Arizona Geology Blog

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blog of the State Geologist of ArizonaLee Allison
Updated: 1 hour 34 min ago

Baja quake in 2010 generated hundreds of landslides

Sat, 2014-12-20 20:09

The 2010 Cucapah earthquake in Baja California, triggered hundreds of landslides that sent up dust clouds all along the mountain range.

David Petley, who writes the Landslide Blog, and his colleagues used remote sensing data and  quantified the number (452)  and volume of landslides (2.6 million cubic meters) in the Cucapah Mountains as a direct result of the April 2010, M7.2 earthquake.  Their study is published in the journal Geomorphology

In his blog post, David noted that steep slopes generated more landslides, "But interestingly, we also found that there was a strong influence exerted by slope orientation.  In particular, those slopes orientated perpendicular to the fault were four times more likely to fail than those orientated parallel to the fault.  The reasons for this are not clear at present."
Reference: Barlow, J., Barisin, I., Rosser, N., Petley, D.,  Densmore, A. and Wright, T. 2014. Seismically-induced mass movements and volumetric fluxes resulting from the 2010 Mw = 7.2 earthquake in the Sierra Cucapah, Mexico, Geomorphology, Available online 24 November 2014,

Categories: AZGS Web Posts

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

Fri, 2014-12-19 11:15

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.

Categories: AZGS Web Posts

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

Sun, 2014-12-07 13:53
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
Categories: AZGS Web Posts

Water-related issues facing the new governor and legislature

Sun, 2014-12-07 08:44
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
Categories: AZGS Web Posts

Resolution Copper land swap passes U.S. House

Sun, 2014-12-07 08:34
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.

Categories: AZGS Web Posts

M2.9 aftershock to Duncan earthquake

Thu, 2014-12-04 13:44
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]

Categories: AZGS Web Posts

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

Wed, 2014-12-03 08:36
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.

Categories: AZGS Web Posts

Magnitude 4.7 earthquake rocks Sedona-Flagstaff area

Mon, 2014-12-01 17:16
 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.]
Categories: AZGS Web Posts

Records of 11 aftershocks from Sedona M=4.7 earthquake

Mon, 2014-12-01 16:56
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 -

Categories: AZGS Web Posts

Moderate quake (M=4.7) between Sedona and Flagstaff

Mon, 2014-12-01 13:52

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

Categories: AZGS Web Posts

Geosciences role in making Tucson the "Science City"

Sun, 2014-11-30 16:27
The University of Arizona's 28-page supplement in Sunday's Arizona Daily Star newspaper is one of the many high-profile activities taken by the school to build Tucson's reputation as "Science City."   This now annual feature showcases a wide range of science research and programs that Joaquin Ruiz, Vice President of Innovation & Strategy, Dean of the College of Science, and Professor of Geosciences, says "must be relevant both internationally and to our home community."

This year's edition includes reports from a few geoscientists, including Peter DeCelles describing work on the structure and tectonics in the Himalayas to unravel how mountains and basins form, Matthew Salzer reporting on the use of tree rings to track changes in the Earth's climate going back nearly 5,000 years, Thomas Zega discussing studies of microscopic stardust to understand the origin of the Milky Way and our solar system, and Jon Pelletier's work on predicting post-wildfire erosion better.  Jon's work has direct application to work we are doing at AZGS to predict and mitigate debris flows and related hazards following wildfires.

You can sign up to receive the UA Science biweekly e-newsletter at [right]

Categories: AZGS Web Posts

ASU prof maps geology of asteroid Vesta

Fri, 2014-11-28 16:49

A new geologic map of the asteroid Vesta has been published by Arizona State University planetary scientist David Williams and his colleagues. It's online in the December special issue of the journal Icarus on The Geology of Vesta.

