Scientists say Trinidad-area earthquakes are human-caused

Posted at 9:32 PM, May 15, 2018
and last updated 2018-05-15 23:32:33-04

Seismic experts tell News 5 that earthquakes in the Raton Basin of southern Colorado and northern New Mexico, west of Trinidad and Raton, are induced by human industrial activity in the region.  Wastewater injection from Coal Bed Methane (CBM) mining increases pressure on underground fault lines, causing them to slip occasionally, resulting in earthquakes, the researchers explain.

Jenny Nakai, recently awarded a PhD from the University of Colorado at Boulder, was lead author of a study published in October 2017 that concluded injection of wastewater at more than two dozen sites in the Raton Basin put enough pressure on fault lines to cause the bedrock to slip, resulting in earthquakes.  "What we’ve found is that injection of wastewater that has actually occurred in the Raton Basin, the pressures that it causes underground are large enough to induce the earthquakes, cause the earthquakes that we actually see," Nakai told News 5.  Similarly, scientists at the Golden-based U.S. Geological Survey’s National Earthquake Information Center say the number and frequency of earthquakes in the Raton Basin appears to directly coincide with the beginning of CBM production and injection activity around the year 2000.  "What we do know is that we’re seeing a lot of earthquakes in a small area that seem to be very correlated with the area of wastewater injection," said Dr. Mark Petersen, Chief of the USGS’ National Seismic Hazard Mapping Project.

Through the CBM process, methane gas is separated from water that permeates coal seams beneath the Raton Basin.  The methane is sent via pipeline while the water is stored and then sent back into the Earth via 28 gravity-fed wells throughout the area.  By contrast, there are nearly 3,000 production wells in the region extracting the water and methane.  "You’re pulling all this fluid out of the ground, spread out over a wide area, but when you’re injecting it, you’re injecting it at a greatly decreased number of sites," Nakai said.  The injection wells are drilled much deeper than the production wells, up to a mile deep, according to Las Animas County Oil and Gas Inspector Robert Lucero.

The largest earthquake in the region happened in August 2011 when a 5.3-magnitude temblor during the dark of night, crumbling building façades and tossing merchandise from store shelves in Valdez, Segundo, and Weston.  "Shook me good," said Johnny Cervo, general manager of Ringo’s Super Trading Post in Segundo.  "Broke all the neighbor’s dishes, broke the front of the building, broke the building down the street all the way out into the street."  More recently, a magnitude 3.6 quake in February was felt by people in Weston and a 4.0 quake was felt by people in Gulnare in late December.

The Coal Bed Methane industry in Las Animas County has been in steep decline since the recession of 2008.  "Probably 90 percent of our budget was funded by oil and gas at one time," Lucero said.  "Since I started here (in 2011), we’ve lost a lot of guys in the oil and gas industry in this field," Cervo said.  Cervo and others who live in the area say living with occasional earthquakes is worth it if it means preserving a full-time job and prosperous livelihood for workers in a part of the state with few other employment options.  "The Coal Bed industry has been great for Las Animas County," said local resident Ron Leep.  "Boy, we would really be in bad shape without it.  The earthquakes aren’t any reason to stop or slow down the production here."

Even if production and injection were to suddenly stop, Nakai says the earthquakes would likely continue.  "There’s no way to stop the natural movements of the Earth and you don’t know how long that pressure will take to dissipate," Nakai said.

Other earthquake swarms have been tied to wastewater injection practices, including in Oklahoma, Canada, western Colorado, and during the 1960s in the Denver area from deep well injection at the former Rocky Mountain Arsenal site in Commerce City.