Texas isn’t exactly known for its earthquakes. That’s not to say they don’t happen here. On the contrary, one or more earthquakes are measured somewhere in the state nearly every day. Most are negligible, however, and many occur without being felt.
Yet the past 36 hours have been rather surprising when it comes to earthquakes. That’s because we’ve had eight occur within the DFW metroplex. (The USGS has the scoop.)
Don’t get too excited, though. The strongest was a 3.0. It set off a few car alarms and shook the ground a bit, but its effects were no more noticeable than a heavy truck rumbling through the neighborhood. There will be no national coverage of collapsed highways or buildings turned to rubble.
As for the other seven temblors, they ranged from 2.5 to 2.9 on the Richter scale. More than 16 recorded geological events (earthquakes plus aftershocks) have been measured in DFW since 11:30 PM CDT Thursday night when this all began.
All of the epicenters have been in the same general vicinity (western Dallas county). That obviously begs the question of why so much activity has occurred in such a short time where no earthquake has been measured before. Prior to this volley, the closest earthquake was recorded in March 1950, a 3.3 in Valley View about 70 km northwest of Fort Worth (one in 1985 and another in 1997 were even further away).
In truth, the best explanation comes from the USGS with regards to earthquakes east of the Rocky Mountains:
At well-studied plate boundaries like the San Andreas fault system in California, often scientists can determine the name of the specific fault that is responsible for an earthquake. In contrast, east of the Rocky Mountains this is rarely the case. All parts of this vast region are far from the nearest plate boundaries, which, for the U.S., are to the east in the center of the Atlantic Ocean, to the south in the Caribbean Sea, and to the west in California and offshore from Washington and Oregon. The region is laced with known faults but numerous smaller or deeply buried faults remain undetected. Even most of the known faults are poorly located at earthquake depths. Accordingly, few earthquakes east of the Rockies can be linked to named faults. It is difficult to determine if a known fault is still active and could slip and cause an earthquake. In most areas east of the Rockies, the best guide to earthquake hazards is the earthquakes themselves.
All in all, this apparent swarm of earthquakes probably means little. An unknown fault—or even a known one—likely is catching its breath after a very long period of dormancy. Despite the lack of any real threat, this has offered up an unusual kind of excitement in an area where earthquakes are always spoken of in terms of happening someplace else. To experience eight of them in less than two days, all of them centered right in the heart of the metroplex, gives us something new to talk about besides the terribly boring weather we’ve been having.