It was quiet, but there was rocking and shaking. It “sounded like a freight train” and unsecured objects fell from shelves. The descriptions of a 5.2 magnitude earthquake that struck Greenlee County Saturday night, June 28, depended on where a person’s home was located.
The quake was most strongly felt in Duncan, about 10 miles from the earthquake’s epicenter. About 20 miles north of Duncan, residents of York Valley, particularly those living in trailer parks, also felt the quake as it caused some trailer homes to shake and rock, but otherwise it was quiet. The same occurred in Clifton and Morenci, where it was quiet and houses shook, but less so than in York.
The quake, which lasted from 30-45 seconds, struck at about 10 p.m. Its epicenter was in a rock hounding area in uninhabited desert terrain near the Lazy B Ranch, which straddles the Arizona-New Mexico border. A 5.2 quake, as measured on the Richter scale, which measures the intensity of earthquakes from 1 to 9, is considered as “moderate” and approaching “strong.” An earthquake with a magnitude greater than 4.5 can cause damage to building and other structures.
For Richard and Colleen Lunt, who live between Duncan and Virden, N.M., which is only three miles from Duncan, the noise created by the earthquake was almost overwhelming. “It sounded like a freight train,” Richard Lunt said. “Everything started shaking and we started wondering what in the world was going on. It was frightening. Everything was suddenly shaking – the whole house, everything.”
He added, “No doubt the whole thing caught everybody by surprise. I’ve lived here almost all of my life and the possibility of an earthquake never entered my mind.”
Deborah Mendelsohn, owner of the Simpson Hotel in Duncan, said she immediately knew an earthquake had occurred. She previously lived in earthquake-prone San Francisco. Mendelsohn said her building shook noticeably during the quake.
Glass pitchers on a shelf in her kitchen fell to the floor and broke. Framed photos and art work on the walls hung crookedly. With her knowledge of earthquakes, she immediately ran from the building and out into the street. She did not have any guests when the quake hit.
Although the two-story hotel is a solid brick building, such structures are quite vulnerable to collapse during an earthquake, she said, referring to the knowledge and experience she gained living in San Francisco and other parts of California vulnerable to quakes.
She immediately began checking her building for any structural damage. Lunt, who is a member of the Church of Jesus Christ of Latter-Day Saints, said the large, one-story brick structure in Duncan known as the Duncan Stake Center, is being checked for structural damage. A source erroneously told The Copper Era that the church’s steeple had collapsed.
Ernest Mares, who lives at the 4-Bar trailer park in York Valley about 20 miles north of Duncan, said his trailer house actually began rocking during the quake. Electricity went off for a short period. When it came back on, lights in his home flickered. The same reportedly occurred in the nearby Valley View trailer park.
Mares said there was no sound as his home shook. “It felt pretty strong – enough to rock our trailer,” he said. “But it was quiet. It was nothing like the occasional sonic boom caused by a jet that can rattle windows.”
The quake was far milder in Clifton in central Greenlee, 32 miles north of Duncan. Most Clifton residents with whom The Copper Era spoke said they barely felt some mild trembling of their homes and that was about all. The movement left most wondering what had just happened.
Homes in Morenci a copper mining town situated about 1,000 feet above Clifton, were also shaken by the quake, but as in Clifton, the tremor did not cause objects to fall from shelves. Morenci resident Kelly Baker said she was watching television when “all of a sudden the house rattled and shook.” Baker’s home is made of brick.
There were aftershocks from the quake. Bake reported that at least one occurred in Morenci. Mares also said there were aftershocks in York. Lunt said he felt three aftershocks. One came shortly after the quake and the other two occurred at 1:30 and 7:30 Sunday morning.
The Greenlee County Sheriff’s Office and Clifton Police Department dispatch centers were inundated by calls from people reporting the quake or asking what had happened. A sheriff’s dispatcher said there had been reports of damage to a few homes or other structures in southern Greenlee. However, specifics about damages or exactly where they occurred were not immediately known.
Duncan is located about three miles from the Arizona-New Mexico state line. A U.S. Geological Survey report listed the quake as having occurred about 31 miles from Lordsburg, N.M., and did not mention Duncan, which is about 35 miles from Lordsburg. Some television news stations in Tucson and Phoenix described the quake as having occurred near Lordsburg. National news network MSNBC reported the earthquake’s epicenter was near “the tiny town of Duncan…”.
Earthquakes, also known as a quake, tremor or temblor, result from a sudden release of energy in the earth’s crust that causes seismic waves. They are most often caused by the rupture of geological faults, volcanic activity or landslides.
The Duncan quake’s epicenter was on fairly flat desert terrain, thus eliminating the possibility of a landslide. The closest known underground volcanic activity is in the immediate Clifton area. There are natural hot springs along the banks of the San Francisco River, which runs through Clifton. The hot springs are created by magma, which is molten rock bubbling beneath the earth’s surface. Subsurface water is heated by the magma and then surfaces as hot springs.
That appears to leave only a shift or rupture in a geological fault as the probable cause of the Duncan earthquake.
Earthquakes have occurred fairly recently in Greenlee County. A cluster of quakes occurred in northeastern Greenlee about two years ago. They were considered to be mild, with magnitudes ranging from about 3 to 4. That area is uninhabited and is part of the Apache National Forest.
A fault line exists in the giant Freeport McMoRan Morenci mine, the largest operating open pit copper mine in North America. When the mild quakes occurred in Greenlee, The Copper Era was told by an FMI spokesman that the fault in the mine is dormant and presents no danger whatsoever.