Volcanoes, Earthquakes and Tsunamis
Volcanic eruptions and earthquakes have one important tell-tale sign in common. As the pressure in them builds up before they unleash their fury, they cause small deformations in Earth's crust. If scientists could spot those subtle changes, they might be able to predict more precisely when catastrophic eruptions and quakes will occur.
NASA hopes to help them do that with the Deformation, Ecosystem Structure and Dynamics of Ice, or DESDynI, system, a proposed pair of satellites tentatively scheduled for launch in 2021. One of the spacecraft would bounce radar signals off the Earth's surface, and use them to measure small changes in the Earth's surface over time. Scientists believe this will help them with tracking potential volcanoes and earthquakes [sources: Klotz, NASA].
The second DESDynI satellite would be equipped with a system called LIDAR Surface Topography, which basically will bounce lasers off the Earth's surface and measure the interval it takes for the signal to be reflected. LIDAR similarly would help scientists to spot subtle movements of the Earth's crust, as well as look at shifts in forestry patterns [source: National Academy of Sciences].
When a big earthquake occurs offshore, it can result in a giant wave, or tsunami, which may swamp a coastal area with potentially enormous loss of life and property. But because every earthquake is unique, each individual tsunami exhibits different wavelengths, wave heights and directionality, which makes forecasting their size difficult. In 2010, NASA Jet Propulsion Laboratory scientist Y. Tony Song unveiled a prototype of a new system for assessing earthquakes and predicting the size of resulting tsunamis. The system uses data from NASA's Global Differential GPS network to capture data on movement of Earth's crust, which scientists, in turn, can use to calculate the movement of the seafloor and the amount of energy it puts into a tsunami [source: Schmidt].
In 2011, Song and Ohio State University professor C.K. Shum used Japanese GPS data to analyze the particularly destructive tsunami generated by a March 2011 earthquake off northern Japan, and discovered that the wave actually was composed of two different wave fronts that merged and doubled in intensity as they passed over rugged ridges on the seafloor. That knowledge may help forecasters in the future to predict similarly super-powerful waves, and hopefully speed evacuations of coastal areas [source: NASA].