Talk:Mahuika crater

Is it or isn't it an "Impact Crater"?

How can the crater already be declared a bolide crater when it was only in Nov 2003 that the presentation "suggested" the bolide alternative? Has there been a consensus that this argument is valid? RedWolf 03:07, Jan 17, 2004 (UTC)

The authors of the 2003 paper backed it up with an ice core report in Dec 2005: Jopower (talk) 13:56, 11 March 2020 (UTC)

An impact event that creates a 20 km wide crater would have been noticed all over the world. That mega-tsunami theory is very controversial. --Jyril 15:58, Mar 5, 2005 (UTC)

The crater itself is self evident. Supporting evidence comes from widespread tsunamis debris along New Zealands' South Island east coast and from the South East coastal area of Australia. In both areas it is quite common to find beach sand well inland at the head of bays. Allied to this is the well established, sudden disappearance of the Maori colonists of NZ (who arrived about 1280) from the coastal area of the South Island. There is lots of evidence that the SE area of the South Island especially the coastal strip was populated by many Maori who vanished. — Preceding unsigned comment added by 210.86.93.70 (talk) 01:43, 27 September 2011 (UTC)

The hypothetical Mahuika crater is not "self evident" as falsely claimed above. At this time, the evidence offered for the Mahuika crater is quite speculative and directly disputed by other Earth scientists. Direct geophysical and geological evidence for the putative impact site is either lacking or has never been fully presented by the proponents of the Mahuika crater. The interpretations of the astronomic and atmospheric evidence used to support a 1941 comet impact are disputed along with the significance of tektites found in the region of the alleged Mahuika crater. Many of the alleged tsunami deposits found along the coasts of New Zealand and east Australia are regarded by many geologists as not having been created by tsunami. Also, tsunamis can be created by megaearthquakes that New Zealand is prone to. The nature, origin, and even the existence of the Mahuika crater is highly disputed and still lacking critical published documentation. For a summary of the problems with the Mahuika comet impact tsunami hypothesis and Mahuika crater, go read:

Goff, J., D. Dominey-Howes, C. Chagué-Goff, and C. Courtney (2010) Analysis of the Mahuika comet impact tsunami hypothesis. Marine Geology. v. 271, pp. 292–296. Paul H. (talk) 13:54, 30 September 2011 (UTC)

The "Mahuika crater" fails the evidence test so thoroughly that it is not beyond sheer speculation. None of the physical evidence required to indicate (not to mention confirm) an impact site has ever been presented. The evidence presented is extremely thin, can all be explained other-how, and numerous questions about how a 20km, UNDERSEA, crater could form, and yet the whole human race of 1443AD (other than the purported victims) didn't even notice it, are glaringly unanswered. Until this "crater" is much more fact-based, this page shouldn't even be here, as it tends to mislead anyone not familiar with this field. — Preceding unsigned comment added by Ferrocephalus (talk • contribs) 06:19, 18 April 2013 (UTC)

By the way, I found a MS thesis that examined the alleged tektites associated with the "Mahuika crater". It is "A Reevaluation of the Tektites Associated with the Proposed Mahuika Impact." It found "that they are not glass, but microcrystalline. SEM analysis showed that these nodules are authigenic clays that form rounded casts inside hollow foraminifera" by Mohana Kumar (2008), Earth and Environmental Sciences Journalism, Columbia University, City of New York. Paul H. (talk) 11:10, 29 September 2014 (UTC)

"The hypothetical Mahuika crater" does exist, by whatever means it was made. Otherwise how do we have recent hydrographic imaging of the crater feature and core samples to make comment on (refs already given)? Therefore the opinion "this page shouldn't even be here" can not be supported. Further, major eruptions have gone unnoticed before due to obscurity. One typical example of several I found here on Wikipedia and elsewhere: there was a mystery eruption in the Pacific area in 1465 that may've been as big as Tambora 1815 but went unnoticed during the human travails of the "Little Ice Age": . The Mahuika event may be in the same category. I conclude the event certainly COULD happen without exciting great comment beyond New Zealand and eastern Australia native myths.

