Informing the public without panicking them about an extremely unlikely but life-threatening hazard is tricky. So it’s taken the USGS a while to release this document which they’ve been promising the residents of Volcano:
On HVO website: Volcanic Hazard at the Summit of Kīlauea Update [summary: “This document is a guide for understanding current activity and hazard at and around the summit of Kīlauea Volcano. Here, we summarize activity from late April through the present, detail possible future outcomes, and review hazards associated with these outcomes.”] Presumably it’s called an “update” because it supplements the June 26 “Frequently Asked Questions About Kīlauea Volcano’s Summit Earthquakes” FAQ. [EDIT: No, actually, it’s an update to the May 8th “Preliminary Analysis of Current Explosion Hazards at the Summit“]
This was the chief topic of Thursday’s Volcano Village meeting, led not by the National Park Service this time, but by Civil Defense Administrator Tal Magno.
Here’s the FULL video of the meeting. BigIslandVideoNews excerpted the most important part, HVO Scientist-in-Charge Tina Neal’s 4-minute talk:
[Note: the audio was a bit fuzzy, so I’ve had to leave a few question marks in brackets.]
Talmadge Magno, Civil Defense administrator, introduces meeting.
Mayor Harry Kim: [opening remarks on Civil Defense] I think it’s very important that from the very beginning, HVO briefed us in regards to a possibility, and that’s their job, to tell the community and our government anything of risks or hazards that affect you. It’s our job to take that information and make sure we work as a team responding to it in regards to preparation or to response.
Tina Neal, Scientist-in-Charge HVO: So, good to see you all again. I know we were just here last Thursday night. And I’m going to use some notes tonight, because I want to be absolutely sure that I am crystal clear in what I’m saying. You know, normally I don’t like to talk with notes.
But one thing that I want to start with that’s really important, that the meeting tonight is happening because just today we finally put on our website this document I mentioned last week that summarizes our understanding of the current summit activity and the ongoing hazards. It took us a while longer to get it out there. We wanted to review it and make sure it was as good as we could make it and also get a statement from the county at the very end. So this meeting really coincides with the release of that document and not because we are any more or less concerned about what’s going on at the volcano than we were a week ago. And the mayor called this meeting, just as you heard, because he wants to make sure that the Volcano community is informed and aware.
So in terms of what HVO can bring to the table tonight, as you’ve heard from Don Swanson for many years: Kīlauea volcano has a history of explosive eruptive behavior and cycles of caldera formation. What we’re witnessing now is collapse, partial collapse of the summit in this stepwise process, due to magma withdrawal into the East Rift Zone, feeding the eruption. And it is uncertain how long this will continue. It is uncertain how large this collapse will be. And it is uncertain how violent activity could become associated with this collapse.
Assuming a continued withdrawal of magma evacuation — excuse me, a continued magma evacuation from the summit — assuming that, we feel the most likely course of activity for the next two month timeframe, and that’s the timeframe that we felt comfortable projecting out in our discussions and assessment, is for continued activity that we’ve been seeing, this periodic subsidence of the crater floor, moderate-sized earthquakes that you’re all very familiar with that can be damaging. And small or no ash production. That is our assessment of the most likely activity to continue in the near term.
We think that the duration of this activity and how long it will continue is related to the duration of the Lower East Rift Zone eruption, but there is some uncertainty in that as well.
So very hazardous explosions related to the ongoing subsidence in the caldera are considered unlikely in the near term but it does remain possible if activity should accelerate. And these explosions that we are talking about may or may not be preceeded by a lot of warning. As time goes on, if the subsidence continues, it’s possible that conditions will evolve such that the summit becomes even more hazardous.
And one possible although very unlikely outcome is that large-scale explosive activity associated with caldera collapse could occur— Large-scale caldera collapse. This kind of activity could include the production of high lava fountains (something like you have seen in pictures and movies from Kīlauea Iki, that sort of thing), associated fallout of ash and tephra could reach inhabited areas, and of more concern is that these kinds of large explosions related to large collapse could produce pyroclastic surges. This is a concept we’ve described a couple of times.
