Friday, December 19, 2014

Oak Creek - Mormon Lake graben described in new book on Oak Creek Watershed

There is a new book out from the Oak Creek Watershed Council (OCWC) describing the hydrology, hydrogeology, geology, ecology, and history of the Oak Creek Canyon watershed. Well-known geologist Paul Lindberg contributed to hydrology and wrote the geology section, which includes a description of the newly-discovered Oak Creek - Mormon Lake graben. 

The book is timely and may help put recent earthquakes in the area in context. Paul led several field trips around the Oak Creek-Mormon Lake graben during the past two years for the AIPG, AHS and OCWC as well as presenting two talks to AHS symposia in 2012 and 2013. Paul tells us that "the new graben the newest basin and range feature in Arizona that is slowly migrating eastward into the Colorado Plateau along with a right-lateral torqueing of the boundary between the Colorado Plateau and fully broken-up basin and range topography." 
Paul shared his map showing the boundary of the new graben that he estimates is "only 2-3 million years old and still growing, as evidenced by the recent earthquake 2 weeks ago. It is clear to me that the structural basin is still enlarging and will continue to do so for the foreseeable future, along with modest to locally severe seismic activity."

Paul's talking with our professional societies about leading a day-long field trip around the rift valley in the near future.

We will carrying copies for sale at the Arizona Experience store at AZGS offices in Tucson.   It is paperback, 8.5" x 11" and 104 pages long. It contains 6 chapters dealing with all aspects of the watershed. ISBN 978-1505347623.  Retail price is $25.

Sunday, December 07, 2014

Governor-elect sets up Transition Teams for State Lands, Water, Energy, & Environment

Governor-elect Doug Ducey [right] has set up half a dozen subcommittees as part of his transition team, including one to address State Trust Lands and one on Water, Environment, and Energy.   Co-chairs were announced for each.

His website - - said he is "committed to managing Arizona’s state trust land to maximize a value for its beneficiaries. These co-chairs have significant experience working with state government managing its public lands. They’ll be able to counsel Ducey regarding these issues with Arizona’s best interests in mind."   The co-chairs are:
  • Steve Betts, Former SunCor Development Company President 
  • Cheryl Lombard, Government Relations Director of the Arizona Chapter of The Nature Conservancy 
Ducey said, “Managing our state’s assets is key in my role as state treasurer and it will be just as important as governor. In order to best benefit all Arizonans, I need to ensure we are managing our assets as efficiently and effectively as possible.”

The subcommittee on water, environmental and energy issue is being chaired by:
    •    Lisa Atkins, Board Member, Central Arizona Project
    •    Jose Esparza, Vice President/Energy Solutions, Southwest Gas Corporation
    •    Pat Graham, State Director, The Nature Conservancy in Arizona

Water-related issues facing the new governor and legislature

The current issue of the Arizona Hydrological Society carries an editorial by Alan Dulaney outlining some of the challenges related to water facing the new governor and legislature when they take office in January.   As usual, Alan doesn't pull any punches:
The election season is over.  Once the session begins in January, the new Legislature will have their hands full with the budget for the next fiscal year—a deficit of $1.5 billion is currently projected.  This might mean serious cuts in the General Fund budgets for ADWR and ADEQ.  Yet the head of Governor Ducey’s transition team, former Senator Jon Kyl, has promoted moving the adjudications process somewhat faster than its current glacial gait.  ADWR will likely be called upon to support such an effort.  ADEQ will potentially have new EPA rules or guidance that will increase their regulatory role under the Clean Water Act.  All of which will require a commitment of state resources, meaning money. 

Lack of money is also an issue in the Four Forest Restoration Initiative, headquartered at the Coconino National Forest, to better manage Arizona’s unnaturally dense forests.  Almost 25% of the largest stand of Ponderosa pine in the West has burned over the last decade.  The hydrological damage becomes evident after the fires are out.   We saw the dramatic hydrological aftermath of the Schulz Fire on an AHS field trip in 2011.  Increased sediment load and more frequent flooding are the result of removing the vegetation as the scorched earth no longer slows runoff.  The ash-laden streams cause severe environmental damage downstream.  The sediment can get into the water supply, causing expensive problems at municipal treatment plants. 
It is safer and cheaper to thin forests like the Coconino, Kaibab, Apache-Sitgreaves, and Tonto, than to continue to fight every fire to save every twig.  Thinning keeps the forest more natural; fire stays on the ground and thus becomes less intensive.  Less intensive fires are ultimately less of a threat to the water supply.  Salt River Project has been a leading supporter of large-scale forest thinning in the interest of protecting the water supply.  But money is short, and the target acreage is big.
The aphorism “Water flows uphill towards money,” is only partially true anymore.  Now we should say:  “Money goes where water flows.”  Wall Street banks, bonding agencies, venture firms and other entities with capital to invest—which the state needs—are watching to see if Arizona can solve its water issues.  One measure is the degree to which Arizona will fund its regulatory agencies as well as efforts to address the hydrological problems resulting from forest fires on its watersheds.  Politicians take note:  you weren’t elected to fiddle while we burn.
                                                                                            Alan Dulaney

