A trio of earthquakes between M4.0 and M4.5 hit Oklahoma and rattled Kansas, Texas, Missouri and Arkansas on July 27, 2015.
The USGS estimates at least 1.9 million people felt some sort of shaking triggered by the 3 earthquakes in Oklahoma. AMAZING WHAT FRACKING CAN DO!

The quakes were part of a series of tremors originating from a location 3 to 4 miles north-northeast of Crescent, Oklahoma. And they are most probably linked to fracking!
Two earthquakes hit Oklahoma Monday afternoon, rattling hundreds of thousands of people across at least five states in the middle of the work day. A third quake of similar intensity jolted the region again Monday evening.
In all, there have been eight quakes of magnitude 3.0 or larger at the site just northeast of Crescent since Saturday morning.
The first of the larger tremors hit at 12:49 p.m. CDT near Crescent, Oklahoma. The second, a more powerful M4.5 earthquake, came just 23 minutes later and was also centered near Crescent. This is the strongest earthquake in the region since a M4.9 hit near Conway Springs, Kansas, on November 12, 2014, and was felt across at least in Oklahoma, Kansas, Texas, Missouri and Arkansas. Even people as far as Little Rock, Arkansas, 300 miles away, reported the tremor.
The ground rattled again at 8:18 p.m. CDT when a M4.1 temblor struck at the same location as the early-afternoon quakes.
The USGS estimates at least 1.9 million people felt some sort of shaking.
As explained by The Weather Channel:
[quote_box_center]
In all, there have been eight quakes of magnitude 3.0 or larger at the site just northeast of Crescent since Saturday morning. In addition to those mentioned above, a pair of magnitude-3.9 tremors were recorded in the pre-dawn hours Saturday morning and again before sunrise Sunday morning.
A week ago, a broad swath of this region also felt a shallow earthquake. On Monday, July 20, an estimated 600,000 people felt a 4.4-quake along the Kansas-Oklahoma border. There was no damage.
[/quote_box_center]