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INSAR Analysis of Ground Surface Deformation in Cedar Valley, Iron County, Utah

By: Kurt Katzenstein, Ph.D

This 43-page report presents new Interferometric Synthetic Aperture Radar (InSAR) analysis of ground water subsidence in Cedar Valley in Iron County, Utah. This analysis is based on InSAR data from the ERS-1/2 satellites from 1992 to 2000, and the Envisat satellite from 2004 to 2010. A stack of five consecutive interferograms from the 1992-2000 time period and a stack of four consecutive interferograms from the 2004-2010 time period are included in this report; however, decorrelation in the vicinity of the Enoch graben makes an estimate of total deformation impossible using the stacks. In total, surface deformation has impacted approximately 256 km² (100 mi²) in Cedar Valley. Subsidence rates in the vicinity of the Enoch graben increased from approximately 0.5-1.0 cm/yr to roughly 1-2 cm/yr after 1999. Similarly, rates in central Cedar Valley show a general increasing trend after 1999, but rates appear to be more erratic than the other two sites. The spatial distribution of deformation in Cedar Valley correlates well with both the location of observed fissuring as well as the location of both municipal and private groundwater production wells. The fissuring observed near Quichapa Lake, as well as within the Enoch graben, is likely a direct result of groundwater pumping in these areas.

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POTD October 31, 2013: Iron County, Utah

Iron County, Utah
Photographer: Tyler Knudsen

Finely laminated sandstone of the Chinle Formation, Iron County, Utah.

Wednesday, October 2, 2013: Field Review of New Geologic Mapping, Cedar City area, Iron County, Utah

Mapped by
Tyler R. Knudsen, Robert F. Biek, and Janice M. Hayden
Utah Geological Survey
A STATEMAP project supported by the Utah Geological Survey and the U.S. Geological Survey

Wednesday, October 2, 2013

The purpose of the review is to give the public and local government officials an opportunity to learn about new geologic research in their district, and to give geologists and others an opportunity to critique the maps before they are published.

Highlights

  • Geologic hazards, including landslides, collapsible soils, earth fissures, and earthquake faults
  • Geology of lower Cedar Canyon
  • Kanarra anticline and Hurricane Cliffs
  • North Hills – sub-Claron unconformity and megaboulder deposits
  • Eightmile Hills and eastern Harmony Mountains – ash-flow tuffs and gravity slides
  • Granite Mountain and Three Peaks laccoliths
  • Iron Springs thrust fault
  • Iron mines

Information

  • Assemble at the Utah Geological Survey parking lot, 88 Fiddler Canyon Road, in Cedar City at 7:15 a.m.; depart at 7:30 a.m. sharp.
  • Anyone is invited – please circulate this notice among your colleagues.
  • There is no charge, but for planning purposes, we ask that you RSVP to the Utah Geological Survey (email: starrsoliz@utah.gov; or call 801-537-3300).
  • A few short but strenuous hikes are planned.
  • A high-clearance vehicle is required; we may have some spaces in UGS vehicles within the field area (not to or from Salt Lake City) – please contact us if you would like a ride.
  • Please bring a sack lunch, water, boots, hat, and field clothes.
  • If severe weather threatens, please call the UGS office on day before to see if canceled.

 Questions?  Contact Tyler Knudsen (435-865-9036, tylerknudsen@utah.gov) or Bob Biek (801-537-3356, bobbiek@utah.gov).

IRON COUNTY POSTPONES VOTE ON GEOLOGIC ORDINANCE

sltrib.com

The Iron County Commission was poised to vote Monday on a geologic hazard ordinance that has been in the making for about six months when Commissioner Lois Bulloch threw a wrench in the works.

Bulloch recommended that an independent group review the proposed ordinance and make recommendations.

“I’ve heard a lot of consternation over this issue and had input in letters and calls and am just not comfortable moving forward,” said Bulloch. “Sorry to drop this bomb.”

Bulloch suggested that a committee with representatives of the county’s six municipalities, a city attorney and engineers look at the ordinance line by line and make specific changes.

“This way we won’t be accused of not listening,” said Bulloch.

Bill Lund, a geologist with the Utah Geological Survey, told commissioners a review by new eyes is a good idea and recommended including an official of a city or county in Utah that has already dealt with a similar ordinance.

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THE SLIDE DIVIDE

spectrum.com

A discussion that initially started out over a battle of water rights for a few individuals on Cedar Mountain as escalated to an issue t h a t could affect all of Iron County and its taxpayers.

While the county has put a six-month land use restriction  on residents of the $39 million Cedar Highland subdivision located on Cedar Mountain, developers are worried the restriction to build is affecting property values for homes in the area. Declining values in a multimillion dollar subdivision add up quickly and translate into the county having to make up the tax revenue elsewhere. That cost could fall on all property owners in Iron County.

Iron County is taking action on what could be a multi-million dollar landslide problem, but it might have come nearly 30 years too late, said Utah Geological Survey senior scientist Bill Lund. He said the county made a decision 30 years ago, in his opinion, based on “insufficient information.”

With more than 70 homes now above Cedar City in the Cedar Highlands area, Lund said he is holding his breath to see what will happen to the stability of the land in the area.  The homes have septic tanks, which have u n d e r g r o u n d water seepage, which lubricates the plates beneath the ground, Lund explained. On top of that, roads and paths that cut into the mountain also disrupt the stability of the area. Lund, who has more than 31 years of geological experience, said all of the infrastructure being built without a study becomes a cause for concern because changes on one lot can affect another.

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Spectrum_7-25

MAP 242

GEOLOGIC MAP OF THE ST. GEORGE AND EAST PART OF THE CLOVER MOUNTAINS 30′ x 60′ QUADRANGLES, WASHINGTON AND IRON COUNTIES, UTAH
Robert F. Biek, Peter D. Rowley, Janice M. Hayden, David B. Hacker, Grant C. Willis, Lehi F. Hintze, R. Ernest Anderson, and Kent D. Brown

A just-released map presents southwestern Utah’s geology in unprecedented detail. There is also an innovative 3-D version of the map and a virtual field trip for online viewing. The Utah Geological Survey (UGS) created all versions of the map.

The new geologic map covers 2000 square miles of southwest Utah. It stretches from Zion National Park on the east, through the St. George area, to the Beaver Dam and Bull Valley Mountains on the west, and from the Arizona border north through the Pine Valley Mountains.

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GET IT HERE

Fishing for Fissure Information

fissureThe Utah Geological Survey (UGS) needs your help in locating fissures in the Cedar Valley area of Iron County. The Central Iron Water Conservancy District has asked the UGS to study earth fissures in the Enoch area and adjoining parts of Cedar Valley in Iron County.

“Our hope is that by putting out the information on fissures and what they are, people might recognize them and direct us to where they are,” said Mike Lowe, UGS Ground-Water and Paleontology Program Manager.

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