Samoa & Sumatra
Over the past 24 hours, powerful earthquakes have occurred along the west coasts of Samoa and Sumatra. A secondary tsunami has caused significant damage in Samoa but it is too early to know if the Sumatran quake will result in a tsunami across the Indian Ocean.
The Sumatran quake occurred south of the epicenter of the devastating earthquake and tsunami that shocked the planet earlier this decade but, like its many predecessors, it surely developed along the west Sumatran subduction trench, where the Australian Plate is dipping below the Eurasian Plate. In such regions, the overlying plate is pulled downward by friction with the subducting plate; this building pressure is intermittently released, producing an earthquake and, by lifting the overlying ocean water, often triggering a tsunami.
The Samoan quake is less easy to explain. Not lying along a plate margin, the Samoan Islands have long been characterized as volcanic hotspots, produced by the movement of the Pacific plate over a mant…
The Sumatran quake occurred south of the epicenter of the devastating earthquake and tsunami that shocked the planet earlier this decade but, like its many predecessors, it surely developed along the west Sumatran subduction trench, where the Australian Plate is dipping below the Eurasian Plate. In such regions, the overlying plate is pulled downward by friction with the subducting plate; this building pressure is intermittently released, producing an earthquake and, by lifting the overlying ocean water, often triggering a tsunami.
The Samoan quake is less easy to explain. Not lying along a plate margin, the Samoan Islands have long been characterized as volcanic hotspots, produced by the movement of the Pacific plate over a mant…