Archive for December, 2011

Science Nation–Exploring fault zones

parkfield fault zoneScience Nation, the National Science Foundation’s online magazine, presents an excellent, short video on drilling into an active fault zone.  Researchers from Penn State University examined rock recovered from the Parkfield, California, segment of the San Andreas Fault.  What they discovered was incompetent clay-rich material, which explains the aseismic nature of deformation there.

Other fault segments host more competent rock that seize up until increasing stress causes the rock to fail brittlely. Earthquake!

Mike Conway (26 December 2011)

WESTCARB–Sacramento-San Joaquin Basin

cg_drill_12_19-20The West Coast Regional Carbon Sequestration Partnership (WESTCARB) is drilling a deep well in the Sacramento-San Joaquin Basin, California, to characterize two potential CO2 storage areas.  The first is a depleted natural gas reservoir and the second an underlying saline formation. 

Drilling began on 1 December and 0n 21 December the drillers were 7000 feet deep in a mixed sandstone-shale unit. 

For daily drilling reports and graphic, visit their Drilling Progress page. 

Mike Conway (24 December 2011)

QuakeSmart – Mitigation Works for Business

The Federal Emergency Management Agency’s (FEMA) newest publication, FEMA P-811, contains a mitigation toolkit for businesses. image

From their introductory page, “Actionable and scalable guidance and tools to the private sector, its owners, managers, and employees about the importance of earthquake mitigation and the simple things they can do to reduce the potential of earthquake damages, injuries, and financial losses.”

The QuakeSmart website includes documents, videos, and artwork.  Some prominent chapter headings:

  • How Earthquakes Affect Businesses
  • How QuakeSmart Can Help
  • Step 1: Identify Your Risk
  • Step 2: Make a Plan
  • Step 3: Take Action

There are three videos including, Mitigation Works for Business.

Mike Conway (24 December 2011)

Colorado City Earthquakes

A small swarm of earthquakes occurred south of Colorado City between December 12th and 13th. The largest event in the swarm was magnitude 3.1, the smallest was 1.7.

Year Month Day Lat Long Depth Hour Min Sec Mag (local) Location Catalog
2011 12 13 36.765 -113.018 13.9 0 43 0 2.8 Colorado City, AZ UU
2011 12 13 36.764 -113.017 8.2 23 36 22 3.1 Colorado City, AZ UU
2011 12 12 36.782 -113.001 2.8 9 44 37 1.7 Colorado City, AZ UU
2011 12 12 36.757 -113.02 7.9 8 3 0 2.2 Colorado City, AZ UU

This small swarm occurred between the terminus of the Southern Intermontain Seismic Belt (ISB) and the start of the Northern Arizona Seismic Belt. This region regularly experiences small to moderate sized earthquakes.  Earlier this summer there were several quakes of similar magnitude in the same area between the Hurricane and Sevier/Toroweap faults.

The National Earthquake Information Center Reports of the southern ISB:
The ISB in southern Utah coincides with a transition between east-west-directed stretching in the Basin and Range to the west and more stable crust of the Colorado Plateau to the east. Tectonic movement on generally north-trending, east- and west-dipping range- and plateau-bounding normal faults, which results in horizontal extension, characterizes this part of Utah. The Sevier Valley is an area of variable and complex deformation involving significant components of folding and both normal and strike-slip faulting. The most prominent geologically young faults in southwestern Utah are the Hurricane and Sevier faults. The Hurricane fault forms the west-facing Hurricane Cliffs, which define the eastern edge of the Basin and Range within the ISB. Faults in the ISB in southern Utah locally show evidence of displacement younger than 10,000 years, but average recurrence intervals are generally longer than those on faults in the ISB in northern Utah. Recurrence intervals for surface faulting on the most active segments of ISB faults in southern Utah are generally many thousand to tens of thousands of years.

http://earthquake.usgs.gov/earthquakes/recenteqsus/Quakes/uu00008793.php#summary

The largest event in the swarm (3.1) as seen on the Arizona Broadband Seismic Network

 

 

Lisa LinvilleDecember 17, 2011

Lake Mary Fault – Potential Earthquake Threat to Flagstaff, Arizona

The Lake Mary Fault, situated immediately south of Flagstaff, Arizona, Dave brumbaughrepresents the greatest earthquake hazard to the more than 70,000 people of Flagstaff and environs. In a new video, Dr. David Brumbaugh, Arizona Earthquake Information Center (AEIC) at Northern Arizona University, narrates the, “Lake Mary Fault – Potential Earthquake Threat to Flagstaff, Arizona”. Since the mid-1980’s, Dr. Brumbaugh has studied faults and monitored earthquakes of northern Arizona using the AEIC seismic network.

As Dave Brumbaugh notes in the video, the maximum probable earthquake of the ~ 25 mile long, Lake Mary fault is estimated at magnitude (M) M6.9 to M7.0. An event of that magnitude wouldlake Mary swarm-video have dire consequences for older structures and for unreinforced masonry buildings in the Flagstaff area. And Flagstaff is no stranger to moderate-sized earthquakes. From 1906 to 1912, three magnitude 6.0 to 6.2 earthquakes occurred within 24 miles of the town.

Video LinkLake Mary Fault – Potential Earthquake Threat to Flagstaff, AZ

Mike Conway (9 December 2011)

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