Talk:Virginia Seismic Zone

5.9 Magnitude quake 2011-08-23

just experienced a side to side earthshake in Hampton Roads area 8/23/2011 at 1:53 pm

USGS Confirmation — Preceding unsigned comment added by 67.208.9.215 (talk) 18:05, 23 August 2011 (UTC)

USGS confirmed the earthquake at 1:50 PM Eastern Time (USA). Tremors felt in Manhattan. --Uncle Ed (talk) 18:27, 23 August 2011 (UTC)

USGS says 5.9 with updates coming. Also we need to consider downgrading the 1897 Giles earthquake from "largest" to "Large". Kanaugle (talk) 18:32, 23 August 2011 (UTC)

I agree re: Giles earthquake. The list of earthquakes lists Giles at 5.9, the detailed account of the 2011 refers to Giles as 5.8; the two need to be reconciled, and if Giles is equal should be listed as large. More appropriately, the adjective should simply be removed, as the reader can ascertain from the included measurements which listed earthquake was "largest" or tied for the title. Wolfraem (talk) 19:45, 23 August 2011 (UTC)

MODERATOR, please lock this ASAP

Self explanatory.... - Fan Railer (talk) 18:19, 23 August 2011 (UTC)

Have to disagree. It is a developing story.Kanaugle (talk) 18:30, 23 August 2011 (UTC)

I second. Wolfraem (talk) 20:45, 23 August 2011 (UTC)

Updates to the 2003 earthquakes

The section about the 2003 Earthquake needs updated too. Everyone wants to add their 2 cents about the one we just had, but the 2003 earthquake is still listed as the largest recorded with modern equipment, and notes that the largest was estimated to be a 5.8. 24.170.248.74 (talk) 18:34, 23 August 2011 (UTC)

Edits have been made to achieve more neutral delivery and align section with current information. Wolfraem (talk) 20:45, 23 August 2011 (UTC)

Richter vs. Moment Magnitude scales

I object to the use of "richer scale" in the article. Earthquakes are no longer measured by richer, but by moment magnitude scale, right?" can someone with more knowledge than me update this — Preceding unsigned comment added by 165.112.61.208 (talk) 18:38, 23 August 2011 (UTC)

It's not clear to me which scale was used for the older quakes. The Giles County quake link does not specify the scale, so did they use Richter or convert to Mw? Also, the Giles quake is still considered the most intense - it reached VIII on the Mercalli intensity scale (see Giles link), whereas the "current" one only hit VI (http://earthquake.usgs.gov/earthquakes/dyfi/events/se/082311a/us/index.html). — Preceding unsigned comment added by 71.207.23.157 (talk) 01:40, 24 August 2011 (UTC)

No 4.2 Aftershock

There was no 4.2 aftershock. There was a 2.8 aftershock, but it was at 2:46:50 PM local time. Any aftershock above 2.5 would be listed on teh USGS website. — Preceding unsigned comment added by Exit 0 (talk • contribs) 03:44, 24 August 2011 (UTC)

Rename (and somewhat revise) this article?

I am not a professional geologist, but as near as I can tell as a layman who has read a fair amount about seismology, neither the USGS nor any other authoritative body recognizes such a thing as the “Virginia Seismic Zone.” There are many references in the literature to the “Central Virginia Seismic Zone,” a roughly circular area centered in northern Cumberland County and extending eastward approximately to Richmond, southward approximately to Lynchburg, and northwestward approximately to Waynesboro.

The Central Virginia Seismic Zone is one of three distinct seismic zones in the state, the other two being the Giles County Seismic Zone in the southwest of the state (centered in Giles County) and a small part of the Eastern Tennessee Seismic Zone which extends (barely) into the southwestern tip of Virginia (though nearly all of the activity of this zone is in Tennessee). The most authoritative reference I have found thus far is an extensively annotated USGS map, "Earthquakes in Virginia and Vicinity, 1774-2004" by Arthur C. Tarr and Russell L. Wheeler (http://pubs.usgs.gov/of/2006/1017/).

Many of the earthquakes listed in this article occurred in the Giles County Seismic Zone, not in the Central Virginia Seismic Zone (or in the apparently spurious “Virginia Seismic Zone”). It might be most helpful to the layman if the article were simply renamed “Earthquakes in Virginia” or something similar, with an introductory paragraph mentioning the three distinct areas of greatest seismic activity. If the list of earthquakes were to be presented as a table, it might also have a column indicating in which seismic zone each quake occurred.

