Talk:1971 San Fernando earthquake

Epicenter location
The previous Wiki page stated, "In actuality, the epicenter of the quake was located underground, roughly at the intersection of Kenya Street and Wilbur Avenue in the Los Angeles district of Northridge" without listing references for this data.

However, the sources I cited indicate something else.

I have removed the original statement because there were no references, but I retained the original text above just in case the author wants to document the information. —Preceding unsigned comment added by 24.255.50.234 (talk • contribs) 06:04, 24 November 2005 (UTC)

Irony
Adjustment here. With regards to the 5/14 overpass collapsing twice, it's not actually ironic that it collapsed during the Sylmar quake and again during the Northridge quake - it's nothing more than unfortunate coincidence. I can't think of any circumstance that would be an ironic collapse of a freeway overpass. --Dennis The TIger 21:55, 9 February 2006 (UTC)


 * It could be. It was built again, and I'm sure it was built with earthquake prtections (I assumed that the original collapsed due to less strigent earthquake codes at the time of its erecting).  To see it collapse again after another earthquake IMO qualifies it as ironic.  But that may not be what the true definition of irony. - Hbdragon88 21:57, 9 February 2006 (UTC)


 * It might be ironic if they had done so with earthquake retrofitting, but that would likely be a sign of a job not done well. -- Dennis The TIger 21:59, 9 February 2006 (UTC)

6.6 Magnitude
The first paragraph states the magnitude as 6.6, yet the LAFire.com reference states 6.5. —Preceding unsigned comment added by 67.169.175.130 (talk • contribs) 03:54, 31 October 2007 (UTC)


 * LAFire.com was basing their number on a report from the following day's Herald-Examiner. I just looked at a copy of the 2/10/1971 L.A. Times and it also shows 6.5.  Either the number was later finalized at 6.6 or the publication that sourced 6.6 is incorrect.


 * Also, the Times reports a different fault (San Gabriel Fault) and slightly different time (6:00:42). But with all that was happening right after the earthquake, some of the newspaper accounts may be off.   Alanraywiki 04:44, 31 October 2007 (UTC)

According to the USGS website (http://earthquake.usgs.gov/earthquakes/states/events/1971_02_09.php) the earthquake measured 6.6 on the scale.

This destructive earthquake occurred in a sparsely populated area of the San Gabriel Mountains, near San Fernando. It lasted about 60 seconds, and, in that brief span of time, took 65 lives, injured more than 2,000, and caused property damage estimated at $505 million.

The earthquake created a zone of discontinuous surface faulting, named the San Fernando fault zone, which partly follows the boundary between the San Gabriel Mountains and the San Fernando - Tujunga Valleys and partly transects the northern salient of the San Fernando Valley. This latter zone of tectonic ruptures was associated with some of the heaviest property damage sustained in the region. Within the entire length of the surface faulting, which extended roughly east-west for about 15 kilometers, the maximum vertical offset measured on a single scarp was about 1 meter, the maximum lateral offset about 1 meter, and the maximum shortening (thrust component) about 0.9 meters.

The most spectacular damage included the destruction of major structures at the Olive View and the Veterans Administration Hospitals and the collapse of freeway overpasses. The newly built, earthquake-resistant buildings at the Olive View Hospital in Sylmar were destroyed - four five-story wings pulled away from the main building and three stair towers toppled. Older, unreinforced masonry buildings collapsed at the Veterans Administration Hospital at San Fernando, killing 49 people. Many older buildings in the Alhambra, Beverly Hills, Burbank, and Glendale areas were damaged beyond repair, and thousands of chimneys were damaged in the region. Public utilities and facilities of all kinds were damaged, both above and below ground.

Severe ground fracturing and landslides were responsible for extensive damage in areas where faulting was not observed. The most damaging landslide occurred in the Upper Lake area of Van Norman Lakes, where highway overpasses, railroads, pipelines, and almost all structures in the path of the slide were damaged severely. Several overpasses collapsed. Two dams were damaged severely (Lower Van Norman Dam and Pacoima Dam), and three others sustained minor damage. Widespread landslides and rockfalls blocked many highways in the area.

