Despite common belief, several countries in the Middle East contain active volcanoes.
Many of these volcanoes have produced vast black lava flows, so they can easily be seen
from satellite.
One of these volcanoes is quite notable as it nearly produced an eruption in 2009 in
a remote section of Saudi Arabia.
However, the magma stopped only a few hundred meters beneath the surface.
The volcano I am referring to is called Harrat Lunayyir, which is likely to erupt in the
next century.
This video will discuss this volcano, and mention what its future hazards are.
The Harrat Lunayyir volcanic field is located in west central Saudi Arabia, where it is
200 kilometers west northwest of the city of Medina.
Like the other volcanoes in the country, it does not contain a tall singular vent.
Rather, it contains dozens of vents which are spread out over an area of 2600 square
kilometers.
Due to the nature of this volcanic field, individual vents erupt once and then never
erupt again.
As such, this volcanic field is called "monogenetic".
The Harrat Lunayyir volcanic field began forming 500,000 years ago, when magma forced its way
upwards through a series of cracks in the region.
These cracks paralleled the spreading of the Red Sea to the west, indicating the origin
of these faults.
Initially, this lava erupted at several vents concurrently in a straight line, forming a
series of cinder cones.
These cinder cones each grew to a height of 100 to 200 meters as they ejected ash in a
several kilometer radius.
The majority of ash fell close to the erupting vent, thus building the volcanic cone.
Concurrently, each of these cinder cones emitted a quantity of lava, which then flowed downhill.
Some of these lava flows traveled up to 11 kilometers away before they stopped.
Over the subsequent tens of thousands of years, additional eruptions output basaltic lava
in a northwest trending chain further to the north.
Since then, volcanic eruptions have slowly trended in an eastward direction.
One of these eruptions sent a slow moving river of lava through a series of canyons
which traveled more than 30 kilometers before it stopped just short of the modern town of
Qrash.
The most recent eruption from this volcanic field was witnessed around 1000 AD.
Although the exact location of this eruption remains a mystery, it likely originated from
four different closely spaced cinder cones in the center of the volcanic complex.
These cinder cones ejected bombs of lava and ash, which fell in a several kilometer radius
in what is termed a strombolian style eruption.
By the time the eruption was over, 18 square kilometers had been covered with a fresh black
layer of volcanic rock.
Since this eruption, seismic activity in the vicinity has increased.
In 2009, satellites detected a strong heat signature originating from several vents adjacent
to the site of the most recent eruption.
These satellites detected temperatures as high as 70 degrees Celsius, indicating that
hot volcanic gasses related to a shallow body of magma were being emitted.
Eventually, this shallow body of magma caused a 3 kilometer long fissure in the crust to
quickly lengthen to 8 kilometers in length.
Temperature levels continued to increase, causing an evacuation of several thousand
people in the vicinity.
However, these earthquakes eventually stopped, indicating that the magma stopped just short
of the surface.
Although it is debated how close the magma got to the surface, estimates agree that it
got between 500 and 1000 meters of the surface, meaning an eruption nearly occurred in 2009.
Due to the presence of this recent magma intrusion, another eruption is likely within the next
century.
Such an eruption would likely originate from the recently expanded fissure, and result
in the creation of more cinder cones.
A cinder cone forming eruption would pose two hazards.
First, long distance lava flows could travel up to 30 kilometers away in a generally downhill
direction, burying property.
Second, high amounts of carbon dioxide gas could travel downhill and pool in low points.
This could cause suffocation if people were not evacuated from at risk areas.
Using the US Geological Survey method of rating volcanoes, Harrat Lunayyir would be classified
as a moderate threat volcano.
I hope that you enjoyed this video!
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