ST. GEORGE – Theories are plentiful regarding what may be generating recurring loud booms that have been shaking buildings and rattling windows over the past week or so in Southern Utah, but the most likely explanation is training exercises at Nellis Air Force Base in Nevada.
The University of Utah seismology station at Zion National Park detected considerable activity Thursday between about 11 a.m. and 1 p.m., as pictured in the image accompanying this report. The activity shown is not an earthquake, research seismologist Katherine Whidden said. Similar bursts of activity appear on the seismology graphs for recent days.
“We see a signal on the seismic station at Zion National Park,” Whidden said, “but we don’t know what it is.”
From Nov. 7-21, Nellis is conducting Green Flag-West training exercises, according to its website, in which aircraft and crews fly from Nellis AFB, Nevada, in support of ground combat training at Fort Irwin in Barstow, California.
Green Flag-West is a realistic air-land integration combat training exercise involving the air forces of the United States and its allies and is primarily conducted in conjunction with U.S. Army Combat Training Center exercises at Ft. Irwin, California. It is a Close Air Support and Joint exercise administered by the US Air Force Air Warfare Center and Nellis AFB through the 549th Combat Training Squadron.
Although officials contacted at the Air Force Base have not confirmed that the booms experienced in Southern Utah are generated from Nellis, it seems the most likely explanation.
If you actually look at the huge geographic footprint in which those explosions are being heard, Washington County Administrator Dean Cox said, there’s only one explanation in his mind, and that’s sonic booms from Nellis.
“… it’s the only thing that could cover that kind of a footprint, geographically,” Cox said. “I’ve been a pilot for 40 years, and I’m confident that it’s a sonic boom.”
A Green Flag exercise described in a 2012 fact sheet release issued by Nellis Air Force Base gives an idea of what the exercises underway may involve. It stated:
A typical Green Flag exercise involves two multi-role fighter and/or bomber squadrons (F-15Es, F-16s, F/A-18s, A-10s, B-1s, B-52s, etc.), unmanned aircraft (MQ-1, MQ-9, Shadow, Raven), electronic warfare aircraft (EC-130s, EP-3s), and aerial refueling aircraft (KC-130s, KC-135s, and KC-10s). Additionally, USAF command and control assets consisting of E-3 Airborne Warning and Control System (AWACS) and the E-8C Joint Stars (JSTARS) play a significant role in the exercise by using their unique capabilities to monitor and support many aspects of both air and ground force maneuvers.
During exercise execution, Green Flag staff members direct, monitor, and instruct visiting units in the conduct of air operations in support of ground forces. To aid in this endeavor, the 549th CTS maintains a cadre of current and qualified air-to-ground experts who fly with visiting squadrons during most exercises. When not actively flying in the exercises, the same cadre provide exercise oversight and ensure the highest level of integration between air and ground forces.
Key to the GFW staff’s oversight of the exercise is the Individual Combat Aircrew Display Systems. ICADS is the world’s most sophisticated tracking system for combat training exercises and allows commanders, safety observers, and exercise directors to monitor the mission in real-time.
On average, all four military services, including the guard and reserve components, participate in two Green Flag exercises each year. Air forces of other countries participate in one or more designated coalition exercises annually. Green Flag exercises provide critical joint training for approximately 75,000 joint and coalition personnel per year, including 3,000 sorties, 6,000 flight hours, and the expenditure of over 700,000 pounds of live and training ordnance.
During Red Flag Exercises at Nellis in 2012, 125 aircraft were scheduled to depart Nellis twice a day for high-intensity air-to-air combat exercises, resulting in bursts of booms and disturbances felt in Southern Utah during those take-off periods. Similar disturbances are experienced during other exercises.
St. George News contacted Cedar City Corporation – they weren’t aware of anything on their part.
Forthcoming Green Flag Exercises at Nellis in 2015 are scheduled as follows: Jan. 18-Feb. 1; Feb. 20 to March 6; March 20 to April 3; April 24 to May 8; May 29 to June 12; July 17-31; Aug. 14-26; Sept. 11-25
Red Flag Exercises, high-intensity air-to-air combat exercises, are next scheduled to run in 2015 from Jan. 26-Feb. 13; March 2-13; July 13-31; and Aug. 17-28.
Minimal blasting has occurred in the St. George Area recently but is not likely to account for the notable booms that have been heard, Air Quality Manager Bill Swensen said. The only blasting permit out right now, Cox said, is for the area out by the landfill, and no calls have been made from the unincorporated areas dispatch, as required, for blasting.
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