Felt throughout southern California and into western Arizona and southern Nevada. No foreshocks were recorded, but aftershocks were reported in the area for several months.

Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993. —Preceding unsigned comment added by 64.210.199.233 (talk) 17:16, 21 January 2010 (UTC)


 * The article clearly says that 3 people were killed by the collapses of Olive View Hospital but it does not specify how many were killed by the collapse of the Veterans Administration Hospital. I found a NOAA page that says 47 were killed by the collapse of the Veterans Administration Hospital so I will add that to the article. Sam Tomato (talk) 19:14, 2 May 2017 (UTC)

I intentionally wrote the paragraph that way, saying "which resulted in a large loss of life at the facility" because there are conflicting reports on the total number of casualties there. I think it's fine as it is and will be submitting it as GA soon. Dawnseeker2000 23:58, 2 May 2017 (UTC)

Dead link
During several automated bot runs the following external link was found to be unavailable. Please check if the link is in fact down and fix or remove it in that case!


 * http://maps.google.com/maps?q=34°+24.67'+N,+118°+24.04'+W&spn=.386934,.662750&t=h&iwloc=A&hl=en
 * In 1971 San Fernando earthquake on 2011-05-25 04:12:37, 404 Not Found
 * In 1971 San Fernando earthquake on 2011-06-06 15:00:57, 404 Not Found

--JeffGBot (talk) 15:01, 6 June 2011 (UTC)

Dead link 2
During several automated bot runs the following external link was found to be unavailable. Please check if the link is in fact down and fix or remove it in that case!


 * http://www.lafire.com/famous_fires/710209_SylmarEarthquake/020971_LAHerald_KillerQuake.htm
 * In 1971 San Fernando earthquake on 2011-05-25 04:12:37, 404 Object Not Found
 * In 1971 San Fernando earthquake on 2011-06-06 15:01:08, 404 Object Not Found

--JeffGBot (talk) 15:01, 6 June 2011 (UTC)

USGS photos of earthquake damage
I've uploaded one of the photos - there are many more (155 in total), if anyone feels like going through them - look |San+Fernando|Earthquake|1971 here. Mikenorton (talk) 21:57, 20 August 2012 (UTC)


 * Thanks, working on it. Dawnseeker2000   04:09, 14 April 2013 (UTC)

Olive view collapse
A project for a structural dynamics course (~1976) resulted in me analyzing the Olive View collapse. Photos published in a report on the construction of the building clearly showed spiral rebar left on the ground in the corner of the property after the second story concrete pouring had commenced. Since only the ground floor columns were circular, they clearly had not had all the reinforcing placed. Photos of the building after the collapse showed that the joints between the circular columns and the floor of the upper storey had disintegrated as the vertical rebar was there but inadequate spiral rebar was in place; the spiral reinforcing had stopped just short of the top of the column. This made the joints extremely flexible once the concrete had shattered in the initial earthquake shock, resulting in the building collapsing. These documents were in the university engineering library and were part of reports on the collapse; I'd don't have a reference handy. Someone with access to an engineering library may be able to find the relevant docs and provide a commentary to the article. 99.245.230.104 (talk) 20:45, 18 May 2014 (UTC)

Imveracious's errors
So, going for a good article here. It's a long process. I started on it in mid-2013. Today, Imveracious came in an modified some sources that made the article completely contradict itself. That is not an improvement, so I reversed the change. What his edit did was not only make the article in disagreement with itself, but left a whole bunch of material without sources. Please, stop introducing errors while I get this article to good article status. Dawnseeker2000  20:25, 11 October 2014 (UTC)


 * No editor owns the article, see- WP:OWN yet this is very much what you are doing, or trying to. Accuracy is not an improvement? The changes I made did not make the article disagree with itself, please tell me where it did, and my changes were referenced. What was left without references? If you are such a perfectionist, why then are you using references which contradict themselves? Stover, C. W.; Coffman, J. L. (1993), Seismicity of the United States, 1568-1989 (Revised) has the duration listed as 60 seconds. (as was referenced) Are they wrong? The USGS has it the same, are they incorrect as well? Also, I do believe MOS for distance with the metric equivalent that you are using is incorrect. This is a US en Wiki and as such the US standard should appear first. I also see that in this aspect you are using both and yet you are a perfectionist trying to get this article to good status, interesting.

