 and welcome back to Hawaii, the state of clean energy on Think Tech Hawaii. Giving a plug in for our sponsors, sponsored by the Hawaii Energy Policy Forum and the Hawaii Natural Energy Institute. And I'm your host, Mitch Ewan. My guest today is my very good friend, Michael Knight. He's a volcanologist and a new author. So today we're going to be talking about Michael's new book, Exploring the Geology of Hawaii. I'm sorry, Direction of Oahu, and it's a guide book. And you can see a picture of the Volkswagen Microwave. And if you look really hard, you can see a little license plate which says magma, which is Michael's license plate. He has on the car his personal license. So welcome, Michael. How are you? Thank you, I appreciate it. Aloha. It's good to be here. So it's great to have you. And I love your background. That's a bunch of magma in the background. You just walked out of it to come on the show. Yeah, yeah. That was a lava flow in Mariloa back in 1984, eruption. Very good. So I want to start off, Michael, with you giving us like a top level overview of your book, you know, what's it all about and how is it organized? And I've read it many times. Yes, yeah. I like that I have. So tell us about your book, top level. Why did you write it and how was it formatted? Well, three and a half years ago, I had a friend of mine, a volcanologist, a professor in Iceland, said no one's written a geology book, a guidebook for strictly Oahu. There's been guidebooks for all of the Hawaiian islands, but none have been written that specific to Oahu. And he said, you're the perfect guy to write it. I said, no way. There's so many other guys that can write it. I don't think I want to do it. But anyway, I decided it was a great idea. And so I started this book now. It's being self published through a self publishing company called Lightning Source. And I just filled out the contract today. Hopefully it'll be available in fall. It's a large book. It's 375, 78 pages. It's got 350 plus images. They're drawings, illustrations, maps, and to guide you around the island to look at 39 of some of the best geology stops on our island. Let's bring up the next slide. Okay. So this shows how it's divided into four different areas. We start in southern Oahu, area one, which is Diamond Head, where most people, when they come to Hawaii, they stay in Waikiki. So it's a great place to start with. And there's 10 stops in this area. And then we're going to move to East Oahu, which has Hanama Bay and Cocoa Crater Rift System. These are all these young volcanoes. The small volcanoes that are erupted on the surface of these large shield volcanoes that make up the island. And then the third stop is north of Oahu. And that starts in Laiea, then moves over to Sunset Beach, where we're going to remove the ocean and look at the sea floor there and determine why. See if we can figure out why there's such large, beautiful ways that come in there. And then we'll move over to Moka Laiea. And there's a couple of spots over there. There's a climbing rock. That's a great place to hike to and see some really good geology there as well. And then the last stop is mainly all of the Waianae Shield Volcano, which is the western side of the island. And there's beautiful stops. Always recommend going out to Cayena Point. It's a bit of a hike. It takes about three hours to get to. But it's maybe going to be one of these national heritage sites. It's up for review for that. And it has some great geology as well. I'd just like to make a comment having read the book myself when it was in draft. Is that this is a great guidebook too for going around all these different spots. It's just not all about volcanology and geology. It actually gives you really good advice on what kind of clothes to wear, how hard the hike is, what are the dangers, what are the good things. And it's really done and friendly. It tells about the history. Some mythology is thrown in there, Adam Pele and all that. So it's a really interesting read. So over to you, Mike. Okay. Well, that kind of describes most of the book I kind of designed it. So the beginning few chapters, all science has a vocabulary, a certain type of language that you need to get up to speed on. So I try to describe in this as easy a term for a layman to understand as well as a seasoned geologist or maybe a young scientist that wants to learn about volcanics and geology in general. And I've taken it that step. And then I begin with these 39 sites and the travel log where you can drive to, you can take a bus to, you can, some sites you have to paddle to, maybe you have to have a surfboard or canoe to get out to on some of these island stops. And I've swam to some of them. And then also you can bicycle to some of them. I bicycle to some of the ones around Waikiki as well. So that's how it's kind of set up. Okay. On the next slide, I guess we're going to get into some of the beginning geologies. Yeah. But what geologists like to do is they like to compare what's happening now to what happened in the past. So we use what we learn about things now to kind of determine things that happened in the past and how they are similar. So this is showing, it's an illustration. It was actually drawn by Ryan back in 1987. This is a more up-to-date one. And he used seismic activity below Kilauea to come up with a model of what the, how magma got into the caldera and then flowed along the different rift systems of Kilauea, Caldera, and Hali Maumau, which is the crater inside of Kilauea. If you've heard anything recently is what's erupting very vigorously in 2018. And it started up again in 2020. Do you want to ask a question? Oh, no, I'm good so far. Okay. So back to that slide, I just wanted to show that we're showing magma starting it. Great depth. So geologists, they have different scales. Sometimes we're on the mega scale. This is a mega scale where we're looking from 40 kilometers depth to the surface. Other times we're looking at the macroscopic, which is inches to hundreds of meters, where we're looking at a face of rock, or we're looking at a