Talk:Hilina Slump

Needs development in view of current events

It appears that the Hilina Slump is closely associated with – and I am beginning to suspect may be the cause of – the 2018 lower Puna eruption and 2018 Hawaii earthquake, and could even cause a mega-tsunami. More development is needed, and now would be most opportune time. For anyone interested there's a TON (and a half) of authoritative material on this (do a search on Google Scholar). Highest priority probably should be getting a high-quality image. (There are quite few out there, but I don't know the copyright status.)

In anticipation of adding a lot more sources I propose to move the existing source citations to their own section (i.e., not embedded in the text). Any objections? ♦ J. Johnson (JJ) (talk) 22:14, 14 May 2018 (UTC)

I don't see anything wrong with the current referencing. If the style you propose is common in the related articles, then this one should match. I am most familiar with inline citations like WP:INCITE, but have already tripped up by following that in a related article. I agree the most important thing is to improve and update the content, and make it more accessible to typical readers. I, for example, am having trouble working out exactly what this thing is - a "section of an island", in categories for landform, tsunami and landslide. Photos and diagrams would definitely help. Thank you. --Scott Davis ^Talk 23:05, 14 May 2018 (UTC)

I am hesitant to get very involved in this article as I have lots of other work to. Prepatory to any work would be putting the full citations into their own section, to make the rest of the work easier. You have no objection to that?

What's "wrong" with the current "referencing" (poor term) is putting full citations into a note (i.e., between the <ref>...</ref> tags) in the text, where they clutter the text, and are harder to check. For very short articles, where a source is cited only once, this might be acceptable, but for longer articles it gets too cumbersome. It also leads to use of named-refs (when sources get cited more than once) which leads to other problems (like discouraging use of in-source specifiers, which makes verification harder).

I don't know what use a photo would be, but a quality map showing the locations of the slump relative to the volcano, quake epicenter, and current eruptions pretty much essential so readers can see the inter-relatedness. That may take some searching. ♦ J. Johnson (JJ) (talk) 00:26, 15 May 2018 (UTC)

I just added a photo of Hilina Pali (which marks one of the most prominent faults in the Hilina fault system) to the article. There are one or two (public domain) diagrams in USGS Professional Paper 1801 that could possibly be used in this article, but it would require expanding the text to put the diagrams into proper context. Care should also be taken to not over-sensationalize the issue, as the USGS itself has stated that "[t]he chances of the south side of Kīlauea suddenly peeling away into the sea are, in Dizzy Dean's famous words, 'slim and none.'" In any case, when I have a chance, I'll see if I can pull some diagrams from the USGS report for this article. 青い(Aoi) (talk) 00:46, 15 May 2018 (UTC)

Yes, and I just grabbed a couple. I'll have them uploaded shortly, with insertion and explanation "RSN".

[Update: New image for the lead is in; more tweaking to be done later. ♦ J. Johnson (JJ) (talk) 01:36, 16 May 2018 (UTC)]

I agree about not over sensationalizing. In particular, any mention of mega-tsunamis should be "slim". The story I see shaping up is along the lines of the broader context and general relatedness of various current phenomena, all part of the extended process of how the islands are built. ♦ J. Johnson (JJ) (talk) 23:35, 15 May 2018 (UTC)

OK, go ahead with no objection from me. I agree that in-source specifiers for larger sources are very helpful. I've read a bit more and am gradually understanding what the Hilina Slump is, but not up to the level of being able to write about it sensibly. A map and diagrams would certainly help. Thank you. (edit conflict) Thank you for the photo and caption. --Scott Davis ^Talk 00:50, 15 May 2018 (UTC)

From what I've read, any connection between what's going on now and slumping would be speculative at best. I would ask that sources be balanced carefully. John2510 (talk) 20:30, 15 May 2018 (UTC)

I think the scientific literature shows (so far I have only done some fast skimming) that they are inter-related. I have not seen (so far) an indications of any major differences of scientific opinion that need "balancing"; my concern would be more about proper interpretation. To that end I think we should have an understanding that for the geologic and volcanic aspects there are enough scientific sources that we do not need to rely on any "popular", sensationalistic sources. ♦ J. Johnson (JJ) (talk) 23:37, 15 May 2018 (UTC)

