Volcanic Activity Causing Tremors in Saudi Arabia
PARIS – 30,000 minor earthquakes recorded between April and June 2009 in western Saudi Arabia are due to volcanism, according to a study just released by the journal Nature Geoscience.
The largest of these earthquakes had a magnitude of 5.4 on the Richter scale, damaging buildings in the Al-Aissa and prompting authorities to evacuate 40,000 people.
According to U.S. and Saudi geologists, ground deformation detected by satellites, the signature of seismic waves and depth, everything points towards a volcanic origin of these shocks.
They had also produced on a former site of solidified lava called Harrat Lunayyir.
In the divide by 8 km long, which has expanded from 45 cm during this series of earthquakes, magma snuck. He came so close to the surface that the risk of volcanic eruption “in the coming decades” have increased, according to John Pallister (USGS), the main author of the study.
But the risk is low and, even in cases of eruption, the lava flow is slow, lay immediately to specialists.
“An eruption, if it occurred at Lunayyir pose little risk given the expected type of volcanism on this site and the remoteness of the area led” volcano, told AFP John Pallister.
“There is a low probability of earthquakes causing severe damage in association with this type of activity,” does he want to highlight, warning against exaggerated fears.
On the scale of a human life, volcanic eruptions are rare in Saudi Arabia, because they occur at intervals of several centuries, the best known back in the year 1256.
But on a geological scale, volcanism in Saudi Arabia is a modern phenomenon, said John Pallister.
“Several areas of recent lava characteristics (a geologist), including deposits covering the Neolithic sites,” he told AFP.
The tremors registered last year Harrat Lunayyir occurred in an area previously regarded by experts as seismically and volcanically inactive, some 200 km from a large active area of the earth’s crust beneath the Red Sea.