plate tectonics

It may seem that there has been an unusual amount of volcanic activity lately, with major eruptions occurring in Iceland, Guatemala and Ecuador. But is it really unusual, and are the eruptions connected?

The short answer to both questions is no.

When an Icelandic volcano with a nearly unpronounceable name erupted after 200 years of quiet in March, it was little more than a curiosity. But when it erupted again in April — this time spewing huge clouds of ash as high as 11 kilometers into the stratosphere, quickly choking airways across Europe and costing airlines billions of dollars — it captured the world’s attention. As the ashfall decreased and airlines resumed normal routes this week, the headlines began to fade.

Update:

In 2008, it was the Longmen Shan Fault, a 250-kilometer long thrust fault that divides the 6,500-meter-high Tibetan Plateau from the lower Sichuan basin, which ruptured. However, today's series of quakes occurred several hundred kilometers to the northwest, in the eastern Tibetan Plateau, and were the result of strike-slip faulting, according to USGS.

A magnitude-7.2 earthquake struck northern Baja California, Mexico, at about 3:40 p.m. local time Sunday, according to the U.S. Geological Survey. At least two people were killed, several hundred were injured and thousands were without power as a result of the quake. Aftershocks as high as magnitude 5.0 have continued to rattle the region today.

Today, the surface of Venus is a hellhole, seared by scorching temperatures, crushing pressures and a toxic atmosphere of carbon dioxide with occasional clouds of sulfuric acid. But evidence is mounting that billions of years ago, Earth’s evil twin planet was a much more pleasant place — a second blue marble covered by water. The latest data come from the European Space Agency’s Venus Express spacecraft, which has spent three years constructing a detailed map of the surface of the planet’s southern hemisphere and finding new evidence for Earth-like plate tectonics and a watery past.

Reconstructing the history of supercontinents requires careful detective work. A variety of geological processes wipes the evidence clean, like a burglar who smears away his fingerprints. Yet even the most cautious criminals leave clues behind — and so do supercontinents.

Mars may be mythologically known as the Red Planet, but its topography can be as captivating as its celestial glow. Several striking features stand out with only a glance at a topographic map of Mars: the odd distribution of land on its surface and the equatorial string of giant volcanoes known as the Tharsis Rise. Since Mars has no plate tectonics, how these unique features formed has been a longstanding mystery.

Wednesday, Sept. 10, 12:30 p.m. EDT — At 3:30 p.m. local time, a magnitude-6.0 earthquake struck Iran near the southern port city of Bandar Abbas. Tremors from the quake were felt as far away as the United Arab Emirates and Qatar, according to the U.S. Geological Survey.

USGS detected a magnitude-4.8 aftershock about 30 minutes after the quake, although John Bellini, a geophysicist at the National Earthquake Information Center in Golden, Colo., says that many other aftershocks have and will bypass U.S. detection.