Mega-tsunami

[Split this off as it is more narrowly focused. ♦ J. Johnson (JJ) (talk) 22:07, 18 May 2018 (UTC)]

Berkeley Seismological Laboratory concludes about a megatsunami "... a repeat of such a rare catastrophic event is highly unlikely and it may take many millenia for it to occur." It seems to connect the slump movement and the eruption as being interrelated, initiated by the magma. The page is called a blog, but seems to be written by experts. --Scott Davis ^Talk 03:25, 16 May 2018 (UTC)

They are experts, and comments there should be given due regard. But for WP:reliable sources we should cite a peer-reviewed article from a journal. There is a sizable literature on this topic, so I am sure this point is covered. ♦ J. Johnson (JJ) (talk) 18:44, 16 May 2018 (UTC)

Various reliable and authoritative sources are trying to calm people down from the sensationalist fear-mongers who are trying to fabricate news stories by drawing a connection between the recent volcanic activity, severe as it is, and the potential for a "mega tsunami." My property is a half a block from the leading edge of Fissure #8, so I've had occasion to be reading up on the subject. Volcanologists and geologists are universally appalled that people are trying to to connect these things up. If there are ANY reliable and authoritative sources that connect them, I would be interested, and quite surprised, to see them.

Here's what USGS has to say about the subject: https://volcanoes.usgs.gov/observatories/hvo/hvo_news_archive.html

Rather than the slump causing the 2018 phenomena, the belief is that the earthquakes caused by the 2018 lava flow have caused a minor, and quite expected, advance in the slump.

As USGS put it, " Kilauea tends to 'slump', which is a slower type of movement that is not associated with tsunamis." John2510 (talk) 02:31, 18 May 2018 (UTC)

West Hawaii Today (February 25, 2018) Hawaii Volcano Observatory (HVO) Volcano Watch: Slow slip event on Kilauea Volcano's south flank is expected this year [1]

Uni Berkeley - Seismo Blog: A slow emergency and a sudden slump (May 7, 2018) [2]

High‐resolution locations of triggered earthquakes and tomographic imaging of Kilauea Volcano's south flank (26 October 2010) Journal of Geophysical Research [3]

Magmatically Triggered Slow Slip at Kilauea Volcano, Hawaii (August 29, 2008) Science [4]

Overview, slow slip events (SSEs): Nov. 29, 1975 (11 feet); February 1998; September 1998; November 1999; May 2000; November 2000; September 2001; July 2003; May 2004; January 2005; June 2007; February 2010; May 2012; October 2015; May 4, 2018 (2 feet). Slips trigger earthquakes. Dike intrusions trigger slips. You can not be sure that it will be a slip or a slow slip (slump). --Chris.urs-o (talk) 15:16, 18 May 2018 (UTC)

• As I anticipated in my prior comment: yes, the point of any mega-tsunami being a very low probability is covered by one or more sources, but (having just plowed through a dozen papers) I'll have to consult my notes to figure out which one. This should be addressed in a separate section (not the lead), and Real Soon. BTW, my thanks to John2510 for taking that bit out of the lead. ♦ J. Johnson (JJ) (talk) 22:16, 18 May 2018 (UTC)

• Nowadays this is possibly not true. With the Mayan calendar end, we are possibly under the influence of Nemesis (hypothetical star) and Nibiru (hypothetical planet). If this is true, Nibiru's magnetic field could trigger many ruptures: Hilina slump, La Palma sturzstrom, Cascadia subduction zone, San Andreas Fault, Hayward Fault Zone, New Madrid Seismic Zone and a embrionic subduction zone (Gibraltar and its opposite). --Chris.urs-o (talk) 06:45, 19 May 2018 (UTC)

Alternative translation of the Mayan inscriptions: I should grab some beer and go sit in the sun. Right? :) ♦ J. Johnson (JJ) (talk) 22:06, 19 May 2018 (UTC)

EVERYONE (!!) interested in the prospect of mega-tsunami's (at Hawaii, or elsewhere) should read George Pararas-Carayannis' 2002 article in The International Journal of The Tsunami Society, "Evaluation of the Threat of Mega Tsunami Generation from Postulated Massive Slope Failure of Island Stratovolcanoes on La Palma, Canary Islands, and on the Island of Hawaii". (Available here. See also Cumbre Vieja.) Some of it is a bit technical, but understandable, and his conclusions quite clear:

The threat of mega tsunami generation from collapses of oceanic island stratovolcanoes has been greatly overstated. No mega tsunamis can be expected ....

