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Comment by itcrowd | Hacker News Reader

How close is this eruption to settlements and/or telescopes?

Telescopes are on another mountain, Mauna Kea. Lava from Mauno Loa can't reach Mauna Kea. Ash or earthquakes I guess could be an issue.

Settlements would be at risk if lava leaves the crater.

Close to settlements; the city of Hilo is built on a fairly recent lava flow.

The telescopes are on another, dormant summit.

How big is the island? I have a friend living there at the moment but worrying.

According to the USGS:

> Mauna Loa is among Earth's most active volcanoes, having erupted 33 times since its first well-documented historical eruption in 1843. It has produced large, voluminous flows of basalt that have reached the ocean eight times since 1868. It last erupted in 1984, when a lava flow came within 7.2 km (4.5 mi) of Hilo, the largest population center on the island. Mauna Loa is certain to erupt again, and with such a propensity to produce large flows, we carefully monitor the volcano for signs of unrest.

Source: https://www.usgs.gov/volcanoes/mauna-loa

Edit: The island is decently big, so the impacts probably won't affect a significant amount of the island. That said, some settlements like Hilo are in the impact zone for a significant event.

Decent doesn't quite cover it for people unfamiliar with the size of the state. The island that this volcano is on is bigger than the states of Delaware and Rhode Island combined.

So the good news is Hawaii isn't the "sudden explosion and everyone dies" kind of volcano. It's the oozy kind. You just have to not stand still and let the lava take you.

That's not to say it's risk free or that some people -- maybe even lots of people -- won't be homeless when the lava finishes flowing, but this isn't a high casualty sort of disaster.

Thanks. I sent my friend a message because I’m not sure where abouts in Hawaii he lives. Hopefully he replies soon. But happy to hear it’s not high casualty disaster. Obviously no casualty is better tho.

It is probably going to be a no casualty event -- according to the USGS, only one person has died due to an eruption in Hawaii this century. Radios and cars make evacuations a lot easier.

I'm not even sure we'd expect casualties from the evacuation -- if 100,000 people (twice the population of Hilo) drove entirely around the Big Island (300 miles), you'd only be at around 30 million passenger-miles, well short of the statistical 1 death per 100 million passenger-miles.

FYI: despite popular misconception, "casualty" doesn't imply death. A casualty of war, for example, might actually refer to someone who is wounded/maimed/etc. but still survives.

If a house is consumed by lava and the occupant becomes displaced/homeless, it could reasonably be argued that it didn't result in zero casualties. Same goes for other things that might be more commonly understood as "collateral damage".

Well, Mauna Loa has a fast moving lava in much larger quantities than the nearby Kilauea, so the scenario might be grim there as well. Large areas can be flooded within hours, especially on the south-west.

Flooded with lava? The flow is that fast? Wow

See the map; the red area is the one with fast flows:

https://specials-images.forbesimg.com/imageserve/604bccae8e1...

Lava can move quite fast.

A fair amount of recorded photos and videos of eruptions were taken by people who realized they would not escape.

The lahars are the scariest. They’re landslides that can go down river valleys at speeds exceeding 200km/hr. https://www.usgs.gov/programs/VHP/lahars-move-rapidly-down-v...

Roughly 5300 square kilometres. About three times the area of Los Angeles.

Eruptions on the big island happen pretty frequently, maybe about 1-2 times per decade (partly because there are several volcanoes there; Kilauea was erupting when I was there less than a decade ago). It's in some ways comparable to hurricanes on the gulf coast, but with fewer deaths historically. Not to say that it is safe as such, but residents of the big island are very good at dealing with it.

Wow, I guess in Asia I don't hear about it as much. I had no idea it was that frequent.

Kilauea (the other active volcano on Hawaii island) erupted continuously from 1983–2018. It erupted, again, in 2020-2021, and is currently erupting as best I can tell. It is more notable when it is not erupting!

https://en.wikipedia.org/wiki/K%C4%ABlauea

The island is huge, 70 miles East-West and 90 miles North-South. If you've seen islands on inland lakes, on the Great Lakes, or off the Atlantic or Pacific coast, you're thinking too small. As long as you're not standing on the summit of Pike's Peak (or Mauna Loa), you're probably unable to see beyond the curvature of the earth to a horizon comparable to the distance from the caldera to where your friend lives, and the probability that a lava flow oozes all the way to the horizon is vanishingly remote.

However, the bigger factor in your friend's safety is that the vast majority of the population live near the coasts of the island, very very very few live near the peaks. Also, 5x as many people live on the 5x smaller island of Oahu in the city of Honolulu rather than on the island of Hawaii...if your friend lives "in Hawaii", statistically they probably live on an island 200 miles away, or potentially on the coast 40+ miles from the summit, it's extremely unlikely that a random Hawaiian lives on the slopes of Mauna Loa.

So I got curious because it's difficult for me to understand the size. So comparing to places I live.

NZ: Total 268,021 km2 (103,483 sq mi)

SG: Total 733.1 km2 (283.1 sq mi)

TW: Total 36,197 km2 (13,976 sq mi)

Hawaii: Land 6,423 sq mi (16,638 km2) (I picked land as it appears to be several islands?)

So it's in between SG and TW. So it's quite large. Bigger than I imagined.

There are a number of islands in the Hawaiian Islands spread over a fairly large area. (For commercial travel, you need to fly between them.) The biggest, where the eruption is happening, is also called Hawaii although locals refer to it as Big Island unless they're referring to the state as a whole. Big Island is 4,028 square miles (10,430 km2) and has a population of about 200,000 most of which is on either the east or the west coast.

Most of the population of the state though is in Honolulu on Oahu (also where Pearl Harbor is). There are over 100 islands but just 8 main ones of which casual visitors might visit 5.

> The island is huge ... If you've seen islands ... or off the Atlantic or Pacific coast, you're thinking too small.

Maybe along the US coasts, but a bit further up north, there are significantly larger islands along both coasts[0]:

>> 16 Newfoundland | 108,860 square km | 42,030 square miles | Canada (Newfoundland and Labrador)

>> 43 Vancouver Island | 31,285 square km | 12,079 square miles | Canada (British Columbia)

>> 75 Hawaiʻi (Big Island) | 10,434 square km | 4,029 square miles United States (Hawaii)

[0]https://en.wikipedia.org/wiki/List_of_islands_by_area

(edited for clarity)

There is nothing to worry about. The local officials see these things all the time, they will relocate anyone in danger to a safe locale.

It'll be days before the lava is potentially dangerous. It's slow moving so plenty of time to evacuate. It can take weeks for the lava to make its way to the ocean

what's this? https://www.google.com/maps/place/Mauna+Loa+Observatory/@19....

There is a meteorological observatory 4/5 way to the top. And there is some NASA practice area/habitat for Mars missions somewhere.

Atmospheric monitoring, mostly[1]. Notably, the picture on Google is wrong, it shows Gemini, which is here: https://www.google.com/maps/place/Gemini+North+Telescope/@19...

[1]https://en.wikipedia.org/wiki/Mauna_Loa_Observatory

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