These are potentially life-threatening phenomena that involve rapidly-moving “ash hurricanes” that move away from the summit area. That kind of activity we suspect and we feel should be preceeded by signals that we will recognize with our monitoring equipment: things like increased earthquakes, more severe earthquakes, constant earthquakes, or low-level explosive activity beginning— signs that we should see with our monitoring and our observation ongoing. However, it’s important to know that the timeframes of that warning are really uncertain, and they could be short. So that is why we are here tonight, for you to make connection with your Hawai’i County Civil Defense, and know what they are doing for you to provide warning. And residents should heed those warnings, and be prepared to self-evacuate.
So to sum up, it’s really not known how long this activity can continue without any kind of change. The duration Of the eruption in the Lower East Rift Zone is uncertain, where we’ve said before the historical eruptions there, the most recent ones, have gone on between 36 and 88 days. And what are we now, into the 60something day of this eruption? And it’s also important to know that those events are really not perfect analogues, and just about every eruption has its own characteristics.
So that’s my summary. I’ll stop there, and when we get to the question-and-answer period, you’ll recognize Kyle Anderson from previous discussions. [points] He’ll be here to answer questions, and also Don Swanson. Thank you.
[Tal, head of Civil Defense, talks in specific detail about preparations and family plans all residents need to make to be ready to evacuate. He discusses existing notification systems and new ones they’re implementing, including new siren being installed outside the building.]
Questions and Answers
Q: [I was at the meeting up here a month ago, and this sounds a lot more ominous than that meeting. Are you just being cautious, or is there reason for this?]
Tal: We’re being cautious and proactive, but I’ll let Tina address what they’re seeing that might be more revealing for you guys.
Tina: If you were at the May 9 meeting in the park, you may remember there was discussion in that meeting about, “Could this scenario unfold where there would be potentially deadly phenomena occurring in association with this?” And the answer then was, “Yes.” But we said then what we’re saying now, and that is it’s very unlikely. So it remains a very unlikely outcome of this event in our best estimation. But the longer things go on, the more we want to make sure people think about this, and are prepared for this, because it is not a zero probability.
Q: [The usual “rumor of something dramatically different from what scientists are saying, which lets one put off thinking about or preparing for what scientists are actually saying.” In this case, a wild idea about what’s causing local streets to crack]
Tina: There is a lot of ground-breaking going on up here, from all the intense shaking from these daily events, but there is no “ancient lava lake” below the golf course related to Mauna Loa. There are lots of lava flows from Mauna Loa and Kīlauea kind of interleaved there, but there’s no lava lake. [person continues with wild rumor.] Tina: No. There is no geophysical evidence for any kind of magma reservoir under the golf course. But there are very thick and dense lava flows, so not a surprise it’s hard to drill through.
Q: For the benefit of the laypeople, could you help us all understand even though it’s a very unlikely scenario, a little bit more about larger caldera collapse, the distinction between subsidence of the caldera which has been going on, collapse events in the past, how those might unfold, and also what your estimates have been in the past over how far these go? Because some people confuse like you bring up pyroclastic, they think aout something like St. Helens, and it’s not like that, the reach isn’t as far and so on. if you could give us, even though it’s a highly unlikely scenario, a little bit of background on what’s involved if it moves from subsidence to collapse.
[Tina summons Don, since this is his life’s work: St. Helens and explosive activity at Kīlauea.] Tina: And I’ll point out that some of the answers to your questions are in this document. I apologize that it’s only available on the web right now. I know not everybody is on the internet. Didn’t come up with extra copies today but I’ll make sure some extra copies get up here in the next couple days.
Don Swanson: First of all, let me define what I mean by subsidence and collapse. The way that I use the terms—I’ll try to do that this discussion— Subsidence is the slow, downdropping, bowl like [?] of the summit, and that’s going on now. Collapse, to me, means a more precisely defined zone which is going down faster than the surrounding area of subsidence, and is bounded by faults, downdropping on the faults. So subsidence is a larger, lesser feature. Collapse is a smaller but deeper [?] feature surrounded by faults. Does that seem reasonable to you?
So what we have now ongoing is both. We have subsidence of the entire caldera, and a collapse of part of the caldera.
