From the epicenter of the 2014 magnitude 6.0 Napa earthquake (red star), the P-wave (yellow circle) raced ahead of the more damaging S-wave (red circle). The blind zone, for which no warning was possible, is shown by the solid gray circle with a red slash. Small green circles show seismic stations. Credit: video produced by the Incorporated Research Institutions for Seismology (IRIS).

From the epicenter of the 2014 magnitude 6.0 Napa earthquake (red star), the P-wave (yellow circle) raced ahead of the more damaging S-wave (red circle). The blind zone, for which no warning was possible, is shown by the solid gray circle with a red slash. Small green circles show seismic stations. Credit: video produced by the Incorporated Research Institutions for Seismology (IRIS).

From the epicenter of the 2014 magnitude 6.0 Napa earthquake (red star), the P-wave (yellow circle) raced ahead of the more damaging S-wave (red circle). The blind zone, for which no warning was possible, is shown by the solid gray circle with a red slash. Small green circles show seismic stations. Credit: video produced by the Incorporated Research Institutions for Seismology (IRIS).

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Alka Tripathy-Lang, PhD

Alka Tripathy-Lang is a freelance science writer based in Chandler, Arizona, and holds a Ph.D. in geoscience.
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