Some have been used as scientific instruments to measure earthquake waves and other geomagnetic events.
Other scientists, however, questioned the analysis, which was based on the speed of earthquake waves passing through the earth.
Unfortunately, this is the same "pitch" as a number of shallow earthquake waves.
As earthquake waves take time to travel around the globe, the estimated moment magnitude may change as more information is received.
Soil, rocks and the way the earthquake waves travel all affect how well a building withstands the tremors.
Additionally, the motion of the earthquake waves at the surface can cause cracks to form in a non-liquefied layer.
That was probably the initial earthquake waves radiating outward at 14,000 miles an hour.
Studies of the way in which earthquake waves are transmitted through the Earth have shown that its interior has a concentric structure.
Three-dimensional structure of the interior was plotted from earthquake waves traveling along different paths.
The information wave on Twitter went faster than the earthquake wave.