Going back in time, to answer your question, we know or can reasonably infer that about 500 years ago, there was collapse, fault-bounded downdropping, of the entire summit region, going east-west from Namakanipaio— you all know there’s a little pali right behind Namakanipaio— going from there eastward to, essentially, Thurston lava tube. That entire area dropped down. From north to south, the northern boundary is the pali that the road to the golf course crosses that bounds Highway 11 on the north side, and the south end of it is out in the desert; it’s kind of hard to find there, but in total the area of collapse has double the diameter, about four miles, 6 kilometers, of the area of the topographic caldera, which is bounded by Uwēkahuna and Steaming Bluffs and so forth. That has a diameter of about 3 kilometers or 2 miles.
What was associated with the large collapse 500 years ago is that, first off, there were two or more small explosions that distributed sand-sized particles around the rim of the caldera.
And then we had a unique event in Kīlauea’s history: there were very tall lava fountains that were erupted from an arcuate [bow-shaped, arc-shaped] or circumferential [circular] fissure within the topographic caldera area that [has now been formed?]. Some of those fountains were inclined to the north so that those fountains produced a lot of the material that a lot of you have in your lawns and gardens in Volcano: reticulite. It’s very lightweight material, crunchy, has black charcoal mixed in with it. That was produced by these very tall — probably more than 2000 feet tall — inclined lava fountains. They were very hot. Where the material landed, they started lots of fires. And you can imagine what might happen today if we had one of these things happen.
But this is unique, so far as we know, in Kīlauea’s history.
And then after that, there were a number of smaller explosive events for 250-300 years, culminating with the very large eruption in 1790 that killed so many people.
So that’s the kind of thing you can expect if we have this unlikely scenario of a summit-wide collapse taking place.
Q: That was a lovely, detailed job of painting the worst-case scenario. The question I have— if you were betting scientists [audience laughs], and you went to the bookmaker’s shop, what scenario would you put your money down on as to how it’s actually going to end? [Don chuckles uneasily] And as you said in the previous briefing, you said, “Come to me in a couple of months and ask me the same question, and my answer may be different.” So. But you’ve got the money in your hand now, and you gotta put it down.
Don: Well, I would put it down at “continuation of what’s going on now” for the next two months. And then, ask me again in two months, and I might change my bet. I think that’s the way that we have to do this. We have to approach it incrementally. Calderas usually collapse incrementally. They don’t go down 1000 feet one time. And that’s the way my thinking is about this. We just have to see how things develop, and then make our decisions based on the longevity of what’s happening now, and on the basis of any changing situations that we might be able to measure. And right now I can’t anticipate what those would be.
Q: Related to what you were talking about, the caldera and the potential collapses, would that potentially increase the actual diameter of the Kīlauea caldera proper? Or do you just see collapses within what you define as the Kīlauea caldera today?
Don: The question is would this very lar— would a worst-case scenario involve a collapse on a larger scale than what we have at the summit today? Potentially it could. There was probably a larger caldera that existed before the current one was formed. That one formed around 2200 years ago. And the tree-molds area, there’s a little pali near the tree-molds, and that is probably the outermost boundary of that caldera. So it’s possible, but… if I were a betting man [grins], I would bet against that.
Q (followup): You tend to think that any collapses would stay within the existing Kīlauea Crater boundaries.
[0:31:35] Don: Yeah, Kyle can talk about
. I think that the evidence we have today looks to me as if it’s going to be confined to within the caldera, because the outermost circumferential fractures that have been occurring on the caldera floor have not extended outward in the last 2-3 weeks or so. So to me, that suggests that they may be defining the outermost limit of potential caldera collapse.
Kyle Anderson: Yeah, so I agree. I think, as time goes on, that there’s no fundamental reason that subsidence can’t extend further outward beyond the existing caldera. But we’re a long ways from that happening. The amount of subsidence in the caldera right now is large, and it’s gradually getting larger, but it’s still— it’s a fraction of the full volume of Kīlauea Caldera. So, really a long ways before I think we’ll extend outside of the caldera. I think, additionally, there’s probably some reasonable evidence that the rock inside the caldera, certainly closer to the Halemaʻumaʻu reservoir, it’s hotter, it’s weaker, certainly that material will slump and collapse first preferentially, before we start moving outside of the caldera. So, bottom line is there’s no physical why it can’t eventually, but we’re a long ways from that happening, I think.