Imveracious (talk) 21:49, 11 October 2014 (UTC)


 * This article uses sources that are dense in material and one citation is given at the end of each paragraph. When you replaced the source in the paragraphs for the duration, you left material that was no longer cited.


 * I chose the 12 second figure for several reasons:


 * It is in agreement across several sources. The first source is one where the earthquake was looked at much more closely than the Stover & Coffman figure. Remember, Stover & Coffman is great (the USGS use it as a basis for their web pages on lots of these shocks, including this one) but this first source I'm going to list is a study of the strong motion for the event, and the reason I chose it over Stover & Coffman is because it's a better choice (more detailed study) for that piece of information, AND, there are two other sources that agree with it. These are the three sources for 12 seconds duration:


 * Maley, R. P.; Cloud, W. K. (1971), "Preliminary strong-motion results from the San Fernando earthquake of February 9, 1971", The San Fernando, California, earthquake of February 9, 1971; a preliminary report published jointly by the U.S. Geological Survey and the National Oceanic and Atmospheric Administration, Geological Survey Professional Paper 733, United States Government Printing Office, p. 163


 * Steinbrugge, K. V.; Schader, E. E.; Bigglestone, H. C.; Weers, C. A. (1971). San Fernando Earthquake: February 9, 1971. Pacific Fire Rating Bureau. p. vii.


 * Steinbrugge, K. V.; Schader, E. E.; Moran, D. F. (1975), "Building damage in the San Fernando Valley", San Fernando, California, earthquake of 9 February 1971, Bulletin 196, California Division of Mines and Geology, pp. 341–346


 * No, this is not WP:OWN. It's similar as last time we were going back and forth (at 1925 Santa Barbara earthquake):


 * The three citations for duration are strong and no good reason for the change was provided AND
 * The change left material hanging (due to the one citation per paragraph)
 * For clarity, ALL material in each paragraph is covered by the citation at the ends
 * Your edit broke the article (that didn't happen on the other one, of course. Just the lack of a sound reason...)


 * Stover and Coffman is great, and I use it for quite a bit, and there is no contradiction on my part by using a more specific reference for the duration. That's what is going on here. Stover & Coffman is a large earthquake catalog that is great for supporting lots of detail in many WP earthquake articles. But for some events, like this one where there are many studies that were done, it makes more sense to use Stover & Coffman where possible (especially if it agrees with other sources) and use sources that are more specific to a certain detail of the shock. If there's a certain source that really looks closely at an event, then I use that, and that is what's happening here. I thought: Well, I've got Stover and Coffman on the one side, and on the other side I have Maley & Cloud, Steinbrugge, Schader, Bigglestone & Weers PLUS Steinbrugge, Shader, and Moran on the other. I felt good about using the three sources. No contradicting going on; just using the best of what's available for specific portions of the story.


 * So you came in and changed one for the other and it broke the article. That's why I undid your change. The sources in most of the articles I do are just like this one. They usually compliment each other.


 * As far as WP:OWN goes: Stop saying that :) You know that is not what's going on here. You just haven't been giving good reasons for your changes.


 * Dawnseeker2000  22:18, 11 October 2014 (UTC)


 * Wow, changing the duration using the information obtained from a reference which you, yourself, have in the past touted as "The Source" for the sake of accuracy, given the references used were preliminary studies, and that is what you base the claim of "breaking" your article on? All it took to fix it was what you did~Undo. The reference used for the duration was used for that alone, it did not reference any other materiel. Check the changes in the history, if I am incorrect, please show me where and I'll apologize for my mistake. If you can not, will you? The changes as to the dates of construction and method used in connection with the Van Norman have been reverted so they are now correct. All the rest including, your inconsistent and improperly formatted metric equivalents are all yours to deal with. Imveracious (talk) 00:00, 12 October 2014 (UTC)

Just posted on your talk about the miscommunication we're having. I want to try to clear this up for you, and anyone else that passes by. I have put a monumental effort into this article and it's not even finished yet. I reverted your change today because it was left in a broken state. The sources that are used for the 12 second duration figure are also used for several paragraphs.

