Talk:Cascadia subduction zone

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Another Interpretation?

What is with this section? It is both extremely technical and unsourced except the cite to Lyatsky at the top of it. Is the whole section the "summary"? What is quoted and what is not needs to be clearer, and it would help to make, at the least, the purpose of this section of the entry make more sense to the layperson.

24.21.86.235 09:48, 16 May 2007 (UTC)

Assessment

After reviewing this article, it is no longer a B class article and has been downgraded. The reviewed version contained more information, but much gas been removed as I guess OR. To get back to B class this needs a proper WP:LEAD; some information on the volcanoes, not just a list (aren't they supposed to be formed from the lava that is created buy the subduction of the ocean plate or something?); a better description of location in the geography section that should mention the US and Canada for those less familiar with the region. As a bounus, in-line citations would be a great addition, and I believe are now required to reach GA. Aboutmovies (talk) 06:41, 21 February 2008 (UTC)

Yes, downgrade was proper. This article's coverage of the topic is incomplete and uneven, and really needs reorganization by someone with some grasp of the topic. - J. Johnson (JJ) (talk) 18:14, 11 August 2010 (UTC)

Question.

How do i do to translate this article to Spanish? —Preceding unsigned comment added by 190.208.74.141 (talk) 19:53, 6 March 2010 (UTC)

"Great Earthquakes" chart

I copied a chart of past Cascadian subduction earthquakes from the 1700 Cascadia earthquake article, and reformatted it a little. It's not well sourced there, however; a newly-added citation ("Cascadian Megaquake 4 of 5". BBC. Retrieved 2011-03-15.) has a lot of good information. On the other hand, it's a BBC show, but not on the BBC site, and looks like it was uploaded without proper authorization; the citation could go away if the BBC objects.

Anyway, one of the scientists in the BBC citation points out three layers of evidence for past earthquakes: "about 600 BC", "about AD 400", "about AD 700". That seems to cover, more or less, the table's 600 BCE, 400 CE, and 810 CE quakes, and the program in general is all about the 1700 quake. But that segment (part four of five) doesn't mention 170 BCE or 1310 CE quakes. While it's a really good program (shaky upload permission issues aside), it's not so good as backing for the table.

Great Earthquakes

est. year	interval (years)
F 1700 CE	390
E 1310 CE	500
D 810 CE	410
C 400 CE	570
B 170 BCE	430
A 600 BCE	unknown

I'm duplicating the chart at right, to save it in case someone finds better sources for the dates cited there, but I'm replacing it in the article with the chart below, because I think my chart (which has more rows, and data that are in some cases dramatically different) is very solidly sourced.

However, there is a much better source for all sorts of information about the 1700 earthquake, the associated tsunami, and Cascadia in general:

Brian F Atwater (2005). The Orphan Tsunami of 1700 — Japanese Clues to a Parent Earthquake in North America (U.S. Geological Survey Professional Paper 1707 ed.). Seattle and London: University of Washington Press. ISBN 0-295-98535-6. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

For purposes of the table, we don't need the whole book, just the timeline chart on page 100 of the book:

Brian F Atwater (2005). The Orphan Tsunami of 1700 — Japanese Clues to a Parent Earthquake in North America (PDF) (U.S. Geological Survey Professional Paper 1707 ed.). Seattle and London: University of Washington Press. p. 100 (timeline diagram). ISBN 0-295-98535-6. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

In turn, that chart cites this source (from the pages noted): The book cites an earlier journal article, with some of the same authors, specifically Figures 10 and 11 on pages 341 and 341 (of an article that runs pages 331 through 350):

Brian F Atwater (2003). "Earthquake Recurrence Inferred from Paleoseismology" (PDF). Developments in Quaternary Science. 1. Elsevier BV: 341, 342. doi:10.1016/S1571-0866(03)01015-7. ISSN 1571-0866. Retrieved 2011-03-15. {{cite journal}}: More than one of |pages=, |at=, and |page= specified (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

Somewhat annoyingly, the citation template doesn't let me show that the entire article occupies pages 331 through 350, but the only parts that matter are Figures 10 and 11, on pages 341 and 342 (with more details in the appendix on pages 349 and 350). This citation twists the template to generate a reference that looks decent, but the citation looks pretty ugly behind the scenes:

