Arizona Geology Blog

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blog of the State Geologist of ArizonaLee Allison
Updated: 2 hours 22 min ago

Industry encouged to participate in Fraser Institute "Survey of Mining Companies"

Sun, 2014-09-14 14:18

I want to encourage Arizona mining company executives to participate in this year's survey of government jurisdictions based on their attractiveness to mining investment.  We review the findings each year for Arizona and share them with state and legislative leaders.  

The Fraser Institute, Canada’s leading public policy think-tank, conducts this annual global survey and "the results help identify the countries, states, and provinces whose mining policies either attract or repel investors. Participants also offer critical insight into the policy issues that matter most to the global mining industry."

We also interview the survey director on our online video magazine "Arizona Mining Review" to answer questions about Arizona's favorability.

To participate in this year’s survey, visit To learn more about this project, please contact Taylor Jackson, survey coordinator, at (604) 688-0221 ext. 553 or
From Fraser Institute:   Our Survey of Mining Companies: 2013 (published March 2014) ranked the investment climate of 112 jurisdictions around the world based on the opinions of mining executives representing 690 mineral exploration and development companies. Participating companies reported exploration spending of $4.6 billion US in 2012 and $3.4 billion US in 2013.
Categories: AZGS Web Posts

Permits issued for helium exploration

Mon, 2014-09-08 21:00

The Arizona Oil & Gas Conservation Commission has approved permits for two new wells in the Holbrook area, reportedly to evaluate helium potential.  State permits #1194 and #1195 are posted on the AZOGCC website.    The permits were issued to Ranger Development LLC, based in Ft. Worth, Texas.

The well proposed in Sec. 33-20n-26e is located in the old Pinta Dome helium field [right, from AZGS report "Oil, Gas and Helium in Arizona: Its Occurrence and Potential," 1961]. The well in 31-20n-27e is located in the old Navajo Springs field.

Categories: AZGS Web Posts

A day of flooding across Arizona

Mon, 2014-09-08 20:35
We sent AZGS employees home a little early today after the City of Tucson sent their non-essential staff home at 3 p.m. News reports said the city had closed or was closing bridges across the Santa Cruz River, which lies only a block west of our offices.  There were fears that the high waters might undermine the river banks and threaten the structural integrity of the bridges.   I left at 5 p.m. worried that I would not be be able to get over the river to get to our home in the Tucson Mountains.  But the river level was down as I drove over it.  City workers were measuring the water flow, and local tv crews were capturing it all.  [Right, flooding on Interstate 10 in downtown Phoenix]

Visitors to Tucson are often surprised at the general lack of culverts and storm drains.   Streets typically follow the lay of the land, dropping down as they cross washes and gulleys.    Runoff from rain storms flows down washes and right across the roads.  Motorists are repeatedly warned not to cross washes with even what seem to be low levels of flowing water, not realizing the power of that water to sweep away vehicles or at least strand them.

AZGS geologists were responding to reports of heavy runoff eroding and undercutting roadways and other structures.    

Governor Jan Brewer issued a declaration of emergency in response to flooding statewide:

            PHOENIX – Governor Jan Brewer today declared a State of Emergency in response to record flooding in Arizona.  

            On September 8, 2014, powerful rains combined with remnants of Hurricane Norbert caused record precipitation and flooding throughout Arizona. The storms resulted in significant impacts to transportation infrastructure throughout the Phoenix metropolitan area in Maricopa County, including the closure of State Route 51, Interstate 10 and 17 and U.S. Route 60. The heavy rains also threatened lives, caused residential damages, forced evacuations in La Paz County and required emergency response search and rescue missions, including the American Red Cross opening shelters in Maricopa and La Paz Counties. The threat of flooding remains high due to heavily saturated soils and the anticipation of additional waves of precipitation.
            Governor Brewer is authorized under to A.R.S. § 26-303(D) to declare a State of Emergency to provide financial support for eligible response and recovery costs.  Maricopa and La Paz Counties have declared a state of emergency and are requesting the state’s financial assistance to recover from the flooding. The Governor’s Declaration:
a.         Declares that a State of Emergency exists in Maricopa and La Paz Counties due to flooding, effective September 8, 2014; and
b.         Acknowledges that this weather system is still passing through the State of Arizona, and will be amended to include additional counties as the situation requires; and
c.         Directs that the sum of $200,000 from the general fund be made available to the Director of the Arizona Division of Emergency Management; and
d.         Directs that the State of Arizona Emergency Response and Recovery Plan be used to direct and control state and other assets and authorize the Director of the Arizona Division of Emergency Management to coordinate state assets; and
e.         Authorizes the Adjutant General to mobilize and call to activate all or such part of the Arizona National Guard as is determined necessary to assist in the protection of life and property throughout the State.        
            Preliminary damage assessments will be scheduled by the Arizona Department of Emergency Management’s Recovery Office in conjunction with the counties, as requested. Response costs and damage to public infrastructure have not yet been estimated by the counties.
            Visit the Arizona Emergency Information Network website – – for emergency updates, preparedness and hazard information, and multimedia resources.