The source that states 12 seconds, "Steinbrugge, K. V.; Schader, E. E.; Bigglestone, H. C.; Weers, C. A. (1971). San Fernando Earthquake: February 9, 1971. Pacific Fire Rating Bureau. p. vii." (ref #7), is the source for the first paragraph in the Earthquake section.

Another source that states 12 seconds, "Steinbrugge, Schader & Moran 1975, pp. 341–346" (ref #18), is the source for all of the paragraphs in the Olive View Hospital section under Damage.

I want to reiterate that it would not be a good idea to change these sources. They're firmly embedded in the article, and are more accurate than the Stover & Coffman source. I'm not abandoning that source. Like I said, it's fantastic, but for this article we have other more specific sources that cover the duration. My sources are tied to an instrument at the Pacoima Dam, and I'm remembering why I chose this source last year when I did the expansion. There's another source that I have that shows the accelerogram with the time clearly labeled. This 60 second figure has neither of those things. No location or instrument. Dawnseeker2000  00:22, 12 October 2014 (UTC)


 * My only "error" was simply in making a couple of well referenced changes for the sake of accuracy. You on the other hand want nothing in this article other than your sources and writing. As you wrote, I use that, articles I do, I have put a monumental effort into this article, I chose this source last year when I did the expansion etc. Count the number of times you have used  "I" !! In short we again return to if Dawnseeker2000 did not add it, it is reverted-to his version. Undoubtedly any number of reputable and far more recent sources would not suffice. Perhaps you should inform (NISEE), National Information Service for Earthquake Engineering of the University of California, Berkeley that they are incorrect. Though the confirmation bias which you clearly show would most certainly preclude that. This is all yours Dawnseeker2000, the good the bad, the correct and incorrect. I'm done with this---   Imveracious (talk) 16:08, 12 October 2014 (UTC)

The 48 seconds was "very fast severe constant shaking, knocking over walls etc etc...", not shaking as you described it You interview "anyone" that lives in Sylmar and was awake or semi-awake during the earthquake they will all agree. I lived in Sylmar. If the edit is not done within the next 20 years or so, the accuracy of this earthquake will be lost forever. I am people that lived in Sylmar are the best source of information. The USGS has this but you doubt the shaking severity obviously. — Preceding unsigned comment added by Dalewob (talk • contribs) 00:59, 11 October 2016 (UTC)
 * Sorry to be stiff about this, but Wikipedia articles are not based on the experiences of people that were in the area at the time. Dawnseeker2000  01:29, 11 October 2016 (UTC)


 * I know the shaking lasted long enough for me to wake up, jump out the window onto the roof and sit on the roof to see multiple transformers explode. Sam Tomato (talk) 18:58, 2 May 2017 (UTC)


 * Also, you say "they will all agree" but you don't make it clear what it is that we will agree about so there is no value in saying that. Sam Tomato (talk) 19:10, 2 May 2017 (UTC)

You have one source; I have another (Van Norman Dam)
What you changed regarding the reservoirs was already cited, so I don't see a need to change it, so I put it back the way it was. Just trying to keep this as simple as possible for the GA reviewer. Sorry about the miscommunications we've been having. Dawnseeker2000  00:32, 12 October 2014 (UTC)


 * Perhaps if you centered less on keeping it simple for the GA reviewer, which appears to take precedence over accuracy as your ultimate goal, the article may be worthy to be such. Imveracious (talk) 16:07, 12 October 2014 (UTC)

1994 Northridge earthquake surface rupture
According to the EQE Summary Report, March 1994 it did cause surface rupture. This may be read @-http://www.lafire.com/famous_fires/1994-0117_NorthridgeEarthquake/quake/02_EQE_geology.htm Thank you Shyncat (talk) 20:29, 24 October 2014 (UTC)


 * Hi again. Please stop editing the article until you understand what's happening. The 1994 event is known as a blind thrust earthquake, and that means the fault rupture did not reach the surface. The existing source in the article (a book from Bruce Bolt) supports that and there are others that say the same. You are not going to add a source from "lafire.com" that says the contrary. Dawnseeker2000   20:51, 24 October 2014 (UTC)


