Close to 1,000 earthquakes shook Ariz. in 3-year period, study shows

August 14, 2012

Earthquakes are among the most destructive and common of geologic phenomena. Several million earthquakes are estimated to occur worldwide each year, with the vast majority being too small to feel but their motions can be measured by arrays of seismometers.

Historically, most of Arizona has experienced low levels of recorded seismicity, with infrequent moderate and large earthquakes in the state. Comprehensive analyses of seismicity within Arizona have not been previously possible due to a lack of seismic stations in most regions, contributing to the perception that widespread earthquakes in Arizona are rare. USArray station Download Full Image

Debunking that myth, a new study published by researchers from Arizona State University found nearly 1,000 earthquakes rattling the state over a three-year period.

Jeffrey Lockridge, a graduate student in ASU’s School of Earth and Space Exploration and the project’s lead researcher, used new seismic data collected as part of the EarthScope project to develop methods to detect and locate small-magnitude earthquakes across the entire state. EarthScope’s USArray Transportable Array was deployed within Arizona from April 2006 to March 2009 and provided the first opportunity to examine seismicity on a statewide scale. Its increased sensitivity allowed Lockridge to find almost 1,000 earthquakes during the three-year period, including many in regions of Arizona that were previously thought to be seismically inactive.

“It is significant that we found events in areas where none had been detected before, but not necessarily surprising given the fact that many parts of the state had never been sampled by seismometers prior to the deployment of the EarthScope USArray,” says Lockridge. “I expected to find some earthquakes outside of north-central Arizona, where the most and largest events had previously been recorded, just not quite so many in other areas of the state.”

One-thousand earthquakes over three years may sound alarmingly high, but the large number of earthquakes detected in the study is a direct result of the improved volume and quality of seismic data provided by EarthScope. Ninety-one percent of the earthquakes Lockridge detected in Arizona were “microquakes” with a magnitude of 2.0 or smaller, which are not usually felt by humans. Detecting small-magnitude earthquakes is not only important because some regions experiencing small earthquakes may produce larger earthquakes, but also because geologists use small magnitude earthquakes to map otherwise hidden faults beneath the surface.

Historically, the largest earthquakes and the majority of seismicity recorded within Arizona have been located in an area of north-central Arizona. More recently, a pair of magnitude 4.9 and 5.3 earthquakes occurred in the Cataract Creek area outside of Flagstaff. Earthquakes of magnitude 4.0 or larger also have occurred in other areas of the state, including a magnitude 4.2 earthquake in December 2003 in eastern Arizona and a magnitude 4.9 earthquake near Chino Valley in 1976.

“The wealth of data provided by the EarthScope project is an unprecedented opportunity to detect and locate small-magnitude earthquakes in regions where seismic monitoring (i.e. seismic stations) has historically been sparse,” explains Lockridge. “Our study is the first to use EarthScope data to build a regional catalog that detects all earthquakes magnitude 1.2 or larger.”

His results appear in a paper titled “Seismicity within Arizona during the Deployment of the EarthScope USArray Transportable Array,” published in the August 2012 issue of the Bulletin of the Seismological Society of America. Ramon Arrowsmith and Matt Fouch, professors in ASU’s School of Earth and Space Exploration, are Lockridge’s dissertation advisors and coauthors on the paper. Fouch also is a geophysicist at the Carnegie Institution’s Department of Terrestrial Magnetism in Washington, D.C.

“The most surprising result was the degree to which the EarthScope data were able to improve upon existing catalogs generated by regional and national networks," Lockridge says. "From April 2007 through November 2008, other networks detected only 80 earthquakes within the state, yet over that same time we found 884 earthquakes, or 11 times as many, which is really quite staggering. It’s one of countless examples of how powerful the EarthScope project is and how much it is improving our ability to study Earth.”

Lockridge also is lead author on a study that focuses on a cluster of earthquakes located east of Phoenix, near Theodore Roosevelt Lake. The results from this study will be published in Seismological Research Letters later this year. In his current studies as doctoral student, Lockridge is using the same methods used for Arizona to develop a comprehensive earthquake catalog for the Great Basin region in Nevada and western Utah.

