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Comment by jfoster | Hacker News Reader

I don't know much about volcanoes. Am I correct in thinking that even though Mauna Loa is the largest volcano on Earth, this eruption is not a global threat in the same way that eruption of Yellowstone could be, since it doesn't tend to be explosive?

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You are correct. The volcanoes in the Hawaiian chain are so-called mafic volcanoes.

In general, volcanoes are classified as silicic or mafic. The silicic ones contain more gas and tend to erupt explosively; the mafic ones, more lava floes.

Compare Mauna Loa (mafic) to Mount St. Helens (silicic), the latter of which was far more explosive due to high silica content, which increases magma viscosity and acts as a trap for (superheated) water and other substances.

I encourage you and others to use the excellent USGS resources, such as:

https://volcanoes.usgs.gov/vsc/glossary/

https://www.usgs.gov/news/volcano-watch-why-are-mount-st-hel...

I hold a M.A. in geology and am a licensed geoscientist-in-training in Texas.

Out of curiosity, why is geology a MA?

Good question. It's specific in my case to the school/department that awarded it.

When I earned my M.A. at the University of Texas at Austin in 1995, the M.A. was the option for coursework and original research in the form of a thesis. The M.S. was reserved for the coursework-only option (rarely awarded).

In 1996 (I believe), the department changed the thesis-based Master's to an M.S. degree and did away with any no-thesis degrees higher than Bachelor's. This decision short-sells the awardee, unfortunately.

In general, an M.S. in STEM fields indicates a coursework-only degree (typically 6 classes, no thesis or original research) and an M.A. indicates a more rigorous course of study and research.

My Master's thesis, btw, is "Desorption of High Explosives from Soil: Thermodynamics and the Role of Soil Organic Carbon."

> In general, an M.S. in STEM fields indicates a coursework-only degree (typically 6 classes, no thesis or original research) and an M.A. indicates a more rigorous course of study and research.

I did not know that. Thanks for the explanation!

I don’t know that this is a reasonable generalization. Certainly in my CS department one could write a thesis to receive an MS, and no MAs were offered. Just one data point, from a very large state school; YMMV.

You're correct, it's not a reasonable generalization. See my reply above.

The essence of my answer is based on the way things were in my graduate programs at my university when I was in school there; and some observations from so-called terminal Master's degree programs.

I should clarify that the M.S. is available in some departments as a terminal degree, or is awarded along the way towards a Ph.D. upon completion of coursework and admission to candidacy (oral/written exams), as is the M.Phil. The main thing is knowing what the degree was awarded for at the end of the day, which may or may not matter to the degree holder or the employer.

In my doctoral program in chemistry, the M.S. was "awarded" to Ph.D. candidates who did not pass orals and was referred to as "the booby prize." Having been admitted to candidacy and completing my doctorate, I have only a Ph.D. in chemistry and not a Master's of any kind.

Having said all that, almost every M.S. I've seen during interviews over the past 20 years has been a terminal degree lacking a thesis - but I am a scientist, and I see mostly physics/chemistry/geology/mathematics resumes and not engineering or CS ones.

That is strange and interesting as it seems counter-intuitive since a B.A. in say, physics, is less rigorous than a B.S. from a pure physics/mathematics standpoint.

That depends a lot on the issuing university. At some of the medieval university, e.g. Cambridge, the only undergraduate degree is a BA, regardless of subject. Likely because the naming of the degree predates the modern usage of the word science.

Few would argue that a BA in physics (which would actually be in Natural Sciences) from Cambridge is "less rigorous"

Sure, that's "old-fashioned" as a friend once told me (who was a Rhodes scholar.) At the two universities I've attended, the B.S. in physics required more rigor and the B.A. offered more breadth and didn't require as many courses starting in "PHY". I'm guessing it's an American thing too.

Cambridge and Oxford and a few others also then grant students an MA more or less automatically¹ a handful of years after graduation², a process sometimes referred to jocularly as the "MA for FA"!

¹ There's a fee...

² https://en.m.wikipedia.org/wiki/Master_of_Arts_(Oxford,_Camb...

Sir you owe me a new pince nez because mine just shot across the room.

This reminds me of a bunch of people trying to claim that Elon Musk didn't have a degree in Physics because the degree was a B.A. instead of a B.S.

What goes into becoming a fully licensed geologist? I'm curious how it compares to engineering.

Generally speaking, though it varies by state, Engineer in Training after passing the Fundamentals of Engineering exam, then you must work under a Professional Engineer (PE) for $x years and pass the PE exam to officially call yourself an engineer.

Almost exactly the same process.

