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International Press & MediaBriefing
Wednesday 9 February 2005
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Welcome to The United Kingdom Hydrographic Office
Dr Wyn WilliamsCE UKHO
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Introduction
Captain Ian Turner RNHydrographer of the Navy
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HMS SCOTT
Hydrographic Instruction 1123BAY OF BENGAL
EARTHQUAKE RUPTURE ZONE
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HMS Scott
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HMS SCOTT
Hydrographic Survey Vessel
Commander Steve Malcolm RN
Commanding Officer
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Outline Plan
• Why did we need the survey?• Why this ship?• Capability – Equipment and People• Operational Environment• Co-operation• Survey Results• What next?• Questions and Panel Discussion
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Why did we need the survey?
Existing Chart Data
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Channel and ridge
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Why HMS SCOTT?
Equipment and Capability
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Why HMS SCOTT?
Personnel
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Co-operation
• Government Agencies (FCO, MoD)• Military, Scientific and Academic
institutions (RN, BGS and SOC)• Indonesian authorities
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Results
• Background to the December 26 earthquake– Plate tectonic setting and structure of
subduction zones– Seismology– Tsunami generation and observations
• General survey plan, area covered and overview of results so far
• Active tectonic features• Active erosion/sedimentary features
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Why did it happen?• Indian plate is
being subducted beneath Eurasia / Burma plate
• Rate 50-60mm/yr but very oblique
• Two large earthquakes during C19th further to south (Figure from studies by Kerry Sieh, CalTech)
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Generic subduction zone cross section
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Earthquake-generated tsunamis
• Seafloor deformed by earthquake
• Wave initiated with small amplitude and high speed in deep water
• Speed decreases and amplitude increases in shallow water
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Survey Area
Position of maximummovement
Position of Epicentre
TTW BASELINE
Secondary SurveyArea from HI
Primary SurveyArea from HI
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Lines Run
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OVERLAY OF DATA COLLECTED
AND CURRENT CHART
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Examples of Landslide Scars
Length of image approx. 25km
Slide Scar Complex
Canyon leading on to abyssal plain
Slide Scar
Processed by Caris
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Slide Scars and Thrust Faults
(Approx. 40km across)
Plate boundary
Slide scar propagating southwards
Ridges from thrust faulting
Canyon
Processed by Caris
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Plate Boundary
Accretionary wedge Plate Boundary
Abyssal Plain
Slide Blocks
Evidence of slope failure
Processed by Caris
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Youthful Slide with Slide Blocks
Youthful Slide Scar
Slide Blocks
Slide Scar
Abyssal Plain
CanyonYouthful Slide Scar
Slide Blocks
Slide Scar
Abyssal Plain
Canyon
Processed by Caris
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Example of Slide Scar
Abyssal Plain
Slide Scar
Canyon
Mature slide scar areawith cross cutting canyons
Processed by Caris
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Diversion of Canyon
Canyon
Abyssal Plain
Ridge causing diversion of canyonas it is forcedupwardsProcessed by Caris
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Area of Active ErosionSlide scars
Canyons
Processed by Caris
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Older slide on newer ridge
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Large bedforms
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Thank you
Questions?
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HMS ScottHMS SCOTTHMS SCOTT