Question

which statement describes how geologists use data from seismographs to learn about earthquakes?
○ they often compare information from all over the world.
○ they map the location of an earthquake’s focus.
○ they use one reading to determine the location of an epicenter.
○ they measure the difference between the arrival times of surface waves

Explanation:

• Comparing global seismograph data is not the core method for direct earthquake analysis here.
• Locating the focus directly via seismographs is not standard; epicenters are mapped first.
• A single seismograph reading cannot pinpoint an epicenter (3 readings are needed for triangulation).
• Geologists use the time difference between P-waves and S-waves (both body waves, with surface waves arriving later) from seismographs to calculate distance to the epicenter, and measuring arrival time differences is a key step.

Answer:

They measure the difference between the arrival times of surface waves