Brian F Atwater (2003). "Earthquake Recurrence Inferred from Paleoseismology" (PDF). Developments in Quaternary Science. 1. Elsevier BV. Figures 10 and 11 (pp 341, 342); article pp 331-350. doi:10.1016/S1571-0866(03)01015-7. ISSN 1571-0866. Retrieved 2011-03-15. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

Great Earthquakes

estimated year		interval
(book's timeline)	(article's carbon dates)	(years)
Y about 9 pm, January 26, 1700 (NS)		780
W 780-1190 CE (985)	1040-1120 age; 960-880 CE (920)	210
U 690-730 CE (710)	1246-1454 age; 754-546 CE (650)	325
S 350-420 CE (385)	1681-1755 age; 319-245 CE (282)	914
N 660-440 BCE (550 BCE)	2449-2610 age; 449-610 BCE (529 BCE)	396
L 980-890 BCE (935 BCE)	2777-2909 age; 777-909 BCE (843 BCE)	248
J 1440-1340 BCE (1390 BCE)	3148-3217 age; 1148-1217 BCE (1183 BCE)	unknown

Anyway, the charts in both sources include ranges of years (except for the 1700 quake, which has been isolated to a specific date), since the sources show spans of years. I got the year spans from the timeline in the book (The Orphan Tsunami of 1700) because its images are much clearer, but I use the strata names (Y, W, U, S, N, L, J; as sorting keys) from the article ("Earthquake Recurrence Inferred from Paleoseismology").

The book's timeline doesn't have exact year numbers on it, just gray bars; I converted those to dates by counting pixels in the images. The article has both a timeline and before-2000 ages±uncertainty; for those I calculated age±uncertainty from the sample dates in Figure 11, and subtracted for CE or BCE dates for the table. To calculate intervals, I found the middle of each range (parenthesized) as best-estimate date (using the narrower range; bolded), and subtracting consecutive dates.

In the table on this talk page, I show exact years, but in the article I round to nearest tens (except in the case of 1700) because all of the uncertainties are in the tens of years. (I rounded 385 CE and 935 BCE toward 282 CE and 843 BCE, respectively.)

I hope calculating years the way I've done doesn't stray into original research territory, but I admit this pushes the limits of WP:CALC, since it shouldn't take this much to explain how I converted well-sourced material into tabular form.

The table isn't as pretty as I'd like; I think it would look better without the border between the first and second rows of the column headings (and without a border between the citations), but I'm not sure how to do that without losing the desirable borders.

— Steve98052 (talk) 03:02, 16 March 2011 (UTC)

Oops, I forgot to get back to the BBC citation. The on-screen scientist mentions "about 600 BC", "about AD 400", "about AD 700", and 1700. Those correspond well with the new table's circa 529 BCE, 385 CE, 710 CE, and 1700 quakes – better than with the previous table.

The book has the text "Soil inconspicuous in most outcrops" in reference to the circa 920 CE quake. It says "Soil below water in photo" in reference to the circa 1183 BCE quake, and the soil layer for the circa 935 BCE quake may also be inaccessible to the on-screen scientist. That suggests that the new table improves on the old. Even if I've pushed WP:CALC somewhat, I think it's better than the old table, which lacks any citations.

— Steve98052 (talk) 03:24, 16 March 2011 (UTC)

Major cities affected by a disturbance in this subduction zone should be revised.

This is being picky, but I would suggest that the list of cities affected by a subduction zone earthquake be revised, specifically Sacramento should not be included in the list. Sacramento like San Francisco would likely feel the earthquake but is 200+ miles south of the southern edge of the subduction zone and therefore the expected impact would be significantly less compared with a city such as Seattle or Portland.

The article that is referencing the statement is by a journalist rather than a scientist, I would question whether this should be used as a reference for a scientific matter?? — Preceding unsigned comment added by 216.16.236.14 (talk) 16:46, 2 April 2012 (UTC)

Recurrence rate

For anyone interested in taking a closer look at the scientific thinking regarding recurrence rate: take look at USGS Open-File Report 2011–1310. Additional comment at Talk:1700 Cascadia earthquake#Resource. ~ J. Johnson (JJ) (talk) 23:29, 25 May 2012 (UTC)

History

There ought to be a history section, as its discovery is really interesting—its existence was not fully confirmed until the 80s/90s. During a tsunami that hit the coast of Japan, it had been referred to as an "orphan tsunami" until researchers lined up dynastic dates with the Gregorian calendar. Further researchers compiled oral history among American Indian tribes to approximate a location of this earthquake, since Europeans (and writing systems) hadn't arrived there by that point. Geologists eventually confirmed it after they came upon a "ghost forest" in the Copalis River, remnants of 300-year-old trees that had suddenly been killed by the ground plummeting on the fault, and after analyzing rock samples in that area and on the sea floor.

