Wednesday, July 10, 2013

Podcast: Man-Made Earthquakes?

This week on the podcast I talk with seismologist and geophysicist Katie Keranen about a troubling trend: man-made earthquakes.

Scientists have known for at least 50 years that human activities can lead to seismic events. Potential triggers include anything that might change the pressure or the friction between portions of the earth's crust, such as removing large reserves of oil and gas, building artificial lakes, and injecting wastewater into the ground.

In March, a paper published in Geology created a stir when it implicated waste-water injection as the likely cause of a 5.7 magnitude earthquake that occurred in Oklahoma. The November 2011 quake (one of three in a series) was the largest earthquake on record in the state. It destoryed 14 homes and injured two people.

The Oklahoma earthquake is also the largest seismic event to be linked to human activity, but unfortunately, that link remains tentative: the scientists who investigated the quake can't say for sure if the wastewater injection caused it, because they are lacking critical information about when, where and how much water was injected into the ground near the earthquake's source. Without that detailed history, it's impossible to conclusively implicate injection as the earthquake's cause.

Moving forward, the scientists say they'd like companies to keep track of that information and make it available. But, there is reason to believe some companies wouldn't agree to release that information unless they were legally required to do so. If the company's activities did cause an earthquake, they might be liable for the damage the quake caused, and it could tarnish the company's reputation.  (It's important to note that the vast majority of waste water injection instances do not lead to seismic activity).

Listen to the podcast to learn more.

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