Resolution Copper land swap passes U.S. House

The U.S. House of Representatives passed the National Defense Authorization Act, which includes a package of lands bills, among them the Southeast Arizona Land Exchange and Conservation Act.  The latter involves transfer of about 2,400 acres of Forest Service and BLM lands for 5,300 acres of private lands identified by conservation groups as critical lands [right, map of lands involved in exchange. Credit, Resolution Copper].   Resolution Copper says the land exchange is essential for them to move forward with development of the giant underground copper mine near Superior.  The

Congresswoman Ann Kirkpatrick, whose district includes the mine site released this statement:
The land exchange in this legislation has been modified from the original bill so that the transfer of the federal Oak Flat property will not occur until after an environmental study is performed on the mine and other activities related to the land exchange — which meets a key concern of environmental advocates. Native American interests are also reflected in the bill, which has been modified to ensure that tribes can access the Oak Flat campground for years to come unless the area is deemed unsafe. And the legislation designates 807 acres of the Apache Leap Cliffs as a “special management area,” which places it under U.S. Forest Service protection and ensures the cliffs cannot be damaged by the mine.
Resolution Copper described the key provisions of the land exchange bill at

  • Land in and around the Oak Flat Campground, which is needed for our mining operations, will be transferred from the federal government to Resolution Copper. In return, Resolution Copper will transfer to the government more than 5,300 acres of high-priority conservation lands.
  • 110 acres of Resolution Copper’s private land transferred to the US Forest Service to protect the south end of Apache Leap.
  • The scenic escarpment above the Town of Superior, known as Apache Leap, remains under management of the US Forest Service.
  • 3,050 acres known as the 7B Ranch on the San Pedro River, possibly the largest and oldest mesquite bosque in Arizona, transfers to the Bureau of Land Management and becomes a new unit of the San Pedro Riparian National Conservation Area.
  • The BLM acquires an additional 940-acre parcel inside the Appleton-Whittell Research Ranch and Las Cienegas National Conservation Area.
The legislation must also be approved by the Senate and signed by the President.

Thursday, December 04, 2014

M2.9 aftershock to Duncan earthquake

One of the larger aftershocks in weeks, at magnitude 2.9, hit the Duncan area on Wednesday at 3:53 p.m.  The magnitude 5.3 Duncan earthquake occurred on June 28 and since then hundreds of aftershocks have been recorded, with a score or so of them having been felt by local and regional residents.  [Right, orange star marks epicenter of aftershock.  Credit, USGS]

Wednesday, December 03, 2014

Map of aftershocks to Sunday's M4.7Oak Creek earthquake

AZGS geologist Jeri Young has compiled all of the aftershocks greater than magnitude 2.0 from Sunday night's magnitude 4.7 earthquake in the Oak Creek Canyon area between Sedona and Flagstaff.

The figure also shows the M=3.5 quake from November 25 in the same area.

Monday, December 01, 2014

Magnitude 4.7 earthquake rocks Sedona-Flagstaff area

 AZGS released the following statement this afternoon:

A magnitude (M) 4.7 earthquake shook Sedona and Flagstaff in Sunday evening. The event occurred at 10:57 p.m. about 7 miles north of Sedona, near Munds Park.

The earthquake and smaller aftershocks are shallow, with depths estimated at 1.3 miles. More than 1,100 people reported feeling the event to the U.S. Geological Survey's, "Did you feel it," online forum at

One individual from near the Village of Oak Creek said, "It rocked my desk chair (on casters) back and forth, shook windows, and caused my mac desktop to tremble as well as the desk lamp... ."

According to Phil Pearthree, Chief of Environmental Geology at the Arizona Geological Survey, "the location is quite close to the Oak Creek fault zone, a down-to-the-east normal fault with 700 feet of vertical displacement in the past 10 million years or so. We think this fault has been active in the past 2 million years, but don't know how recently it has ruptured in a large earthquake."

