Yes the number of earthquakes felt in 2009 and 2010 are unusual.  The frequency of earthquakes has temporarily increased in Oklahoma, these earthquakes do not appear to be inconsistent with what might be called normal seismicity for Oklahoma.

Explanation by James Lawson
  Earthquakes produce two types of seismic waves through  the earth. P waves move the eatrh's surface mainly up and down, and S waves move it mainly side to side. The P waves travel faster so they arrive first.
  As the P waves arrive at your location, they cause the ground surface around you, and your floor, to vibrate up and down, just like a loudspeaker cone. The movement is too tiny to be seen, but just large enough to cause a low frequency sound. These sounds are often described as a boom or rumble. To persons who expierenced the Oklahoma City bombing, the earthquake sounds are similar to the air blast sounds from that atrocity. Many check to see if their furnace exploded, or go outside to look for an explosion. The sounds are frequently described as "like a sonic boom, only somehow different".
  Persons near an Oklahoma earthquake epicenter may hear and/or feel the P wave, and shortly after (only a second or so) may feel and/or hear the S wave. So you may have any of the following:

        1. sound only
        2. vibration only
        3. sound and vibration
        4. sound followed by vibration
        5. vibration followed by sound
        6. sound and vibration followed by vibration

or any other possible combination. 1., 2., 3., and 4. are the most common.

  There have been a number of instances (especially in Europe) in which vibration and/or sound from relatively small earthquakes, have precipitated heart attacks. Some of these attacks have been fatal.  Particularly in recent times when car and truck bombs have become relatively frequent, an unexpected boom and/or shake may cause sudden fear, which may threaten the lives of persons with known or unknown heart conditions. This is the greatest danger in most small felt earthquakes.
   When something goes boom in the night, try not to be startled. It may only be a small earthquake. Even if it is an explosion, it is over by the time you hear it.
 

By Rusty Surette, NEWS 9

OKLAHOMA CITY -- A one-page letter laced with racism and hate has shown up at a number of Oklahoma businesses.

The letter's opening line is, "Hello Fellow White Oklahomans and Christians," followed by "Oklahoma is Redneck KKK Country." The top of the page reads "White Christians' Fraternal Order."

The letter, dated April 7, is a promotion for the Ku Klux Klan and an upcoming rally at the Oklahoma State Capitol. It was sent to a number of businesses including an Edmond bank and the Black Chronicle newspaper in Oklahoma City.

Read the full letter.

The letter goes on to read, "We want to reassert white supremacy through terrorism and intimidation. We want to bring back lynching" and "we want a law passed so that Oklahoma Darkies are only allowed to come out from 9 p.m. to 12 p.m."

"It almost makes me want to vomit," said Ladonna Holmes, an Oklahoma City resident who read the letter.

The name listed on the envelope's return address is the John Birch Institute. Wisconsin-based John Birch Society said they are not responsible for the letter.

See the addressed envelope.

"We do not know who sent it. We do not approve of the letter's message and strongly denounce both the message and the individual or group involved in this disgusting and illegal activity. We have reported this to the Oklahoma City Police Department," said Bill Hahn, Public Relations Manager for The John Birch Society.

What's more puzzling, the return address on the envelope is 701 Colcord Drive, which is the address for Oklahoma City Police headquarters. Since the letter did not originate from there, according to police, investigators are now trying to track down where they came from.

"The content of these letters is very disturbing," said Oklahoma City Police Sgt. Jennifer Wardlow. "We have not been able to find any type of originating fax number to trace it to, which obviously is a problem in any kind of investigation."

Police are asking anyone who knows who is responsible for the letters to contact authorities.

The letter goes on to promote a KKK rally called "Mighty Whitie's Day" at the state Capitol. It's scheduled for later this month, but at last check, the necessary reservations for a rally at the State Capitol have not been made by any group associated with the letters.

To prove the KKK is still active in our state, the Oklahoma City-based Web site HateTrackers.com sent nine recent photos of Klansmen near Shawnee and Broken Arrow. In the photos, members of the KKK can be seen carrying the Oklahoma flag.

HateTrackers.com's Klu Klux Klan Photos in Oklahoma

The editors of HateTrackers.com, which carefully follows hate groups across America, questioned the legitimacy and source of the letters.

"It's a hoax. The United White Knights do not openly declare illegal or terrorist acts and they're now more into white separatism than white supremacy, and more likely to be raging against illegal immigrants," stated the editor of HateTrackers.com in an e-mail. "The phone number they're using [on the letter] is to the John Birch Society, which has been referred to as the White Collar KKK, but they wouldn't dare be so openly blatant about things or directly associate with the UWK. In any event, even if a bad joke, the climate out there is too tender to be getting tweaked like this."