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Harrat Lunayyir Volcanic Field
A recent swarm of 30,000 earthquakes and rifting alert geologists that Harrat Lunayyir is still active.
| A satellite image view of the Harrat Lunayyir Volcanic Field by Google Maps. The dark brown to dark black areas are basaltic lava flows. Note how the lava has followed stream valleys in a radial pattern around the central lava field. Use the + and - buttons in the upper left corner of the map to zoom in and out of the image. The arrow buttons will help you move across the map. If you zoom in close you will be able to see numerous volcanic cones in the center of the field. |
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 at right).
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:
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.
Contributor: Hobart King
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| Harrat Lunayyir basalt cinder cones and lava flows in Saudi Arabia seen from an aerial perspective. Deposits from the cinder cones cover nearby ridges and form fans at the base of the older non-volcanic ridge in the background. These well-preserved geomorphic forms indicate the relative youth of this northern part of the volcanic field. Photograph by John Pallister, United States Geological Survey. |
| Wendy McCausland of the USGS Volcano Disaster Assistance Program and Hani Zahran of the Saudi Geological Survey view the southern end of the surface fault rupture caused by a M5.4 earthquake in the Saudi Arabian desert on May 19, 2009. The ground displacements in the soft sediments of the foreground are greater than in basement rocks of the background because sediments respond differently than hard rock to the ground shaking and rupture. Photograph by John Pallister, United States Geological Survey. |
| Landsat GeoCover image of the Harrat Lunayyir volcanic area. Data courtesy of NASA, John C. Stennis Space Center. Enlarge image. |
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