Number 220 (Story #1), April 3, 1995 by Phillip F. Schewe and Ben Stein THE FASTEST TECTONIC MOTION so far measured anywhere in the world occurs near the Samoan Islands, where the Pacific plate is subducted at the Tonga Trench. In this region of the Earth's crust, the Australian and Pacific plates are in general convergence. Meanwhile a small platelet, the Tonga microplate, is moving out ahead of the Australian plate toward the Pacific plate at an even greater rate, opening up a rift called the Lau Basin. The net convergence, as measured with ground stations using signals from the Global Positioning System of satellites, is 24 cm/year. The multinational consortium of scientists performing the observations believe that the high seismic activity in the region (more earthquakes than other subducting slabs worldwide) is related to the rapid subduction rate. (Michael Bevis et al., Nature 16 March 1995.)