Six large earthquakes (ranging from 4.6 and 5.7 in magnitude) took place in northwestern Saudi Arabia today. This has led to a mandatory evacuation of the villages around the Al-Ais/El-Eis volcano (dormant, but perhaps awakening). Some 60,000 people are now sheltering with friends and family or in apartments and temporary housing provided through Saudi Civil Defense.
For those who are using Google Earth, you can download a .KML file that will integrate with the program and show the location of two of the earthquakes in much greater detail than is available through Google Maps.
You can follow discussion of the earthquake and the likelihood that they are precursors to volcanic activity as several science blogs. One I am following is Eruptions.
Arab News reports on the evacuations. It says that large numbers of people are leaving the cities of Madinah and Yanbu (the two nearest large cities) due to the tremors, causing serious traffic congestion. Interestingly, the paper also reports that rescue and recovery equipment is being moved into the area as a precautionary measure.
Aftershocks rock Al-Ais
Muhammad Al-Sheikh & Yousuf Muhammad | Arab News
YANBU: Strong aftershocks were felt in the village of Harrah Al-Shaqah and its adjoining settlements in the Al-Ais area yesterday with the Civil Defense declaring emergency in the region and ordering complete evacuation.
According to the US Geological Survey (USGS), the strongest of the aftershocks measured 5.6 on the Richter scale at 8:10 p.m. yesterday. Earlier, a Saudi Geological Survey (SGS) statement said: “The magnitude of the earthquake has been rising notably from 3 to 4.81 on the Richter scale with a total of 46 earthquakes recorded between 2 p.m. Monday and 2 p.m. today. The strongest tremor occurred 7.7 km beneath Harrah Al-Shaqah and its adjoining villages.” Aftershocks were felt in Umlaj, Wajh and Ula.
An SGS team that is conducting an aerial survey of the quake-hit area found a large crack in the earth and opened a quake detection station at Harrah Al-Shaqah.
On its part, Saudi Gazette reports that Saudi state TV has been running public safety announcements about the situation and covers the evacuation as well. It also notes that rumors of smoke, gas, and changes in the color of local water sources are yet to be confirmed.
Residents told to leave Al-Eis amid stronger tremors
RIYADH – The Civil Defense urged the remaining residents of Al-Eis in northwest of the country, to leave their homes for shelters after considerable seismic activities were measured Tuesday night. Warning sirens reportedly echoed in vulnerable neighboring areas of Al-Eis as safety instructions during disaster were announced on the state TV.
Two medium-size earthquakes hit a volcanic region in Al-Eis Tuesday, but there were no injuries and no damage to buildings, a seismological official said. A 5.4 earthquake hit the northwestern region in Al-Eis on Tuesday, just hours after a 4.8 tremor, said Ahmad Al-Attas, vice president of the Saudi Geological Survey (SGS).
Reports of toxic gas emissions and change of the color of well waters have not been confirmed.
As I’ve said before, I’m not a geologist. This activity is, however, very suggestive of a coming volcanic event. As I’ve also said, this seismic activity might peter out, with no more excitement than has already happened. It is also possible that a major eruption might occur. They have in Saudi Arabia’s past, both geologic and historic.
Given the complex nature of Saudi geology, a volcano might be one of several types. Most likely is a ‘shield volcano‘ which doesn’t create huge mountains, but does create vast amounts of lava with low viscosity which spreads over large areas, similar to the volcanoes currently making Hawaii. But there are also ‘scoria volcanoes‘ in the Kingdom, ones which produce cones up to several hundred meters in height. These are most like Stromboli, off the coast of Sicily. There is always a possibility—though I rate it low—for a stratovolcano, similar to Mt. Saint Helen or Mt. Mayon in the Philippines. These are hugely explosive and can lead to pyroclastic flows of hot gases and ash.