Some sources:

reflist

- SweetNightmares 04:23, 15 July 2015 (UTC)

I am working on a history section. - SweetNightmares 21:01, 15 July 2015 (UTC

The "history" section is confusing. It seems to be essentially a history of the several pieces of evidence for the 1700 earthquake, not of activity along the entire fault zone. But it does not announce itself as such. There is already a page on the 1700 earthquake where this material should be found. Not saying you need to get rid of this section, but maybe relabel or contextualize it.66.190.3.150 (talk) 18:15, 29 March 2017 (UTC)

New Yorker

The July 20, 2015, issue of the NEW YORKER, pp 52-58: ANNALS OF SEISMOLOGY - THE REALLY BIG ONE: An earthquake will destory a siable portion of the coastal Northwest. The question is when. Does this comprehensive treatment of the likely imminent diaster merit a reference in this artcle? Frankatca (talk) 13:33, 19 July 2015 (UTC)

From my short research on the fault, it's a bit alarmist, but you'll notice it's already cited in the article. Planning to include more material from it in a history section I'm working on. - SweetNightmares 15:54, 20 July 2015 (UTC)

That news story is not the right kind of source for this type of article. Dawnseeker2000 15:56, 20 July 2015 (UTC)

I beg to differ. It's not all geological and seismological information that we should be taking from dry peer-reviewed journals; the New Yorker article, with all its faults, does contain a useful summary of the discovery of the fault. Did you even bother to take a look at the writeup I linked? - SweetNightmares 15:06, 21 July 2015 (UTC)

The New Yorker story is too editorial to be a good primary source. Every fact in it can be found in a more appropriate source (I know because nothing in it was new information to me, a geophysicist). I see 3 specific ways it could be used in this article: 1) If its popularity continues long enough to impact public awareness or action, it could be mentioned at the end of a history section; 2) If it used extensively in outlining and/or writing such a history section, it should be included as a reference, even though every inline citation should be a less derivative source; 3) If one of the quotations from the scientists interviewed seems both striking and important enough for inclusion. Elriana (talk) 18:15, 21 July 2015 (UTC)

As for the addition of a 'History' section mentioned by SweetNightmares, I have no objection to adding more of the facts discussed in the New Yorker story to this article. However, particular care should be exercised to maintain an encyclopedic tone and to communicate the important information in a clear and concise manner, without getting caught up in story-telling. What SweetNightmares has drafted so far is actually more of a section on Evidence of Past Large Earthquakes than it is a History. Merging this into the current flow of the article may take a bit of rearranging, but I think it could work.Elriana (talk) 18:15, 21 July 2015 (UTC)

Normally I dislike bringing up policy, but for valid reasons, Wikipedia actually prefers secondary sources. See WP:PRIMARY. - SweetNightmares 19:59, 21 July 2015 (UTC)

I am not sure that you've thought this through. Let me ask you this: Are you saying that our geology/earthquake articles would be best sourced to stories that are written by journalists from newspapers, TV stations, and magazines? I don't think that's a good direction for us to be going, and I'm certain that's not what's going to happen in the long run. I am not sure that you're editing the right kind of articles. It strikes me as odd that you're interested in writing about a feature like the CSZ and are willing to discard proper scientific articles because they're dry and they're primary sources. First, step back a moment and think about that and second, do some searching around for some decent sources; not just the latest (and slightly alarmist) news story. Dawnseeker2000 03:45, 22 July 2015 (UTC)

Please keep a professional, rather than belittling, tone. You inferred we should discard peer-reviewed sources; I said this article should not exclusively include them. What is wrong with diversification anyhow? As long as the information is not outright wrong, using other sources to back up an article is pretty standard fare. It's not as though the New Yorker is unreliable blogspam/clickbait. Yes, the article is sensationalist, but that's why we need to prune through it and select the good parts, then present them neutrally. This article is not just about hard science, and besides, as I mentioned above, WP:PRIMARY lists a host of reasons why secondary sources are oftentimes preferable. - SweetNightmares 13:40, 22 July 2015 (UTC)