Categories: AZGS Web Posts

Small quake near Holbrook

Sun, 2014-09-07 08:58
A magnitude 2.6 earthquake hit about 6 miles northeast of Holbrook at 2:07 a.m. this morning. This area rarely sees measurable earthquakes.  [Right, orange star marks the epicenter. Credit, USGS]
Categories: AZGS Web Posts

New global potash commodity report from USGS

Sat, 2014-09-06 09:54
The USGS has released the 2014 minerals commodity study for potash, which describes the global disruption of the market and price last year due to the breakup of the Russia-Belarus marketing company.  

We're following developments because the Holbrook basin [right, thickness map of potash. source AZGS] holds a significant potash resource at shallow depths and located on a major rail line and interstate. The US imports about 85% of the potash used in the country, mostly for fertilizer.  The one mine in Michigan shut down, while a new mine opened in New Mexico.

The USGS reported:
A Canadian company continued development of a new underground potash mine in southeastern New Mexico. Initial production was expected to begin in 2016, with annual production of 568,000 tons of SOP and 275,000 tons of SOPM.

In 2013, progress continued in the development of new mines and expansion of existing facilities in more than 15 countries worldwide. Projects in Canada, Laos, and Russia were expected to be completed by 2017. Other important projects in Belarus, Brazil, Congo (Brazzaville), Eritrea, Ethiopia, Russia, Turkmenistan, United Kingdom, and Uzbekistan were not expected to be operational until after 2018.
World consumption of potash, for all applications, was expected to increase by about 3% per year over the next several years. The Holbrook basin proposed developments seem to be on hold while the market sorts itself out.
Categories: AZGS Web Posts

Did lithium mines seal the deal for Tesla battery factory going to Nevada?

Thu, 2014-09-04 18:25
Tesla has chosen Reno, Nevada as the site for its  $5 billion factory to supply lithium batteries for its electric cars, beating out competitors including Arizona. 

A story today by Dorothy Kosich at quotes John Boyd, a principal of the site selection firm The Boyd Company, as telling the Wall Street Journal, “I think the single most important factor is the [site’s] low-cost green power, including solar, wind and geothermal energy for the plant. He also cited Nevada’s lack of corporate and personal income taxes as positive factors."

Arizona may have sent mixed messages on this front, offering tax breaks and other incentives, but with concurrent debates at the Arizona Corporation Commission over continuing utility subsidies for solar power, and proposals to roll back the requirement for utilities to provide 15% of their electrical power from renewable energy resources.

Dorothy also points out that  "Nevada currently is home to the only brine lithium operation in the United States. Rockwood Lithium, which produces lithium carbonate from brines near Silver Peak, Nevada, has invested $75 million in an expansion of its U.S. lithium production. Pure Energy Minerals holds contiguous claims near the Silver Peak operation."   She notes that Western Lithium’s King Valley project is often promoted thusly: “Nevada is uniquely positioned to support the world-wide increase in renewable energy production and demand for electric vehicles through lithium mining—the key ingredients to the high-performance batteries, which will power electric vehicles and be used in utility-scale energy storage projects.”

How much did Nevada's support for producing the minerals needed for manufacturing batteries play into Tesla's decision?