Using the Arizona Integrated Seismic Network to track seismic events, AZGS geologist Jeri Young identified at least 10 aftershocks, three of which approach M 3.0. See the attached map for two aftershocks: M 2.2 at 12:10 a.m. and an M 3.0 at 12:53 a.m. (MST). On Nov. 25, 2014, an M 3.5 event occurred proximal to last night's earthquake.

Both Denny Foulk, Yavapai County Emergency Manager, and Rob Rowley, Coconino County Emergency Manager, confirmed that there were no reports of damage to homes or roads. There was one minor rock fall in Oak Creek Canyon that was rapidly cleared.

The largest historical earthquakes in the region, a series of three M 6.0 events, occurred between 1906 and 1912, near Flagstaff. More recently, a M 5.1 earthquake occurred in 2005 about 50 miles southwest of this epicenter, and a M3.5 earthquake occurred very close to this epicenter last week (Nov. 25,2014).

Historical earthquake activity for all of Arizona is available online at the interactive Natural Hazards in Arizona Viewer.

For additional information and updates contact the Arizona Geological Survey or follow us at our social media information outlets:

Arizona Geology Blog

Arizona Geological Survey Facebook

Arizona Geological Survey Twitter

Arizona Geological Survey Web

Online Resources. The Arizona Geological Survey hosts a number of online resources relevant to earthquakes and earthquake hazards in Arizona:

• Natural Hazards in Arizona Active Faults | Earthquake Epicenters themes

• Earthquakes in Arizona 1852-2011 - Time lapse video showing locations and magnitudes of earthquake events in Arizona. Length: 90 seconds.

• Arizona is Earthquake Country - Forty-four page primer on earthquakes, earthquake hazards and mitigation in Arizona.

• AzEIN - Earthquake Preparedness page from Arizona Emergency Information Network.

[AZGS news release.  12-1-14 2:00 p.m.]

Records of 11 aftershocks from Sedona M=4.7 earthquake

The helicorder station at Flagstaff captured the records of the magnitude 4.7 earthquake last night between Sedona and Flagstaff and 11 aftershocks.  Most occurred in the two hours following the main shock, with another around 5 a.m. this morning local time, and one after 1:30 p.m. this afternoon.  More aftershocks are expected in the coming days and weeks.    Thanks to Jeri Young here at AZGS for providing this record.

More details on Channel 15 ABC news' site in Phoenix -

Moderate quake (M=4.7) between Sedona and Flagstaff

A magnitude 4.7 earthquake struck north of Sedona on Sunday night at 10:57 p.m. local time and was widely reported by residents across the region. One small rockfall was reported on highway 89A but it was quickly cleared by ADOT.  [Right top, AZGS Hazards Viewer shows active faults and historical earthquakes.    The new quake is shown in red. Bottom right, waveforms from the Arizona Broadband Seismic Network, operated by AZGS.  Prepared by Jeri Young.   Bottom left, rock fall on Highway 89A, Credit, David Mendez, Channel 10 News, Phoenix]

A number of aftershocks in the magnitude 3 range have also been felt. The main shock was preceded by a  nearby magnitude 3.5 earthquake on November 25, that itself had minor foreshocks (yellow circles abutting  southwest of last nights quake).    Our location of the epicenter is a few miles NNE of where the USGS plots the events, based Dr. Jeri Young's calculation using the stations of the Arizona Broadband Seismic Network, operated by AZGS.

Dr. Phil Pearthree at AZGS has mapped this area extensively and reports that the location reported by the USGS is quite close to the Oak Creek Canyon fault zone, a down-to-the-east normal fault with substantial late Cenozoic displacement. The AZGS fault map and data currently depict the northern part of this fault zone as "Quaternary" age, as early Pleistocene basalts are displaced there. During the recent AEG Grand Canyon field trip that he led up Oak Creek Canyon, there was discussion about adding the section of the fault that the canyon follows (where this earthquake occurred) as Quaternary. Perhaps the only reason it is not so designated is lack of units of suitable age that are clearly displaced.

The USGS focal mechanism for this event suggests primarily normal slip on a steeply SE-dipping, NE-SW striking fault zone. If correct, Phil suggests the earthquake most likely did not occur on the Oak Creek Canyon fault per se, or on the mapped NW-striking faults on the Colorado Plateau margin that are also close to the the epicenter (purple and green faults to the west and west-northwest of the epicenter).

Flagstaff-based geologist and blogger Wayne Ranney posted an extensive discussion of the Oak Creek Canyon fault and its offsets over geologic time, at