Thursday, September 30, 2010

Things are Splitting

Harrat Lunayyir Volcanic Field

A recent swarm of 30,000 earthquakes and rifting alert geologists that Harrat Lunayyir is still active.

Harrat Lunayyir: Location and Description:

The Harrat Lunayyir Volcanic Area is located in the desert of northwestern Saudi Arabia, immediately east of the Red Sea port of Umm Lajj. It is an area of extensive basaltic lava flows and about fifty small volcanic cones (see photo below).

The center of the volcanic field is about thirty miles inland from the Red Sea. Individual lava flows radiate out in all directions from the center of the field. They follow stream valleys through the desert. Two of the flows have reached the Red Sea but they are now covered by sand along the coast.

Recent Activity at Harrat Lunayyir:
East Africa Rift
Synthetic Diamonds
Teaching Plate Tectonics with Drawings
Mineral Rights
The youngest lava flows at Harrat Lunayyir were produced by eruptions that occurred about 1000 years ago. Until 2009 the field was considered to be inactive because no evidence of recent activity had been identified.

Then, between April and June of 2009, a swarm of over 30,000 earthquakes occurred beneath the volcanic field and a fissure about five miles long opened to a width of about three feet (see photo at right).

The enormous number of earthquakes was a cause for concern. About twenty earthquakes were over magnitude 4 and a magnitude 5.4 earthquake on May 19th, 2010 damaged buildings in the town of Al Ays. These stronger earthquakes prompted the Saudi Arabian government to order evacuations and 40,000 people left their homes. They were allowed to return to their homes in August, two months after the earthquake activity subsided.

Why Is This Area Active?

Harrat Lunayyir Volcanic Area is located along the Red Sea Rift where active rifting still occurs – the Arabian Peninsula and Africa are still moving away from one another. A chain of active volcanoes runs down the center of the Red Sea. These are fed by rising magma from below. Intrusions of magma occasionally occur along the flanks of this active rift. These intrusions can cause rifting, earthquake activity and occasional volcanic eruptions. The earthquake activity and rifting of 2009 is believed to be a result of intrusions of magma into the Harrat Lunayyir area.

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