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Towards a Transparent Earth. S.D. Glaser, UC, Berkeley W. Roggenthen , SDSMT L.R. Johnson, E.L. Majer , LBNL. Install an acoustic “microscope” surrounding the Homestake workings – 1 st NSF funded DUSEL research. signal. Deep is Quiet, and Quiet is Good. noise.

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slide2

Towards a Transparent Earth

S.D. Glaser, UC, Berkeley

W. Roggenthen, SDSMT

L.R. Johnson, E.L. Majer, LBNL

Install an acoustic “microscope” surrounding the Homestake workings – 1st NSF funded DUSEL research

signal

Deep is Quiet, and Quiet is Good

noise

  • Develop deep in-situ seismic observatory for rapid imaging of dynamical geo-processes at depth.
  • Provide rock mass dynamics and safety information to miners and tunnelers
  • Provide an infrastructure for all earth scientists
  • Improve ability to detect and characterize underground structures and activity
slide3

Seismic Imaging of Subsurface Stress

    • The time-varying stress field at depth is perhaps the most crucial parameter for understanding the earthquake triggering process.
  • The Speed of Seismic Waves is a Measures of Stress in Rocks. This holds at seismogenic depth and can be used as a “stress meter”.

Why at Homestake?

Stress changes at seismogenic depth could be more difficult to observe with conventional surface instruments.

Temperature variation at surface is a large noise source in the electronics.

Deep observation could avoid surface environmental effects, such as precipitation.

Need a deep natural experiment site that bridges laboratory study and large scale seismic experiment.

FenglinNiu Rice University

P. G. Silver, Carnegie Institution of Washington

T. Daley, Lawrence Berkeley National Lab

erik c westman virginia tech

TOMOGRAPHIC IMAGING OF STRESS-REDISTRIBUTION FOR PREDICTION OF CATASTROPHIC ROCK MASS FAILURE

Stress concentration prior to pillar failure caused by slip along a discontinuity or by overburden stress (in a solid rock mass)

Multiple pillars (of differing dimension) constructed at multiple depths; may include discontinuities

Seismic tomography used to image stress-induced density contrasts within rock mass, allowing stress level to be determined and failure projected

Catastrophic failure extends to all aspects of rock mechanics including tunnels, mines, rock slopes, earthquakes, waste repositories, and bridge and dam abutments

Accomplishing the ultimate goal of predicting these catastrophic failures will result in significantly reduced fatalities, lowered construction costs, and increased environmental protection.

Erik C. Westman , Virginia Tech

Rock failures are associated with the redistribution and concentration of stresses from mine excavations

To predict rock failure, monitor the redistribution of stresses within the rock.

Use tomograms of seismic stress field toimage redistribution of stress

Shown clearly in the laboratory but limited testing at the field scale.

This experiment will enhance miner’s life safety

This experiment will put the method of imaging stress-induced changes within rock masses on a sound theoretical and practical basis. Itrequires a DUSEL, as deep, long-term, dedicated access is not available at current underground tests sites.

fracto em emissions in rocks

Conduction Modulation

Charge acceleration

Piezoelectricity

Mech. wave

=0

EM-wave

Microseismicity sensor network

ü

E

Antennae network

VA

P

P=0

+ + + + +

B

- - - - - -

VB

Fracture current

Fracture-Atm. Interaction

Charge separation

F

F

EM emissions

E(t)

EM emission

t

i(t)

Fracto-emission generating fault

Diffusion of electrically neutral gas

F

F

Fracto-EM Emissions in Rocks

Dante Fratta, University of Wisconsin-Madison

DUSEL provides unique research opportunity for the development of a new engineering monitoring system based on the complementary interpretation of microseismic and EM emissions in a quiet electrical environment – Homestake mine

slide6

Geoinformation processing of multi‐dimensional spatial

monitoring data

Christian D. Klose, Columbia University

Monitoring the Earth\'s system

from a global perspective.

Geophysical Data

Classify multi-dimensional and complex data

Geological Data

Interpret & Predict

in areas of interest

- zones of weakness

- seismic events

- zones of fluid migrations

Applied data interpretation methods are based on Artificial Intelligence

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