Experimental Tectonics: Quantifying Models and Lab Techniques

"RECIPE" TO BUILD UP A LAB MODEL

1. identification of the problem to study
2. application of the similarity criteria
3. determining materials that satisfy the similarity criteria
4. running of models
5. ensure repeatability
6. interpretation of obtained results
7. definition of a theory

WHY DO WE NEED IMAGES OF THE MODEL EVOLUTION?

• RECORDING
• QUANTIFICATION

"I drink coffee every day"

Qualitative Descriptive information

K Data

7 Discrete (Counted)

"I drink 4 coffees every day"

Quantitative Numerical information

7 Continuous (Measured)

P 80g "I drink 80grs of coffee every day"

• geometry
• kinematics & deformations
• temperature

OPERATOR TOOLS

CAMERAS

VIDEO CAMERAS HD ::::::: Xacti CCD (charge-coupled-device) VIDEO CAMERAS

3D LASER SCANNER

X RAY SCANNER

D (modified after Schreurs et al., 2003) Helical X-ray CT scanner Experimental box

KINETIC MICROSOFT

SEISMIC REFLECTION TECHNIQUES

KINECT (modified after Sherlock et al., 1996)

TECHNIQUES: TEATR

Available tools Experimental goal Analogue material

SELECTED METHODS

Surface view -> Earth's surface. Side views (transparent sidewalls) > model evolution at depth (might not necessarily reflect the geometry and processes occurring towards the center of the model) Bottom view -> processes occurring at depth Oblique views > to better visualize (qualitatively) specific views or by using stereoscopic techniques

THE EASIEST TOOL: GRAPHIC DESIGN SOFTWARES

(Adobe Illustrator, FreeHand, Corel Draw, .... ) ADOBE ILLUSTRATOR CS4 ADOBE ILLUSTRATOR CS4 Ai Adobe Adobe https://www.youtube.com/watch?v=IJN4GFP rHI

TECHNIQUES FOR SAND /SILICONES: Analyzing Displacement Field

"Manual" techniques using passive marker printed on the model surface

(> it provides kinematic data with a resolution around 0.5-2 cm, depending on the size of the markers, the quality of the photographs and the time available for carrying the study. The accuracy of the measurement is about that of the photograph pixel, which is about few mm

A B 0 (modified after Davy & Cobbold, 1991) 1 t S (modified after Davy & Cobbold, 1991) D ! P (modified after Martinod & Davy, 1994) (modified after Marques & Cobbold, 2002) Gravelau et al., 2012

DIGITAL IMAGE CORRELATION: WHAT IS IT?

It means reconstruct 3-D digital models of objects from a collection of images. The concept of reconstructing topography or depth using pairs of images was first introduced by photographers and engineers in the middle eighteenth century (the word photogrammetry was first used by Meydenbauer,1867); however, it was the automation of the process through what is known as Structure from Motion (SfM) that made it so popular in a wide range of applications.

TECHNIQUES FOR SAND /SILICONES: Analyzing Displacement Field with Digital Methods

"Manual" techniques using passive marker printed on the model surface

(> it provides kinematic data with a resolution around 0.5-2 cm, depending on the size of the markers, the quality of the photographs and the time available for carrying the study. The accuracy of the measurement is about that of the photograph pixel, which is about few mm

Digital technique: Particle Image Velocimetry

(or Particle Tracking Velocimetry or Feature Tracking)

A B C U 1 t S (modified after Davy & Cobbold, 1991) D (modified after Martinod & Davy, 1994) (modified after Marques & Cobbold, 2002) E F Successive pictures Displacement field Picture A A B Picture B ...... Correlation window Interrogation Window + (t+dt) Displacement vector . dy dx Correlation map (modified after Hoth, 2005) G Z axis X axis mm 1,5 15 1 1 0,5 0.5 0 [modified after Graveleau et al., 2008) DIGITAL IMAGE CORRELATION (-> Structure from Motion) Gravelau et al., 2012

Digital technique: Optical flow

20 cm A B A Horizontal displacement profiles Y axis (modified after Adam et al., 2005) Peak search · . Interrogation Window (t) Cross correlation (modified after Davy & Cobbold, 1991)

TECHNIQUES FOR SAND /SILICONES: Analyzing Displacement Field and Optical Distortions

"Manual" techniques using passive marker printed on the model surface

(> it provides kinematic data with a resolution around 0.5-2 cm, depending on the size of the markers, the quality of the photographs and the time available for carrying the study. The accuracy of the measurement is about that of the photograph pixel, which is about few mm

Digital technique: Particle Image Velocimetry

(or Particle Tracking Velocimetry or Feature Tracking)

A B C U 1 t S (modified after Davy & Cobbold, 1991) D (modified after Martinod & Davy, 1994) (modified after Marques & Cobbold, 2002) E Interrogation Window (t) · spatial resolution: camera resolution (and tracers' distribution for PIV) Interrogation Window + (t+dt) . . . time resolution: frame rate G WATCH OUT: OPTICAL DISTORSIONS (especially when subvertical features are involved)! -X-axis A Horizontal displacement profiles B ,5 1.5 mm - 1 0,5 0,5 Y axis 0 (modified after Adam et al., 2005) (modified after Graveleau et al., 2008) DIGITAL IMAGE CORRELATION (-> Structure from Motion) Gravelau et al., 2012

Digital technique: Optical flow

A B (modified after Davy & Cobbold, 1991) XBLY

TECHNIQUES FOR SAND /SILICONE: Analyzing Displacement Field & Topography with MicMac