thin section of cut, thin slice of the rock at 0.03 millimeters in size, which is 30, I guess that's about 30 microns, which are millions of a meter. And then, and then you can even get to even finer detail. Use a laser where we shoot beams of electrons at these thin sections, and then we're looking really microscopically at the rock. This is a mega scale. And what I want to show there is just how we assume the magma is flowing up from the caldera and then out along these two-riff systems, the east-riff and the northwest-riff. On the next slide, this is kind of, this is about a 13-year period. I know it's hard to read, but it shows seismic activity from shallow earthquakes down to about four kilometers depth. And where you see them, each dot is a hypocenter, and a hypocenter is an earthquake point in the subsurface where the first motion of these seismic activity starts at. And you can, and these areas that are really dark, big areas that are really dark over this long period, there were a lot of seismic activities. And recently, in the last few months or so, you can have activity where you have hundreds of these small micro-earthquakes, magnitude two to four max, but using magnitude two to three, they're fairly small earthquakes. They can be felt, but they don't really do a lot of damage. And they come in swarms. And these swarms are when the rock is being fractured, and the magma is trying to push its way through the rift system along these linear plumbing features that are like blade-like structures that we call dykes. Next slide. So just to give you kind of a realization for how big these shield volcanoes are, this doesn't even look like a volcano. It just looks like a mound of a hill to climb up. But that hill goes up over 17,000 feet. And from the ocean floor, it's 17 kilometers where it's depressed, the oceanic crust from the sheer weight of this shield volcano. What that is showing there in that view is about a 90 kilometer length of the upper part of Montelua volcano. But it really doesn't look, but if you try to walk up that hill, it would take you a long time. On the next slide. So these shield volcanoes are formed by dykes, and yours shows these blade-like features that yours too, a couple of dykes, those blades, they're sticking out as rocks. Those are these kind of vertical dykes that form, and they're differentially eroded away where they're stronger than the rock that surrounds them. The rock has gas bubbles, the lava flows have a lot of gas bubbles. They're softer, easier to erode over these millions of years that a wall whose has been formed. It's a five million-year-old island if you count all three shield volcanoes that are forming it. And anyway, the Hawaiian Shields got their name from Iceland, and where they, the first people of Cali for a shield volcano originated from. On the next slide, we're looking at an island. It's called, it's an island where there's a dykes form. It's called Moku Nui Island, which means North Island. It's part of the Montelua Islands off of Lanikai in the Kailua area of Oahu, over on the East Coast. And what we're looking at is kind of what a rift system would look like if you were, if you were a kilometer under the earth, because we've removed the upper kilometer of the volcano, the shield volcano of the Colau, and we're now looking at the plumbing system and these intrusive dykes that have formed. Here we have nearly 85% dykes. We're right in the rift zone of the Colau volcano. And you can see as these dykes are kind of sloping away from each other, that's because as new dykes are intruding along this rift, they push away the older dykes and they slope towards the center of the rift system. And then in the next slide, here we're looking at a bathymetric map, which is a marine topography map, where you remove the ocean and this has been developed over many years of research from various people from Japan and Hawaii that have used Sidescans sonar to balance sonar waves off the seafloor to cope with a map of the seafloor. And you can see Oahu in the middle and then we have these slides, these large mega slides that have slumped off of the island. And the biggest one is the Waianae slump, which is a continuous slumping over millions or hundreds of thousands of years that removed a large portion of the of that shield volcano, the Waianae shield volcano towards the southwest. And then in the northeast, we think that the new Waianae slide, which is a debris avalanche, was more of a spontaneous, instantaneous event. And that removed blocks that were 30 kilometers long, 17 kilometers wide. You can see this block in the upper kind of northeast corner that's it's called the Tungalusa block. And it rises about two kilometers off the seafloor. It's been sampled. And these blocks came from the Coalau volcano during this slide and would have produced probably a tsunami 100 meters high as the material went out over 120 kilometers from the volcano. So that's huge. Huge last slide. Yeah. And if we have another one of these last slides, so what the idea is that these volcanoes are sitting on more uses the analogy that they're sitting on top of watermelons or marbles both. And these marbles and watermelons act they're part of the sediment that the ocean floor is covered with the volcanoes grow on top of that. So they're like ball bearings that allow when the volcano becomes unstable because of maybe another larger volcano next to it. Eventually if it rises high enough and the pressure from the neighboring volcano makes these slides occur and they just come out with tremendous force. They can. This is a cross section across Oahu showing the crustal flexure deformation from the weight of the three large shield volcanoes forming the island of Oahu. The Cayena volcano, the Waianae volcano on top of it, which is younger than the Cayena and then the Coalau being the youngest volcano of the three. And it's the weight of the mass of these large shield volcanoes is actually depressed and bent down the oceanic crust above the mantle. Several kilometers, as you can see. And it's not that the