[updated 9-6-14]
Categories: AZGS Web Posts

Position Opening: Deputy Director, Arizona Geological Survey

Thu, 2014-09-04 10:58

The Arizona Geological Survey (, an independent state agency reporting directly to the Governor, seeks to hire a Deputy Director at its headquarters in Tucson, Arizona, with strong team-building, leadership, management, and communication skills and the ability to design, implement, and manage complex, multidisciplinary scientific programs in support of agency and state needs. The agency has never had a Deputy Director position, but increased demands to manage the growing staff, carry out the portfolio of large complex projects, and seek state and grant funding, require establishment of the position. 
Job SummaryActs in a senior capacity to manage the internal operations of the agency that are necessary to carry out its programs and activities. Assists the Director and Section Chiefs in developing the agency’s programs, maintain scientific and technical proficiency of staff members and the agency, helps construct and implement the agency’s annual work plans and priorities based on available resources, allocates agency human and fiscal resources, and responds to requests and inquiries from the Governor, Legislature, local, state, and federal agencies, business and industry, news media, professional organizations, and the public.  Supervises the agency’s Section Chiefs.   Acts on behalf of department director in the Director´s absence; represents the agency with its stakeholders, clients, and partners.  Carries out geoscience projects in the incumbent’s area of scientific expertise or as needed.  
Education and Experience Requirements·         Degree in Geological or Earth Sciences or closely related field, and at least 5 years of experience in the management of scientific programs; advanced degree encouraged·         Managerial experience overseeing complex projects involving teams of geologists, computer and information scientists, and other professionals and support staff with diverse educational and work experience backgrounds 
Position Type: Permanent position, E1, in Arizona State Government, salary range, $51,499 - $97,335.The State of Arizona offers a comprehensive benefits package that can be effective within the first two weeks of your employment that includes affordable health, dental and vision insurance, accrued vacation and sick leave, 10 holidays per year; long-term disability; retirement plan; and life insurance. Optional employee benefits include deferred compensation, short-term disability, flexible spending account for medical/dependent care expenses and supplemental life insurance.  We also offer free covered garage parking, Tuition Reimbursement and Public Transit Discounts. Position is located in Tucson.
How to Apply: Fill out an application at: or applications may be sent in the form of a resume and cover letter to Please include “Deputy Director” in your subject line to distinguish your application from other recruitments currently open. First review of applicants will take place September 20, 2014 and continue until the position is filled. 

Arizona State Government is an EOE/ADA Reasonable Accommodation Employer.All newly hired employees will be subject to the E-Verify Employment Eligibility Verification Program.
Categories: AZGS Web Posts

Updated Arizona energy profile

Thu, 2014-09-04 07:38

The U.S. Energy Information Administration (EIA) has updated Arizona’s state profile with new monthly data and analysis.  According to the message they sent me, "the updated information includes price, supply, and consumption data for electricity, petroleum, and natural gas resources." The site provides an online interactive map with a wide range of data layers ranging from power plants, pipelines, transmission lines, processing facilities, and fossil and renewable energy resources.
Some quick facts from the Arizona page:
    • Arizona's Palo Verde Nuclear Generating Station, rated at 3,937 net megawatts, is the largest nuclear power plant in the nation.
    • Arizona ranked second in the nation in utility-scale electricity generation from solar energy in 2013.
    • Arizona, the 15th most populous state in 2012, ranked 43rd in per capita energy consumption, partly because of the state’s small industrial sector.
    • Arizona's only operating coal mine, Kayenta, on the Navajo and Hopi reservations, supplies the 7-to-8 million short tons burned annually by the Navajo Generating Station's three 750-megawatt units.
    • Arizona's Renewable Environmental Standard requires 15% of the state’s electricity consumed in 2025 to come from renewable energy resources; in 2013, 7.8 % of Arizona’s net electricity generation came from renewable resources, primarily from the Glen Canyon and Hoover Dams.
    • Twenty-five percent of the energy consumed in Arizona homes is for air conditioning, which is more than four times the national average of 6 percent, according to EIA's Residential Energy Consumption Survey. 
    Also, they note that Arizona’s album on EIA’s Flickr page provides access all of EIA’s data graphics related to Arizona’s energy sector.
    Categories: AZGS Web Posts

    M2.8 aftershock to Duncan earthquake

    Wed, 2014-09-03 11:20
    There was another measurable Duncan aftershock last night about 7p.m.  The M2.8 followed a M2.6 event that morning.   [Right, orange star marks epicenter. Credit, USGS]

    Categories: AZGS Web Posts

    Small aftershock in Duncan area

    Tue, 2014-09-02 15:01
    A M2.6 earthquake on the Arizona-New Mexico border is likely an aftershock from the June 28, M5.3 Duncan earthquake.  Because of it's small size and the limited seismic station coverage in the area, we suspect the location is not well constrained.     The quake hit at 9:21 a.m. this morning.  We expect aftershocks will continue for weeks to months.  [Right, orange star marks epicenter. Credit, USGS]
    Categories: AZGS Web Posts

    Portable seismometers pulled from Duncan, heading to Napa

    Sat, 2014-08-30 20:38
    AZGS geologists Jeri Young and Phil Pearthree pulled out four of the seven portable seismometers deployed in the area around June's M5.2 earthquake near Duncan, Arizona.  The portable instruments were installed in July to monitor the aftershocks from the June 28 event, detect small events, and provide accurate locations for all of the aftershocks.

