4 ms·

Is the big island the biggest just because it is the newest? Were the other islands bigger and have eroded over time?

by gangstead 4y ago

deleted 4y ago
[deleted]
dreamcompiler 4y ago
Good question. I expect so but I'm not a geologist.
ouid 4y ago
They're pretty young geologically, <5 mya. Hawaii gets insane amounts of rain, but its hard to imagine that being enough to fully erode an islnd the size of mauna kea, and i think you would expect to see similar volume between the islands if it were just erosion, since it would mainly just be flattening them, rather than dissolving them, but i'm also not a geologist.
- vikingerik 4y ago
  The volume from an eroded island is still there, it's just flattened below sea level, ultimately down to a wider base at the sea floor.
  - RajT88 4y ago
    My wife and I go to Hawaii some winters to celebrate our anniversary (it was our honeymoon spot, of course it was). We've taken a few tours there to learn about the place. What I recall from those tours is that the islands are all slowly sinking. Indeed Big Island is the biggest because it's the newest - the older ones are smaller because they have had more time to sink / erode.
s1artibartfast 4y ago
Keep in mind that the exposed area and volume of the Hawaiian islands is a very small portion of their overall volume. It is also worth noting that most of the volcanos in the Hawaiian chain are part of a single ridge which connects bellow the surface. [1] The depth of the ocean also differs significantly along the emperor seamount chain. With all that said, This paper suggests that the rate of magma has increased recently. [2] https://www.researchgate.net/publication/222958454_Calculated_volumes_of_individual_shield_volcanoes_at_the_young_end_of_the_Hawaiian_Ridge https://www.researchgate.net/publication/222958454_Calculate... https://www.researchgate.net/profile/Michael-Garcia-15/publication/282070552/figure/fig4/AS:668448883478535@1536382041330/Multibeam-bathymetry-map-of-the-Hawaiian-Islands-illuminated-from-the-NW-grid-available.png https://www.researchgate.net/profile/Michael-Garcia-15/publi...
saiya-jin 4y ago
Cold magma gets relatively quickly weathered by elements, so volcanic islands tend to go through process of creation and destruction on multiple levels. Only when foliage creates thick and cohesive enough layer to slow down weathering they become more long term (till new eruption swallows that foliage and here we go again). Ie Iceland get from time to time new small islands created and they disappear by same process usually within few years.
msworddebugger 4y ago
> 1.2 million years ago, Maui Nui was 14,600 square kilometres (5,600 sq mi),[1] 40% larger than the present-day island of Hawaiʻi. Sea levels were lower than today's, due to distant glaciation locking up the Earth's water during ice ages, thus exposing more land. As the volcanoes slowly settled by subsidence, due to the weight of the shield volcanoes and erosion, the saddles between them slowly flooded, forming four islands: Maui, Molokaʻi, Lānaʻi, and Kahoʻolawe by about 200,000 years ago. Another former volcanic island lying west of Molokaʻi was completely submerged, and covered with a cap of coral; it is now known as Penguin Bank. https://en.m.wikipedia.org/wiki/Maui_Nui https://en.m.wikipedia.org/wiki/Maui_Nui

Is the big island the biggest just because it is the newest? Were the other islands bigger and have eroded over time?

deleted 4y ago

[deleted]

dreamcompiler 4y ago

Good question. I expect so but I'm not a geologist.

ouid 4y ago

They're pretty young geologically, <5 mya. Hawaii gets insane amounts of rain, but its hard to imagine that being enough to fully erode an islnd the size of mauna kea, and i think you would expect to see similar volume between the islands if it were just erosion, since it would mainly just be flattening them, rather than dissolving them, but i'm also not a geologist.

vikingerik 4y ago
The volume from an eroded island is still there, it's just flattened below sea level, ultimately down to a wider base at the sea floor.
- RajT88 4y ago
  My wife and I go to Hawaii some winters to celebrate our anniversary (it was our honeymoon spot, of course it was). We've taken a few tours there to learn about the place. What I recall from those tours is that the islands are all slowly sinking. Indeed Big Island is the biggest because it's the newest - the older ones are smaller because they have had more time to sink / erode.

s1artibartfast 4y ago

Keep in mind that the exposed area and volume of the Hawaiian islands is a very small portion of their overall volume. It is also worth noting that most of the volcanos in the Hawaiian chain are part of a single ridge which connects bellow the surface. [1] The depth of the ocean also differs significantly along the emperor seamount chain. With all that said, This paper suggests that the rate of magma has increased recently. [2] https://www.researchgate.net/publication/222958454_Calculated_volumes_of_individual_shield_volcanoes_at_the_young_end_of_the_Hawaiian_Ridge https://www.researchgate.net/publication/222958454_Calculate... https://www.researchgate.net/profile/Michael-Garcia-15/publication/282070552/figure/fig4/AS:668448883478535@1536382041330/Multibeam-bathymetry-map-of-the-Hawaiian-Islands-illuminated-from-the-NW-grid-available.png https://www.researchgate.net/profile/Michael-Garcia-15/publi...

saiya-jin 4y ago

Cold magma gets relatively quickly weathered by elements, so volcanic islands tend to go through process of creation and destruction on multiple levels. Only when foliage creates thick and cohesive enough layer to slow down weathering they become more long term (till new eruption swallows that foliage and here we go again). Ie Iceland get from time to time new small islands created and they disappear by same process usually within few years.

msworddebugger 4y ago

> 1.2 million years ago, Maui Nui was 14,600 square kilometres (5,600 sq mi),[1] 40% larger than the present-day island of Hawaiʻi. Sea levels were lower than today's, due to distant glaciation locking up the Earth's water during ice ages, thus exposing more land. As the volcanoes slowly settled by subsidence, due to the weight of the shield volcanoes and erosion, the saddles between them slowly flooded, forming four islands: Maui, Molokaʻi, Lānaʻi, and Kahoʻolawe by about 200,000 years ago. Another former volcanic island lying west of Molokaʻi was completely submerged, and covered with a cap of coral; it is now known as Penguin Bank. https://en.m.wikipedia.org/wiki/Maui_Nui https://en.m.wikipedia.org/wiki/Maui_Nui