the earth travels 18.5 kilometers in a second.
the earth travels 18.5 kilometers in a second.
how many kilometers does the earth travel in a second?
18.5
Na
Na
the travel time must be calculated very accurately in order to compute a precise hypocenter. since p waves move at many kilometers per second, being off on travel-time calculation by even a half second can mean an error of many kilometers in terms of distance. in practice, p arrivals from many stations are used and the errors cancel out, so the computed epicenter is likely to be quite accurate, on the order of 10–50 km or so around the world. dense arrays of nearby sensors such as those that exist in california can provide accuracy of roughly a kilometer, and much greater accuracy is possible when timing is measured directly by cross-correlation of seismogram waveforms.
seismic wave