For the PG (Professional Geologist):

https://tbpg.state.tx.us/licensing/p-g-licensure/p-g-licensi...

and, for the GIT (geoscientist-in-training):

https://tbpg.state.tx.us/licensing/geoscientist-in-training-...

In my case, I took and passed the Fundamentals of Geology (ASBOG) exam in 2014 (and have at least a Bachelor's degree AND a minimum of 30 hours of geosciences coursework). I've held and renewed (continuing education) my license (GIT-98) yearly.

What has stopped me from getting my PG is that I haven't accumulated enough time working in the geosciences since earning my degree almost 30 years ago!

But I very much would like to, and that's a different story.

FWIW I have a BES and MSc in geography (focusing on GIS and remote sensing with numerous ecology, geology, climatology course sets to back it all up). My programs offered BA and MA (and MES) and you basically got to pick which you wanted to earn with very minimal (think 1-3 different courses) differences on how far you went towards the "human geography" vs. "physical geography" angles. A lot of similar geography programs in Ontario were also BA degrees despite being plenty heavy in "hard" sciences.

Obviously can't speak for parent's case (and I recognize geography is not geology), who has provided a very nice answer, but I wanted to just throw out there that sometimes it's all kind of... nebulous.

To add a little more color to the below for CS grads - University of Illinois actually issued BAs and BSs in CS when I attended. Different colleges, different "flavors" of CS - the BA was far more formal and logic heavy.

Unless I'm wrong wouldn't a large concentration of mafic eruptions also be extremely (if slowly) dangerous? The Siberian traps apparently caused history's biggest known extinction event and they were mostly a huge concentration of slow magma outflows.

The event you refer to might have been the cause of mass extinction at the end of the Permian period, but only because the magmatic flow cooked enough carbonaceous material to raise the temperature of the Earth significantly due to increased concentrations of carbon dioxide in the atmosphere; I would call this a secondary effect related to magmatic combustion and not an aerosol-heavy event associated with a silicic eruption.

>In general, volcanoes are classified as silicic or mafic. The silicic ones contain more gas and tend to erupt explosively; the mafic ones, more lava floes.

A few geology papers were part of my engineering study way back when - we were taught 3 types: basalt, andesite, and rhyolite in order of explosiveness. It might have been NZ biased.

I presume basalt is in the mafic group, and the other two are silicic?

Yes, you are correct. The difference between andesitic and rhyolitic classifications is based on silica content.

Andesitic is the midrange member of the continuum from rhyolitic (silicic, explosive) and basaltic (mafic/ultramafic, more lava and oozing) end members.

Short answer: Yes.

Longer answer: Very occasionally, a Hawaii-type volcano has a major landslide, which can create a huge tsunami - https://en.wikipedia.org/wiki/Nu%CA%BBuanu_Slide

Wow, I didn't know about that. A link to a model from that page suggests massive tsunami heights around the pacific, including 70m in southern california! Something of that size would be cataclysmic, and wipe out most populated areas around the pacific rim... probably not likely since it hasn't happened for a million years.

Not a vulcanologist but, the hawaiian volcanoes largely erupt low viscosity (low silica) basalt lavas. Consequently they are not generally explosive in the way volcanoes with higher viscosity lavas (higher silica content) like andesite or dacite are. They don’t produce ash in a way that could have a major effect on the global climate.

Happy to be corrected by someone more in the know, but I think the main risk to the wider pacific would be a flank collapse and associated tsunami but the probabilities of this are very low.

There is evidence of previous such events: https://en.m.wikipedia.org/wiki/Hilina_Slump

When I was there in 1998, there was a little river of lava that reached the Pacific. You couldn't get anywhere near it, but you could see the steam rising up.

It’s just the largest active volcano, not the largest period. Super volcanoes are certainly much larger.

No, they actually aren't. The heat flow that powers Yellowstone is roughly similar to the one that powers Mauna Loa.

The difference is that Hawaii hotspot is constantly erupting, and has produced roughly 6000km^3 of new rock in the past 650 kyears, which is how long it is from a proper Yellowstone supereruption, while the Yellowstone hot spot just builds and builds material and heat, until it finally all goes off at once. This is what's believed to be the difference between supervolcanoes and normal ones.

There has been volcanism on a much larger scale in the past (see: large igneous province), but they aren't really volcanoes in the sense we understand them, and are not related to supervolcanoes.

Since this question has been answered already, I will suggest a documentary I watched recently: Fire of Love. It uses footage filmed by a French vulcanologist couple in the 60s-90s to tell their story and how the study of volcanoes has saved lives (and taken, as you'll see in the documentary). It's currently streaming on Disney+ in the USA.

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