Duncan is a small ranching community of about 700 people on the border of Arizona and New Mexico. The town has been destroyed twice by flood and once by fire. On the sweltering summer evening of June 28, 2014, the intense groundshaking of a nearby magnitude (M) 5.3 earthquake rocked Duncan. The ground shaking lasted for upwards of 30 seconds; books flew off the central library shelves; cabinet doors flew open and dishes and glassware spilled to the floor.
Following the M5.3 earthquake, the Arizona Geological Survey became a primary source of information for the people of Duncan. We issued a news release summarizing the main event and describing what people could expect over the next months in terms of the number and magnitude of aftershocks. Using social media outlets – Facebook and Twitter – we reported US Geological Survey findings of the location, time, and magnitude of aftershocks. Each facebook post included an intensity or 1“Did you feel it” map (see Fig. 2). AZGS social media became a sounding board for frequently asked questions, ranging from, what caused the earthquake, to how big will the aftershocks be and when will they end. As fast as questions appeared, we addressed them. In return people from Duncan became our eyes on the ground, reporting the onset of aftershocks.
Below are a few of the dozens of comments we received at our facebook feed. It became clear that people in Duncan frequently felt earthquakes that went unreported by the U.S. Geological Survey. (The U.S. Geological Survey reports earthquakes of 2.5 M level or greater, but the general absence of reports of events between 2.5 and 3.0 for Duncan indicate that many such events go unreported.) People expressed frustration about the felt but unreported temblors as they looked for the U.S. Geological Survey and the AZGS to validate their experience.
I think this one felt pretty strong! I felt the whole house shift! (16 Aug, TCC)
Sure is a heck of a lot of aftershocks for such a minor quake. What’s going on here? (16 Aug, FG)
Thanks for the updates MC, we really do appreciate all your posts. It may have been minor in other parts of the world but the M5.2 and following aftershocks are not common here and really shook our little community. (16 Aug, KL)
Heard it coming. Loud boom and jolt. I would of guessed it to be between 3.5 - 4.0. I live at... (17 Aug, KGC)
Yes we felt it shook the whole house! And these aftershocks are just as annoying. Is it volcanic or shifting plates? Noticed that when there is one in Oklahoma we have another too. (3 Aug, RD)
1U.S. Geological Survey Earthquake Hazards Program, 2014, USGS, "Did You Feel It?"