    However, the PASSCAL facility that owns the instruments needs to redeploy them in the Napa California area to monitor the aftershocks from last weeks M6.1 earthquake there.

    Since they were installed, the portable instruments have recorded hundreds of aftershocks, with the largest a M4.1 event [right.  waveforms of aftershock as recorded by different stations]

    Categories: AZGS Web Posts

    New Geologic Map of Black Peak and Bobs Well 7.5" quadrangles released

    Sat, 2014-08-30 10:07
    AZGS has published a new geologic map of the Black Peak and Bobs Well 7.5" quadrangles as a digital map.  It is available at our online repository for free viewing and downloading.

    Most of the map area is covered by sand dunes and related features of Cactus Plain. The dune field of Cactus Plain is on a low plateau formed primarily on older eroded sediments, with minor bedrock hills protruding from the plain locally. The oldest late Cenozoic deposits in Cactus Plain are undeformed fan deposits composed primarily of crystalline metamorphic clasts, obviously derived from the east and northeast. These deposits are overlain by, and locally may interfinger with, fine-g rained clay, silt, sand and minor limestone deposits that we consider to be part of the Bouse Formation. Bouse carbonate deposits are also extensively exposed on the flanks of Black Peak and related hills near the northern margin of the map area. On the western, north eastern, and southern margins of Cactus Plain, there are extensive well-rounded, lithologically diverse gravel and sand deposits that we tentatively correlate with the early Pliocene Bullhead alluvium. T h is major river aggradation sequence is found all along the Colorado River below the mouth of the Grand Canyon (House et al., 2008; Howard et al., in prep.).
    The map was funded in part by the StateMap component of the National Cooperative Geologic Mapping Program managed by the USGS.

    Ref: Pearthree, P.A. and Spencer, J.E., 2014, “Geologic Map of the Black Peak and Bobs Well 7.5 Quadrangles, La Paz County, Arizona,” Arizona Geological Survey Digital Geologic Maps DGM-108 v1, scale 1:24,000.
    Categories: AZGS Web Posts

    Flagstaff's Wayne Ranney leading world tour of northern locales

    Fri, 2014-08-29 07:48
    Today's mail brought a slick brochure from Smithsonian Journeys offering a private jet tour next June around the world of northern locales hopping from Seattle to, among others, Mongolia to Siberia to Svalbard, Greenland, and Iceland before returning home 22 days later. The Boeing 757 private jet seats up to 78 passengers in "two-by-two, VIP-style leather seats."

    And it's being led by Flagstaff-based geologist and fellow geo-blogger, Wayne Ranney [photo credit Smithsonian Journeys]    The Smithsonian bio for Wayne says in part:

    Wayne Ranney is a veteran of expedition travel, and has lectured on and journeyed to all seven of the Earth’'s continents. With a lifelong interest in the natural and earth sciences, Wayne specializes in making the fascinating story of our planet come alive for fellow travelers. His travels have taken him to all areas of South America including Patagonia; the Polar regions from Antarctica to Iceland, the desert lands of Africa and the American Southwest, and most of Earth’'s outstanding landscapes. He was elected to the Explorers Club and has visited more than 80 countries. Wayne is a retired professor of geology but still teaches an occasional honors course at Northern Arizona University in his hometown of Flagstaff, Arizona.Now, I have a schedule conflict next June, so I won't be able to join Wayne and the other trip participants. The trip cost of $64,950 per person is also a bit daunting for someone on a state salary.
    Categories: AZGS Web Posts

    Small quake northeast of Kingman

    Fri, 2014-08-29 07:28
    There was a magnitude 1.7 earthquake just after 3a.m. local time this morning, about 27 miles northeast of Kingman, Arizona. [Right, orange star marks the epicenter. Credit, USGS]

    An area 40 miles east of Kingman was hit with a cluster of quakes in the magnitude 3+ range two weeks ago.
    Categories: AZGS Web Posts

    Latest episode of Arizona Mining Review online

    Thu, 2014-08-28 20:48
    The August episode of Arizona Mining Review, our online video magazine, was broadcast yesterday and is now available on YouTube at

    I interview Phil Pearthree about the new geologic map of the Phoenix valley, to help urban planners  identify remaining aggregate resources that are needed to support development.

