A PORTRAIT OF JAPAN’S MONSTER EARTHQUAKE
The image above shows the initial shudders of the 9.0-magnitude
earthquake that devastated Japan in March, as registered by seismic
sensors (yellow dots) across the world. From measurements like these,
scientists can infer a wave’s speed and determine if a structure within
the earth slowed it down or sped it up. A network of seismometers
concentrated in one region allows scientists to create detailed 3-D
images of the interior beneath that area. The readings clustered on the
right side of the globe in the above image represent some of the 1,000-
plus seismic stations deployed in North America. About 400 of those
are part of EarthScope, a National Science Foundation–funded project
that aims to understand when and how earthquakes strike. The image
at left shows how seismic waves play out when they reach the surface:
This elevation map depicts the wave height of the tsunami triggered by
the Sendai earthquake as it radiated through the Pacific Ocean.
