earthquake. The location and power of an earthquake can be determined by the information recorded on a seismograph.
Developed in 1935 by Charles F. Richter, the Richter scale measures the intensity of an earthquake. A ground-shaking event registering less than a 2.0 is considered minor, while one above 4.5 is considered a major event. The largest earthquake ever recorded was in 1977 in Chile, and it registered a devastating 9.5.
Questions 7-8
Earthquakes cause direct damage when the seismic disturbance weakens and collapses buildings and other infrastructures not built to withstand the tremors. This often causes great loss of life. Other damage caused by earthquakes results from landslides, mudslides, avalanches, fires, soil liquefaction and tsunamis.
In the Tangshan earthquake of 1976, considered the most devastating earthquake of the twentieth century, up to 650,000 people died, mostly due to inadequate building construction. Often roads, bridges and railroads buckle and crack because of the shifting ground.
Questions 9
Landslides, mudslides and avalanches result from the instability on slopes affected by earthquakes. Fires are caused by damaged electric and gas lines, and once they start fires are difficult to control due to overwhelmed emergency services. After buildings collapsed in the initial tremors of the Kobe earthquake, thousands of buildings burned to the ground. Soil liquefaction occurs during intense shaking when the soil loses its stability and turns into a quicksand-like fluid that can swallow buildings.
Questions 10-12
Tsunamis are often caused by earthquakes beneath the ocean floor. Barely recognizable at sea, they can rapidly travel vast distances, increase dramatically in height as they approach land. Tsunamis cause the most damage to costal environments.
Earthquakes are extremely destructive, causing damage to property, landslides, mudslides, avalanches, fires and triggering tsunamis. Earthquakes aren't a solely negative force, they do have a positive effect by creating beautiful mountain ranges, such as the Himalayas.