 * "You are not going to add a source from "lafire.com" that says the contrary." So if another source exists though is not in agreement with what you think is right it can't be used--according to who? Shyncat (talk) 22:46, 24 October 2014 (UTC)


 * The Northridge earthquake did not cause ground rupture, which is normally interpreted as the surface trace of the fault that moved. There were zones of local surface fractures, but these are not ground rupture. The linked map pdf explains the nature of these fractures in detail. Note that this source explains that the earthquake rupture stopped 8 km below the surface. The 1994 Northridge earthquake article needs a lot of work. The lafire source says "Unlike the 1971 San Fernando Earthquake, the Northridge Earthquake did not produce obvious fault ruptures at the surface. At the time of this writing, it was not yet clear that any of the mapped zones of ground breakage represented surficial faulting associated with slip on the causative fault." Mikenorton (talk) 07:48, 25 October 2014 (UTC)

Thanks for pointing this out. Was at work yesterday when this latest round round of back and forth editing took place, and felt like the time was not spent well, especially after reading the link that supported the article as it stands. Dawnseeker2000  15:18, 25 October 2014 (UTC)


 * Yes, I now see that I was mistaken. Thank you Mikenorton for not only pointing out the mistake but doing it in a civil manner. Shyncat (talk) 15:52, 25 October 2014 (UTC)

Duration
This keeps on coming up. The USGS, quoting Stover & Coffman give 60 seconds, other seismological sources give 12 seconds or thereabouts. Perhaps this needs to be actually discussed in the article. Boore 1973 shows seismograms (filtered to remove anything over 15 Hz) from the Pacoima Dam and the duration of significant shaking is obviously a lot less than 60 seconds (as would be expected from an M6.5 earthquake). The earthquake report (source 1) has contradictory numbers in it. The duration of strong shaking is given as 12 seconds based on the Pacoima Dam seismogram (page 163), but elsewhere (page 5) it gives 60 seconds. In Bulletin 196 of the California Divisin of Mines & Geology, the duration of strong motion is unequivocally given as 'about 12 seconds' (page 323 Chapter 25). I suspect (but cannot prove) that difference is because they are measuring different things - the duration of 'strong shaking' versus the duration of 'shaking'. There are a lot of BSSA papers on this earthquake that I don't have access to and perhaps one of them would clarify this discrepancy. Mikenorton (talk) 22:27, 9 November 2014 (UTC)


 * First, I should just say that I didn't think it would be responsible for us to list the 60 second duration because there is no location given for that figure. That is what was listed for the duration prior to the expansion in May 2013. At that time, I located a number of references that show a 12 second (or shorter) duration for "strong ground motion", and along with that is a precise location of the accelerometer. These are attenuated devices, of course, and so are not going to have a record of all the lower amplitude vibrations. As I understand it, the problem with using a seismogram (from a high gain seismometer) would be that it would show, in fine detail, all the localized shaking. There should be seismograms available from earby the mainshock that would be longer in duration than the 12 seconds. We know from simulations that the Los Angels Basin shakes like a bowl of jello for a very long time when seismic waves pass through it. I haven't seen one of these seismograms that would support a longer duration and this 12 second value is just about everywhere I look.


 * These things are why I chose to keep it simple and accurate by using the various sources that state the duration of the accelerograms. Those seismometers are extremely sensitive; they'll pick up ground vibration caused by wind blowing through the trees. People certainly can't feel that. I'm not opposed to making a distinction in the article, but I don't know of a good source that sums up these ideas well.


 * By the way, I have a source that shows the record from the Pacoima Dam accelerometer, and it has the time scale across the bottom. It's hard to argue with that because it also matches what's already being said in the article. There's a website that has seismograms from all over the world for the event, but they're impossible to use because there's no time reference. Oh yes, I remember seeing the paper from Reuben Kachadoorian on page 5. I chose not to use that because the (very short) paper is about damage and not about the seismological aspects. That's a name I haven't seen elsewhere and so decided to go with the bulk of sources that state 12 seconds, and because Maley & Cloud (1971) is cited in numerous other journals and books. Dawnseeker2000   23:11, 9 November 2014 (UTC)


