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Hawaiian Volcanoes Field Course 2010

Volcano National Park, HI
1239 m above sea level

Today was our first full day in the field on Hawai’i. We drove to visit Kilauea Iki crater. The crater was like one large bathtub (lava lake), with bathtub rings of various lava levels left behind on the walls, and steaming vents inside. The vent of the lava fountain, also known as the throat, almost swallowed Phillip who climbed the scree slope and slid his way back down. On the Devastation trail, a large group of us got separated from Hubert and ended up walking to the end of the trail without examining our surroundings in detail. At the end of the day we tripped our way through the Thurston Lava tube, especially the unlighted part, until reaching the end where we congregated, crouching once the tube tapered and we couldn’t stand.

Today we saw excellent examples of the geological deposits of a lava fountain, including lava lakes, pahoehoe and a’a flows. The fire fountain formed in 1959, first as a fissure eruption on the side of a cliff and finally choosing Pu’u Pua’i as its nozzle from which to spew magma in a fountain reaching 1900 feet at its maximum. Pu’u Pua’i is the name given to the cinder cone formed by the lava fountain.

Stop 1: Discussion at the flagpole at KMC

Latitude: N 19.43233’

Longitude: W 155.27389’

Elevation: 1239 m

Time: 18:00

We met at 8 am at the flagpole at KMC.  We synchronized our cameras and GPS.  It took a lot longer than it should have, why I don't know.  We were disapointed when Hubert told us that we will have to write a report on a specific topic from the following list:

  1. Kilauea: Features, History, etc.
  2. Mauna Loa
  3. Pahoehoe flows
  4. A’a flows
  5. Lava Lakes
  6. Littoral Cones
  7. Lava Trees
  8. Phreatomagmatic Processes
  9. Lava Fountains
  10. Lava Tubes
  11. Hilina Pali

Stop 2: Kilauea Iki Overlook

Latitude: N 19.41665’

Longitude: W 155.24305’

Elevation: 1208 m

Time: 19:50

Finally we were able to head out and see some exciting things.  We drove to an overlook of the Kilauea Iki crater and took pictures.  We learned that in this crater there was a lava fountain eruption in 1959 that formed a lava lake.  Pu’u Pua’i is the name of the hill that was formed, and Mauna Loa means “Long Mountain.”  This was the location where we began our hike into the crater.

Stop 3: Kilauea Iki Crater

Latitude: N 19.41192’

Longitude: W 155.24181’

Elevation: 1098 m

Time: 20:40

After a beautiful leisurely trek through the warm moist rain forest, we came upon a trail leading down into the crater.  I knew that we would not have shade again for a very long time.  Thus began our tedious but rewarding lectures and note taking beneath the sweltering sun and unforgiving earth. At this location, we first entered the crater.  We studied the rocks that we found.  We were amazed by the green colored olivine crystals in the lava.  The basaltic rocks that we saw contain Magnesium.  We learned that the eruption that deposited this lava started from a fissure, a “curtain of fire,” that later coalesced into one vent at Pu’u Pua’i.  We observed that the rocks had a rough, bubbly surface instead of a smooth, shiny, pahoehoe lava surface because the top, smooth layer is very thin and has been broken off by hikers walking on it.  Some of the rocks had a very shiny, iridescent surface.  

The iridescence comes from a very thin film on the surface caused by a stretched bubble of glass. Next we looked at a cross section of the lava.  We saw that there is a dense layer at the top of the Pahoehoe flow that cools quickly with only the gas that is in it.  Beneath this layer, the vesicles are much larger because the gas could not escape through the solid layer that had formed above. The vesicles decrease in size to the bottom because the gas in the bottom rose within the layer and coalesced with the gas that was there.

 We saw lava drips on the bottom of the rocks, formed where the bubbles separated from the melt and coalesced, leaving behind the dense drips.  There was a landslide nearby that must have happened after 1959 because the blocks from the landslide were interrupting the bathtub rings around the lake.  Pu’u Pua’i is a scoria cone formed from tephra.  It is breaking up and has fragmented pieces. We measured the angle of repose of the scoria cone, and found that it was at a 32º angle. 

