06 September 2010

Seismology: Not a word I used everyday, previously . . .

Christchurch Earthquake already on Wikipedia! 2010 Canterbury Earthquake The entry talks about aftershocks and the epicentre, alluvial sediments and strike-slip faulting. No, I don't really now what I'm talking about, thus the quest for info. Curious, I am.

Unfortunately we are all learning heaps about earthquakes at the present. Earth Scientists are coming in to their own, as are geologists, seismologists and disaster preparedness experts. What causes the rumble of an earthquake? How do you measure an earthquake?

  • ‘P’ waves or (primary or ‘push’) waves are the waves that travel at 20,000 km per hour and are responsible for the low rumbling sound that you may hear just before an earthquake. ‘S’ waves are the (secondary or ‘shear’) waves that travel at10,000 km per hour. They shake the ground sideways and cause the most damage.
  • The Modified Mercalli scale is a way of measuring the observable effects of the shaking on the environment. The higher the earthquake’s rating the greater the damage. The Richter scale is a way of measuring the vibrations of the earthquake to tell how much energy was released at the source of the quake.
Who was Richter that his name came in to such common household usage near fault lines?
One of the interesting facts about Charles Richter is that he was born just north of Cincinnati, OH, near the Indiana-Ohio State line, a place in which very very few earthquakes ever occur. I know the place well, but only now learned the connection with Richter of the Richter Scale. Wikipedia
Research suggests that the Christchurch region can expect a sizable earthquake every 55 years and that the conditions are right there for liquefaction of the soil which is the cause of so much disruption of buried lines and pipes, and of surface damage to roads and tracks. Wikipedia's Links for the 2010 Canterbury Earthquake

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