 * I found a very useful discussion about strong motion duration definition and the relationship to magnitude here (you may need to add .pdf to the file name to get it to display). It also includes two duration values for the 1971 quake (see Table 1) of 7.4 seconds (from Pacoima) and 11.7 (from another location). The graphs of observed strong motion duration versus magnitude show clearly that 12 seconds is about the expected value for the quake and that 60 would be very unusual. We should perhaps make it clear that the duration is for strong motion. Mikenorton (talk) 19:23, 10 November 2014 (UTC)

OK, just having a quick look at the paper now, and it definitely looks to be useful. At the very least, we should do as you suggested by making clear that what is stated is the strong motion duration. Duh, Dawnseeker. Thanks for that, and this source could even be used to add a small paragraph on the matter. Dawnseeker2000  22:23, 10 November 2014 (UTC)

USGS ShakeMap
The map has it showing as a M6.7 but that's not what the size is given in the rest of this. If you goggle that size you get a bunch of results that say 6.7 so what size was it? DavidCarson73 (talk) 19:00, 4 December 2014 (UTC)


 * It was 6.6 on the local magnitude scale, but the USGS may have recalculated it as 6.7 on the moment magnitude scale - these two rarely give the same value. The most recent estimate that I can find is that from the ISC-GEM earthquake catalogue, which gives a value of Mw=6.7±0.2. The Southern California Seismic Data Center gives it as a Mw=6.5 event. Searching on Google Scholar I can find citations that support Mw=6.5, 6.6 & 6.7. This is often a problem, even with relatively recent, well documented earthquakes. We could add that the earthquake has been given an estimated moment magnitude in the range M6.5—6.7, with a few example refs. Mikenorton (talk) 19:26, 4 December 2014 (UTC)


 * Since there's a lot of different figures out there that might be a good idea. I'm sure I'm not the only one to wonder about it. Thanks! DavidCarson73 (talk) 20:04, 4 December 2014 (UTC)

Duration
According to the USGS the duration was 60 seconds. The 12 seconds mentioned here refer to the period of "strongest shaking", which apparently was much shorter than the total earthquake. Huon (talk) 00:49, 18 May 2016 (UTC)
 * I just saw this has been discussed in the past. I'll try to clarify the article. Huon (talk) 00:50, 18 May 2016 (UTC)
 * Sorry about that, I have added the total duration too. Huon (talk) 00:56, 18 May 2016 (UTC)
 * Please do not use the sixty second claim from Stover & Coffman. It was deliberately not included. Dawnseeker2000  01:00, 18 May 2016 (UTC)
 * For future reference, could you please explain why it wasn't included? Maybe I'm too much of a layperson, but unless that's just a typo, it seems reasonable that the total duration is longer than the strong motion duration, so 60 seconds seemed plausible to me. Huon (talk) 02:11, 18 May 2016 (UTC)
 * When writing about earthquake articles, I have found that it's best to use only the most reliable and appropriate sources. So we're talking about seismologists and seismological organizations. I've collected quite a bit of material on earthquakes since I've been writing these articles and I spend a lot of my time perusing it. I'm interested because I have experienced several large earthquakes and many light and moderate events. This had a strong impact on me and that is why I'm doing this. Back to the sources then. These sources that I've collected, especially from the organizations, are full of errors. The USGS and the NGDC are the worst, but others have made mistakes as well, including Stover and Coffman, which the USGS uses for their web pages on quite a few events.


 * We're talking about a large earthquake, not a very large earthquake. Duration goes up with magnitude. This sixty second claim should not be included for several reasons. These ~M6 events are relatively short. The strong motion duration that's listed is right on the money. It's simple and we don't have to get into describing what the overall duration was and where. It's too complicated. Forget about it. What does Stover and Coffman say? Sixty seconds. Doesn't that seem a little too even? It shook for exactly a minute? No, not buying that. Also, just where did this duration occur? That the location was omitted makes the figure even more suspect.


 * These seismological organizations make mistakes. We should not make the mistake of repeating them. Dawnseeker2000  02:43, 18 May 2016 (UTC)


 * In the earlier discussion I suggested that the 60 seconds might describe the duration of total shaking, but that's just my OR. We should only say that if another source has also made that suggestion. Mikenorton (talk) 10:36, 22 May 2016 (UTC)


 * I lived in Tujunga when the earthquake happened, I was 12 years old at the time. I still remember what happened. It definitely was closer to one minute than to 12 seconds. It was 60 seconds of loud noise and it was not possible to stay on your feet without holding on to something. I remember my parent told me it was 59 seconds.