mantle is liquid but that it acts as a plastic body and weight actually bends the crust. On the next slide we'll look at the rift system of the Coalau volcano, which is on the northeast side of Oahu. And here Dr. Walker in 1987 had measured nearly 3,000, a little over almost 3,000 dikes. And he estimated that we're over 7,400 dikes probably making up the shield volcano. And you can see that they form along three different rift systems, one to the northwest and one to the southwest and then one to the east. And it shows the Caldera complex, which is made up of two Calderas, the Kaniui Caldera and the Kailua Caldera, which kind of intermix and are kind of connected to each other to some degree though it's not well understood. And the center of the Caldera is the Kaniui swamp. It's just a low-lying area now. Okay, and then in the next slide we're showing the first stop, stops one through four, which starts at Diamond Hill, the iconic crater, which is one of these post-erosional volcanoes meaning that it erupted after a major erosional event of the Coalau Shield Volcano. And they're very small eruptions, but they were water-magma interaction as the magma intruded the rock. It ran into a lot of water that was stored in the limestone underneath the of the sediments that were overlying it and that water caused these very explosive eruptions, we call ferrado-magnetic eruptions in form of diamondhead crater. And then we're going to show a cross-section in the next slide. And here they show a cross-section of diamondhead tough cone and this was done by Sterns and Vastic back in 1935, a long time ago, but they used some drilling information when they drilled some water wells and they inferred there is one dike in this area that this was a dike-fed eruption and when the magma hit the limestone area, that white area of those bends that were forming below the surface, there was a lot of water there and that caused this very eruptive explosive eruption, we call a pyroclastic eruption, and these ferrado-magnetic eruptions blew ash probably tens of kilometers into the air and produced surge deposits and tough and ash that are forming the cone itself. In the next slide, we're going to move over to Hanama Bay, which are more of these younger eruptions, they're one-time events, they don't re-erupt usually. Here we're showing Hanama Bay and several stops around Hanama Bay, a beautiful place that anybody that comes to Oahu should see. It has some of the pristine fish resources for coral reef fishes that can be seen in Hawaii and very, very beautiful place to access. This eruption here formed two main tough rings. Hanama Bay is one that have two vats associated with it and then also there's the cocoa head tough ring which also formed in this area and those were both these ferrado-magnetic very explosive eruptions produced space surge eruptions in this area as well. In the next slide, this is one of the areas that most people don't know about but you can actually climb up this arch. It's an arch formed by the lithified tough that forms on cocoa crater. Most people take the hike that goes up the old tramway but this is a much more scenic view though. It's considered a challenging hike and not a family hike. It's fairly steep but gets you right up to the top of the crater and it's quite amazing to take this hike and it's shown in the guidebook as well. In the next slide, now this is from the Lanai lookout area below cocoa crater and it shows the vetted tufts that were erupted from the kāloa tough ring and this eruption was a wet eruption and you can see that the layers of ash have actually been deformed as this limestone block was blown out of the vent and traveled about a kilometer and then was embedded into the ash here and you can see small pieces of coral that are infilling behind this block where it formed the ash beds and what we geologists use is the angle of trajectory to determine where the source area of these type of explosive blocks when they were deposited. In the next slide, we're going to move to the Waianae side of the volcano of the island of Oahu. Here on the west side is a very unusual eruption probably the only of all the Waian Islands. It's the most solistic eruption. It's called the Rio Dei site. The crew lay Rio Dei site and John Sitton named this lava flow and it's also a beautiful area to visit very unusual. There's no other island that has one of these highly solistic nearly 68% silica silicon oxide in this deposit and so it's unusual for these very usually basaltic type volcanoes. And then on the next slide, we show one of the trails up the Kamaili Unu Ridge trail and this is also another beautiful scenic hike that goes up the Kamaili Unu Ridge and this is the site location for the Kamaili Unu member of the Waianae Volcanics. They hiked up the Hunter's Trail which is that steep slope on the kind of the right side of the ridge and that's where they mapped all the different variations in the foliated basalts and characterized these lava flows as part of the Waianae Volcanics and this kind of concludes most of the picture slides. So here's the last slide so Michael this is how we contact it. So how do we contact you Michael? Yes you can email me at michaeldenightatme.com or you can call me if you really want to talk to me directly at 808-349-2243. I'd be glad to talk to you about this book when it's going to be out for purchase or if you want to maybe go on a individual hike it's possible we could set something up and I can explain the geology in person. That's great Michael I know that this book was a labor of love for you and you put a heck of a lot of work in it took you about three years to write it yes and it's got hundreds of really great diagrams you just had a like a little brief introduction to it it's really well done it's written for the layman plus also for new students so a really great job Michael and so we're going to leave it there today we've been exploring the geology of Oahu with volcanologists Michael Knight thanks Michael a really great having you aloha thank you for inviting me I appreciate it