Q: I just want to start by saying you are all doing a magnificent job — Civil Defense, HVO, USGS, and the park. Thank you very much. And I wondered if you could elaborate on what the triggers are we want to watch for. Because a lot of people in the room are watching what’s going on up here really closely. What would the triggers be, in the very unlikely event that we have large-scale caldera collapse fast, that could result in some of the things you all have talked about? What are some of the things that we might watch for as residents in the area? You mentioned increased earthquakes, increased magnitude earthquakes. Can you elaborate on that a little bit more? How big might the earthquakes be? How fast might they come? Because this will inform many of our… some evacuation plans. And it would give us a heads up before the texts came out and [something].
Kyle: So I’ll get started answering that very difficult question, and then I’ll let Tina come up to finish what I do incorrectly and incomplete. So, it’s a great question, and we’ve been discussing this. I think naming triggers ahead of time is very difficult, because we don’t know what we’re going to see, and we don’t know what the exact progression is going to be to something more hazardous. The bottom line is we’re probably going to look for changes in rates. So, increases in earthquake rates above what you’re already seeing. We’re talking about high rates of earthquakes; well, those are already happening. So that in and of itself is clearly not a trigger. So we look for changes in rates of earthquakes, changes in the pattern of ground deformation at the summit, maybe a broader pattern that’s increasing in rate, rapid subsidence outside of the caldera, for example. Accelerating change is something we look for. So really, it’s about changes.
In terms of things that you might feel yourself, uh, continuous ground shaking. If you feel something that’s really outside the bounds of what you’ve already felt in the past, maybe there’s no harm in making your own decision. But that’s your decision to make. So, yeah, it’s very hard to lay out specific triggers. So, numbers of earthquakes, sizes of earthquakes. We look at the locations of earthquakes… is the pattern moving? Are they getting deeper? Are they moving elsewhere in the caldera?
But the bottom line for geophysical monitoring, for eruption forecasting is generally just looking for changes, and in particular, accelerating changes.
Tina, do you want to take anything else?
Tina: Thank, Kyle. I think you hit on the main ones. And as he says, it’s very hard to establish hard thresholds in terms of numbers. To coin a phrase you’ve heard before, we think we’ll know it when we see it. And that’s why we’re watching things as closely as we are. I think, based on experience elsewhere in the world, the onset of rapid and severe ground shaking that doesn’t stop, or is much more severe than what you’re feeling today would be something that I personally would take as a trigger. And as Kyle said, that may be a decision point for you all individually. Another trigger is if we start to see explosive activity inside the caldera, which we really haven’t seen yet. Early on in the episode, when the lava lake was draining, and the column was emptying, and we were having rockfalls and explosions— at that point, those were pretty mild. If we start to see activity of a more intense nature inside the caldera, or from fractures within the caldera, that will give a clear trigger for some response.
We have people up here 24/7. We right now have someone in the Volcano House from 6 to 7 in the morning to 7 at night or so, and Don Swanson is usually there for half of that shift. So we have eyes on the volcano for 12 hours a day. We have our monitoring network in place. We have alarms set up. Right now these [air quotes] Type A events that we’re calling, these events that are happening, bigger collapse events happening every day we see an alarm coming in our infrasound network. So we have some alarms out there to alert us, our scientists, in the middle of the night. And those alarms are being configured for the kinds of changes we think are important to see. So I think: combination of rates that Kyle talked about, onset of explosive activity— any significant change in this pattern will be a red flag to us that we need to look more carefully, more— in fact, I’m meaning to talk to Civil Defense about next steps. Don, do you have anything you want to add, at least from your geologic perspective?
Don: No, I don’t think so. I think that’s pretty much what I would expect.
Q: We hear it that an explosive eruption is unlikely. And HVO, you guys are doing an amazing job at analyzing the evidence and the data you collect. And for basic guys like me to kind of wrap my mind around that, is there any way that you can kind of just put it plainly and give us a percentage of likelihood for an eruption? Maybe… ten percent likelihood we might see it? Thirty?
