Ide culled seismograms from the profusion of earthquakes that strike off the east coast of Japan, where the Pacific Plate plunges beneath the Japanese archipelago. Here we show the past month of magnitude-3 and larger shocks during the past month from the Temblor app. Credit: Temblor

Ide culled seismograms from the profusion of earthquakes that strike off the east coast of Japan, where the Pacific Plate plunges beneath the Japanese archipelago. Here we show the past month of magnitude-3 and larger shocks during the past month from the Temblor app. Credit: Temblor

Earthquake size is not foretold in the first second of rupture, study finds, shortening warning times


By Alka Tripathy-Lang

October 14, 2019

One of the many unanswered questions in earthquake science is how earthquakes grow, and whether predicting the final magnitude of an earthquake is possible when it is still small and developing. Earthquake Early Warning systems were originally based on the hotly debated premise that the rate of growth in the initial 4 seconds was enough to estimate an earthquake’s ultimate magnitude [Allen and Melgar, 2019]. Now, the systems initially use a half-second to 4 seconds of data and are constantly updated as a quake progresses. A key to understanding how an earthquake grows, and thus how big it will eventually be, is an even more basic question: How does an earthquake begin?

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