Transcript Finding faults with LIDAR in the Puget Lowland

Seeing through the trees:
LIDAR for the Puget Lowland
Ralph Haugerud, Craig Weaver
U. S. Geological Survey
Jerry Harless
Puget Sound Regional Council
and thanks to TerraPoint LLC, Houston TX
• Why LIDAR?
• What is LIDAR?
• How are we doing LIDAR?
• What are we finding?
30 km
In some
places, it
is easy
to see
where
the
active
faults
are.
Seattle
Tacoma
30 km
In other
places,
it is not.
What are the salient differences?
SF Bay
area
Puget
Lowland
slip rate
3 cm/yr
strike slip
4 mm/yr
shortening
average tree
height
? 10 ft
? 100 ft
~106
18,000
years
years
age of
landscape
age  slip rate = feature size
18,000 yr  1 mm/yr = 18 m
106 yr  1 mm/yr = 1 km
In the Puget Lowland, to see a fault with the
same slip rate as in the SF Bay area, we have
to look more closely.
LIght Detection And Ranging
• Airborne scanning laser
rangefinder
• Differential GPS
• Inertial Navigation System
30,000 points per second at
~15 cm accuracy
• $400–$1000/mi2,
106 points/mi2, or
0.04–0.1 cents/point
Extensive filtering to remove
tree canopy (virtual deforestation)
10-meter DEM from contours
12-ft DEM from LIDAR
Picture: Oblique view of S end
Rockaway Beach
High-resolution
LIDAR topography
Uses for high-resolution topography
• Finding faults (earthquake frequency,
kinematics)
• Geologic mapping
• Landslide hazards
• Flood hazards, groundwater infiltration,
runoff modelling
• Fish habitat
• Precision forestry
? Noise propagation
Why is LIDAR better than photogrammetry?
(It’s the trees)
Suppose timber allows 1 of
3 arbitrary rays to reach
ground; 1/3 of ground can
be surveyed by LIDAR
Photogrammetry requires
2 separate views of a
point; only 1/9 of ground
will be locatable
Bainbridge
Island,
KPUD
1996-1997
Seattle
Snoqualmie,
USGS-NMD
1998-2001?
Tacoma
Puget Sound LIDAR Consortium
Participants
•Kitsap County
•Kitsap PUD
•City of Seattle
•Puget Sound
Regional Council
•NASA
•USGS
Expertise
(exclusive of USGS)
–Contracting
–Surveyor
–prior LIDAR
experience
–Geologist
–GIS
Puget Sound LIDAR Consortium
•
•
•
•
•
•
No formal structure
One agenda
One contract
Separate payments
Share data
Release all data to public domain
(www.GetItYourselfBob,
to be hosted by UW library)
PSLC
Feb 2001
March-April 2000,
Feb 2001
Seattle
Tacoma
~$3M
LIDAR
already
flown
Seattle
to be
flown
Winter
2001-2002
Tacoma
~$3.3M
15 km west of Seattle
Toe Jam Hill
fault scarp
Waterman Point
scarp
beach uplifted
during 900 AD
earthquake