Archive for the 'Weather' Category

Earthquake Exceeded North Anna’s Designed Tolerances

Published by Waldo Jaquith on September 9, 2011 in Business and Weather. 2 Comments

Last month’s earthquake exceeded the design standards of the North Anna nuclear plant, the Associated Press reports. That came out after a Nuclear Regulatory Commission inspection of the plant, using USGS data. That’s based not on the magnitude of the quake, but based on the peak ground acceleration (PGA)—the measurement of how hard and fast the ground was shaking at the plant. You can see that on the USGS’ “shakemap” of the earthquake. PGA varies enormously, based on distance from the quake, soil makeup, and other factors. It’s measured in G-force, a term that you’ll have heard in the descriptions of the forces on fighter pilots when pulling sharp turns, or on astronauts upon launch. Lake Anna was constructed to withstand 0.12–0.18g, but the 5.8 earthquake caused peak ground movement of 0.26g, substantially more than the designed limits of the reactor.

The plant remains closed, as it has been since the August 23 earthquake. The NRC says that it suffered “minor” damage, but no specifics have been provided.

5.8 Earthquake Centered on Mineral

Published by Waldo Jaquith on August 23, 2011 in Weather. 15 Comments

An impressively strong earthquake shook up the central east coast just a few minutes ago, a 5.8 magnitude quake centered on Mineral, which is midway between Charlottesville and Richmond. Though we’ve had a few quakes of this size in the past few hundred years, it’s been a while since we’ve had one this big. We had one in 2001, a 4.5 in 2003, and a 2.7 in Nelson in late 2009, but a 5.8 is a lot stronger than any of those. The shaking was felt from North Carolina clear to New York. What was it like where you are?

5pm Update: Note that it was just in March when Dominion Power’s Lake Anna nuclear plant was named the 7th most at-risk nuclear plant, in the event of an earthquake. So what was the facility designed to withstand? “A magnitude 5.9–6.1 earthquake.” The plant’s reactors shut down automatically, but after the Fukushima nuclear plants reduced the surrounding area to a radioactive wasteland following their March earthquake, that’s not as reassuring as Dominion might think it is.

Things Are On Fire

Published by Waldo Jaquith on February 19, 2011 in Weather. 9 Comments
Smoke
The smoke from a wildfire between between 29N and the Blue Ridge Mountains. By Jocelyn Dale / CC BY-NC-ND 2.0

There are brush fires all over the area, as CBS-19 and NBC-29 report, or as you might have noticed if you’ve breathed today. The high wind means that small fires quickly become big fires. Lots of people are providing reports of small fires via Facebook, and Albemarle’s Fire Incident Display System is thick with responses to brush fires. Over at The Hook, Hawes Spencer has a dramatic photo of a wall of flames advancing through an Ivy neighborhood, said to be the result of some jackass deciding that the day with a 20 mph average wind speed would be the day to burn some brush. There are also good-sized fires in Esmont, 53, north of Crozet, and a thousand-acre fire in Louisa.

Here in northwest Albemarle, the air has been filled with smoke all day, the result of a fire between 20N and 29N. My house is perched on the side of the Southwest Mountains, and as the sun set, the low rays illuminated the huge cloud of smoke that is hovering over the area.

The strongest winds should peter out overnight, although it’ll still be decently breezy tomorrow, so it could be a bit until these fires are out and new ones stop popping up.

Council Votes for Dredging; Pipeline Loses

Published by Waldo Jaquith on September 21, 2010 in Development, Politics and Weather. 15 Comments

City Council has voted 5-0 in favor dredging the Rivanna Reservoir rather than building a pipeline, Hawes Spencer writes for The Hook. The vote was held just before midnight, after dozens of speakers—two to one in favor of dredging—expressed their support for one plan or another. The plan also includes increasing the height of the existing Ragged Mountain dam by thirteen feet.

This unanimous vote represents a pretty enormous turn-around for Council, which had been all about the pipeline just a few years ago, and did a 180° on this after a great deal of study and community input. This looks like a big victory for Mayor Dave Norris, who at least appears publicly to have been the guy who turned around opinion on what to do about our long-term water supply.

10:30 PM Update: City spokesman Ric Barrack points out that the pipeline is still in the plan, which is a pretty important correction. It’s just no longer the plan.

Tornado at Barracks Road?

Published by Waldo Jaquith on June 24, 2010 in Weather. 33 Comments

A particularly nasty storm swept through town a couple of hours ago, and based on the reports right now, it sure sounds like a small tornado may be to blame for the corridor of damage that high winds left behind. Accounts by local media outlets and on Twitter report trees down, power out for 41,000 people, and a bunch of reports of property damage. A lot of the damage, at least anecdotally, is in a swath running from Best Buy through Barracks Road over to Ivy Road. While it could be a microburst, those generally last for less time, and are isolated to one location, rather than running along a path.

When we had a tornado in May 2000, it was a few days before the microburst was confirmed to be an F0 tornado, as the path of damage made obvious. On the other hand, our 2002 tornado was never confirmed as such.

At 5:00, I was on 81 in West Virginia, headed home after being out of town for a week, so I missed the whole affair. What was your experience? What do you think–bad thunderstorm, microburst, or tornado? Who’s got pictures?

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