Michael Hopkins' research at Volcanic Tableland

Michael Hopkins research work took him to an area located in east central California on what is known as the Volcanic Tableland.  The Volcanic Tableland is upper surface of a volcanic rock which was formed after an eruption ~760,000 years ago.  Since the Tableland formed, a population of north-south trending normal faults and an extensive fluvial network (presently inactive) became established on the surface. 

volcanic tableland

Research site:  Incised ramp channel looking upstream, Volcanic Tableland.

The focus of Michael's research is to understand how bedrock channels are responding to the evolution of normal faults.  As fault segments grow through time, they may interact with one another and eventually link to form a single fault.  Prior to linkage, two interacting faults may experience acceleration in their displacement rate but the exact timing of the acceleration and how it affects the relay ramp surface (the areas between the faults) remains poorly constrained.

In his previous field season he collected data at three sites that are in different stages of fault linkage.  His field work consisted of mapping, via GPS, the ramp channels and faults.  The data he has analyzed so far has shown that in the earliest stages (even before complete linkage) the ramp channels have responded to accelerated displacement.  We see changes in channel slope, width and depth that seem to suggest the landscape responds very early in the fault linkage process. 

Grad student, Heather Hoey, taking a break at a knickpoint, Volcanic Tableland.

Grad student, Heather Hoey, taking a break at a knickpoint, Volcanic Tableland.

In June of 2012, Michael travelled with field assistant Heather Hoey to the Tableland to finish data collection for his thesis research.  His goal for this trip was to acquire an additional field site to complement previous data and collect new data on rock strength.    Because changes in channel morphology (slope, width, depth) may be driven by factors other than tectonics, he collected measurements of rock strength near knickpoints (waterfalls).  The goal of this is to demonstrate that changes in rock strength are not driving knickpoint generation. 

This field season lasted two weeks and (unfortunately) is the final trip Michael plans on making to the Tableland.  The area of California where his study sites are located is between the White Mts. and Sierra Nevada.  He and his field assistant camped just west of the town of Bishop, CA which offers awesome views of the Sierra and Whites.  While working in the desert has its drawbacks (it got to the upper 90s a few days) it was nice to get out of the humidity for a few weeks!  Other than work, Heather and Michael took a day off here and there to do some sightseeing.  Some of the things they did:  they visited the Bristlecone pines (the world's oldest living trees), they took day trips into the mountains, and they did some exploring near Long Valley Caldera.  All and all, it was a great field season!    

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