Harry Kim: I’m going to answer.
Tina: Thank you, mayor, for the rescue.
Harry Kim: Because like you, we always like to know percentage odds. And she knows; I asked her that. And I’d like to answer because she said, “One percent.” And I [told Tal just now, the words he put down?] It is our job to present a scenario. And [this, in our office], we say is the worst-case scenario. But that’s our job. And that’s Tina’s job. … I like that one percent.
Tina: If I could just add, thank you very much for that answer. The way that we’ve come to those conclusions about percentages is through a process that has been done at many volcanic crises around the world. And they involve soliciting expert opinion from a whole variety of scientists with expertise in this sort of process, and in this case expertise with Kīlauea Caldera, Kīlauea eruptive history. And we’ve been through a number of these exercises with our colleagues to try to come up with worst-case scenarios and walk through these probabilities, and come to numbers like that. So, this is an exercise we’ll do again, within the next month for certain, and probably sooner.
Q: Earlier someone mentioned some big events having to do with, being bounded by faults. I know on Highway 11 there’s a sign that indicates a fault that crosses the highway there. What are the other faults? Can you give us some idea about… where are they?
[I know! I know! Kyle showed this at the Volcano meeting last week! Yellow are faults.]
Tina: Well… all of the very high cliffs, of course, that you see inside the park, out in the modern topographic caldera, those are all fault structures. And then the circumferential cracks, and by that I mean the cracks that are parallel to those high walls, some of them are little escarpments [makes motion of a drop-off with a curved upper rim] little cliffs that you can drive down from the Volcano Arts Center down to Steaming Bluffs, you go down a fault surface. The little hill that you rise up to, to go to the Golf Course subdivision, that long hill that you follow, [that] parallels the highway there, that’s a fault. So those are some of them. If you look at a geologic map of the summit of Kīlauea, if you can find one, you’ll see these are outlined in black lines [Here’s a detailed 2003 geologic map made by Tina and a colleague], many of them, probably not all of them, because there are many small faults as well that are too small to even map.
Q: Update on Jaggar?
Tina: I can’t speak to the condition of Jaggar, but I can say a few things about HVO right next door, and the annex building. The building is suffering a lot of damage. It’s very close to the epicenter of these daily magnitude 5-ish equivalents. And each one of those really slams and shakes and moves the building. So we’re seeing increasing interior damage from ceiling tiles falling. The floor is rupturing in places, the tile. Things are certainly falling off shelves if we haven’t taken them out of the building. Around the exterior of the building, we’re seeing cracks in the ground. We’re seeing places where the foundation is shaking, and so you’re developing a gap between the foundation and the adjacent fill. Lots of things like that. We have heavy map cabinets than were hit hard with the lateral acceleration and all the drawers went flying out. So it’s taking quite a pounding. And I assume some similar damage is probably in Jaggar. I’ve seen pictures of the inside of Jaggar, and they’re also suffering floor damage and cracks in the exterior stone façade. The annex building at HVO, that’s the older building, it’s called the [Something] wing, it’s perpendicular to the main HVO building, it’s suffering much less damage. In fact, there’s very little at this point. So as we retreated and pulled our equipment out, we’ve actually put a lot of our gear in that building to stage for further moving offsite. We had folks up there today waiting for the event of the day to get in and retrieve some more gear. And I understand from their description that it was a pretty violent event, that cars were swaying and bouncing — and of course this is probably what you all are experiencing every day. They actually saw the tower of HVO swaying.
Q: We talked a lot about the very low-possibility event. How about the one that will almost certainly happen? What signs should we look for when the lava’s starting to return? What dangers might there be in that?
