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Hello everybody!
I was wandering is oil and gas extraction from earth is one of the reasons for earthquakes?

Well, it can be. I know that in Holland for instance in the mayor Groningen gas field there are frequent earthquakes and subsidence of the ground. An earhtquake like experienced in Japan is not the result of oil and gas extracting but relates to far more mayor stress regimes coupled to plate tectonics.

I just watched this interview by the way: http://www.setyoufreenews.com/2011/03/f ... north.html It has some interesting views on the causes for earthquakes and how we can predict them...

I do not know about any major earthquake being caused by oil or gas extraction, but small movements with little or no damage are common (as they are in a more severe manner also in mining activities). The main cause are pressure depletion and consequential subsidence, these are often capped to a limit by the regulator when an area is particularly sensitive. In addition, like in the case of Groningen, the regulator might ask for a compensation fund to be created.

Extremely rarely the regulator might go further and prevent the drilling of oil wells in an area, as - I believe - is the case in some areas around the San Andreas fault. Most recently, a court in The Netherlands also stopped a planned underground gas storage as there were local concerns about possible earthquakes.

All activities related to injection of fluids are more sensitive than those relating to extraction, but both are well understood and the risk can be kept at a minimum with good geological data acquisition and operational control. A case where something went wrong happened in Switzerland a few years ago, when a court ruled that a minor earthquake with damage to buildings was caused by geothermal wells.

Recent concerns about fracking or fracturing in wells are also in the news, but fracking is a mature technology that has been used successfully already for several decades.

Thanks for giving some different information.

A growing number of companies around the globe are using hydraulic fracturing, commonly referred to as fracking, as a procedure to extract natural gas and oil. disposal of drilling waste water used in fracking has now been scientifically linked to earthquakes.
At the same time, local communities — here in the US, but also in other countries — fiercely oppose the practice because of concerns about ground water pollution and earthquakes.

Actual results could vary depending on several factors.

Earthquakes happen because of stresses and strains in the sub-surface.

These can be released slowly - over days - or rapidly - in a few seconds. The "slow earthquakes" have only recently been identified by having fixed GPS markers and monitoring accurately how things move; we tend to feel the "fast" ones, especially when the magnitude pushes above 2.5-3.0

The additional stresses and strains caused by drilling, oil and gas extraction and hydraulic fracturing are usually much smaller than those that already exist in the earth, so in that sense these activities alone do not "cause" earthquakes.

However, some activities associated with oil and gas production can make critical changes to the stress/strain underground, and can "trigger" a quake under certain circumstances; where this happens the chances are that a slow or fast earthquake was going to happen sooner or later anyway, the exploration activities just brought the timeline forward.

When oil or gas is produced water - which at those depths is heavily contaminated with salt and other minerals, not drinking water - replaces the oil or gas in the rock pores; in the short term this makes no difference, but over many years the overall pressure can drop. The pressure in the fluids - oil, gas or water - is one of the things that help to support the weight of the rocks, so when this drops, you get subsidence and associated earth tremors. The Groningen "super giant" gas field has been in production for more than 25 years, and the subsidence was known and being monitored as far back as the mid 1990s.

Hydraulic fracturing has been shown to lead to an increased earthquake risk in several studies, however only as a result of the disposal of the water-waste in deep bore holes. This practice is banned in some states and in Europe. The deep disposal of waste water (many km below the drinkable water table) is not just used in hydraulic fracturing, but other industries too. Disposal of the waste water is a big problem for hydraulic fracturing - there's a huge R+D effort into using less water, as well as better ways of "cleaning" the water. Its a big issue for farming too - hydraulic fracturing of a single well needs about the same amount of water as 70 dairy cows need in a year, with similar effluent disposal problems.

So :

- oil and gas production does not "create" earthquakes
- in some geological settings it can be a contributing factor to the timing of an earthquake
- disposal of waste water in deep bore holes can be a significant factor in this triggering
- some places allow the disposal of waste water from hydraulic fracturing in deep bore holes

How the stress and strain released in one earthquake event modifies the probability of other events is very complex; the longer the interval between events the more catastrophic the earthquake is likely to be.