They propose a chronostratigraphic scheme and geologic timescale for Vesta with four periods based on major impact events.  The conclude that the proposed vestan geologic timescale is comparable to those developed for other airless terrestrial planets, and Vesta’s youngest period is not based on rayed craters, due to different space weathering.

Ref: D.A. Williamsa, R. Jaumannb, H.Y. McSween Jr., S. Marchie, N. Schmedemann, C.A. Raymond, C.T. Russell, "The chronostratigraphy of protoplanet Vesta,"Icarus, Volume 244, December 2014, Pages 158–165

Categories: AZGS Web Posts

Opening for UA Mineral Museum Collections Manager

Thu, 2014-11-27 10:13
The University of Arizona Mineral Museum looking for a full-time, permanent position, collections manager. The mineral museum is located in the Flandreau Science Center [right] on the University of Arizona campus in Tucson as part of the Department of Geosciences.Duties include managing current mineral collections, museum displays, outreach programs and the day to day operations of museum. 

Requirements includ a Bachelor's degree in Geosciences or related field; or experience working with display minerals. Candidates must have knowledge of minerals and the collector community.  Review begins December 1, 2014.  [bottom right, from the Bisbee exhibit. Credit, UA Mineral Museum]

The announcement is posted at

[excerpted in part from the UA announcement]

Categories: AZGS Web Posts

Appeal filed to lift federal ban on uranium claims, exploration in northern Arizona

Thu, 2014-11-27 10:05
Reuters reports that the National Mining Association and the American Exploration and Mining Association filed an appeal late on Tuesday with the 9th U.S. Circuit Court of Appeals, to overturn last month's decision by U.S. District Judge David Campbell that the U.S. Interior Secretary was empowered under federal law "to err on the side of caution in protecting a national treasure - Grand Canyon national park" by banning new uranium claims and exploration in northern Arizona outside the park.

Secretary of Interior Ken Salazar imposed the 20-year ban on nearly 1 million acres of federally managed lands in 2012. [Right, withdrawal areas outlined in red. Credit, BLM]

Categories: AZGS Web Posts

Helium exploration geologist position open in Phoenix

Thu, 2014-11-27 09:51
Exploration for helium in Arizona heated up this year with two wells drilled in the Holbrook area where it was produced for decades. [Right, AZGS map of helium fields in Arizona] One of our correspondents passed along a new job posting for a Phoenix-based geologist to help with helium exploration in the region.
Progressive Global Energy & Natural Resources posted the job notice on on November 14 (Job Reference1041244).
 Job Description:Our client, is in the business of addressing the supply of helium to industry, government, medical and the research communities. Our client, has accumulated working interests in oil and gas lease holdings composed of more than 35,000 acres in a geographic region that historically has been recognized to contain some of the highest helium concentrations found. The extent of our clients recoverable helium reserves will be identified by drilling and third party engineering analysis. The fields will be developed through production well drilling and completion, infrastructure gathering system and processing equipment construction.
Our client is located in Phoenix, Arizona and is looking for an experienced Exploration Geologist to participate in this exciting opportunity.Requirements:
  • 15+ years of experience as an Exploration Geologist
  • -experience working in gas field
  • -prospect generation
  • -cross sections
  • -mapping
  • -field development
  • -well planning
Categories: AZGS Web Posts

New president of Nevada Mining Association has Arizona ties

Wed, 2014-11-26 13:42
The new president of the Nevada Mining Association has extensive ties to Arizona.

The Association announced that Dana Bennett [right, Linkedin photo], the former regional director of the Nevada Governor’s Office of Economic Development and current owner of Bennett Historical Research Services, will become President of NVMA effective Dec. 1.

Bennette received her doctorate in history from Arizona State University, worked in historical research and policy analysis with Morrison Institute for Public Policy in Phoenix, and was a Research Historian with Arizona State Archives.

Arizona and Nevada have traded positions in recent years as the number one non-fuel mining state in the country, with Nevada in first place when gold prices are high.

