Recent Earthquakes near Trinidad Colorado

In the recent years there has been a number of small earthquakes near Trinidad. There is an article on this topic called Investigation of an Earthquake Swarm near Trinidad Colorado by the USGS. There is speculation that the extraction of ground water by the Oil and Gas Industry and then the reinjection of that ground water into deeper formations may be the root cause of this swarm of earthquakes. You may find this article interesting.

Here are some excerts from that article.

In recent years, the area west of Trinidad has become the focus of extensive drilling for the production of coal-bed methane.  Water from the coal-bed methane production is returned to the subsurface in disposal wells, and local citizens and officials in the Trinidad area expressed concern that the earthquakes might be somehow related to this fluid disposal.  Previous cases of subsurface fluid disposal causing earthquakes have been reported elsewhere in Colorado.

Other circumstances also contributed to USGS’s decision to respond to the Trinidad earthquake swarm.  Currently coal-bed methane gas is under production west of Trinidad.  The process of coal-bed methane gas extraction involves the removal of large amounts of water from the shallow coal beds and, due to environmental regulations, the excess water is returned to deeper underground layers.  Thus, data from a local seismograph network might be able to shed some light on whether a relationship between the earthquake activity and the fluid disposal operation existed.

The process of coal-bed methane gas extraction results in the production of large amounts of excess water.  The Colorado Oil and Gas Conservation Commission’s (COGCC) rules and regulations require that some of the excess water be returned to the subsurface in disposal wells, and 10 fluid disposal wells are presently operating in the earthquake-monitored area (Figure 9).  The first fluid disposal well began operating in mid-1988 and the latest well began September 4, 2001.  All wells are disposing of the water at various flow rates at depths of 1.5 – 2.1 km (4,000 – 7,000 ft).

Just recently between September and October 2008 there were some small earthquakes between 2.7 and 3.2 that were centered near the base of the East Spanish Peak at the top of Trujillo Creek that were felt in the area near Aguilar and the last one interesting enough was centered on the other side of the Sangre de Cristo Range north and West of San Luis.

Are these earthquakes just a natural occurance? or are they being initiated by the Oil and Gas Activity? What do you think?