    Steve Fortier talks about projects and resources at the USGS National Minerals Information Center.

    The AZGS Channel is at, with previous episodes of at AMR at
    Categories: AZGS Web Posts

    Hudbay announces $8 million Rosemont Copper drilling program

    Thu, 2014-08-28 20:15
    I reported a couple weeks ago that Hudbay Minerals, new owner of the Rosemont Copper project [right, credit Rosemont Copper], was planning a drilling program to confirm the extent and quality of the ore body.   Yesterday they put out a news release described the drilling plans:

    HudBay Minerals Inc. (“Hudbay”) will employ approximately 70 consultants and contractors over the next four months in an $8 million confirmatory drill program on Rosemont project private land. Project site preparation is underway and drilling is anticipated to begin in September.

    The US Forest Service has been notified of the drill program, including the access routes to ensure public safety. The drill program components were designed to ensure compliance with existing environmental plans, permits and other constraints, such as dark skies concerns and water recycling. Archeological sites and wildlife locations are being avoided in the program. The Forest Service has made a determination that the use of approximately 1.5 miles of existing Forest Service roads would not cause a significant disturbance of surface resources and therefore would not require a plan of operations.

    The drilling program’s goal is to improve the company’s understanding of the geology and mineralization and to collect rock characteristic information to validate the current mine plan. The drilling program does not include any areas outside of the currently proposed mining zones within the Rosemont Final Environmental Impact Statement (FEIS). The program will engage six diamond drilling rigs at the site, operating 24 hours a day, 7 days a week, to complete the core sampling of approximately 85,000 linear feet. Hudbay expects the drilling program to be completed by the end of 2014.

    Hudbay is not anticipating that the drilling program will modify the current mine plan that was analyzed in the Rosemont FEIS that was recently completed. If such a modification were to be required, then Hudbay would submit an updated plan for consideration by the US Forest Service.

    Supporting the drilling at the designated Rosemont project pit, the Rosemont Camp facility and Hidden Valley ranch will be used for temporary office trailers and storage to accommodate additional work needs for the program. With the start of the work, there is no public access allowed on Rosemont project private property in keeping with Mine Safety and Health Administration (MSHA) compliance. Personnel and signs will be in place to direct the public around the private property.Water for the drilling program will be provided by wells on private property that are located at the Rosemont Junction and Rosemont Camp areas. Well cleaning, development, and drilling has been on-going and will continue through September to ensure adequate supply of water for the drilling program.
    Categories: AZGS Web Posts

    Preliminary Announcement: Basin and Range Province Seismic Hazards Summit III

    Wed, 2014-08-27 11:26

    The Utah Geological Survey and Western States Seismic Policy Council will convene a Basin and Range Province Seismic Hazard Summit III (BRPSHSIII) January 12 - 17, 2015 in Salt Lake City, Utah.  The purpose of BRPSHSIII is to bring together geologists, seismologists, geodesists, engineers, emergency managers, and policy makers to present and discuss the latest earthquake-hazards research, and to evaluate research implications for hazard reduction and public policy in the Basin and Range Province.

    BRPSHSIII will include a paleoseismology workshop, fieldtrip along the Salt Lake City segment of the Wasatch fault, poster session, and a proceedings volume.  Paper contributed to the proceedings volume will be published digitally in the Utah Geological Survey's Miscellaneous Publication series.  Digital versions of posters will also be included in the proceedings volume.
    BRPSHSIII will include a proceedings volume and a poster session. The papers contributed to the proceedings volume will be published digitally by the UGS, and digital versions of posters can also be included in the volume. Manuscripts are due to the proceedings volume editor by November 31, 2014. If interested in contributing a paper or poster on Basin and Range seismic-hazard research or public policy, please submit a title by September 30, 2014 to:

    William Lund, Proceedings Volume Editor | Utah Geological Survey | tel 435-865-9034 | fax 435-865-9037

    For additional information and online registration, see the BRPSHSIII webpage at

    [taken from the announcement]

    Categories: AZGS Web Posts

    Asteroids named after two ASU professors

    Sun, 2014-08-24 18:51
    Asteroids have been named after two ASU professors, Phil Christensen and Dave Williams. The two planetary geologists, both faculty members in ASU’s School of Earth and Space Exploration.

