Earthquake Shaker

References: http://latur.nic.in/html/earthquake.htm http://www.drgeorgepc.com/Tsunami2006Kurils.html 2) How are faults, foci (plural of focus), and epicenters related? Faults that are experiencing no active creep (relatively consistent yet minor movements) may be considered “safe.” Rebut or defend this statement with what you have learned so far about faults. The points in the lithosphere of Earth where fracturing originates are called foci. In other words, foci are the points at which energy-release takes place. Foci are also termed as hypocenters. Large fractures inside the Earth’s crust are called faults. Typically, news reports talk about epicenters when they are reporting an Earthquake. As large fractures inside Earth’s crust begin to shift, there is a release of energy inside Earth, right at the displacement (focus) point. An epicenter is nothing but the point on the surface of Earth that lies directly over the focus. It is not true that faults experiencing no active creep are safe. Fault creep refers to slow rock movement arising out of the application of constant stress over a prolonged period of time. A fault creep is a slippage that occurs alongside a fault. A fault creep may produce a small earthquake that can be detected through a seismometer. An active creep zone is one in which the most significant of displacements are likely to take place. Current absence of active creeps neither means that there is no fault creep at all, nor that there will not be any movement in future. A currently inactive fault could become active in future and cause an earthquake, so safe is not a term that one can always associate with the absence of an active creep. 3) At one time it was thought that the deep-ocean trenches at subduction zones would be a good place for disposal of high-level radioactive waste. Why is this not a good idea? Explain what can happen at a subduction zone and what might occur if the waste were buried there. (Hint: see oceanic-continental convergence.) Over the years, different options have been considered as suitable permanent repositories for disposing high-level radioactive waste. The intent has been to find a way of permanently isolating high-level nuclear waste from the environment used by humans. It is true that at one point in time, subduction zone trenches in deep oceans were a good option for disposing high-level radioactive waste. It was thought that sticky mud and clay at trenches in deep-open subduction zones could be ideal places to bury high-level radioactive waste. It was assumed that radioactive waste canisters deposited in such places would slowly leak, only to be bound by sticky mud and clay for several millions of years. It was expected that burying high-level radioactive waste inside a subduction zone of a deep-ocean would gradually carry waste into the mantle of Earth. Today however, this approach is not a matter of serious consideration because of the technical considerations that are in play, legal restrictions associated with Law of the Sea, and the fect that leakages could lead to widespread contamination. The fact that oceanic-continental convergence helps create geologic formations and sustain many active volcanoes of Earth mean that contamination can be a serious threat when considering the burial of high-level radioactive waste in subduction zone trenches of deep oceans.