37. What if there is an earthquake near a CO2 storage site?

Whether earthquakes are common in your part of the world or do not occur at all, when it comes to discussing CO2 storage, people always ask about earthquakes.

CO2 storage sites are characterised and investigated using technologies such as seismic imaging to identify their stability, and are selected because they are unlikely to be affected by an earthquake. The WMP chose a stable location to store CO2 in an oilfield that contains no active faults, and in an area of North America that is not very seismically active.

Even in geologically active places on earth, like Japan or the west coast of North America, if an earthquake does occur it is highly improbable that a leak from the geological formations deep in the earth would occur. Both California and Japan have evidence to back this up.

California has many gas and oil deposits both on and off shore near seismically active faults and earthquakes. Some of these deposits are potential CO2 storage locations – depending on their depth and availability of caprock – and have remained secure storage locations for oil and gas over many millions of years (including several decades of oil production and study) and hundreds of earthquakes. Some nearer-surface reservoirs have shown movement of oil and gas to the surface along faults, but any potential CO2 storage locations would be characterised ahead of injection to identify these potential leakage routes and avoid them. As one of the more seismically active places on earth, with a sizable endowment of oil and gas, California can still safely store CO2 underground provided the proper characterisation of potential storage sites takes place.

Another recent, specific example of an earthquake happening very close to an actual CO2 storage site comes from Nagaoka, Japan. In 2004, a major earthquake measuring 6.8 on the Richter scale occurred a mere 20 kilometres away from a CO2 injection site 1,100 metres below the ground. The injected CO2 has been monitored by scientists before, during and after the earthquake and no leaks have been detected to date.