Mercalli vs Richter Scales Earthquakes Mercalli vs Richter Scales

How do we measure earthquakes? Richter Scale The Richter magnitude scale is used to describe the strength of an earthquake and is based on the height of the lines on the seismogram. Magnitude is a measure of the energy that is released during an earthquake. For each increase of 1.0 on the Richter scale, the height of the line on a seismogram is ten times greater. However, about 32 times as much energy is released for every increase of 1.0 on the scale.

How do we measure earthquakes? Mercalli Scale Measures the intensity of an earthquake. It measures the effects of an earthquake

Seven Factors That Contribute to the Destructiveness of an Earthquake A magnitude-6.3 earthquake shook Christchurch, New Zealand yesterday, collapsing buildings, triggering landslides and flooding, and killing dozens of people. A more powerful magnitude-7.1 quake rattled the city last September but didn’t cause nearly as much damage, with no fatalities. Why do some e… By Sarah Zielinski smithsonian.com February 23, 2011 34 13 25 0 14 5 8.5K 34 13 0 14 25 8.5K image: http://blogs.smithsonianmag.com/science/files/2011/02/NZintensity-255x300.jpg                                        A magnitude-6.3 earthquake shook Christchurch, New Zealand yesterday, collapsing buildings, triggering landslides and flooding, and killing dozens of people. A more powerful magnitude-7.1 quake rattled the city last September but didn't cause nearly as much damage, with no fatalities. Why do some earthquakes kill hundreds or thousands of people while others do little damage? There are several factors that determine just how destructive an earthquake can be: Read more: http://www.smithsonianmag.com/science-nature/seven-factors-that-contribute-to-the-destructiveness-of-an-earthquake-44395116/#8hLqHRLPkfuEVDdD.99 Give the gift of Smithsonian magazine for only $12! http://bit.ly/1cGUiGv Follow us: @SmithsonianMag on Twitter Why 2 different scales? A magnitude-6.3 earthquake shook Christchurch, New Zealand yesterday, collapsing buildings, triggering landslides and flooding, and killing dozens of people. A more powerful magnitude-7.1 quake rattled the city last September but didn't cause nearly as much damage, with no fatalities. Why do some earthquakes kill hundreds or thousands of people while others do little damage? While Richter measures energy released, it does not convey the type of damage that could occur. Earthquake damage is dependent on seven factors: :

Location An earthquake that hits in a populated area is more likely to do damage than one that hits an unpopulated area or the middle of the ocean. Scientists assign a number to represent the amount of seismic energy released by an earthquake. The Richter magnitude scale, as it is known, is logarithmic, so each step up represents an increase in energy of a factor of 10. The more energy in an earthquake, the more destructive it can be. Magnitude

Distance from the epicenter Depth Earthquakes can happen anywhere from at the surface to 700 kilometers below. In general, deeper earthquakes are less damaging because their energy dissipates before it reaches the surface. The recent New Zealand earthquake is thought to have occurred at a more shallow depth than the one last year. The epicenter is the point at the surface right above where the earthquake originates and is usually the place where the earthquake's intensity is the greatest. Distance from the epicenter

Local geologic conditions The nature of the ground at the surface of an earthquake can have a profound influence on the level of damage. Loose, sandy, soggy soil, like in Mexico City, can liquefy if the shaking is strong and long enough, for example. That doesn't bode well for any structures on the surface. Earthquakes can trigger landslides, fires, floods or tsunamis. It was not the 2004 Sumatran-Andaman earthquake that caused so much damage in 2004 but the Indian Ocean tsunami it triggered. Nearly a quarter of a million people in 14 countries were killed when coastal communities were inundated by the water. Secondary effects

Architecture Even the strongest buildings may not survive a bad earthquake, but architecture plays a huge role in what and who survives a quake. The January 2010 Haiti earthquake, for example, was made far worse by poor construction, weak cement and unenforced building codes. Damaged Building New Zealand 2016 Mag: 7.8 MEI: VIII Moderate 2 people killed

Earthquake Hazards

Liquefaction

Tsunamis A tsunami, also known as a seismic sea wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions, landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami. Unlike normal ocean waves which are generated by wind, or tides which are generated by the gravitational pull of the Moon and Sun, a tsunami is generated by the displacement of water. - https://en.wikipedia.org/wiki/Tsu nami

Japan Sendai 2011 Earthquake

1989 Loma Prieta Quake

Bibliography http://www.smithsonianmag.com/science-nature/seven-factors-that- contribute-to-the-destructiveness-of-an-earthquake-44395116/