Alan Nelson's Daily Commentary for 13 September 1999 (Second time-International Date Line!)

Hawaii Volcanoes National Park, Big Island, Hawaii

The volcano began the current eruption in 1983. On the 12th, a series of earthquakes signalled a "pause" in the current eruption. So today there is no lava flowing. Anywhere. Bummer.

These pauses can be a few days to a few weeks. As long as the lava eventually flows again from the same crater, it will be regarded as the same eruption. If the internal forces in the earth force lava out of a new opening, then it would be regarded as a new eruption.

The exciting part of a pause is that whatever happens next is virtually unpredictable. Up until a couple days ago, the lava had been coming up under the Kilauea caldera, flowing sideways for about 8 miles to Pu'u O'o crater and then through 9 miles of lava tubes down to the ocean. One of the items on my agenda had been to hike at night to where the lava entered the ocean. That item is no longer on the agenda!

One of the possibilities at the end of the current pause is that the flow of lava will return and try to go through the same lava tubes as before. If the tubes are still open, lava will flow the same 9 miles down the side of the mountain and into the sea. But more likely, the tubes will be clogged somewhere and so the lava will have to find a new route. That would mean new red lava on the surface--and spectacular sightseeing.

Usually when one speaks of geologic time, they are referring to millions of years. Here in the park, changes in geology are visible in days to decades. So even though there is no lava flowing, this is still a very active area--today.

Here's some geologic change from the last couple decades. The road now goes smoothly over this rift, but the road that was here in the 1970's was split open along with the Earth's crust. This rift is big enough to drive a bus through it.

But sometimes the changes result in the deposit of new rocks. This road was first covered in the 1980's and repeatedly (almost continually!) ever since. When the current eruption first started flowing out of Pu'u O'o crater in the early 1980's, it was a bit of a surprise. Over the next couple years, almost 200 homes were destroyed as lava slowly encroached and then consumed these home sites that had been without liquid lava for centuries. One possibility is that the current pause might be the end of the current eruption and the lava may pop out in some brand new place as it did in the 1980's. If so, I would appreciate it if that happened in the next couple days!

We hiked to an old crater named Pu'u Huluhulu, a hike that took us over lava flows from 1973 and 1974. The edges of lava flows can be very abrupt and the scars last for a long time. But the lava is also a good foundation for rich soil, so eventually plants find a very happy home.

Though most plants are destroyed by lava flows, some do leave their mark. These columns of lava are called lava trees because they are caused by the trunks of trees. This lava tree still has the wooden tree trunk inside it. The trunk was sturdy enough to hold up to the flow long enough for some of the lava to cool around it and become rock. Then the tree/rock combination continued to withstand the flow and become still larger as the lava continued to flow. We could see down into some of these lava trees for a depth of 6 to 7 feet. We found several that had surrounded low branches on trees and so there were double holes on the top of the lava tree that soon joined below what is now the surface of the flow.

For the vacation part of the trip, I have been joined by my wife. That's her behind the lava tree. I invited her along on the trip just so that she could stand in these pictures and show you how tall these formations are!

Alan Nelson