AZGS Web Posts

Magnitude 3.7 earthquake is largest one yet in Arizona swarm

Arizona Geology Blog - Sun, 2016-04-17 04:41
There was only one earthquake greater than magnitude 1.0 in the past week in the area of the quake swarm in northwest Arizona until Saturday night when a magnitude 3.7 event struck just after 9 p.m. local time, followed by three apparent aftershocks in less than an hour.  The main event is the largest one yet in the swarm of the past few weeks, surpassing the previous one of M=2.7.   [Right, orange star marks the epicenter of the M=3.7 quake, with contours showing distribution of shaking.   Red lines are active faults.  Credit, USGS]

There are reports of the earthquake being felt in the sparsely populated region.

[Below, magnitudes, location, and time of Saturday night quakes in the swarm area.]

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Small quake in Intermountain Seismic Belt south of Utah

Arizona Geology Blog - Sat, 2016-04-16 09:06
A small earthquake, magnitude 2.0 hit in the midst of the active faults of the Intermountain Seismic Belt at 4:28 a.m. Friday morning, just south of the Utah border.  This does not appear to be related to the earthquake swarm of the past couple of weeks going on about 50 km to the southwest.   There have been only a few small events in that area in the past week.  [Right, orange star marks Friday's epicenter. Red lines are active faults. Credit, USGS]
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Hunt for helium ramps up in Arizona

Arizona Geology Blog - Tue, 2016-04-12 15:35
Three companies now have active exploration programs underway in Arizona to develop underground helium resources.

Ranger Development, a Texas-based joint venture, made a presentation last Friday to the Arizona Oil & Gas Conservation Commission on their efforts to reopen the Pinta Dome and Navajo Springs helium fields in the Holbrook basin of eastern Arizona.   The fields are at the northern edge of the Holbrook salt basin and potash deposit.   [note, the original post mis-stated the name of the Navajo Springs field]

They described the two fields as some of the richest in the world in terms of percentages of helium in the reservoir.   In most situations, 1% helium is considered economic.  In the Arizona fields, helium accounts for ~8% with the remainder almost entirely nitrogen, according to the Ranger presentation. They said Arizona is the "Saudi Arabia of helium."

The two fields were shut-in in the 1970s due to low prices resulting from the US government selling the gas at a low price from the national reserves rather than the fields being depleted.  Since then, there has been little incentive for the private sector to explore and develop helium resources. However, the US is getting out of the helium business, and extended sales from the reserve while private sources are developed.  There is a global shortage of helium, pushing up prices.  Helium prices are about $90 per thousand cubic feet (MCF) on the spot market, but Ranger said there is a great variability allowing them to sell their product at $125 to as high as $200 per MCF.   They expect to have the processing plant running by May, 2016 to separate the helium from nitrogen and start commercial production.  The plant will handle 2 million cubic feet of gas (MMCF) per day. The primary reservoir target is the Coconino Sandstone, followed by the Supai Formation.

Ranger Development filed permits for wells with the Oil & Gas Conservation Commission for new drilling, and got a spacing exemption for two wells to address local geologic conditions.  They  estimate about 1 billion cubic feet of gas remaining in each of the two fields. 

Meanwhile Blackstone Exploration got permits approved by the Commission for 5 new gas wells in the area, which are expected to target helium as well.  

A third company has advised us that they are getting ready to file their drilling permits.
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Earthquake activity ramps up in southeastern Arizona

Arizona Geology Blog - Tue, 2016-04-12 10:08
There have been at least 22 small earthquakes in the last 24 hours south of Duncan in southeastern Arizona, near the New Mexico border, according to Dr. Jeri Young, who manages the state seismic monitoring network here at AZGS.   A magnitude 3.0 earthquake at 8:22 a.m. today is the largest one detected.  There are reports of shaking being felt  by residents in the area.   [Right, orange star marks the epicenter of the M=3.0 event. Credit, USGS]

The earthquakes are occurring in the same area that experienced a magnitude 5.3 quake in June 2014.   Aftershocks have continued in the area since then.

