Archive of Steve’s Blog
THE UNNERVING TENSION OF SILENCE
Moderate to damaging earthquakes can and have rattled every county in Wyoming. But Teton County is special. One look at a seismicity map shows that our county resides smack dab in the center of a hornets’ nest of seismic activity. www.wrds.uwyo.edu/wrds/wsgs/hazards/quakes/quake.html
A closer inspection of this map reveals something even more interesting, however. There is a narrow zone of tranquility just north of the Town of Jackson that traces the eastern edge of the Tetons. Here, there has not been a single earthquake in recorded history. In fact, in the 1990’s Professor Bob Smith (GJH member) and his team dug a trench bisecting this zone of pure quiescence. Their work “in the trenches” suggests that the Teton Fault has not been active for at least 4,800 years and perhaps as much as 7,000 years. www.wrds.uwyo.edu/wrds/wsgs/hazards/quakes/seischar/Teton.pdf (see page 15). This long period of stability – especially in a region beset with frequent earthquakes – could imply to some that the Teton Range represents an island of safety surrounded by a sea of seismic unrest.
But geologists know better. It would be a fantastic mistake to infer safety from the Teton Fault’s long period of slumber. After all, it is the silent dog that bites the hardest. And other clues offered by the landscape indicate that the Teton Fault has generated some four miles of vertical motion in a geologic blink of the eye. In truth, the Teton Fault presents an ironic and unnerving paradox. The one place in Teton County with the most motion has for all of recorded human history remained motionless, as if it is waiting for us to accrue even greater debt before it chooses to settle the score.
Knowing this, we at GJH tip our hats to all of the earth scientists within and without our organization who strive to raise public awareness and better understanding of the danger presented by the Teton Fault. This Tuesday, (June 21st) at the Teton County Library Auditorium at 6:00 pm we get to hear about the Teton Fault from University of Pittsburg and Occidental College Post-Doctorate researcher Darren Larsen. Dr. Larsen has turned his attention to the sediments at the bottom of the lakes that dot the east side of our passive-aggressive fault. These sediments constitute a new lens through which we can look back thousands of years for more discriminating information about the frequency and strength of Teton Fault earthquakes. When was the last quake? How big was it? Are we overdue for another? This is one of those subjects that touch all of us living near the fault. We hope to see many of you Tuesday.