Final answer:
A seismogram is the record of an earthquake recorded by a seismograph. Seismographs with a 0.100-second precision allow for calculating the distance to an earthquake's epicenter with corresponding accuracy, which is important for both natural earthquake analysis and detection of underground nuclear tests.
Step-by-step explanation:
The record of an earthquake obtained from a seismic instrument is known as a seismogram. The seismogram is the actual data or recording of the earthquake waves, while the seismograph is the instrument that records the seismic events. When analyzing seismograms, seismologists can determine the distance to an earthquake's epicenter by comparing the arrival times of S-waves and P-waves, which travel at different speeds through the Earth's crust.
Regarding the precision with which the distance to the earthquake source can be determined, if the precision of the seismograph timing is 0.100 seconds, and knowing the speeds of S-waves and P-waves are 4.00 km/s and 7.20 km/s respectively, the distance can be calculated with a corresponding level of accuracy. For example, an uncertainty of 0.100 seconds in the arrival time can translate to an uncertainty in distance calculation based on the wave speeds. This level of precision may have implications for detecting underground nuclear tests, as the ability to precisely locate the source of seismic waves is critical for enforcing test bans.