Stories tagged seismic activity

Nov
11
2011

On November 10, 2011, at 17:25 UTC (or 11:25am Central Standard Time), a shallow quake occured in Greece about 11.8 miles NE of the town of Patras. According to the European-Mediterranean Seismological Centre, this earthquake had a magnitude of 5.1 (later downgraded to a 4.6) and was a relatively shallow quake at 5 km (approximately 3.1 miles) below the Earth's surface.

This region is characterized by a high level of seismicity, and small tremors are continually recorded along the coast of Patras. Another interesting aspect of Patras is that in antiquity, there was an ancient oracle, over a sacred spring, dedicated to the goddess Demeter. Professor Iain Stewart from the University of Plymouth has been studying a supposed link between ancient. sacred places in Greece and Turkey and seismic fault lines. Many ancient temples and cities lie along those fault lines and this may not be merely due to chance, but they may have been placed there deliberately.The Temple of Apollo at Delphi with Mount Parnassus in the Background
The Temple of Apollo at Delphi with Mount Parnassus in the BackgroundCourtesy Wikimedia Commons

For example, the Oracle at Delphi has been given a geological explanation. The Delphi Fault (running east-west) and the Kerna Fault (running SE-NW) intersect near the oracular chamber in the Temple of Apollo. In that area, bituminous limestone (i.e. limestone containing bitumen, a tarlike deriviative of petroleum) has a petrochemical content as high as 20%. Analysis of spring water in the area showed the presence of hydrocarbon gases, such as ethylene. Geologists have hypothesized that friction from fault movement heats the limestone, causing the petrochemicals within to vaporize. It has been suggested that exposure to low levels of the sweet-smelling gas ethylene would induce a trance, or euphoric state. Could the naturally occuring ethylene account for the strange, prophetic behavior of the Pythia (the priestess at the Temple of Apollo)?

The Delphi research is certainly persuasive, and received favorable coverage in the popular press and Scientific American, but it has come under criticism. Critics argue that the concentrations of ethylene identified by the researchers would not be sufficient to induce a trance-like state, and thus the connection to the mantic behavior of the Pythia is dubious.

Report: Geomythology: Geological Origins of Myths and Legends
Article: Breaking the Vapour Barrier: What Made the Delphic Oracle Work?
Report: Oracle at Delphi May Have Been Inhaling Ethylene Gas Fumes

Related Report: Earthquake Faulting at Ancient Cnidus, SW Turkey

Check out this amazing map. It shows the number of foreshocks, the big quake, and aftershocks, as well their location, date/time, depth, and magnitude. Stick with it: it starts off slowly, but it gets pretty horrifyingly spectacular.

Apr
16
2010

Tracking worldwide earthquakes: Here is a map showing the epicenters of worldwide earthquakes over a 35-year span. No wonder it seems like earthquakes are happening all over the globe.
Tracking worldwide earthquakes: Here is a map showing the epicenters of worldwide earthquakes over a 35-year span. No wonder it seems like earthquakes are happening all over the globe.Courtesy Wikipedia
Geology may not be the "sexiest" of sciences, but when it gets cranked up, it can really make its presence known. And we've had a very interesting run of geological news in the past few months. The recent focus on earthquake matters is really summed up well in this commentary piece by Craig Childs of the Los Angeles Times.

Just in case you don't click the link, here are a few important notes from the piece to keep in mind while you're trying to figure out if the world is indeed coming to an end:

• With population increasing across the globe, more people are living in more hazardous regions.

• With our explosion of communications, we're hearing about earthquakes more often and in more depth.

• Since records have been kept on seismic activity, we know that about 50 earthquakes are recorded every day. Annually, the Earth averages 17 major earthquakes (7.0 to 7.9 on the Richter scale) and one doozy (8.0 or higher). The activity we've been seeing this year fits into those numbers so far.

Here are a few more items to points to take home regarding the recent geological frenzy:

Latest Chinese earthquake

As of Friday midday, the death toll in the China earthquake had climbed to over 1,100. While the devastation is much like the quakes in Haiti and Chile, the quake's cause, we're learning, was different.

Not all earthquakes start the same way. While most at the result of interactions between Earth's tectonic plates, this week's earthquake in China was different. It was an "intraplate" quake contained within an individual tectonic plate. Here's a full explanation. Basically, a quake occurs along a smaller fault that forms inside the plate, which is caused by other plates pushing on that plate's edges.

The New Madrid Seismic Zone in the central U.S., stretching from Arkansas to southern Illinois, is another example where "intraplate" earthquakes occur. On average, there's about an earthquake every-other-day in that zone, but they're very mild. But a large quake in the zone can spread damage over a much larger area.

Volcanic ash aloft: This aerial photo shows a volcano in Alaska spewing ash into the air in 2006.
Volcanic ash aloft: This aerial photo shows a volcano in Alaska spewing ash into the air in 2006.Courtesy Wikipedia

Iceland volcano update

Iceland's Eyjafjallajokull volcano continues to erupt and its ash continues to interrupt airline travel. Geologists have no idea how long the eruption might last. Back in 1821, the volcano erupted for several months. And the larger neighboring volcano, Katla, has not erupted yet. Typically it follows after Eyjafjallajokull's initial eruptions, and geologists say if that happens again, Katla could send out even greater amounts of volcanic ash.