More particularly:

In summary, there is no indication that Kilauea's southern flank is unusually unstable at this time, or that a catastrophic massive, failure can occur as postulated by the recent tsunami modeling studies (Ward 2001).

It's first-rate stuff. ♦ J. Johnson (JJ) (talk) 22:38, 20 May 2018 (UTC)

George Pararas Carayannis seems to ignore evidence that mega tsunamis have occurred on the Hawaiian Islands. Even the USGS acknowledges that they happen. They're just very rare and the probability of seeing one in our lifetime is exceedingly small. I would dismiss his claims as well. Just because people are spewing falsehoods doesn't mean you should do it yourself. https://walrus.wr.usgs.gov/posters/underlandslides.html — Preceding unsigned comment added by 2600:1702:890:6320:69D4:C942:1543:C68E (talk) 21:41, 29 May 2018 (UTC)

Also, here is evidence of ancient megatsunamis on Hawaii. Perhaps Carayannis is only referring to Kilauea, which hasn't experienced a flank collapse as of yet. https://www.researchgate.net/publication/233529887_Megatsunami_deposits_on_Kohala_volcano_Hawaii_from_flank_collapse_of_Mauna_Loa — Preceding unsigned comment added by AndrewT2. (talk • contribs) 22:12, 29 May 2018 (UTC)

Another interesting article about the slump. Seems to suggest that at some point, the slump will eventually have a catastrophic collapse, but not for a few thousand years. Still I would disregard any rumors on a near future collapse https://pubs.usgs.gov/ds/2006/171/data/cruise-reports/2001/html/24.htm — Preceding unsigned comment added by AndrewT2. (talk • contribs) 04:24, 30 May 2018 (UTC)

[You all please "sign" your comments by adding the four tildes: ~~~~. And note how we use prefixed colons to indent.]

Anon.: You misunderstand what Pararas-Carayannis was doing. He was not examining the question of tsunamis in Hawaii; he was showing that Ward's method for calculating the height of a tsuami from a postulated event in La Palma, including the prospect of Florida seeing 25 meter high waves, is way out of whack. There will be something on this in artice, when I can get to it.

Andrew: A prospect of Kilauea undergoing catastrophic flank collapse has been linked to Kilauea reaching a certain stage of development, not expected for another couple hundred-thousand years, so I wouldn't wait up for it. ♦ J. Johnson (JJ) (talk) 22:43, 30 May 2018 (UTC)

• I added a new section on this yesterday, and today I revised the summary statement in the lead. None of this is perfect (it's been a bit of a rush job), but it should be good enough for the present. I see the article as substantially complete now, except for some qualms about the earthquake section (see below). ♦ J. Johnson (JJ) (talk) 23:09, 11 June 2018 (UTC)

The threat of a mega tsunami is not overstated and massive tsunami deposits have been found. This should be rephrased. Mega tsunamis are not overstated, they're just extremely rare. If someone could edit this to reflect that, that would probably be more accurate. https://www.researchgate.net/publication/233529887_Megatsunami_deposits_on_Kohala_volcano_Hawaii_from_flank_collapse_of_Mauna_Loa — Preceding unsigned comment added by AndrewT2. (talk • contribs) 03:56, 12 June 2018 (UTC)

I made a couple of edits in response to this issue. I do believe that Kilauea is almost certainly not going to experience a flank failure large enough to generate a local mega tsunami in the next few thousand years, but from evidence from ancient tsunami deposits from other flank failures on other volcanoes, I feel it is important to state that catastrophic debris avalanches and local mega tsunamis are indeed a part of Hawaii's geological history and should not be discarded as fiction. Unfortunately, these events have fallen under unjust scrutiny because of fear mongering idiots who say a collapse is likely in the near future. Forgive me if I'm misinterpreting this, but I just want the information to be accurate. — Preceding unsigned comment added by AndrewT2. (talk • contribs) 04:13, 12 June 2018 (UTC)

Andrew: You are new here, so let's get you up to speed on several things. First, and as previously advised: when you leave a comment, always sign with the "four tildes" ("~~~~") That will automatically be replaced with your username and the timestamp of the edit.