Stop 4: Steam Vents inside Kilauea Iki Crater

Latitude: N 19.41440’

Longitude: W 155.24521’

Elevation: 1084 m

Time: 21:54

While we were observing the rocks, we spotted some steam vents on the opposite side of the crater, so we went over for a closer look.  We learned that the more it rains, the more the vents steam. Either rainwater or groundwater seeping through cracks to the hot rocks below forms steam vents. The water gets vaporized and significantly cools the rock.  

We observed that the steam had turned the rocks a reddish orange color.  The rocks were originally formed in a high temperature environment, so they have a reducing, high temperature mineral assemblage (e.g. olivine, pyroxene, etc.). With the addition of steam, the rocks alter through oxidation and hydration, turning the rocks red.  We learned that the beige clay that we saw comes from glass in the rocks. Glass is not a crystalline substance but it wants to crystallize, so with the addition of steam, it alters to clay.  Other minerals formed by the steam are zeolites, carbonates, and iron oxides.

We also observed green and black patches on the rocks.  We learned that in addition to alteration, certain living organisms like lichen, algae, or microbes may be present in the hydrothermal environment.

 We also discussed why amphibole and serpentine are not the minerals found at this location. Both of these minerals are higher temperature and pressure hydrous minerals often found at subduction zones where a slightly anoxic environment in addition to water extracted from the subducting slab alters the minerals present to the hydrous minerals: amphibole and serpentine. When zeolites were mentioned, Geoff got excited. Geoff rhapsodized about zeolites and their various applications.

Stop 5: Lava Borehole

Latitude: N 19.41459’

Longitude: W 155.24604’

Elevation: 1083 m

Time: 22:25

Professor Staudigel challenged us to find a borehole in the crater.  I had no idea what it would even look like.  We found this small rusted pipe sticking out of the ground, and apparently this was it. We learned that the lava lake was drilled here in the seventies.  This study allowed scientists to observe how the lava lake was cooling over time.

On our way from the drill hole across the lava lake we first saw strands of Pele’s hair.  I did not think it would actually look like hair, but it did!  Someone even mistook Caitlin's hair for Pele's hair and Professor Staudigel had to test it because it was not obvious just by looking at it.

Stop 6: Bathtub Rings

Latitude: N 19.41360’

Longitude: W 155.24901’

Elevation: 1078 m

Time: 22:45

Next, we walked over to the opposite side of the crater to observe the bathtub rings we noticed when we first entered the crater floor.  The bathtub rings indicate a lowering of the lava lake surface. The surface cools, then lava drains out and the level of the lake drops and leaves a ring where the cooled surface used to be.  It may or may not indicate episodic drainage. 

We saw scratch marks in the rings, which is evidence of crust breaking open and scraping the more deformable layers beneath as it falls.  

We also observed white crystals forming on the lava drips.

Stop 7: Lava Drips

Latitude: N 19.41310’

Longitude: W 155.24969’

Elevation: 1077 m

Time: 22:50

We walked around the corner and found a place in the wall of the crater with long thin drips of lava called “lavacicles”.  They were on the bottom surface of a reddish colored rock (red due to oxidation of that surface). 

The lava drips were in a location that was very difficult to get to, so I had to wait for some people to stumble back down over the rocks before I could go up, and then by the time I got up there and was able to see, Professor Staudigel had left.  It seemed like a very rushed stop.

Stop 8: Lava Vent

Latitude: N 19.41389’

Longitude: W 155.25245’

Elevation: 1086 m

Time: 23:10

We walked a bit further and found the MOUTH OF PELE!  There was a very deep depression filled with large red rocks.  As we approached the vent, we saw very shiny, gold colored iridescent rocks.  When we turned them over, there were very large vesicles on the other side.  The vesicles were able to grow this large because the temperature is hotter closer to the vent and larger bubbles are less mechanically stable, so they can only form in very hot lava.

