Eddie Aikau is a Hawai'i legend. Born in 1946, he was an ancestor of Hawaiian kings, who in antiquity were the only ones allowed to surf. Eddie trained himself to become one of the great surfers of his day, but more importantly he was the first state paid lifeguard on the North Shore of Oahu. He ultimately saved 500 people, often under terrifying conditions. He lost is life in 1978 trying to rescue a crew of a Polynesian-style voyaging canoe. They were trying to travel 2,500 miles to Tahiti, but only made it 12 miles offshore of Molokai before floundering. Eddy, who had volunteered as a crew member, offered to swim for help. The crew was later rescued, but Eddy was never found. Not long afterward, the phrase "Eddie would go" was heard throughout the islands.
I thought of Eddie when I encountered Devils Throat on Chain of Craters Road in Hawai'i Volcanoes National Park. Devils Throat is a stark example of a pit crater. There are a number of them along Chain of Craters Road (you didn't guess that one, did you?), Some of them are hundreds of feet deep. They are odd because there are no lava flows associated with their origin. They form when underground magma chambers on the rift zone of Kilauea drain, causing the land above to suddenly collapse inwards.
Devils Throat is unique in that it formed in historical time, in 1912. When discovered, the opening was only 20 feet across, but it was found to be more than 250 deep. The Eddie connection? When it was discovered, a man was lowered by rope into the dark pit. What do you think? Would you have gone?
What he found inside was an immense inverted cone more than 200 feet across at the bottom. All the walls of the pit were overhanging. Given the fragmented nature of basaltic lava flows, such overhangs are extremely unstable. Boulders started falling essentially from the moment the pit formed. Over time, debris filled the bottom of the pit so that today it is 161 feet deep, and the opening has expanded to 164 feet. The National Park Service has never really publicized the existence of the pit over fears that people would get too close to the edge and have the rock collapse beneath them.
Today, the vertical walls of the pit may be a bit more stable, but who can really say? It's a fascinating place to visit if you can find it (a bit of map work is all it takes; it's just a few hundred feet from Chain of Craters Road).
The ongoing eruptive activity at the summit caldera of Kilauea on the Big Island of Hawai'i.
You aren’t hearing this from me (well, okay, you are), but sometimes teaching is just a little bit
like carnival barking. You have to be entertaining about something that
actually isn’t all that unusual or interesting. And sometimes you have to
reveal just a little at a time to keep the interest going until the dramatic
finish (“the butler did it!”). During our recent exploration of the Hawaiian
Islands, I chucked all that. We started our trip in Hilo on the Big Island, we
were only thirty miles from Hawai’i Volcanoes National Park, the volcano was
erupting, so our first morning as a group we headed up the highway to see an
erupting volcano. It was a first for everyone on the trip.
When was the last time you saw a class paying complete attention to the subject?
There's a secret to keeping the attention of a class of students. It's easy really...just put them in front of an erupting volcano! What we could see was astounding: a lava pit that has been erupting continuously since 2008, on a volcanic shield that has been erupting continuously since 1983! The shield volcano is called Kilauea, and the crater within the summit caldera is called Halemaʻumaʻu. The crater is said to be the current home of Pele, the volcano goddess of Hawai'i.
The current volcanism of Hawai'i is occurring only on the Big Island, and only on two of the five volcanoes that make up the island: Mauna Loa, and Kilauea. Mauna Loa is clearly visible on a physiographic map of the island (above), while Kilauea is less so (refer to the map below to see where it is). Mauna Loa is gigantic, covering half of the island, reaching an elevation of
13,679 feet (4,169 m) with a volume measured at more than 10,000 cubic miles. From her base on the sea floor, Mauna Loa is the highest mountain on the planet at 31,000 feet. Kilauea is less massive, rising to only 4,091 feet (1,247 m). Mauna Loa and Kilauea produce roughly similar amounts of lava, but Mauna Loa tends to produce lots of volume in periodic eruptions (the last was in 1984), but Kilauea has become known for continuing eruptions that simmer along for years, with occasional outbreaks that flow down to the coast (or unfortunately through nearby villages).
Source: USGS
The eruptions don't come just from the summit calderas. Most of Kilauea's activity is actually elsewhere along rift zones, especially at a cone called Pu'u O'o (watch for a future blog discussion). There are two rift zones extending from each volcano, trending roughly northeast to southwest. It's tricky to determine the age of the volcanoes, since younger eruptions are constantly covering older eruptions, but Mauna Loa has probably been erupting for around 700,000 years (the oldest exposed flows are 200,000 years old), while Kilauea is perhaps 600,000 years old, with exposed rocks ranging from around 70,000 to 43,000 years ago.
Halemaʻumaʻu in 2002 before the present eruptive activity
This is a view that is no longer accessible for visitors to the park. In 2008, the lava pit in Halemaʻumaʻu exploded and tossed foot-wide boulders at this overlook, and since then noxious and poisonous gases have made this spot dangerous. The frozen lava in the main crater dates to the 1920s when a molten lake of lava filled the crater floor. The gifts left at the crater rim show that many take the existence of the volcano goddess Pele quite seriously.
For this blog series on the "Hawai'i That Was", I'm intending to follow the itinerary we followed as a class, but I want to skip ahead a couple of days. In the daytime, the view of the lava pit in Halemaʻumaʻu was awe-inspiring, especially to those in our group who had never seen an active volcano (mainly all of them except Mrs. Geotripper and my fellow professor), but what happened three days later left me stunned.
Halemaʻumaʻu at twilight in 2009
When I was last on the island with students in 2009, a few of us waited for the sunset at Kilauea, long enough to see the glow of the lava lake in the twilight (it's overwhelmed by sunlight). It was neat, but not earth-shakingly spectacular, as can be seen above. At the time, the pit was maybe 200 feet across and 500-600 feet deep. We made arrangements to stay through the evening again, and I wasn't expecting much, but as we pulled up into the parking lot, I could see something was very different. The sky was glowing brightly long before we could see the crater (below).
The pit today is 500-600 feet across now, and in the weeks prior to our arrival on the islands the lava lake had been at a depth of 100-150 feet. But on the night we arrived, the lava had risen to within 88 feet of the floor of the crater, and the lava was splashing about over the rim. It was, as I said before, a stunning spectacle. We ran to the edge of the observation deck.
The lava lake was about a mile away. We couldn't hear anything, but what we saw was beautiful.
It was difficult in the dark to catch photographs of the fountaining lava, but the video did. I posted this a few weeks ago, but it's one of my favorite geology moments ever, so here it is again.
Coming up: explorations in a rapidly changing national park!
