iTemblor - Definition: a shaking and vibration at the surface of the earth resulting from underground movement along a fault plane or from volcanic activity.
Want to imagine what it's like to be in a large earthquake? Use iTemblor and your onboard iPhone accelerometer to simulate earthquakes through shaking and explore the relationship between acceleration and earthquake size!
iTemblor takes the accelerations you impart on your phone by shaking and through seismological relationships translates them into approximate earthquake intensity. Better yet, place iTemblor on a flat surface and shake the surface to simulate an earthquake! You can leave iTemblor on and see if you can record an earthquake!
iTemblor plots your acceleration data in four different views:
(1) Earthquake Intensity and instantaneous direction of horizontal motion.
(2) Peak Acceleration and instantaneous direction of horizontal motion.
(3) Three component real time acceleration time history
The peak acceleration data in (2) is used as the input to calculate the earthquake intensity (1) and is provided to allow you to develop some intuition between the presentations.
Because data views (1) and (2) plot horizontal accelerations only, for best results, hold your phone horizontally when shaking, or even better, place it on a flat surface and shake the surface like in a real earthquake.
View (3) shows two recordings per x,y and zaxis. The yellow line is the uncorrected or raw recording of your iPhone accelerations. The orange line is the corrected or filtered recording that is used in the iTemblor calculations. The signal is filtered so to be consistent with the seismological relationships used in iTemblor. It's interesting to observe the difference between the two recordings. The filtered version has the affects of gravity and high frequency impulse motions removed.
iTemblor also contains a detailed information page that provides a description of earthquake intensity and more.