Post #300! A Pahoehoe Party!

It's my 300th post! In celebration, I am throwing a pahoehoe party with some pictures from our recent Hawaii field studies journey (and one older picture from the pre-blogging days). If you have been following my last few posts, you have learned a bit about the current ongoing eruption of Pu'u O'o on the flank of the Kilauea volcano on the Big Island of Hawai'i. The flows have continued unabated for more than two decades, starting in 1983.

Pahoehoe is a term used by the Hawaiians to describe lavas with a smooth shiny surface, that reminded them of shark skin. We were lucky enough on this trip to witness a number of breakouts from the lava tube system that were forming pahoehoe surfaces. They were far up on the pali, and best viewed in the evening twilight, as can be seen in the top photo. Our view the next day was astounding, as our helicopter flew right over the breakouts just 1,500 feet above.

The center photo shows the active breakouts, with the main lava flow snaking along the right side of the picture, and two breakouts at the top and bottom. Despite the bright sunlight, the orange glow of the lava can be seen in places. The shiny, silvery appearance results from the thin coating of glass on the surface of the lava where it cools first. It is a blasted hellish surface.

We didn't have a chance to stand next to an advancing flow, but in 2002 I was able to get a photo of the front of a lava stream on the coastal plain. The lumpy surfaces expand as they fill with the hot basalt and then the lava squeezes out the edge of the bulbous masses. It is hypnotic to watch, and there is little to fear, since the only way it will get you is if you stand really still and let it surround you (for all I know, this is how some photographers I know will buy the farm!).

Pu'u O'o: the Big Picture

More details to follow about the Pu'u O'o flow, but going through my pictures, I discovered that I had a single shot that included the entire flow from start to finish: the copter was flying east of the flow, so Pu'u O'o is where the massive steam plume is rising on the right, while the Kalapana ocean entry is visible on the far left. The series of cliffs and rises are the palis, or fault scarps generated by slippage of the volcanoes towards the sea along major fault systems. Smaller steam plumes are vents and windows over the lava tube system, and the occasional surface flow. Note especially the pattern of forest islands, called kipuka. They are important biological refugia where some native species are protected from invasive predator species.

Pele's March to the Sea: Taking the Subway!

The lavas of Hawaii's Pu'u O'o emerge at the East Rift Zone around seven miles from the sea, and yet most visitors to the volcano only see lava pouring into the sea. Where are all the fountains and rivers of lava that grace every single tourist brochure about the islands? Well, it is not always dramatic that way, even though the eruption is the longest continuous eruption in recorded history. Most of the time the lava is flowing to the sea in lava tubes, a few feet beneath the surface where the lava has crusted over. The rock is an excellent insulator, so the temperature drops only a few degrees over the seven mile journey down the volcano.

Sometimes no lava is really ever seen at all, but we were quite lucky with our timing. As we flew over the Pu'u O'o cone we could see the numerous vents and windows marking the location of the tube system. At times lava breaks through to the surface forming miniature shield volcanoes called rootless shields (that's one of them in the foreground of the picture). The perspective of the picture is a bit difficult to perceive: I was flying right over the Pu'u O'o cone looking downslope towards the sea. The steam vents mark the downhill location of skylights in the lava tubes before they disappear over the pali, or coastal cliff. In the far distance are the two ocean entries at the coast, with the Pacific Ocean beyond.

Looking into the gates of hell...

Flying closer to the vent of Pu'u O'o, we were able to look at the steam and sulfur dioxide emanating from the cone. No lava has been visible here for a few months, but it is there, traveling down the cone through lava tube systems. In the foreground of the lower picture, one can see the very fresh pahoehoe flows. They are silvery in color because they have a thin coating of glass. On the older surface, oxidation has removed the glass and given the rock the prominent reddish brown color. It is a ghastly landscape!

Accretionary Wedge #17: Caught in a time warp!

Lockwood has graciously consented to host the new Accretionary Wedge, and asks where we would want to go in the geologic past with a time machine. I could imagine many moments, including some from childhood (I really wanted to see living dinosaurs), but I come back to one thing: I think I most would like to see the moment the Grand Canyon began!

One could argue that it didn't just begin, but some imaginative hypotheses have been suggested over the years that include some form of stream piracy, where a Colorado River once flowed elsewhere, possibly into the Gulf of Mexico, or points northwest in the Basin and Range. A separate drainage system related to extensional stresses to the southwest evolved which eventually captured the river, and from there the giant canyon was carved in just a few million years.

I have many times imagined seeing that first trickle of water that spilled over the low divide, and how it would have become a torrent, and within hours the work of building a new canyon would have begun. Whether the hypothesis is correct or not, it is a wonderful piece of work for the imagination!

Volcanoes in Hawaii: Finding Pu'u O'o

Pu'u O'o is a vent on the eastern rift zone of Kilauea volcano on the Big Island of Hawai'i. It is, and has been the focus of most of the volcanic activity of the last 24 years. I've been on the big island three times now, and until the other day I had never seen the source of all the lavas that have brought great interest and great misery to the region. The problem is that being a shield complex, the slopes of the volcano angle away from the vent in such a way that it is almost impossible to see the cone from anywhere, except as a plume of ash and steam in the sky. Although I am told that you can see the cone from a gas station parking lot in Glenwood, I had never found the place.

It took a helicopter flight to finally see the vent. From a thousand feet above the ground it wasn't hard to find the volcano at all. During active phases early on, the cone was much higher, but it collapsed and is now primarily a smoking pit. No lava is visible in the daytime, mostly steam, but it is clear where the lavas are going, as will be seen in some coming posts. It is a desolate blasted landscape in the area of the cone, a place that I wouldn't really want to visit up close, even as a geologist (we LAUGH in the face of danger!).

Report from the Road: Hawaii volcanoes 3

More excitement from Hawaii Volcanoes National Park in today's post. The pictures are from days ago, but trip organizing and conducting is a very busy business, especially when the trip leader fails to triple check some of the logistical arrangements. Someday I may talk about it...

Halemaumau is a pit crater in the caldera of Kilauea volcano on the Big Island. It is reputed to be the home of Pele, the Hawaiian volcano goddess. I'm beginning to think she is watching over us, in a good way. There had been not a whisper of activity in the crater for most of the last quarter century, but in late March 2008 an explosion and collapse of a pit within the pit (which is itself a pit within a bigger pit, kind of like a Bushka doll) showed that activity was resuming. In the last few days, lava has been detected at the bottom of the pit, sloshing back and forth. The ever-present steam plume has begun glowing at night, causing a local sensation as hundreds come up the mountain at night to see the eerie looking orange light.

I kinda cheated, and I hope my students don't really notice this. I was done hiking only an hour before sunset, so instead of heading back to Hilo with everyone else, I wandered back to the Jagger Museum, and watched the glow for a bit while the moon rose. It was eeriely beautiful ('eerie' is a common word for the day).

I'm so glad to be here and seeing these precious gifts of nature! And even better is that I am able to share the experience with 26 of my students.