1) In the case of most geological phenomena, the line between primary and secondary sources is a bit blurry. Wikipedia's guidelines state: "A secondary source provides an author's own thinking based on primary sources, generally at least one step removed from an event. It contains an author's interpretation, analysis, or evaluation of the facts, evidence, concepts, and ideas taken from primary sources." Most of the scientific articles people find so dry contain loads of interpretation, analysis and evaluation of facts/evidence/concepts/ideas. The datasets themselves are the true primary sources, and the articles can be viewed as mostly secondary. The guidelines cited by SweetNightmares also list peer-reviewed journals as some of the most reliable sources. Elriana (talk) 14:27, 22 July 2015 (UTC)

2) Restating my point from before (since I seem to have used the wrong words): the New Yorker article is, at best, a tertiary source, essentially interpreting interpretations. Every inference and correlation in the article has been made before. This isn't even the first synthesis of these facts and interpretations out there. There have been news articles and television documentaries on this topic for several years, not to mention the scientific review articles (bringing together facts and interpretations from a wide variety of different studies into a single paper). The tone is narrative, and while the facts and numbers are generally correct, I would check each one with the original source(s) before trusting it. (Many of those "original" sources are not technically primary sources.) Since I'm basing my trust of the facts on the other sources, (and probably adding details from those sources) I would cite those sources rather than the editorial that led me to them. I have no issue with diversification, but I do believe the point of citation is to show where the information came from. We do a disservice to readers when we cite the reporter rather than the scientist for no other reason than that the reporter's article was more popular this week. In cases where the scientific paper is behind a pay-wall or overly technical, a news article might be appropriate, but that is largely not true in this case. Elriana (talk) 14:27, 22 July 2015 (UTC)

Yes, diversification is fine, but I would still prefer to use a compilation of scientific articles instead. If we apply Elriana's recommendation, "particular care should be exercised to maintain an encyclopedic tone and to communicate the important information in a clear and concise manner, without getting caught up in story-telling", the magazine article (shudders) can be used in limited fashion. That's all from me, Dawnseeker2000 17:41, 22 July 2015 (UTC)

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Mythology?

Is 99% of this massive quake/tsunami/flood/end of Oregon, California, and Washington really based on ancient Indian and Japanese legends? How is that science?2601:806:4301:C100:5833:B99E:9E1C:211A (talk) 23:58, 18 June 2017 (UTC)

No. Most of the history of the Cascadia subduction zone has been pieced together by geologists and geophysicists using scientific paleo-seismic techniques. Most notably, geophysicists in Oregon and Washington have spent the last 20-30 years identifying, mapping and correlating tsunami deposits and earthquake-triggered landslides (and turbidites) in the sedimentary record, both onshore and offshore. Field geologists have mapped the faults on land and both active and passive source seismology have been used to map the subduction interface (and other, smaller faults) offshore.

The one event where the Japanese and Native American accounts are relevant is the tsunami of 1700. In that case, scientists looking at sedimentary layers in Cascadia recognized a possible tsunami sometime around the year 1700. Dates were only as precise as could be achieved using carbon dating. But several contemporary written records in Japan recorded a tsunami on a specific date in 1700 that was not associated with a Japanese earthquake. These accounts are not oral traditions or changeable stories handed down through generations, but rather written accounts from people who witnessed the actual event. Japanese written records, including individual diaries, crop yields, flooding accounts, etc. go back more than 1000 years. Subsequent modeling and mapping of tsunami deposits on both coasts led scientists to link the Japanese historical report with the tsunami deposits in Cascadia. It was only after this link was established that geologists/anthropologists realized the significance of the Native American stories about ghost forests and missing coastal communities. The accounts that many scientists assumed were 'myths' are actually very close to what the models say happened during that earthquake and tsunami in 1700. Subsequently, geologists (and I assume anthropologists, but I don't know them personally) have used the Native American accounts to guide them to locations of interest.

Perhaps this sequence of reasoning needs to be made more clear in the article?? Elriana (talk) 20:37, 6 July 2017 (UTC)

Subduction zone vs megathrust fault

The Cascadia subduction zone is a Subduction zone (redirects to the process of Subduction) that is a result of the Cascadia megathrust fault. This distinction should probably be made clear as the article currently seems to identify the zone as the fault itself rather than the zone of subduction that is a result of the fault. AHIOH ^[T]/_[C] 03:45, 4 August 2024 (UTC)