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Earthquake in northwest Arizona - magnitude 3.4

Arizona Geology Blog - Fri, 2016-04-08 07:59
There was a magnitude 3.4 earthquake in northwest Arizona at 2:23 a.m. local time this morning.   The preliminary USGS location puts it about 30-40 km east of the ongoing earthquake swarm west of the Grand Wash Cliffs.  We are examining the records to see if adding data from the Arizona seismic network will change the location.   [Right, orange star marks epicenter.  Red lines are active faults, which are part of the Intermountain Seismic Belt. Credit, USGS]
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Earthquake swarm continues, M=2.7 is largest one yet

Arizona Geology Blog - Thu, 2016-04-07 08:25
The earthquake swarm in northwest Arizona continues with two events occurring shortly before 1 a.m. this morning, one at magnitude 2.7 and another two minutes later with magnitude 2.2.   The locations are being replotted by Dr.Jeri Young here at AZGS, using data from the Arizona Broadband Seismic Network that we manage.  This could result in the epicenters being revised by a number of kilometers based on previous re-calculations.  [Right, today's quakes are shown in orange. The blue dot is Wednesday's event.  The yellow dots are some of the previous events.  Red lines are active faults. Credit, USGS]

The swarm began March 28 and we now have recorded 22 events, ranging in magnitude 0.7 to today's 2.7.     This is a remote area and there are no reports of anyone feeling the quakes, let alone any damage.   The area sits between the Mesquite and Grand Wash faults, at the eastern edge of the Basin and Range Province which is still stretching east-west, and at southern end of the Intermountain Seismic Belt.

The Arizona seismic network is funded by internal funds generated by the Arizona Geological Survey. We receive no state or federal funds to operate the network or process the data.   

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Another small quake today in NW Arizona swarm

Arizona Geology Blog - Wed, 2016-04-06 15:02
We had a magnitude 2.4 earthquake this morning at 10:12 a.m. local time in area between the Mesquite and Grand Wash faults in northwest Arizona along the Nevada border.  This brings the total to 19 events since March 28. This is the second largest quake in the series, with the biggest one at M=2.6.  However, given the remote location, these magnitudes will have some margin of error in location and size.   [Right, orange star marks the epicenter of this latest quake. Credit, USGS]

Meanwhile, our news release on the weekly swarm of earthquakes in the area has been picked up by news media nationwide.    Alexa Liacko, reporter for Tucson's  KGUN channel 9 news, interviewed me this afternoon about the quakes and what it means for Arizonans [below].

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Arizona Oil & Gas Conservation Commission continued for 6 years

Arizona Geology Blog - Wed, 2016-04-06 09:45
Gov. Doug Ducey signed SB1059, continuing the Arizona Oil & Gas Conservation Commission for 6 years, until July 1, 2022.  The Sunset Review panel had originally recommended an 8 year continuation but the Arizona House cut that to match the Sunset Review for the Dept. of Environmental Quality.    Gov. Ducey has proposed shifting the duties to provide technical and admin support to the Commission from AZGS to ADEQ, starting July 1, 2016, as part of his consolidation plans which involve transferring the AZGS duties to the University of Arizona.

The Legislative Fact Sheet on the continuation bill states:

In July 1991, the Legislature eliminated the Arizona Oil and Gas Conservation Commission (OGCC) agency and attached the OGCC governing board to the Arizona Geological Survey (AZGS). The OGCC consists of the State Land Commissioner and five members appointed by the Governor, only three of whom may be of the same political party. Appointed members must be United States citizens and Arizona residents of at least five years (A.R.S. § 27-514).
The OGCC administers and enforces state laws with the purpose of: 1) conserving and preventing waste of oil, gas and geothermal resources; 2) providing for protection of owners of land wherein these resources lie; 3) encouraging responsible development of these resources; 4) encouraging a continuous and economic supply of and demand for these resources; and 5) safeguarding the health, property, environment and public welfare of the citizens of this state (A.R.S. § 27-502).
The OGCC fulfills its mission by: 1) issuing permits for oil, gas and geothermal wells; 2) monitoring and inspecting wells and facilities for compliance with rules; 3) maintaining rules; 4) compiling and maintaining drilling, production and subsurface data for public use; 5) coordinating enforcement with the Attorney General; and 6) preparing and publishing geologic studies to encourage exploration for and development of Arizona’s oil, gas and geothermal resources.
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Update on northwest Arizona earthquake swarm - 19 events so far

