11._earthquakes_09.doc

OBJECTIVES FOR EARTHQUAKES 1) What was the most destructive earthquake in history, and what was the first predicted earthquake in history? Most destructive 1556- Shesi, China 830,000 people dead 1811 mew Madrid Missouri First predicted 1975-liaoning providence, china 2) What type of strain (brittle, ductile, or elastic) is most important in creating earthquakes? Elastic rebound theory 3) Where do most earthquakes occur in a specific/local sense, and what is the difference between the focus and the epicenter of an earthquake? Occurs on faults Focus- point where strain is released (along the fault deep in earth interior) Epicenter- point on surface above focus 4) Where do most earthquakes occur in a general/global sense? Tectonic plate boundaries 5) What are the four modes of generation for earthquakes? Tectonic earthquakes, volcanic earthquakes, collapse earthquakes, explosion earthquakes 6) What type of plate boundary produces earthquakes with the deepest foci? Convergent boundries 7) Is there any place on Earth that is safe from earthquakes? no 8) What are energy waves released from an earthquake called, what are the two main types of these waves, the two divisions within each type, and what are the characteristics of each (which ones are fastest/slowest, go through liquids or don't, are or aren't trapped at the surface, are most and least destructive)? Seismic waves- body waves p-wave-fastest and can travel through solids and liquids s-wave-more destructive and can only go through solids surface waves love waves- extremely damaging no vertical movement, Rayleigh wave- like ocean waves moves object vertically and horizontally in an elliptical motion 9) What do you call the instrument used to record earthquakes, and what do you call the record this instrument produces? Seismographs machine produces seismograms 10) What are the two basic scales used to measure the strength of earthquakes, and why are two different scales needed (what does each record)? Richter scale- energy released on a logarithmic scale Mercalli- intensity (for local) depends on soil/rock through which earthquake wave travels and construction techniques and materials. 11) Be able to describe how an earthquake's epicenter is located. 1) use seismometers to measure the difference p-wave and s-wave arrival times 2) use known velocities of these waves to calculate the distance of the epicenter from the seismometer 3)use distance calculations from three stations to triangulate the exact position of the earthquake epicenter 12) What characteristics of seismic waves allow us to determine the interior structure of the earth, and what is this structure? a)use seismic waves to look inside the earth can be thought of as the first form of remote sensing b)seismic waves reflect and refract(bend) within the Earth and can reveal layers of differing composition and physical state c) d) nickel core (inner-SOLID), iron core (outer-LIQUID), mantle 13) How many seismographs are on the moon, and what is the main difference between a moonquake and an earthquake? There are six seismographs are on the moon Moonquake ? a lot smaller (no plate tectonic), hour longs, no liquid interior to absorb waves 14) Know what is meant by "foreshocks" and "aftershocks". Foreshocks ? little quakes before the big one Aftershocks ? are little quakes after the big one 15) Know at least 7 ways that earthquakes can cause damage. Shaking Freeway damage Buildings Wave amplification Unconsolidated sediment Damping and reinforcing of waves Resonance Liquefaction Buildings sink into the ground Fire Ground Rupture Landslides Tsunamis (aka Tidal Waves) 16) Know the ways that have been used, or are being considered, for earthquake prediction, and how well they have proven themselves (i.e. if they are dubious or less dubious techniques) Dubious Animal behavior Earthquake Weather (eerily calm) Glow in the sky Tidal pull of sun and moon (and other planets) Semi successful near volcanoes for minor quakes Less Dubious Changes in P-Wave velocity Ground uplift and tilt Radon emission Electrical resistivity of the rocks Number of local earthquakes (foreshocks) Geyser activity (changes in water table) Very Low Frequency (VLF) EMR Two recently launched satellites measure magnetic field of the earth 17) What is the other option besides earthquake prediction that can be used to lower damage and casualties? Risk Management Paleoseismicity If we can determine when past earthquakes took place we may be able to judge the frequency of major events Tree Ring Data Sand boils Sea terraces due to uplift Historical records