Tina: So what are the dangers of the lava returning? And by that scenario, you mean magma resuming ingress into the shallow reservoir and rising through the system. Well, I miss the lava lake glow. And on the one hand it would be nice to see the lava lake back. But I think we talked about this scenario, and that could be a cause of concern, if molten material begins to ascend in the current configuration, because we would be bringing magma close to the surface. It could potentially become explosive if water became involved, and that’s another variable that we’ve talked about through time. Right now there doesn’t seem to be a lot of water getting into the system, prompting explosivity. But if we get to the point where that does happen, and there’s a lot of magma just under the surface, that could be a reason for explosivity. So I guess in summation, the return of magma to the shallow reservoir may not necessarily be a good thing. [Turns to Kyle and Don] Would you guys like to add anything to that? [No]
Q: Back to the 1% probability. Assuming I make that self-assessment that it’s time for me to get out of Volcano, should I head towards Hilo or Pahala?
Tina: Good question, and I think these are the kinds of things Talmadge and the mayor would like to see people just mentally thinking about, if you have to move quickly. Well, in terms of the hazard situation, it really depends on the locus of activity and which way it’s pointing. And that’s of course impossible to know ahead of time. It may be knowing what the road conditions are like in either direction. I think frankly you get out of the potential zone of impact from the worst phenomenon if you head down to the Hilo side. You get out of there more quickly, whereas Highway 11 to the Pahala side kind of veers around the caldera for a while. But it depends on where you’re starting, of course, and which direction is easier for you to get to, and which way the wind is blowing, and lots of calculations. There’s certainly more services more quickly towards the Hilo side. Talmadge, would you like to answer that one?
Tal: it kind of goes back to the discussion of triggers. As this event would possibly start to ramp up, and we start to lose infrastructure, we start to activate our triggers, just like we did in Lower Puna, where, you know, roadways start failing, communities don’t have evacuation routes, we’re going to have to get those communities into safe places. All those are considered. So when you talk about which way to go… you know we’re already thinking that during the summertime, you get 90% chance of trades blowing out of the northeast, So we know that Ka’u is going to get impacted if there’s any kind of ash fallout. So we’ve got to activate the shelters in those areas for those populations. But like you said, it depends on what side you go, what side you see activities on, maybe where you have alternative housing for yourself. But that’s all the preparations that you’re going to have to make ahead of time. You’re going to have to dig deep, talk to friends, relatives. Start that planning. People in Lower Puna had to do that, some sooner than later. Neighbors had to start opening up their houses for other folks. And so it becomes an island-wide event. I know some people have relocated to Kona, just for the housing. So my philosophy for you guys or words of wisdom is, start now, prepare early, get your plans in place. [Tal, the person was asking for specific info to help them MAKE that plan.] Human nature, we hope for the best. In my position, I have to think about the worst. And so that’s part of why we’re here, even though the percentage is single digits, as low as 1%, I have to be thinking about it for you guys, making sure you’re ready for it.
Q: If that 1% happens, then what does that scenario look like, and what [mile???] readings are we talking about in regards to Volcano Golf Course, Village, [???]?
Tina: Before Don talks a little about that description in the document that will be on the web, there’s a map in the very back [Figure 5] that shows the extent of the area of most concern. Don can describe it.
Don: Probably the thing that would be of most concern would be the generation of pyroclastic surges. The surges, as Tina said, travel outwards at high speeds. They’ve been… some of them are steaming hot, others have been quite cold. And they are mixtures of volcanic material and air. They travel fairly close to the ground. They may result directly from the volcanic vent just bursting out. Or they may result when eruption columns [gestures up, this is the classic pillar/ash cloud rising up from a vent or volcano] become too dense for themselves and the columns fall back down, hit the ground, and spread out as surges.
I think, if I were living in Volcano, or the golf course, and we had the worst case, I would want to head toward Hilo, irregardless of which way the wind was blowing. Now that might seem strange, but the reason is that surges will preferentially leave the volcano, leave the volcano, toward the south and the southwest, because the caldera wall is lower and almost nonexistent. Whereas if the surge were directed north, it would have to overtop the wall. Now, that can happen. And so in our report, we show the maximum potential extant of a surge going into the Volcano area. But the probability of that happening in that area I think is very much less than the surge going toward the south and southwest. And this is based on the geologic mapping that I have done over the years. I have not found any surge in the Volcano area, but lots of surges to the southwest and to the south.
Q: How do we access this document on the web? I mean, the document’s been spoken of, it’s on the web, how do we get it?