Second: A url is not a citation. Simply linking to where you found an article is insufficient documentation of the source, who wrote it, when, etc. For this purpose you should create a full citation, using (in the case of this article) the {{citation}} template. Also: the so-called "citation style" established for this article is full citations in the "Sources" section, and {{harv}} templates in the text ("in-line") to link to the full citation. (Examine the text for examples of use; ask if you have questions.)

As to the substance of your comment and edit: well, you are showing some thinking and behavior very typical of newbies. E.g., you found a factlet – this paper about evidence for a megatsunami – which is just so intriguing that you feel it must be mentioned in this article. But it appears you do not understand the true relevance of the paper, or how it fits in with the broader context. Furthermore, it appears you have not been paying careful attention to what that paper paper says, or to the article text, or to what the sources say. E.g., on what basis do you say that the threat of a megatsunami is not overstated? This article? You understand neither what it says, nor what Pararas-Carayannis said. Nor even who you are contradicting. ("Dr George P.C.", quite in addition to having a PhD, is a noted expert on tsunamis, with an extensive list of publications. See his brief bio at http://www.drgeorgepc.com/BioSummary.html.) As an encyclopedia editor you might assess and weigh what the experts say, but you are not expert enough to contradict them.

Please note that this article is about the Hilina slump, and its broader context, the south flank of Kilauea Volcano. Not about megatsunamis in Hawaii. The reason we have a "Mega-tsunamis" section here is because the south flank of Kilauea has been specifically cited as a credible threat. (With such claims probably being a primary driver of interest in the Hilina slump.) What McMurtry et al. address is a 120 k.a. landslide on the Kona Coast, which is a vastly different situation than the current Hilina slump.

Please also note that your comment that "local mega tsunamis ... should not be discarded as fiction" is a red herring, not useful in discussion, because it implies that they are being "discarded as fiction". Which is outright false. No one (well, what would I know, but feel free to show me otherwise) doubts the evidence of gigantic landslides in the Hawaiian Islands (and elsewhere) in the distant past, and likewise that they are tsunamigenic. In issue are matters such as whether any flank collapses are imminent, whether they would be big enough to generate "mega" tsunamis, and the scale of the far-field effects. In respect of the Hilina slump it appears these are all negligible.

To summarize: "evidence for gigantic tsunamis from flank failures on other Hawaiian volcanoes" does NOT mean "a mega tsunami originating from Kilauea is not ruled out". It has nothing to do with current state of the south flank of Kilauea. Therefore I am reverting your edits. ♦ J. Johnson (JJ) (talk) 22:59, 12 June 2018 (UTC)

Citations ("references")

There being no objection (see previous section) I have moved the inline full citations from the text into the new "Sources" section, and replaced them with inline short-cites using the Harvnb template. (And incidentally removing all the named-refs. Please note that Harv has the |p=, |pp=, and |loc= parameters for providing in-source specifiers such as page numbers, and it is a Real Good Thing to supply those in each instance.) I have also switched from {cite xxx} to {citation} (in lieu of adding "|ref=harv" to each). Ask if you have any questions about using these templates.

There are still several "references" that are questionable (and need checking, and possibly replacement) or incomplete. ♦ J. Johnson (JJ) (talk) 19:47, 16 May 2018 (UTC)

@ThT: in order to maintain citation consistency, would you mind putting the JAMSTEC full citation into a citation template and moving it to the "Sources" section? (BTW, nice map.) That should probably be done for the Berkeley Seismo blurb as well. Also, please, please, let's not introduce named-refs here, as {Harv} works much better. ♦ J. Johnson (JJ) (talk) 23:23, 28 May 2018 (UTC)

@J. Johnson: because I'm not very familiar with these templates yet, I wouldn't mind somebody more experienced to do that. Best, --ThT (talk) 07:38, 29 May 2018 (UTC)

They're not that hard. And you already have most of the details for the citation. So start by prefixing all your data with the correct parameter name (e.g.: "|first1= Joel E. |last1= Robinson |first2= ...", "|title= JAMSTEC multibeam surveys ...", etc.), wrap them inside "{{citation }}", and the hard part is done. Do that, and then I'll show you how to do the Harv template. ♦ J. Johnson (JJ) (talk) 00:13, 30 May 2018 (UTC)

Well, I tried, but the footnote is not linked with the source yet. --ThT (talk) 08:21, 30 May 2018 (UTC)

Hey, you're on a roll!