 * Thanks for the reminder about this problem. I am working on a solution. Dawnseeker2000  05:33, 18 October 2017 (UTC)

Van Norman Dam
The lower reservoir, the one that almost lost it's bank, is not in use any longer. The way it's written here it sounds like it is. — Preceding unsigned comment added by 2602:30A:2E63:A250:7DDE:8F7:619F:42A9 (talk) 17:42, 21 May 2016 (UTC)
 * I don't think that it reads that way, but how would you change it so that it's clearer? Mikenorton (talk) 10:34, 22 May 2016 (UTC)

Another round of improvement
This article had been a work in progress since it was expanded in early 2013, but there's been something about it that hasn't been quite right though. I think that I'm now seeing the problem. As a result of paraphrasing dense sources, the article is equally dense and is too long, with a high text-to-source ratio. As of right now, the article's size is 56,653 characters, with 34,828 characters of readable text. For comparison, this article has just under 1,000 readable characters less than the 2010 Chile article, which has twice the number of total characters. I'll be removing just over 4 KB, and we'll get a new article out of it (Sierra Madre Fault Zone).

Dawnseeker2000 23:24, 19 March 2017 (UTC)

The name of it
See M 6.6 - 10km SSW of Agua Dulce, CA. Are the names San Fernando Earthquake and/or Sylmar Earthquake official names? If so then where is there an authority for that? The official epicenter is quite far from San Fernando and Sylmar and therefore those names are misleading. Use of those names are apparently due to people not referring to authoritive sources. Sam Tomato (talk) 04:24, 5 August 2020 (UTC)


 * The current name of this article is based on usage in reliable sources - see WP:COMMONNAME. A scan through google search results (on 1971 California earthquake) gives a slight preponderance for "San Fernando earthquake" over "Sylmar earthquake", with some support for "San Fernando (Sylmar)", "San Fernando - Sylmar" "San Fernando/Sylmar" and "Sylmar - San Fernando". What other name do you suggest? Mikenorton (talk) 23:21, 5 August 2020 (UTC)


 * I think the name should include Sylmar in some form or another, as most of the locals here call it the Sylmar earthquake. Bdonjc talk 02:00, 16 November 2021 (UTC)


 * In my opinion, it should be called the "1971 Sylmar earthquake" because as of 11-21-21 most of the search results for "1971 California earthquake" say Sylmar earthquake .23.243.175.249 (talk) 01:53, 22 November 2021 (UTC)


 * Current search results are affected by many stories run at the time of the anniversary earlier this year particularly in the local press, who certainly seem to favour "Sylmar". However, to quote from WP:COMMONNAME, "In determining which of several alternative names is most frequently used, it is useful to observe the usage of major international organizations, major English-language media outlets, quality encyclopedias, geographic name servers, major scientific bodies, and notable scientific journals." I've used Google Scholar to look at the journals and there is a clear majority using "San Fernando", but I've not had the time to carry out any further analysis. Mikenorton (talk) 20:52, 22 November 2021 (UTC)

50th anniversary
The 50th anniversary of the 1971 San Fernando earthquake is coming up soon. This wikiarticle is now on deck to appear in the On This Day section on MainPage. However, a few minor problems with the article's contents have been reported on WP:ERRORS. Can someone familiar with the topic help smoothen out the kinks in the article before the anniversary, please? Thanks. --PFHLai (talk) 22:08, 7 February 2021 (UTC)


 * I've addressed most of the issues raised on WP:ERRORS. More generally, User:Dawnseeker2000 has nominated the article for GA, which will hopefully fix any remaining concerns. Mikenorton (talk) 11:47, 9 February 2021 (UTC)

Name Change from Sylmar
When I moved here in 1991, this was always referred to as the "1971 Sylmar Earthquake" and especially after Northridge (which is also in the San Fernando Valley). At what point did this get changed? Just go to almost any article about Northridge and it will be referred to as Sylmar.