While I hope to find the time to do at least some of this work myself, this will not be possible in the short term. Also, I have not ever changed the name of an article and I would not know how to do it, assuming that there is consensus that this would be appropriate. Piperh (talk) 21:27, 25 August 2011 (UTC)

I'd be in favor of a rename. The Virginia Seismic Zone article is in the following categories:

• Category:Geology of Virginia - the use of Virginia Seismic Zone maps well to this category which is focused on the that state.
• Category:Earthquakes in Virginia also maps well to Virginia Seismic Zone
• Category:Geographic areas of seismological interest is a lightly populated and category with a seemingly random membership.
• Category:Seismic zones of the United States is another lightly populated category. At present it only has four articles and the other three all seem to be formally defined seimic zones.

The name Piperh suggested, Earthquakes in Virginia, plus minor reorganization of the article, makes perfect sense. This also would fit well as the main article for Category:Earthquakes in Virginia. We would remove the article from the "Seismic zones of the United States" category. As this article is so small I'm not sure how well it would work to split it into articles for the Central Virginia Seismic Zone, Giles County Seismic Zone plus moving content to the existing Eastern Tennessee Seismic Zone article.

I checked the article history. In February 2011 it was tagged for deletion due to copyvio of http://www.geol.vt.edu/outreach/vtso/VA-Eq.html That web page is titled "Virginia's Largest Earthquakes." It appears the term "Virginia Seismic Zone" was invented by a Wikipedia editor. The parent page for that web page mentions the Central Virginia Seismic Zone and Giles County Seismic Zone with the pages for those zones having maps. The zones are not adjacent in the sense that they to not immediately border one another. --Marc Kupper|talk 22:57, 25 August 2011 (UTC)

Update - I realized I'd forgotten to check on previous article names.

• The article started life as Earthquakes in Virginia in 21 March 2007.
• That same day the editor that created the article moved it to "Virginia seismic zone" with the comment "More general, and also from link at 2004 Virginia earthquake. Apparently it was not his/her intent to define a formal "zone" name.
• In 28 April 2008 it was moved to the present title, Virginia Seismic Zone, with the comment "'Virginia Seismic Zone' is a proper name and, as such, should be capitalized." Apparently that editor either found a source for the name or felt it must exist. I would notify the editor of this thread but the account has not been active on Wikipedia since 15 May 2008.

Thus if we move back to Earthquakes in Virginia it'll be full circle. :-) --Marc Kupper|talk 23:14, 25 August 2011 (UTC)

Right, it started as a list on the article Virginia. Not wanting to delete the info, I branched it off into this, and then when it was pointed out that the original info was copyrighted, I edited the list into a neutral format. I forget why it was renamed, but do recall thinking that it should have been "Central Virginia" if anything. Perhaps List of earthquakes in Virginia would be fine as well, since that's its primary function. The last few days have been a boon for the article, and its great that an effort is being put in here to figure out how to present the history.-- Patrick, _oѺ^∞ 02:25, 26 August 2011 (UTC)

The article title "List of earthquakes in Virginia" fits well with the current structure. However, I'm thinking we can pull some text and images from the USGS page for Virginia meaning the article would expand beyond a plain list. Thus Earthquakes in Virginia seems like a better long term name. --Marc Kupper|talk 23:31, 27 August 2011 (UTC)

Update - I suspect for now we should use List of earthquakes in Virginia. I've been trying to write some prose but am really struggling. I'll start a new section below on the challenges. --Marc Kupper|talk 20:44, 28 August 2011 (UTC)

New lead - sources needed

I started to work on a new lead that introduces the zones.

Plate tectonics cause most of the Earth's earthquakes at boundaries between moving plates. However, Virginia is in the middle of the North American plate, far from plate boundaries.

Wonderful! But now I'm wondering why we have earthquakes in VA. The article I was using as a source does not explain this.

I see that three zones, Central Virginia seismic zone, Giles County seismic zone, and Eastern Tennessee Seismic Zone got defined but it's not clear why these were defined rather than the system used in California which is based on individual Earthquake faults.

I got the impression a reason is because the USGS does not know where the faults are. Apparently in California the seismic monitoring network is dense enough the location of earthquakes can be pinpointed. In California our faults are constantly slipping meaning we see small earthquakes nearly every day. They are to small to be fault but are detected by instruments. Combined with the dense seismic monitoring network it means the location and depth of many of California's are well known.

What's not clear about Virginia is if the reasons for using zones rather than faults are because the USGS chose to not install a dense network and/or if the faults are largely static.

Anyway - I realized it's going to take more research to locate some reliable sources that explain why VA has earthquakes and also to explain why the USGS uses zones rather than naming the faults. Note that not all faults are mapped in California. From time to time we'll have an earthquake on a previously unknown fault. If a fault does not slip then it generates no data and we don't know about it. It's possible most of VA is like this. --Marc Kupper|talk 21:13, 28 August 2011 (UTC)

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