The problem you had was using more than four authors in the Harv template: use only the first four, plus the year. (And of course the in-source specifier. Where the source isn't paginated, use |loc= with whatever is appropriate. In this case, I would suggest section numbers and headers.) I fixed that. And it works, but only because you did the hard work. Thank you!

I did some modification of your full citation. Two items of particular note: First, having a space after the "=" makes the value much easier to read. Second, I have found (experience speaking here) that having each author's first and last on the same line (besides being a little more condensed) makes a big difference in not getting different authors' names confused. Also, {citation} does not automatically add a final period like {cite} does (someone thought that was a good feature??), so you do have to remember to add it. I often leave it off until I have tested it, so the absence of that period is a warning I might not have checked it. I'll leave that for you to finish. ♦ J. Johnson (JJ) (talk) 21:49, 30 May 2018 (UTC)

Earthquake References

I'm not sure what connections, if any, these earthquakes supposedly have to the slump and propose to remove them, at least until sources supporting a connection can be provided.

The 1868 earthquake triggered a landslide 5 miles north of Pahala. That's interesting, but what does it have to do with the Hilina Slump? At some point, this article should probably identify the parameters of the Hilina slump, which does not (from what references I have seen) include the area affected by the 1968 earthquake. In fact, the diagrams I've seen suggest that the land mass referred to as the slump are primarily or entirely underwater: http://hilo.hawaii.edu/~kenhon/GEOL205/Landslides/bi-r-ls.gif

There is no suggestion that the 1868 earthquake advanced the slump, and any tsunamis were apparently the product of the earthquake itself, rather than slumping. As the USGS notes, "Kilauea tends to 'slump', which is a slower type of movement that is not associated with tsunamis, although localized tsunamis only affecting the island have been generated by strong earthquakes in the past." https://volcanoes.usgs.gov/observatories/hvo/hvo_news_archive.html

The 1868 earthquake apparently caused a landslide on Mauna Loa, and a tsunami, but all of this was (as far as the sources indicate) unrelated to the Hilina slump.

The 1975 earthquake supposedly opened a crack and advanced the slump, but there is no source provided to support that. The source for the tsunami information does not connect it up to either the earthquake (apparently the cause of any earth movement or tsunami) or anything associated with the slump. John2510 (talk) 03:18, 18 May 2018 (UTC)

• The Berkeley Seismo Blog [5] says that the slump had moved 2 feet after the 6.9 earthquake last week. It says it moved 11 feet during the 1975 earthquake and the 1868 earthquake caused the slump to move, resulting in a tsunami. I doubt that 1868 monitoring equipment was capable of detecting whether the movement of the slump caused the earthquake or the earthquake caused the slump to move. --Scott Davis ^Talk 04:37, 18 May 2018 (UTC)

What both of you seem to have overlooked is that these earthquakes are the manifestation of movement of "the slump" (slumped block?), occurring as both very frequent low magnitude events, and occasional larger magnitude events. It's not that an earthquake is something that just happens, which causes movement; the event that causes the "quaking" is is the movement itself. To say that "the earthquake caused the slump to move" implies that the earthquake is something other than movement, and has some other causation.

"Slump" is a bit a slippery term: does it refer to the movement of material? The locale of that movement? The material itself? Or the resulting physiographic feature? (Try replacing "slump" with "avalanche" for a little different perspective.)

The Hilina "slump" is essentially the missing southeastern flank of Kilauea, now spread out over a large expanse of sea floor. On-shore the portion of Kilauea that is slipping away is demarcated by the Hilina fault system, which roughly corresponds with the the southwestern and east rift zones, and more precisely with the cliffs of Hilina Pali. The 1868 Great Kau quake appears to have been on or near the SWRZ, for which (according to Cannon and Burgmann, 2001) there was 1.2 to 2.1 meters of "permanent coastal subsidence along ~80 km of coastline from Punaluu to Kapaho" (I believe that takes in the entire south coast?), as well as an estimated 8 m of horizontal slip.

