The Plate Boundary On Iceland

These divergent boundaries are mostly on the sea bottom, but here it stretches right across Iceland. The top photo shows the Almannagjá fault in the Þingvellir National Park. One might think that the gorge in the photo is where the continental plates separate, but it's not quite that simple. The western cliff face of the gorge is the edge of the North American Plate, while the edge of the Eurasian Plate is another cliff face 5 km (3 mi) to the east (bottom photo), all the way across the shallow valley. This valley gets on average 7 mm (0.3 in) wider and 1 mm (0.04 in) lower each year, a change that happens during earthquakes. At the latest big earthquake in 1789, the whole valley sank 1-2 m (3-7 ft).