Whether an asteroid impact or some volcanic blast, let's consider the case with the 1400's era in mind beyond annoying details like the Little Ice Age effects, petty and major wars, political disruptions and religious affectations that all kept our minds on basic survival. The Mahuika event occurred in about 300 meters of water, in the far southern regions (48.3 S x 166.4 E) where high dispersing winds moving west to east are common . Adding to this is the fact that it's some 7000 km from ANY objective observers (like China) and none of them had any useful quantitative instruments. Among your likely "noticable" examples are Krakatoa (1881) and Tambora (1815), both of which exploded on or partially on land, in or near populated areas, at a time when observers with some scientific knowledge could record or later evaluate the event. If you may also ref the 65 MYBCE Chicxulub crater (aka: Yucatan impact), it's a vastly greater event due to an asteroid from 11 km diameter (if high density mass) to as large as 81 km (if low density) that also occurred partially on land and very shallow water. Whatever it's diameter, it was still at least 1000 times heavier than any object that may've made the Mahuika crater by impact and VASTLY larger than any volcanic eruption in historical human experience. All of them threw up cubic volumes that greatly affected the regional vicinity immediately. The global atmosphere received vast amounts of dust that persisted. Now consider that we are talking about a near opposite locational event, larger than but more akin to atomic bomb blasts under water in distant atolls or the open ocean (see below). For a small scale visualization, explode a stick of Dynamite/TNT in a 0.3 meter wide x 1 meter deep dirt hole and then try it 1 meter under water in a shallow pond... big difference in results (ask a military demo expert if you don't believe me). There is a further variable: the density of the impact mass. A heavy Iron asteroid and an "Ice Ball" or something in between would make a great difference in impact energy dispersion and the interaction with the atmosphere, ocean and ocean floor. Tektite formation may also be effected. How many studies have been done on ocean floor material conversions (out beyond the shore depth) by an asteroid of these 3 types of a 1-2 km diameter? Those of the Mahuika crater may be the first to give us anything quantitative. Be happy to hear of the others.

As to the Mahuika event, certainly the flash, tsunamis, water vapor, considerable small-grained debris and even sound could carry some 1000's of km, depending on various factors. The concussive shock wave does cause massive displacement of the ocean floor as well as tsunami displacements, but that's where most of the energy is expended. The ejecta energy is severely dampened by the surrounding water volume (liquid and vaporized) and tends to rise straight up on the course of least resistance. See "Baker" atomic test as example of how well sea water contains massive sudden disruptions: . In the Mahuika location, water vapor carried smaller grains up to be swept away by strong winds out of the west, as recorded by Antarctic ice cores. It's about 9000 km to the coast of Chile and the heavy stuff has no chance. Supporting evidence: to the north, nearby Stewart Island and southern New Zealand were scoured by 100-300 meter tsunamis which left considerable coastal debris but there is no mass layer of ejecta on them, unlike the areas around the land-based events mentioned (a research paper to check Chilean glaciers for 1443 dust anyone?). Jopower (talk) 13:56, 11 March 2020 (UTC)

References

Source Web Page of Copyrighted Text

Although it is likely a mute point, The source of the copyrighted material removed by User Huon in Revision as of 16:15, 28 September 2014 is an fringe, unreliable, and self-published web page, 22 The Destruction of Zhou Man and Hong Bao’s fleets in the Southern Ocean by a Tsunami triggered by a comet, by Gavin Menzies.

Although this is a minor point, it is well worth noting the source of and text that is violation of Wikipedia's copyright policies so people can easily judge for themselves. Paul H. (talk) 17:29, 28 September 2014 (UTC)

While I agree that removal of un-authorized copyrighted material is quite appropriate, I do not agree that this material is "fringe, unreliable" in it's entirety. While I freely admit Gavin Menzies is passionate and somewhat hasty in his reasoning, that Mr. Menzies and others have indeed discovered, recovered and documented solid physical evidence of the destruction of a considerable portion of the historic Chinese fleet on a very specific date is of considerable importance to this and many other related articles here on Wikipedia. It is of immediate importance that this evidence be more thoroughly researched and evaluated by scientifically accepted and unbiased organizations before this evidence is further damaged by man or nature. Mr. Menzies has been bombarded by dogmatic authorities and special interests in a manner recalling pre-1940 Europeans protecting their nationalist beliefs that they (and no other) was the seat of Man's rise to civilization. Supporting him is that the existence of these fleets and the extent their voyages is no longer in any question due to the long overdue research and publishing of the extensive records found in Chinese and other archives. See the Wiki on Zheng He . This was also reported to the interested public by the fairly reputable National Geographic Society (among others). See: “China’s Forgotten Fleet: Voyages of Zheng He”, by NGS in 2008.

