An Overview
Academic Affiliation: Colorado School of Mines
Biography
Jenna grew up in Lakewood, Colorado. She currently attends the Colorado School of Mines in Golden, Colorado, studying Geological Engineering. Living in Colorado and being surrounded by some of the most amazing geology in the country sparked her interest in Earth Science. Most of all, the interest came from from seeing minerals in gem shops. She says, “They were all so beautiful and different and I loved them and needed to learn more about them.” When not studying, she enjoys snowboarding and spending time with friends and family.
Abstract
Measurements of possible seiches in Lake Yellowstone
On July 12th 2009, a large and persistent signal was detected on a borehole strainmeter in Grant Village in Lake Yellowstone. A significant wind event and fluctuations in the discharge rate at the Yellowstone River outlet occurring concurrently suggest that the signal was caused by a seiche (a harmonic wave in an enclosed water body). Using Merian’s formula and the dimensions of the West Thumb Basin, the waves’ period was calculated to be 11.2-13.0 minutes. This correlation indicates a concurrent event is occurring in the lake and the river outlet, but it cannot verify a seiche. Some information suggested that the signal wasn’t a seiche. Crustal strain modeling, with a static non-gravitational model, indicates that to create strain such as what was observed at Grant Village, the amplitude of the seiche would have to be 1-5 meters. That is the amplitude of a tsunami, not a common seiche. Also, the wave continued for an uncharacteristically long time for a seiche- up to hundreds of cycles indicating a high Q factor (a dimensionless quantity describing loss of en- ergy compared to stored energy). Normal seiches only oscillate for about 5-6 cycles; exhibiting a low Q fac- tor. Because wind is a typical seiche forcing mechanism, wind data was analyzed and compared with strain data for June 2011. Data from the Yellowstone river outlet was also plotted searching for fluctuations at the same time there is a “seiche” signal detected on strainmeters. To verify a seiche, water level fluctuations were measured using a pressure sensor in mid-August 2011. Preliminary measurements of water levels indicate a 2cm wave with a period of 11.0 minutes.This correlation between water levels, windspeed, river discharge, and the strain strongly support a seiche as the primary source of the strain signal.