Anyway, without getting into it further I'll just say: the earthquakes (large and small) mark the slumping of "the slump". And when I can sort out all this stuff into some intelligible text there will be sources. ♦ J. Johnson (JJ) (talk) 23:32, 18 May 2018 (UTC)

My reading is that there are potentially two different sources of earthquakes, especially smaller ones. The Seismo blog and animation suggested to me that the initial source of earthquakes in the last month was the movement of magma under the rift zone, which would cause small earthquakes and was not at all related to the slump. The slump (the word appears to generally be used as a noun referring to the mass of earth/rock above the fault) then moved, presumably as a result of being loosened by the constant shaking, and caused a larger earthquake. The big jolt is then followed in the animation by more middle-sized ones along the fault (aftershocks of the movement), and a larger concentration under the main volcano (of volcanic rather than seismic origin).

So I agree (and understand) that the earthquakes along the fault are evidence of the movement of the slump. The earthquakes along the rift zone are evidence of the movement of magma from the hotspot. I'm not sure if it is possible to prove causation between the two sets, but it certainly appears to be meaningful to observe the sequence and effects and produce a hypothesis model that includes causative interrelationships between movement of magma and movement of the slump. --Scott Davis ^Talk 06:15, 19 May 2018 (UTC)

I'm learning as I go here, but it sounds like a slump is generally an extremely slow and gradual change, but that earthquakes may cause a more sudden slippage. The slump is moving along its slow and merry way, but an earthquake may cause slippage and tsunamis. Maybe it's a chicken/egg question, but its sounds like there may be some confusion about the order of causality.John2510 (talk) 17:43, 19 May 2018 (UTC)

Again: an earthquake is not a cause of movement, it (the quaking) is a result of movement, whether of slippage of a solid block of rock over another, or passage of liquid rock (magma) through rock.

The slippage (slumping) is, ultimately, due to 1) the pull of gravity, and 2) failure of the rock edifice that is resisting gravity. There is a bit of a chicken/egg question in that some authorities hold that the forceful injection of magma along the rift zone weakens the structure, even forces the slump a little futher downslope. (Two kinds of movement there, and I don't know if they can be distinguished seismically.) On the otherhand, note that the rift zone (well, the ERZ; the SWRZ is more complicated) is parallel to the coast. This follows the zone of tension where gravity has the greatest pull, such that slumping actually creates the rift zoner. Which the magma then opportunistically exploits.

John: When you say "an earthquake may cause slippage and tsunamis" you're probably thinking of tectonically driven events (driven by the movement of the tectonic plates), where the quickness of rock failure can result in a large release of energy in a short time. (In other words: a very sharp kick.) But we don't have that here. These slumpages are gravitationally driven, and can be very unsudden, even slow. Again: earthquakes do not cause slippage, they are the result.

I am still studying all this, but hope to start writing text real soon. BTW, could someone send me a copy of the Smith, Malahoff, Shor 1999 article? ♦ J. Johnson (JJ) (talk) 23:50, 19 May 2018 (UTC)

• Simulation of a La Palma mega tsunami.mov [6]
• Simulation of a mega tsunami from Hawaii [7]
• No, no tectonic plate movement is necessary (see the Vajont Dam disaster). Sturzstroms ages ago from Hawaii and La Palma caused tsunamis. "Again: earthquakes do not cause slippage, they are the result". Again, no. Earthquakes trigger landslides, landslides cause superficial earthquakes. Different earthquakes on a timeline. Volcanic edifices are unstable, actually most mountains have at least one unstable flank. A mountain flank collapse is a very big thing. --Chris.urs-o (talk) 04:04, 20 May 2018 (UTC)

Chris: your "No, no tectonic plate movement is necessary" is quite confusing; I have no idea which way to parse it.