Some of us went down into the vent, and a few went up the other side, but it was very steep and unstable, so I decided not to go.

We couldn’t believe that some young women were hiking in bikinis and flip flops in the crater. The glass really hurts if you step on it, and especially if you fall on it, so I hope they didn't fall.  I'm sure they ended up with a sun burn and covered in dust at least.

Stop 9: Liquid Lava Sheet

Latitude: N 19.41421’

Longitude: W 155.25262’

Elevation: 1084 m

Time: 23:23

A bit farther from the vent, we saw a very smooth surface covering the hill.  We learned that the lava is very hot when it falls to the ground so close to the vent, so it is still liquid enough for the pieces to coalesce and flow down the hill.  It is called an agglutinate.  It forms a thin flow that wrinkles and breaks when it hits steeper terrain. The talus material deposited before the agglutinate is visible is in places where the sheet flow did not reach.

We learned that magma inside the crust moves as sheets but with sudden decompression as it reaches the surface, a nozzle is more efficient. This is why eruptions generally start as fissures and then coalesce to a point source as they exploit zones of crustal weakness.

Stop 10: A’a Flow

Latitude: N 19.41478’

Longitude: W 155.35322’

Elevation: 1089 m

Time: 23:32

Close to the lava sheet, we saw an A’a flow.  We discovered that Pahoehoe flows form a thin skin that confines the melt inside.  However, when the flow cools and becomes more viscous, it is no longer flexible enough to form this skin, so the surface gets jumbled and forms massive layers of breccia at the surface, which also acts to cool the flow. The A’a generally is in areas where the rocks are at a steeper angle, where the rocks cannot keep the thin skin of Pahoehoe without being jumbled up.

We were relieved to finally see the trail going back up and out of the crater so we could get out of the sun and heat. We finally climbed out of the crater and got back in the cars and drove to Devastation Trail.  The thought of another hike was disheartening because I was worn out and starting to feel sick.

Stop 11: Devastation Trail

Latitude: N 19.40884’

Longitude: W 155.25302’

Elevation: 1158 m

Time: 01:00

Professor Staudigel told us to look out for devastation on the devastation trail and explain what happened.  I noticed that there were a lot of trees without leaves and many were knocked over, but that was just too obvious, there must be something else we were looking for.  I saw some holes in the ground too, but I just took them for snake or rabbit holes or something else.  Anyways, we all ended up walking to the end of the trail without stopping so we had to go back to take a closer look.  There we saw the tephra fall out that was blown away from the lava fountain of Pu’u Pua’i. The trade winds blew the tephra in this direction.  What is visible on the surface is the last tephra to be deposited. There is more agglutinate closer to the vent, as the temperatures are hotter, so the tephra can coalesce and form a slightly consolidated sheet. The evidence for this is the fault scarps on the side of the hill. 

The “devastation” for which the trail is named, is the destruction of the forest that used to occupy the area covered in tephra, which was obvious from first glance.

Stop 12: Burnt Tree Hole

Latitude: N 19.40914’

Longitude: W 155.25414’

Elevation: 1163 m

Time: 01:10

Next, we took a closer look at the holes in the tephra.  We saw that one side of the hole is more solid and consists of thicker and more numerous layers of cow paddy tephra.  We found out that trees used to occupy these holes.  The side that is closer to the vent and the direction from which the trade winds blow is where the cow paddies pile up more. Most likely the wind blew the tephra in the direction of the tree and the tephra hit the tree while still hot enough to coalesce and form agglutinates. The tree burned up and now it is gone, leaving behind a mold in the agglutinate material.

Stop 13: Overlook

Latitude: N 19.40957’

Longitude: W 155.25490’

Elevation: 1162 m

Time: 01:25

We walked a bit further up the hill.  Here we had a great view of Kilauea caldera and Mauna Loa. 

Afterwards we hiked back to the cars and drove to the Thurston Lava Tubes.  We took our headlamps and went back as far as we could.  Then we went back to KMC for the night. What an exhausting day!

Prepared by: Natalie Juda and Paula Chojnacki