Nikki Cassis

marketing and communications director, School of Earth and Space Exploration

Construction projects under way on ASU campuses

August 14, 2012

As the 2012-2013 academic year begins, ASU has just completed construction on several new buildings, including Interdisciplinary Science and Technology Building 4 and Villas at Vista Del Sol on the Tempe campus, Century Hall on the Polytechnic campus, and Casa deOro on the West campus.

But the work isn’t done yet. University construction on five other buildings is scheduled to be completed within the next year. McCord Hall Download Full Image

Tempe campus – Manzanita Hall

The Manzanita Hall renovations have been in progress for the last year and are scheduled for completion before the start of the fall 2013 semester. After being in continuous use for 40 years, the residence hall was in need of major restorations and improvements.

The renovation, a partnership endeavor between ASU and American Campus Communities, involves the installation of new infrastructure systems, including an overhaul of the building’s electrical, plumbing and air conditioning.

Manzanita also will receive new room configurations, which are planned to accommodate a total of 816 beds – down from the original 1,000-bed count – as well as new amenities such as a workout room, a small theater, student gathering and meeting rooms, and wireless service. The renovations additionally include new student lounges that connect every two floors as “neighborhoods.”

Tempe campus – McCord Hall

The W. P. Carey School of Business also will have a new building on the Tempe campus with the construction of McCord Hall, set for completion in June 2013. The four-story building emphasizes sustainability, with a minimum goal of LEED silver certification.

McCord Hall will house MBA, executive MBA, MRED, executive education programs, and any other master's programs. The building also will accommodate MBA Administration and Career Management services for graduate students, and undergraduate Carey Academy Suite and team rooms.

The hall will feature state-of-the-art classrooms and computer labs, as well as specialized industry spaces, executive education facilities, conference/seminar rooms, interview and team rooms, and study areas for undergraduate, graduate and executive students.

Tempe campus – Sun Devil Fitness Complex

The Tempe campus Sun Devil Fitness Complex construction project – a direct response to student demand and input – will create an addition to the existing facility that will feature a large, multiple-court gym, strength and cardio areas, free weights area/small gym, multi-purpose space, wellness space, and a social recreation area. A partial renovation to the existing building will be completed as well. The project is set to be finished by August 2013.

Polytechnic campus – Sun Devil Fitness Complex

The Tempe campus isn’t the only one with new facilities under construction. The Polytechnic Campus Sun Devil Fitness Complex is set to be completed in December of this year, and similar to the Tempe addition, is being created in direct response to student demand and input.

The building plans feature a two-story, sustainable structure with a minimum of LEED silver certification. Once complete, students can take advantage of new competition play fields in the form of two soccer fields and one softball field and approximately 10,000 square feet of state-of-the-art weight and fitness areas that include cardiovascular equipment, strength machine equipment and free weights.

The facility will accommodate three multipurpose studios for group fitness classes, such as aerobics, boot camp, yoga, and Pilates, and student club use. The building also will house a two-court gymnasium for basketball, volleyball and badminton, as well as a multi-activity gymnasium for campus events, conference space, concerts and indoor soccer.

That’s not all – the structure will house two racquetball courts, expanded Health Services programming, an outdoor leisure pool with lap lanes, and programs and services open during the day, evening and weekends.

West campus – Sun Devil Fitness Complex

Wrapping up in January 2013, the West Campus Sun Devil Fitness Complex is planned to be a three-story structure with a minimum of LEED silver certification.

The facility will include a six-acre multipurpose field, a green quad for campus activities, a 10,000-square-foot weight and fitness area, as well as studios for group fitness classes and clubs. The building also will house a two-court gymnasium for sports and campus events, two racquetball courts, wellness space with mediated conference room, demonstration kitchen, fitness assessment area, and three alternative medicine studios.

Students can take a dip in a 5,500-square-foot pool with lap lanes for small swim meets as well as plenty of deck space for socializing and games. The facility also will include a social gaming space with lounge furniture, flat screen video displays with gaming systems, pool tables and ping-pong tables, bike rentals and repairs, a three-lane lane indoor running track, exterior exercise terraces, and new locker facilities.

Juno Schaser

Event coordinator, Biodesign Institute