What I was saying above is that tectonically driven earthquakes, where the force driving the quake comes from the movement of the tectonic plates, can deliver a lot of energy (force) in very short period of tilme. But earthquakes in Hawaii are not driven by plate tectonics. They result entirely from gravitationally driven slumping and forceful injection of magma.

Please consider: if (as in your view) an earthquake triggers a landslide, what causes the earthquake in the Hawaiian context?

I agree that a mountain flank collapse can be "a very big thing". But there are a number of caveats that should be considered, starting with: a slump (in our current context) is not the same as the side of a mountain dropping verticalliy into a narrow, closely confined reservoir. What we have in Kilauea is more like a slow motion slide into the sea. And there are geologic reasons why the Hilina slump is not likely to suddenly "let go". More on this below. ♦ J. Johnson (JJ) (talk) 22:29, 20 May 2018 (UTC)

Some of the literature on this is difficult to interpret, but the USGS seems to be saying that slump doesn't cause tsunamis (earthquakes do), and that while slumping is a slow process, an earthquake make cause sudden movement of the slump. I'm getting that from here: https://volcanoes.usgs.gov/observatories/hvo/hvo_news_archive.html

"Kilauea tends to "slump", which is a slower type of movement that is not associated with tsunamis, although localized tsunamis only affecting the island have been generated by strong earthquakes in the past. The May 4 M6.9 earthquake resulted in seaward motion of approximately 0.5 m (1.5 ft) along portions of Kilauea's south flank..."

Maybe the process in place is that the slump is causing the earthquake, and then the earthquake causes sudden movement/tsunamis. If so, I haven't seen that in a source.John2510 (talk) 16:04, 20 May 2018 (UTC)

John: To take your points in reverse order: as Chris said, landslides do cause superficial earthquakes. But neither these, nor the magma quakes, are big enough to cause a tsunami. What causes a tsunami is the sudden displacement of water (because a slow displacement allows the water to flow around whatever causes the displacement). If the displacement is both large enough and fast enough it creates a wave, and possibly a large wave, and no earthquake is necessary. Which gets back to your second point (from the HVO?): "slumping" can be very slow, so no tsunami.

The HVO's statement (a good link, BTW) skips over a few details. When they say "localized tsunamis ... have been generated by strong earthquakes in the past" they don't mention how the quake generated the tsunami. Their statement that the 1975 and 1868 events "were not associated with significant south flank landsliding" is a bit weak, and could be taken to mean that displacement sufficient to cause a local tsunami was not considered a significant landslide.

And see the info on mega-tsunamis, above. ♦ J. Johnson (JJ) (talk) 22:33, 20 May 2018 (UTC)

• I've added an OSM location map in the "Earthquakes" section. As this is the first time I've done that it might be a good idea if someone with more experience with those looked it over. One particular issue: from the template documentation I had the impression that the "mark-title" (which I had in mind to indicate the depth) would appear as a tooltip. Apparently--not?

There are several other quakes in the area which should be added, in order to show the distribution of seismicity in the vicinity of Kilauea. I'm still looking for the data. ♦ J. Johnson (JJ) (talk) 00:20, 9 June 2018 (UTC)

I am not entirely happy with the OSM map of the Hilina Slump#Earthquakes, and have doubts as to the relevance of that section. On one hand, the OSM map looks nice, and I was trying to go with the original content. On the other hand, what is the point of mentioning the earthquakes? The 1975 quake is certainly relevant, as the resultant studies (~45) shed much light on structure of Kilauea and the slump, but it has been suggested that the 1868 quakes were unrelated to the slump. And the recent quake seems not at all notable. As matters now stand only three quakes are shown, which is quite misleading: I have a map showing 30-some quakes on Hawai'i, most of which cluster around Kilauea. I might pull that up to replace the existing map. But that is a bit in front of the key question: why include specific earthquakes (or any quakes?) if there is no definite connection with the slump? ♦ J. Johnson (JJ) (talk) 23:31, 11 June 2018 (UTC)

Lead

@John2510: re your edits here and here in the lead.

