Until 1969 most of the major volcanic activity on Kilauea was at the summit caldera as described in the previous post. But in that year another centre of activity began at what is now known as Mauna Ulu. This was the start of a trend for volcanism to move to the south East. Currently most activity is at Pu’u ‘O’o.
Activity started along a fissure with lava fountaining out of a mile long crack.
Most of the lava went downhill as lava flows but there was a spatter upslope which has left a distinctive “Spatter Rampart”.
The fountaining lava gave rise to huge deposits of cinders, many of which have a colourful irridesence.
Also there are abundant streamlined droplets of flying lava called “Pele’s Tears”.
In a few months the activity had concentrated at the future site of Mauna Ulu and the lava shield began to build. The surrounding countryside was covered with lava and lava flows ran towards the sea. Further along the “Chain of Craters Road” you can see where lava flows from Mauna Ulu ran over a cliff and down towards the sea building lots of new land.
Nearer to Mauna Ulu itself the lava flows covered a tree covered landscape. Often the trees leave a memory of themselves in the shape of “Lava Trees”.
The lava comes against the tree and solidifies immediately due to the water content of the tree. More lava solidifies and the rest of the molten lava flows past the solid mass. Meanwhile the tree burns away just leaving its shape behind. When the lava stops the level drops and the lava tree is left standing proud.
Mauna Ulu built itself up to a height of 120m above its surroundings. This was done by a series of lava flows like that below.
Put a lot of these together and you end up with a lava shield.
From the lookout over Mauna Ulu you can see, on a good day, Pu’u ‘O’o where most of todays activity is.
There is much, much, more to the geology of Hawaii than I have given here but I hope I have given a taster of what can be seen. I’m disappointed that there was no flowing lava to look at but what I saw was very interesting. I suspect I will have to come back again!
A very good map and pamphlet about the geology of Kilauea can be downloaded from HERE.