Drilling study finds faults after earthquakes heal faster than previously thought

Jun 28, 2013 by Bob Yirka report

(Phys.org) —A team of Chinese researchers along with representatives from the US and Japan have found that ground fractures along fault lines due to earthquakes appear to heal faster than previously thought. In their paper published in the journal Science, the team reports on data found by boring holes along the fault line responsible for the 2008 Sichuan earthquake in China.

When earthquakes occur due to tectonic plates rubbing against one another, cracks open up in the ground leaving behind what look like wounds. Researchers have been studying these wounds to see if they might offer any new information that would help scientists better understand earthquakes in general. To that end, the researchers in this new effort embarked on a program called the Wenchuan earthquake Fault Scientific Drilling project. Five boreholes were drilled down into various parts of the fault and then sensors were sent down to collect heat and permeability measurements. The were drilled 178 days after the deadly earthquake in the region struck (which killed over 70,000 people.) At the time of initial drilling, the team found approximately 1 centimeter of new fault gouge, a type of rock that has been pulverized.

Subsequent measurement over a period of 18 months showed that the rock in the fault was slowly becoming less permeable—as the fault healed, water was less able to make its way through the rock. This was expected, of course. What surprised the research team, however, was how quickly the fault was being repaired by left behind by . They described it as "significantly faster" than lab experiments had shown.

Another surprise was a periodic tendency of the faults to lose ground in their . The rock would suddenly become more permeable, the sensors showed, and then once again become less so as the healing process resumed. The team traced this to other such as earthquakes that occurred in Sumatra in 2010 and in Japan in 2011.

The researchers acknowledge their data relates to just one fault zone in the aftermath of one earthquake, but their findings suggest that similar studies should be done following future earthquakes to help determine if what they observed is the normal case for healing fault zones.

Explore further: Slow earthquakes: It's all in the rock mechanics

More information: Science 28 June 2013: Vol. 340 no. 6140 pp. 1555-1559 DOI: 10.1126/science.1237237

Related Stories

Helping to forecast earthquakes in Salt Lake Valley

Apr 17, 2013

Salt Lake Valley, home to the Salt Lake City segment of the Wasatch fault zone and the West Valley fault zone, has been the site of repeated surface-faulting earthquakes (of about magnitude 6.5 to 7). New research trenches ...

Slow earthquakes: It's all in the rock mechanics

May 20, 2013

(Phys.org) —Earthquakes that last minutes rather than seconds are a relatively recent discovery, according to an international team of seismologists. Researchers have been aware of these slow earthquakes, ...

Hoodoos—key to earthquakes?

Feb 04, 2013

In the absence of long-term instrumental data, fragile rock formations, called hoodoos, may be key to understanding seismic hazard risk. In this study, researchers consider two hoodoos in Red Rock Canyon region to put limits ...

Recommended for you

Magnitude-7.2 earthquake shakes Mexican capital

Apr 18, 2014

A powerful magnitude-7.2 earthquake shook central and southern Mexico on Friday, sending panicked people into the streets. Some walls cracked and fell, but there were no reports of major damage or casualties.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Shootist
2 / 5 (4) Jun 28, 2013
Sounds like the same process will be found in fracking zones. If so bad newz for the former Reds now known as Greens.

More news stories

China says massive area of its soil polluted

A huge area of China's soil covering more than twice the size of Spain is estimated to be polluted, the government said Thursday, announcing findings of a survey previously kept secret.

UN weather agency warns of 'El Nino' this year

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...