Practically speaking, an app like Earthquake has little value unless you're a seismologist. Keeping tabs on what temblors have recently occurred around the world is unlikely to give nonspecialists any practical insight into when future ones will take place. On the other hand, like Google Sky Map, Earthquake is a fascinating app to look at for its own sake.
The Earthquake app generates lists of the most recent significant shakers that have occurred worldwide. Since the Earth is a big place--and since smaller earthquakes happen all the time--the list is necessarily limited to the previous couple of days. To the left, the app displays the magnitude of the earthquake on the open-ended Richter scale. To the right it displays the location of the tremor, with a time and date stamp. Clicking any entry will bring up its location on Google Maps; and if you zoom in close enough, you'll see a circle delineating the affected area.
From the settings, you can further customize the app. For instance, you can decide whether to have it refresh automatically or not, and you can specify the frequency of the refreshes. You can also filter your results by setting a minimum magnitude, and if you have your GPS active, you can adjust the maximum distance from yourself. Additional options include receiving notifications of seismic events that occur within a certain area, and arranging for your phone to vibrate with an intensity based on the magnitude of the earth's movement during a shock. Of course, if you make the tracking area around you small enough, the notifications--and the phone vibrations--probably won't be necessary.
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