In summary, Mr. Menzies, while passionate and somewhat hasty in his reasoning, is not a "total fringy" looking for "ancient astronauts", et al. He has evaluate-able evidence in support and should be given a fair and unbiased hearing, uninhibited by dogmatic entities. I would like to see the pertinent details revealed from the various sources included in the article as the data firms up. Jopower (talk) 07:48, 11 March 2020 (UTC)

References

More neutral

I tried to make the article more neutral by adding a footnote to "hypothesized" in the first sentence, reading That an impact created the crater and that it caused a tsunami are issues currently under debate. and citing Goff, but the text was removed by editor Primefac with the edit summary stating it as a hypothesis indicates there is no consensus (and no need for a ref tag there. My own view is that "hypothesized" only indicates a theory, and not that the theory has been challenged, so that the footnote imparted additional information that would allow the article to be appropriately skeptically read. I carefully did not put in any argumentation. What do you all think? --Bejnar (talk) 15:08, 7 October 2014 (UTC)

I removed the footnote/note because a claim like that should be a full sentence/section with references of its own. I've just now redone the lede and sections so that it shows there is debate, though obviously it still requires expansion. Primefac (talk) 15:40, 7 October 2014 (UTC)

Proposed date of AD 1491?

Obviously the proposed date of Febr. 13, 1491 (alluded to in the article and in the 2010 paper currently listed under footnote 4) has to be taken from some observation of a sky event found in Asian (Chinese?) sources - it is much too precise to relate to geological traces at the crater itself and it can hardly be related to Maori traditions either; AFAIK pre-European Maori chronology doesn't offer quite that level of precision in dating non-recurrent events. So it's from some observation of a fireball, a guest star or the like in an Asian chronicle. Could someone find out what observed event it is that the supporters of the impact theory are linking to the crater? This is clearly relevant to an article about this crater/possible astrobleme. Strausszek (talk) 03:06, 11 May 2016 (UTC)

The 1491 date would appear to be from a different astronomical event unrelated to the Mahuika event. The ice core records in this paper: "Evidence from an Ice Core of a Large Impact Circa 1443 A.D." found in the Astrophysics Data System at Harvard combined with records from the destruction of Zhou Man and Hong Bao’s fleets would seem to solidify the date of the Mahuika event, whatever the origin, as occurring early in 1443 ACE. Logically, an impact object that would NOT be easily visible until it's final minutes to pre-telescopic observers, and likely coming from a direction NOT populated by a civilization which might be intently observing the sky, would obviously NOT be reported or archived in detail, except as a regional or local myth. The surviving members of the Chinese fleet, who had likely only a few minutes or seconds to realize the slightest inkling of the cause of what had befallen them would hardly have had time to analyze the event. All they could hope to do would be to archive observations and get home. Whatever event we can head under the 1491 year needs to become a separate article once the dust clears. Jopower (talk) 14:22, 11 March 2020 (UTC)

References

1491 question

Moved from Special:PermaLink/859880928#Mahuika_crater

You said:- "I'm not really sure what the point is, since the related article doesn't mention the crater, just that *this* comet might have been misidentified)"

The paper that included the retraction was published in 2002. How could it possibly mention a crater which was first proposed in 2003. As I already pointed out the comet was not misidentified, "the records of this comet were misunderstood". The point is, the 1491 impact date was suggested because of the published orbit of Comet 1491 II.

You said:- "Neither article says anything about the 1491 comet "not receding from Earth"; the closest is that it *might* be the progenitor of the Quadrantids"

I did not say "not receding from Earth". The referenced 2010 Goff paper says that the comet "was not observed by anyone near its computed closest approach date". You cannot see a comet when it is approaching Earth from the direction of the Sun, so the above comment applies when it enters the night sky, moving away from Earth.

The comet possibly associated with the Quadrantids is Comet 1491 I, a completely different comet. — Preceding unsigned comment added by 58.165.198.47 (talk) 14:53, 4 September 2018 (UTC)

First off, you most definitely did, because the added text said yet the comet was not seen receding from Earth. Second off, the fact that it might have been created in 1941 is refuted in the previous paragraph by Ref #4, making the paragraph unnecessary and somewhat confusing. Primefac (talk) 22:52, 16 September 2018 (UTC)