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Basic principles of lidar data acquisition. The location and motion of the aircraft is tracked to produce the lidar point cloud of x, y, z locations (from Maune, 2001).
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Over 300 active faults intersect the Earth's surface in the Houston
Metropolitan area. These surface faults have caused damage to roads,
pipelines and buildings. Most of the faults form part of a regional down
to the basin fault system along the northern coast of the Gulf of
Mexico. In this study four kinds of information were used to improve
chara...
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Three big rivers of the eastern Himalayas namely, the Lohit, the Dibang, and the Siang confluence in the extreme NE part of India to form the Brahmaputra River. A 240 km long stretch of the Brahmaputra River extending from its 1915 confluence point at Kobo to the end part of the old Majuli Island in the downstream direction was divided into three u...
Citations
... There are three sets of LiDAR data for Houston: 1996, 2001, and 2008. The 1996and 2001 The polygon technique used by Khan et al. (2013) was employed to examine changes between the centers of the salt dome relative to its surrounding areas. ...
Subsidence has been affecting many cities around the world, such as Nagoya (Japan), Venice (Italy), San Joaquin Valley and Long Beach (California), and Houston (Texas). This phenomenon can be caused by natural processes and/or human activities, including but not limited to carbonate dissolution, extraction of material from mines, soil compaction, and fluid withdrawal. Surface deformation has been an ongoing problem in the Houston Metropolitan area because of the city’s location in a passive margin where faulting and subsidence are common. Most of the previous studies attributed the causes of the surface deformation to four major mechanisms: faulting, soil compaction, salt tectonics, and fluid withdrawal (groundwater withdrawal and hydrocarbon extraction). This
work assessed the surface deformation in the greater Houston area and their possible relationship with fluid withdrawal. To achieve this goal, data from three complimentary remote sensing techniques Global Positioning System (GPS), Light Detection and Ranging (LiDAR), and Interferometric Synthetic Aperture Radar were used. GPS rates for the last 17 years show a change in surface deformation patterns. High rates of subsidence in the
northwestern areas (up to*4 cm/year) and signs of uplift in the southeast are observed (up to 2 mm\year). High rates of subsidence appear to be decreasing. Contrary to previous studies in which the location of subsidence appeared to be expanding toward the northwest, current results show that the area of subsidence is shrinking and migrating toward the northeast. Digital elevation model generated from airborne LiDAR, revealed changes
between salt domes and their surrounding areas. The persistent scatterer interferometry was performed using twenty-five (25) European remote sensing-1/2 scenes. Rates of change in groundwater level and hydrocarbon production were calculated using data from 261 observation wells and 658 hydrocarbon wells. A water level decline of 4 m/year was found in area of highest subsidence, this area also show *70 million m3/year of hydrocarbon extraction. This study found strong correlation between fluid withdrawals and subsidence.Therefore, both groundwater and hydrocarbon withdrawal in northwest Harris County are considered to be the major drivers of the surface deformation
Sedimentation and deformation toward the Gulf of Mexico Basin cause faulting in the coastal regions. In particular, many active (but non-seismic) faults underlie the Houston metropolitan area. Using geophysical data, we have examined the Hockley Fault System in northwest Harris County. Airborne LiDAR is an effective tool to identify fault scarps and we have used it to identify several new faults and assemble an updated map for the faults in Houston and surrounding areas. Two different LiDAR data sets (from 2001 to 2008) provide time-lapse images and suggest elevation changes across the Hockley Fault System at the rate of 10.9 mm/yr. This rate is further supported by GPS data from a station located on the downthrown side of the Hockley Fault System indicating movement at 13.8 mm/yr. To help illuminate the subsurface character of the faults, we undertook geophysical surveys (ground-penetrating radar, seismic reflection, and gravity) across two strands of the Hockley Fault System. Ground-penetrating radar data show discontinuous events to a depth of 10 m at the main fault location. Seismic data, from a vibroseis survey along a 1-km line perpendicular to the fault strike, indicate faulting to at least 300-m depth. The faults have a dip of about 70 degrees. Gravity data show distinct changes across the fault. However, there are two contrasting Bouguer anomalies depending on the location of the transects and their underlying geology. Our geophysical surveys were challenged by urban features (especially traffic and access). However, the survey results consistently locate the fault and hold significant potential to understand its deformational features as well as assist in associated building zoning.
