I talked about fault scarps, uplift and subsidence, landslides, and liquefaction. All earthquake-related hazards, and all provide clues to historic and pre-historic earthquakes in the landscape.
Students completed an in-class exercise related to Forecasting Landslides and Liquefaction (see Canvas).
I reviewed the impact of shaking on human-built structures, presenting examples of the types and amount of damage that the strong shaking near a strong earthquake can produce.
No in-class exercise.
I described the tsunami generated by the 2004 Sumatra Andaman Islands earthquake and the 2011 Tohoku, Japan earthquake. We looked at maps, animations, videos, and photo demonstrating the awfulness of large tsunami. No in-class exercise.
We discussed patterns associated with earthquake locations (the global map of seismicity and the depth of earthquakes) and the Gutenberg-Richter pattern associated with earthquake size. The development of quantitative, instrumental measures of earthquake size (e.g. magnitude) led to the analysis of size-related patterns in earthquake occurrence. One important pattern is the Gutenberg-Richter Relation, which describes the pattern observed in earthquake size. If we let NC represent the number of earthquakes occurring in a region that have magnitudes larger than M, then
\(log_{10}(N_C) = a \, – \, b\, M\)
Fortunately, large earthquakes are less frequent than small earthquakes. As a rule of thumb, for each magnitude unit increase, there are 10 times fewer earthquakes during a specified time interval. So, for example, there are 10 times as many earthquakes greater than or equal to magnitude 5 than there are greater than or equal to magnitude 6.