Arizona Geology Blog - Tue, 2016-04-05 14:30
 On March 29th, a magnitude (ML) 2.3 earthquake occurred about 23 miles south-southwest of Littlefield, Arizona. This event marked the onset of a swarm of 18 small magnitude earthquakes that continued through April 3rd. The largest event, ML 2.6, occurred at 8:36 am on April 3rd. There were no reports of damage or injuries.  [Top right. The location of the 19 seismic events in northwestern Arizona; red circles with magnitudes of each event; red lines show location of known, active faults; vertical white line is the NV-AZ border. Background image by Google Earth.]

The magnitude, date, and location of events are tabled below. The Google Earth map shows the locations of individual events which form a distinctly northwest trend. Also included for the ML 2.6 event are seismograms from the Arizona Geological Survey’s Arizona Broadband Seismic Network.

Active faults in the vicinity of the earthquake swarm include the Mesquite/Overton Arm, about 10 miles north along the western front of the Virgin Mountains, and the Grand Wash Fault system 11 miles to the east. The latter represents the boundary between the Colorado Plateau and the Basin and Range Provinces, an area with extensive historical earthquake activity.

Both fault systems are normal faults with down-dropping western blocks, characteristic of many active faults in the Basin and Range Province of northwestern Arizona and Nevada.

The northwest trend of this earthquake swarm (see above) is similar to other earthquake sequences observed in central and northern Arizona. In addition, strong lineaments in the nearby landscape suggests that there are potentially active faults immediately north of the largest event. More investigative mapping is needed to determine if the lineaments in the general area are indeed active faults.  

The 2.0+ events were resolved from data of the Arizona Integrated Seismic Network, while the small magnitude events were approximately located by the Nevada Seismological Laboratory. The small magnitude and dearth of seismometers in this remote area precludes more precise locations. Calculating depths of the individual events in northwestern Arizona’s rugged terrain was similarly difficult, resulting in a broad range of depths from 0.0 miles to 8.6 miles.  [Bottom right, seismograms from AZ stations for the ML 2.6 April 3rd event.]

Over the past 22 months, moderate-size earthquakes have been reported in the Phoenix area - the Black Canyon City ML 4.1 and 4.0 events on the night of Nov. 2, 2015, which were felt widely in the Valley of the Sun; the Kachina Village ML 4.7 event of Nov. 30, 2015, felt in both Sedona and Flagstaff; and the ML 5.3 earthquake that rattled Duncan in eastern Arizona and resulted in aftershocks that were felt more than one year after the main shock. 

Table of earthquake events associated with the Mesquite swarm in northwestern Arizona,
29 March – 3 April 2016

Most Recent
to Oldest
Earthquake Date Magnitude (ML) Latitude (N) Longitude (W) 1 04/04/2016 1 36.489 113.989 2 04/03/2016 1.1 36.514 114.024 3 04/03/2016 2.6 36.456 113.979 4 04/03/2016 0.7 36.521 114.031 5 04/03/2016 1.1 36.481 113.971 6 04/03/2016 1.1 36.489 113.971 7 04/03/2016 1.0 36.489 113.989 8 04/02/2016 1.2 36.488 113.987 9 04/02/2016 1.0 36.473 113.979 10 04/02/2016 1.7 36.492 113.998 11 04/01/2016 1.5 36.493 114.002 12 04/01/2016 2.0 36.498 113.992 13 03/31/2016 1.6 36.486 113.922 14 03/30/2016 1.0 36.524 114.014 15 03/30/2016 1.7 36.439 113.969 17 3/29/2016 1.6 36.506 114.004 18 3/29/2016 0.8 36.483 114.004 19 3/29/2016 2.3 36.54 114.013

This material taken from a report prepared by Dr. Jeri, Young, AZGS, and posted at
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