Seismic issues rumble to surface

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CMRR: Critics point out much more research has to be done in design work

By John Severance

The general thrust of Joni Arends’ presentation at Tuesday night’s Chemistry Metallurgy Research Replacement (CMRR) Project meeting was that the facility had to be designed for an 8.0 magnitude earthquake.

Lab officials, meanwhile, contend that the design should be able to withstand a 7.27 earthquake.

So who is right?

“Some of the points that were brought up in presentations were addressed in responses provided to comments made on the CMRR Supplemental EIS,” LANL’s Larry Goen said Wednesday. “The information we have gathered from the paleoseismic investigations do not suggest earthquakes as large as Magnitude 8 occur on the Pajarito Fault System.”

Arends from Concerned Citizens of Nuclear Safety and registered geologist Robert Gilkeson beg to differ.
Arends said during her presentation that a safe and cost effective engineering design for the proposed facility must include the following:
• Buried active faults close to or below the proposed nuclear facility location;
• Site-specific velocity in volcanic layers down through the dacite (igneous, volcanic rock) to an approximate depth of 900 feet;
• Ground motions – single earthquakes and synchronous earthquakes;
• Kappa – a key parameter for the calculation of ground shaking.

Arends and Gilkeson insist none of these parameters have been taken into account.

Arends cited a 2004 report by LANL’s Ken Wohletz that showed the inferred locations of the north-south trending buried active faults 800 feet west and 2,000 feet east of the proposed facility.

“The buried active fault located 800 feet west of the proposed facility may be an extension of the Guaje Mountain Fault, which may generate ground motions close to the site,” she said

The response from the final CMRR Supplemental Environmental Impact Statement said, “The fault shown 800 feet west of the proposed CMRR-NF is an inferred fault, meaning that the fault is interpreted to be present at some depth below the location at which it is mapped.”

According to Gilkeson, LANL is located within an intracontinental seismically active subduction zone, named the Rio Grande Rift.

“A super volcano sits to the west of LANL and it is similar to the super volcano that formed Yellow Stone National Park,” Gilkeson said in an interview Friday in Santa Fe. “And geologists expect both super volcanoes to erupt some time in the future.”

Gilkeson said at LANL, two powerful eruptions more than a million years ago deposited the volcanic Bandelier Tuff with a thickness of 700 feet at the proposed facility. The thick volcanic ash deposits buried and reenergized a pre-existing network of faults dating back almost 16 million years ago.

“The buried active faults located close to the proposed CMRR-NF were not included in the assessment of the seismic hazard,” Gilkeson said.

DOE responded in the SEIS with “Dozens of mapping studies of the Pajarito fault system have been conducted, including state-of-the art high precision mapping in the vicinity of LANL.

“These studies clearly show that the Pajarito fault system is a series of normal slip faults that form the best-studied fault system in the Rio Grande rift.

“Admittedly, some parts of the fault have not been as well studied as others; these tend to be those portions outside of LANL especially where access issues are a problem.”

Goen said there has been active testing on the western boundary of the lab, which rides the Pajarito fault.
Arends said little testing has been north, east and south of the lab.

Gilkeson points out that the Pajarito Fault System is 30 miles long and greater than six miles wide with five fault systems.

These include the 36-kilometer Pajarito fault, the 12-kilometer long Santa Clara Canyon fault, the Rendija Canyon and Guaje Mountain faults, and the Sawyer Canyon fault.

“The so-called seismic experts need to do a kinematic study,” Gilkeson said. “They say absolutely nothing about the field work they have done.”

Editor’s note: More on the seismic issues at LANL will be featured this week in the Los Alamos Monitor.