Categories: AZGS Web Posts

M3.5 quake near Sedona is felt locally; preceded by foreshocks

Tue, 2014-11-25 17:11
Residents in the Sedona-Flagstaff area report feeling a magnitude 3.5 earthquake that hit about 6 - 10(?) miles north-northeast of Sedona at 2:19 a.m. local time this morning. 

Dr. Jeri Young, who runs the Arizona Broadband Seismic Network here at AZGS, reports there were two smaller events in the area prior to the quake and one aftershock. The foreshocks were at 12:25 and 12:39 a.m. and the aftershock at 9:04 a.m. today.

She also says her preliminary epicenter location is further north, near the Munds Park fault, which may explain why so few people have thus far reported feeling the shaking.  [Above, red star marks the USGS located epicenter, the labelled red circle is the AZGS-ABSN location.  Credit, ABSN]

Categories: AZGS Web Posts

P.K. (Rana) Medhi

Tue, 2014-11-25 15:32
The Arizona Geological Society reports that "Long-time AGS member P. K. (Rana) Medhi [photo credit, AGS] passed away Nov. 7, 2014 at his home in Casa Grande. Medhi, former chairman of the Board of Governors of the Arizona Dept. of Mines and Mineral Resources, former adjunct professor of geology at Central Arizona College, and former Governor of the Mining Foundation of the Southwest retired in 1994 after 28 years at Cyprus Amax Minerals Company. He had a M.S. degree from the University of Arizona and was a certified professional geologist and an Arizona - registered geologist; he worked as an independent mining and exploration geologist after his retirement."

On a personal note, Rana played a key role in preserving the historical mining records and other assets of the Dept. of Mines & Mineral Resources when they shut down in 2011 due to a budget shortfall.  With an hour to go before the agency closed, he signed an agreement to make AZGS temporary custodian of the materials, until the Legislature could approve the merger of the agencies.
Categories: AZGS Web Posts

Aftershock felt in Duncan area

Sun, 2014-11-23 16:37
Local residents reported feeling an aftershock to the Duncan earthquake on at 7:38 a.m. on Friday, Nov. 21.    The USGS posted the location for the event today, with a magnitude of 2.8.  This is the first aftershock felt in the area for many weeks.  The M=5.3 Duncan earthquake hit the eastern Arizona locale on June 28.   [Right, orange star marks aftershock epicenter.  Credit, USGS]

AZGS has posted an article online describing the main shock and our deployment of a temporary portable seismic array to locate and measure the hundreds of aftershocks -
Categories: AZGS Web Posts

How did we miss this story about vampires in abandoned mines in Arizona?

Sat, 2014-11-22 10:21

Well, Arizona, it looks like we had a chance to rid Arizona of vampires in our abandoned mines, but we blew it.   
Joe Hart won re-election as State Mine Inspector  a couple weeks back with over 1 million votes or 98.29% of the votes cast.   There was no organized opposition, but write-in votes totaled 18,312.  The Secretary of State's office has not posted who got those write-ins but I wonder if some of them didn't go to write-in candidate Ian Kobe who ran on a campaign of "No Arizona Mine Draculas."
His Facebook site (his only campaign outlet?) says "A vote for Ian Kobe is a vote for an AZ with less Draculas!" [sic] and laments that children cannot play in abandoned copper mines because Joe Hart has not cleaned out the vampire dens.
I know and work with Joe. I interviewed him on our video magazine "Arizona Mining Review" and I have to admit, never once has he mentioned vampires, let alone vampires in mines, active or abandoned. Joe, all I can say is that I'm speechless!

And the Arizona news media, obviously beholden to the pro-vampire community, ignored this burning issue in the Mine Inspector's race.  I had to read the Chicago Sun Times to find out about it.   


And all this raises the question that if the mines are full of vampires, can zombies be far behind?
So kids, you're going to have to stay out of those old mines for a while longer.

Categories: AZGS Web Posts