GeoNotes

The largest earthquake to occur within Texas since humans have been quantifying their magnitude occurred 7.5 miles southwest of Valentine on August 16, 1931, around 5:30 a.m. CST — 90 years ago. It resulted from movement on a northwest trending normal fault at a depth around 10 km (6.2 miles). Other researchers believe the epicenter was slightly northwest of Valentine.

The Richter scale magnitude was estimated at 5.8-6.0. Keep in mind that the Richter scale is logarithmic, so a 6.0 is 10 times stronger than a 5.0. (in shaking or wave amplitude). The wave amplitude is the distance that the ground moves from at rest to the crest of a wave passing through. Some of you GeoNote readers experienced the 5.5 quake in the Alpine area in 1995 as a comparison. I’m envious. I’ve never been in an earthquake large enough for me to feel. Most of our West Texas (Basin and Range extension like Valentine or oil field brine injection induced like around Pecos) quakes are 3.5 or smaller in magnitude.

The 6.0 quake in the Southern Pacific crew change division point and ranching town of Valentine would have felt fairly violent, and it would have been difficult to stand up.

The contents of houses were scattered around, dishes broken. Chimneys were cracked and fell. Adobe buildings were damaged. The Valentine school chimney was destroyed and the school had to be rebuilt. Many concrete structures were damaged. Fault lines opened on the east side of town. I was able to locate one living survivor of the earthquake 90 years ago who remembers the dust falling from the adobe walls of her home.

The Alpine Avalanche of Friday, August 21, 1931, published a story on the front page above the fold. It reported one death as a result of Texas’ largest earthquake. Pasqual Luchuga, an underground miner in the Study Butte quicksilver district, was killed in a roof fall that was attributed to tunnel damage from the earth tremors. The quake was definitely the talk of the region that week.

The quake was felt in many places such as Study Butte — as noted above — Ft. Davis, Pecos, Marfa, Alpine and Marathon. Tremors were reported in Dallas, 500 miles to the northeast. They were also felt in Ciudad Chihuahua 175 miles to the southwest, although no significant damage occurred there. The waves propagated further to the east and northeast across the relatively flat lying geological strata in that direction. Seismic energies were disrupted by the many basins, ranges and faults of the Cordillera to the west.

The 1930 U.S. Census required by our Constitution reported 630 people living in Valentine, which was about as large as the town ever got. Perhaps the earthquake scared a few away? Valentine is the only incorporated town in Jeff Davis County (named by the Texas legislature in 1887, 17 years after Texas was readmitted to the Union) and sits almost on the southern county line. The epicenter of the quake was probably barely over the line in northwest Presidio County, 7.5 miles southwest of Valentine.

As with any human-experienced natural event, there were exaggerations and tall tales resulting from the 1931 Valentine earthquake. My favorite was from the Pecos newspaper. A local gentleman had supposedly volunteered to supply all the Pecos cantaloupes needed for a large barbecue to be held somewhere in West Texas. He welched on his commitment by reporting that when he and his large truck reached Pecos, all the cantaloupe had been killed by the seismic disturbances. No report of what they had for dessert instead…

Many thanks to Melleta Rogers Bell, recently retired from 35-plus years of faithful service at the Archives of the Big Bend, for her compilation of historical sources regarding the 1931 Valentine earthquake.

The Valentine, Texas Earthquake, Sellards, E.H., University of Texas Bulletin No 3201, Feb 1933.

The 16 August 1931 Valentine, Texas, Earthquake:Evidence for Normal Faulting in West Texas; Doser, D.I., (UTEP), Bulletin of the Seismological Society of America, December 1987.