MicMac (Multi Images Correspondances par Méthodes Automatiques de Corrélation Photogrammetric Open-Source Package) automatic photogrammetry Structure from Motion principle

STEP 1: FINDING TIE POINTS

Set of photographs of the same object taken from different viewpoints. A computer vision spatial resolution: camera resolution (<0.1mm out of a 40 x 40 cm2 box for a camera resolution of 24 MP) ature" points in It viewpoints lat are ht viewpoints, ns in the

ADVANTAGES

• relatively low cost;
• high-resolution and high-precision results
• measurements of topography and horizontal displacements,
• ease of setup in the laboratory (no lengthy calibration procedure)

STEP 2: DEFINING THE 3D MODEL

The SfM algorithm uses the different positions of the homologous feature points in the images to reconstruct the model of the photographed object using image correlation. Galland et al., 2015 https://www.youtube.com/watch?v=i7ierVkXYa8

TECHNIQUES FOR SAND /SILICONE: Analyzing Topography

Laser Scanner

B spatial resolution: few mm point grid h (mm) Laser scanner 20 - . 15 10 5 20 150 250- 200 150 100- 8 26 25 -24 23 21 20 19 18 17 16 15 14 13 12 11 10 9876543210 C (modified after Fischer & Keating, 2005) Elevation (mm) (modified after Nilforoushan et al., 2008)

Stereo photogrammetry

(science of making measurements from photographs) spatial resolution: 0.5 mm

Fringe Projection Technique

Phase shifted laser fringes Amplitude 0[ 255 Wrapped interferogram Phase 0 211 Digital Elevation Model (DEM) Elevation 0 17 mm (modified after Graveleau et al., 2008} (project a b/w pattern on the surface to be measured) https://www.youtube.com/watch?v=vMnazVZdhWI Gravelau et al., 2012 spatial resolution: 0.5 mm Control points 22

TECHNIQUES FOR SAND: Analyzing Topography with Microsoft Kinect

Microsoft Kinetc for Xbox360 videogame system USB-input motion capture device consisting of: - a visible (RGB) and infrared (IR) camera; - refractor and light emitter; - three-axis accelerometer; - four microphones. The Kinect emits a known pattern of IR dots and, by correlation and triangulation of the return signal recorded by the IR camera with a reference pattern stored in the sensor's memory, a distance image is derived spatial resolution: 1 mm Cheap and continous acquisition

Invisible 1 . Light Source illuminates Subject 00 3. Unique Embedded Imaging Software uses "depth map" to perceive & identify objects in real time 2. Sensor Chip measures distance light travels, to each pixel within the chip -Kinect 50 cm Box filled with calibrated sand reproducing the substratum Analogue volcanic cone Computer 25 cm 39 cm 39 cm Water supply Analogue magma chambers (rubber balloons) Manometers Deflation Inflation Inflation-Deflation (A) G N (B) ~~~ Volcano base (C) Caldera rim Faults DoD (mm) 0 10 A A' -18 mm 5 cm +9 mm B Tortini et al., 2014 4. End-user device reacts appropriately

TECHNIQUES FOR SAND: Analyzing Internal Structure

Serial cross sections along strike

A Deformation front Viscous coupling 3 cm Frictional coupling (modified after Cotton & Koyi, 2000) Décollement surface Oblique basement ramp Glass microbead décollemerk modified after Jonstartingvskaya et al., 2009) digitising serial cross sections cut at the end of the experiment, then surfaced using a 3-D geomodelling software (here, GoCad®)

X-ray computed Tomography scanner

X-Ray Source 360° rotation Rotor Model Bec Detectors Stator (modified after Colletta et al., 1991) G - (modified after Sherlock irt al. 119961

Seismic-reflection technique applied to a sandbox model

Gravelau et al., 2012

TECHNIQUES FOR SYRUPS: Analyzing Patterns

Dye

Laudenbach and Christensen, 2001 Griffiths, 1986 Weijermars, 1988

Shadowgraph

Mirror Light source Collimating lens Camera Beam splitter Frosted screen Experimental cell Jaupart and Brandeis, 1986

• Refractive index of a fluid depends on temperature and composition
• Convective features in a transparent medium will alter the refractive index distribution,
• From the deformation of the optical wave front, one can therefore deduce information on the refractive index, hence on the temperature or compositional field.

TECHNIQUES FOR SYRUPS: Analyzing Patterns (Video Examples)

https://www.youtube.com/watch?v=pIf5MQBLZS0&list=PLTUXt5H9iEO9ILpl63zqVSwR56CVD9n3E https://www.youtube.com/watch?v=0Tp0zB904Mc https://www.youtube.com/watch?v=3-KnjJ4S7Jo

TECHNIQUES FOR SYRUPS: Analyzing Patterns/Velocity Field

https://www.youtube.com/watch?v=dMWUaxkeEkI Courtesy Funiciello

TECHNIQUES FOR SYRUPS: Analyzing Temperature

Thermometer

975 TaUP .... CE 76.7 Checkten+ 1 232 Chuckling's

Thermocouples

variation with temperature linked to the electrical resistance of two metals

Thermistors

made from metal oxides whose resistance decreases with increasing T

Deflection of a light beam

(a) He-Ne laser Lens Lens Screen Oscillating mirror f f Experimental cell Davaille and Limare, 2007

Interferometry

(a) Test area Beam splitter 2 Mirror 2 Screen Beam splitter 1 Mirror 1 Davaille and Limare, 2007 Shlien and Boxman, 1981

Thermochromic liquid crystals

Courtesy Davaille