GEOL 240Lg 1st Edition Lecture 22 Outline Current Lecture I Earthquake Prediction Observations of Precursory Phenomenon The Holy Grail of Seismology Current Lecture I Earthquakes are so sudden with devastating consequences earthquake prediction is a matter of great interest II earthquake prediction is often used to mean two different things III 1 in the common usage it is a highly reliable prediction to measure emergencies IV 2 in the second usage it means an actual statement and not a prediction of future seismic activity V It is highly reliable information II Changes in seismic velocity changes in the speeds at which seismic waves move through the Earth s crust have been identified during and after many earthquakes III In a new analysis of the 2004 magnitude 6 0 Parkfield earthquake in California David Schaff suggests some limits on how changes measured by ambient seismic noise could be used as a pre earthquake signal IV Ambient seismic noise refers to the background hum of the Earth the surface waves found all over the planet s crust that are caused mostly by wind and ocean waves V Changes in seismic velocity can be measured using seismic noise observations VI which are often recorded continuously at seismic stations and therefore can provide a detailed record of a pre earthquake time period
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