Thread by @shivangi__t

Since there is some spectacularly bad reporting happening - and the confusion is spreading fast - some clarifications:

(THREAD)

1. A glacier is like a river of ice. It looks like this:

(Source: Wikipedia page on Drang Drung glacier)

2. Glaciers tend to erode the land on which they "flow". This can form depressions which fill with water when the glacier melts. This is called a glacial lake. It looks like this:

(Source: blogs.ei.columbia.edu/2018/05/21/cli…)

3. Glaciers tend to carry sediments of varying sizes, and deposit them when they get tired (JK, but let's not go into that here). These deposits are called moraines. One type of moraine is called a terminal moraine. It looks like this:

(Source: Wikipedia page on Wordie glacier)

4. Such terminal moraines can sometimes "dam" a glacial lake. When this breaks, a Glacial Lake Outburst Flood (GLOF) can occur. The 2013 Uttarakhand tragedy was a GLOF.

I would personally wait a bit before this one is termed a GLOF, but to each, their own.

5. If a glacier breaks - i.e. if a chunk of ice broke off - it would take a while before it melted. This melting would happen slowly. It would not lead to a flood like this.

6. GLOFs can be triggered by multiple things, including landslides. Once again, I reiterate - it takes a while for such disasters to be "diagnosed". Don't call it a GLOF on your own. Wait for a proper expert to give a verdict.

7. I don't know where it all started but it seems news articles are just parroting things off without checking if it makes sense.

For example, this is an article by @IndiaToday . Glaciers and moraines are not the same thing.

(Source: indiatoday.in/india/story/ut…)

8. I don't think glaciers get "eroded" like that or "break" due to such reasons. But I could be wrong.

[ @rapiduplift and @Geo_Sophist - What do you think? ]

Yes, glacial lakes can burst due to those reasons.

(Source: indiatoday.in/india/story/ut…)

9. A flash flood is a very rapid flood. GLOFs can cause flash floods. But flash floods also occur outside the realm of glaciers.

10. If you are comparing this event to the 2013 GLOF, you are automatically equating this to a GLOF (which I think is premature and unwise, and unprofessional if done without quoting an expert).

(Source: indiatoday.in/india/story/ut…)

11. But if you must mention it, at least mention that it was a GLOF where the Chorabari glacial lake burst after a cloudburst. (I know, too many bursts.)

(Source: indiatoday.in/india/story/ut…)

12. @IndiaToday - Sorry that I'm picking on you, but this was seriously substandard. Also

EVERY NEWS CHANNEL NEEDS A SCIENCE JOURNALIST.

Lastly, I learnt this stuff during my undergraduate programme in Geology. I haven't discussed anything advanced here.

If an expert says otherwise (about any point), assume I'm the one who's wrong. Please let me know so I can correct myself.

~ FIN