    Nikki Cassis at ASU reports that Asteroid (10461) Dawilliams was discovered on December 6, 1978, by E. Bowell and A. Warnock at Palomar Observatory. It orbits about 2.42 astronomical units from the Earth in the Main Belt, the vast asteroid belt located between the orbits of Mars and Jupiter. [right, image credit: NASA/JPL-Caltech]
    Also honored with an asteroid named for his work is Christensen, the instrument scientist for the OSIRIS-Rex Thermal Emission Spectrometer, a mineral-scouting instrument on the OSIRIS-REx mission to asteroid Bennu. He was also the principal investigator for the infrared spectrometers and imagers on NASA’s Mars Global Surveyor, Mars Odyssey, and Mars Exploration Rovers.

    The asteroid is named (90388) Philchristensen and like Williams’ it too is a Main Belt asteroid that is relatively small – approximately 4.6 kilometers (2.8 miles) across. It was discovered November 24, 2003 by the Catalina Sky Survey. It also poses no risk of collision with Earth.

    The naming of asteroids is serious business, presided over by the International Astronomical Union, an organization of professional astronomers.

    Upon its discovery, an asteroid is assigned a provisional designation by the Minor Planet Center of the IAU that involves the year of discovery, two letters and, if need be, further digits. When its orbit can be reliably predicted, the asteroid receives a permanent number and becomes eligible for naming. Proposed names must be approved by the IAU’s Committee on Small Body Nomenclature.

    Although many objects end up being named after astronomers and other scientists, some discoverers have named the object after celebrities. All four Beatles have their names on asteroids, for example, and there is even one named after James Bond – Asteroid (9007) James Bond.

    “I was very surprised to receive this honor from the astronomical community. Only a select few of the Dawn at Vesta participating scientists, who did exemplary work during the mission, were so honored,” said Williams, whose expertise in mapping of volcanic surfaces has been key to developing geologic maps of planetary bodies that include Mars, Io and Vesta.

    Christensen and Williams share this honor with several colleagues in the School of Earth and Space Exploration. The following all have namesakes in the sky:
    • Professor Erik Asphaug - Asteroid (7939) Asphaug
    • Professor Jim Bell - Asteroid (8146) Jimbell
    • Foundation Professor and SESE Director Lindy Elkins-Tanton - Asteroid (8252) Elkins-Tanton
    • Professor Emeritus Ronald Greeley - Asteroid (30785) Greeley, and Greeley’s Haven (on Mars)
    • Regents Professor Emeritus Carleton Moore - Asteroid (5046) Carletonmoore
    • Regents’ Professor Sumner Starrfield - Asteroid (19208) Starrfield
    • Professor Meenakshi Wadhwa - Asteroid (8356) Wadhwa
    Taken in part from the ASU news release
    Categories: AZGS Web Posts

    Kilometer-long crack opens in Hermosillo - an earth fissure?

    Sun, 2014-08-24 17:08
    A kilometer-long fissure opened up along Mexican Highway 4 between Hermosillo and the Gulf of California coast recently.   Hermosillo Desde el Cielo flew a drone along the fissure capturing excellent video of the  8-m deep feature.

    The local newspaper is reporting that farmers had built levees to collect rainwater.  Such features show up in the drone video, striking perpendicular to the fissure.

    AZGS geologists who reviewed the video and reports say it looks like earth fissures found in Arizona and other areas subject to rapid groundwater withdrawal and subsidence.

    In Arizona we've seen fissures open up in hours during heavy monsoon rains, as the water enters small cracks that extend down hundreds of feet in depth.  The water rapidly erodes the soft basin sediments, carrying them for hundreds or thousands of feet laterally.

    The pooling of rainwater on the ground over an incipient fissure could provide the volumes of water comparable to that of a big rain storm, and cause similar erosion.   So, in this scenario, the fissure does not so much open by extension as the sides are quickly washed away into the long deep narrow incipient crack.   However, it's unprecedented to see one this big form so quickly.

    Categories: AZGS Web Posts

    Ho hum, another M3.2 Duncan aftershock

    Thu, 2014-08-21 02:32

    Aftershocks continue in the Duncan area with a M3.2 event on Tuesday night at about 8:16 pm.
    [right, orange star marks epicenter. Credit, USGS]

    Smaller aftershocks are more common but are not being reported by the USGS.  AZGS is monitoring all the aftershocks with a temporary seismometer network deployed around the main shock area.
    Categories: AZGS Web Posts