How do scientists determine the location of a recent earthquake?

How do scientists determine the location of a recent earthquake?

• A. Use seismic records from three or more stations
• B. Use seismic records from one station
• C. Use seismic records from two stations
• D. Use weather data only

Answer: (A)

Earthquakes are located by triangulating their epicenter using records from multiple seismic stations. When an earthquake happens, seismic waves travel at different speeds, and the difference in arrival times of the fastest P-waves and slower S-waves at a station lets scientists estimate how far away the quake occurred from that station. But a single distance doesn’t give direction, so that station places the epicenter somewhere on a circle around it. With two stations you get two circles that can intersect in up to two points, which isn’t enough for a unique location. Three or more stations provide enough intersections to pinpoint a single point on the Earth's surface, identifying the epicenter. Weather data isn’t used for locating earthquakes. The epicenter is the surface point above the quake’s underground origin, called the focus, and using multiple stations with arrival times is how scientists determine its location.

Earthquakes are located by triangulating their epicenter using records from multiple seismic stations. When an earthquake happens, seismic waves travel at different speeds, and the difference in arrival times of the fastest P-waves and slower S-waves at a station lets scientists estimate how far away the quake occurred from that station. But a single distance doesn’t give direction, so that station places the epicenter somewhere on a circle around it. With two stations you get two circles that can intersect in up to two points, which isn’t enough for a unique location. Three or more stations provide enough intersections to pinpoint a single point on the Earth's surface, identifying the epicenter. Weather data isn’t used for locating earthquakes. The epicenter is the surface point above the quake’s underground origin, called the focus, and using multiple stations with arrival times is how scientists determine its location.