It is arguable whether the distinction between "slumps" and "debris avalanches" needs to be made in the lead. But it does need to be made, because one is tsunamigenic and the other is not. I reverted your second edit, as the point of the sentence is that this slump is a typical feature, characteristic of all the Hawaiian volcanoes. I also question whether "slump" should be capitalized. ♦ J. Johnson (JJ) (talk) 20:13, 25 May 2018 (UTC)

Location and extent of "Hilina slump"

In regard to the extent and location of the Hilina slump, ThT changed "extends from approximately the East Rift Zone" to "extends from the Hilina fault zone approximately south of the East Rift Zone". Which is a curious (and vexatious) point that I am currently working on: is the Hilina slump: just the shallow rotational landslide delimited by the Hilina Pali (as the headscarp)/Hilini fault zone and the off-shore toe? Or: the entire mass seaward of the SWRZ and ERZ (out to Cape Kumukahi) that is slumping down along listric faults behind the ERZ that reach down to the decollement, and including the debris field that extends out some 40 km? [To make things clearer please see figures 3 and 8 in chapter 4 of USGS PP 1801, which I strongly recommend downloading. See also figures 1, 2, 10, and 11 in Moore et al., 1989.]

The sources I have seen so far go both ways; I have yet to find any authoritative resolution. Comments?

Incidentally, I have an expansion of the "Geology" section just about ready. ♦ J. Johnson (JJ) (talk) 00:28, 29 May 2018 (UTC)

Before I used the description in Hilina slump area 2001 to outline the Hilina slump I double-checked some of the illustrations in chapter 4 of USGS PP 1801. All these seem to define the Hilina slump as a much smaller area as compared to the large triangle between SWRZ and ERZ (which includes other slumps marked on Figure 2-4-1 ([8]) like Punaluʻu and Lobate terrace slumps). --ThT (talk) 14:51, 29 May 2018 (UTC)

"Seem to" is quite the problem, as I haven't found any definite statements.

In figure 2-4-1 please note: Punaluʻu is west of Loihi Seamount. Note the "Transverse boundary" just northeast of Loihi: that's a canyon that's considered the edge of the Hilina slump (whether large or small). I believe most authorities include the "Midslope bench" area as part of the Hilina slump, but some (e.g., Moore et al., 1989) extend the slump well past the bench. And also out to Cape Kumukahi. E.g., Brooks et al., 2006, refer to: "Kīlauea's entire south flank, known as the 'Hilina slump' (HS) ....". A big consideration for us is that pretty much everything that is notable or interesting about the Hilina slump in its narrowest sense applies to the entire coast. Which rather leaves the Hilina fault system kind of standing in the corner.

I've spent most of today trying to pin this down, but even some of the experts seem take liberties with the sources. As far as the text goes, I'm trying to finesse it for now. ♦ J. Johnson (JJ) (talk) 01:05, 30 May 2018 (UTC)

• Got it! Morgan et al. (2003) discuss this (paragraph 9}, saying: "Some have assigned the entire south flank of Kilauea to the Hilina slump .... Alternatively, the Hilina slump is a shallow feature, possibly confined to the slope sediments upon the upper flanks ...." It is the latter for which the Hilina Pali is the headscarp, and this was the first indication of off-shore slumping on the south flank. The definite delineation of this "possible slump boundary" was by Lipman et al. (1985); see File:Lipman85-Hilina_slump.jpg. The broader view arises from the mapping done in the 1980s that showed slide debris off-shore of nearly all of the south flank. Moore et al. (1989) named that entire area "Hilina", which others have perpetuated.

Failure to distinguish the Hilina slump from the "Hilina" slide area of the south flank has caused considerable confusion. (E.g., the reported area of 5200 km² applies to the latter, not the slump.) The entire south flank, as delineated by the rift zones, is moving, and there is little doubt that the base is the decollement on ocean floor. But Hilina slump is moving more, and there is a question of whether it is shallow, or deep-seated. As to the undeniable signs of landsliding overall, they appear to be older, and likely laid over pre-Kilauea deposits from Mauna Loa.

So even though there are nominally reliable sources that have applied "Hilina" to the whole south flank (Moore et al.'s slide #15), I think we are justified in following Lipman et al. (1985) and Morgan et al. (2003) in distinguishing "Hilina slump" and the "Kilaueua south flank". Because they are so closely connected both should be covered in the article. ♦ J. Johnson (JJ) (talk) 19:56, 2 June 2018 (UTC)