What’s happening at Kīlauea Volcano?

aloha welcome to volcano awareness month for 2021 i’m david phillips i’m the acting scientist in charge of the usgs hawaiian volcano observatory so i’d like to start by saying a few words about the hawaiian volcano observatory hbo is part of the us geological surveys volcano hazards program hvo’s mission is to monitor investigate and assess hazards from active volcanoes and earthquakes in hawaii to issue warnings and to advance scientific understanding in order to reduce impacts of volcanic eruptions communicating the results of our work to the public emergency managers and the scientific community is another important aspect of our mission the hvo facilities at uwa kahuna bluff within hawaii volcanoes national park were evacuated during the 2018 eruption the main building on the bluff was damaged and we are currently operating out of temporary facilities and two new until new buildings are constructed current plans call for a new primary usgs science center facility to be built in hilo as well as a smaller field station within hawaii volcanoes national park we hope that these new facilities come online within the next several years besides working out of temporary facilities at the present time most of us are also teleworking when we’re not doing field work volcano awareness month was actually initiated back in 2010 primarily through the efforts of janet babb janet retired from hvo this past march but volcano awareness month lives on and has grown over the years activities typically include presentations by hvo staff given it in person at community centers throughout the big island as well as hvo led field trips however volcano awareness month the routine is a little different this year uh first and foremost all of our talks and even our field trips are virtual this year instead of in person and this is because of the ongoing code 19 pandemic so we uh we miss interacting with the community directly and we hope to do so again in the future but for this year right now we hope you find these hbo presentations enjoyable and informative second hvo staff have also been pretty busy uh responding to the current kilauea eruption uh that began on the evening of december 20th 2020 and which continues to feed a lava lake within halema’uma’u the response to this eruption compressed activities related to volcano awareness month down to volcano awareness week but we’re getting these out now and we hope that uh that you will find them informative and interesting um and we hope that they provide some additional insights about what’s happening with the current eruption as well as in general about the past present and future of volcanic activity in hawaii so we have three virtual talks planned focusing on kilauea and mauna loa volcanoes we have recorded conference presentations from december’s american geophysical union conference and we even have a virtual hike uh kilauea summit with don swanson the hike with dawn was always one of the highlights of volcano awareness month and so this this virtual field trip uh made possible thanks to and don recording by katie mullikin is a is not to be missed so that’s great so without further ado let’s uh start the festivities with this uh roughly one hour long presentation about what’s happening at kilauea volcano and i will turn it over to my fellow hbo colleagues to give you updates on the geology the gas geochemistry the ground deformation and the seismology mahalo my name is matthew patrick i’m a geologist at hawaiian volcano observatory and i’ll be talking about some of the geologic observations of the ongoing summit eruption at kilauea

that hbo has been making the eruption’s been going on about a month now this is a view of kilauea caldera and in the southwest corner we have halemaumau crater and this is where the active lava lake has been and this thermal map we’ll be talking about later what these colors represent but it’s important to realize that if you go back just three years ago holy maumau looked very different this was before the the very large eruption that we had in 2018 so before 2018 we had halemaumau crater here it’s very circular about six tenths of a mile across and pretty shallow just 80 to 90 yards deep and we had this lava lake that had been active for about a decade but then in 2018 we had this very large eruption on the lower flank of the uh volcano on the lower east rift zone that drained magma from the summit magma chamber at a very high high rate and it caused the caldera floor and holly and the floor of halima to collapse and so this is what it looked like after that so you can see big changes at the summit here the floor of halemaumau collapsed dropped more than 500 yards so a really significant distance and you see big changes to the topography of the other parts of the caldera floor and what’s also really interesting is in summer of 2019 we started to see water seep into that very deep uh pit and that water lake which is really unprecedented for the past 200 years was there right up until the current eruption so i think the other talks are will mention some of the activity that happened before the eruption uh but at least on the surface there really wasn’t any change any detectable change in say the temperature of the water lake or or uh or hot steam cracks appearing let’s say it really wasn’t indicate any indication of that so the magma you know came up to the surface pretty quick and my for me personally the first indication that i got uh of the eruption was an automated alert on my smartphone uh because we have this thermal camera that’s running and it has an algorithm that kind of detects you know anomalously high temperatures and i got an alert at dinner time saying hey there’s uh there could be lava as you can see here and you know in this case the computer was actually right so um and then so you know we all obviously um headed out in the field and started our work so hbo geologists got to jagger museum overlook about 10 30 and what we could see was this enormous just towering steam plume and we could you know it was pretty obvious that this was that water lake being boiled off presumably by lava that was pouring into the bottom of the crater um yeah this steam plume was really impressive and actually um somewhat similar um we happened to be down um in the 2018 lower east rift zone eruption when we saw green lake uh in kapoho crater boil off another you know towering steam plume but it’s important to realize that that water leg was quite large was boiled off in just about an hour and a half so on that first night around 11 we got to the western caldera rim and this is what we saw so this is the first view in halema and we could see here numerous fissures of fountains that were active and they were all pouring lava into the bottom of the crater the water lake is gone at this point it’s about 11 pm and what we have is the development of a growth of a lava lake a closer view of that dominant fountaining source on the north side of the crater it’s about 50 yards high you can see it’s producing this really uh vigorous cascade of lava that’s just pouring and plunging into the lake so at first light you know we flew and we were able to get kind of the first daytime views of of this eruption and you can see the lava is filling in the bottom of the crater but then there’s also this island and this you know close later looks um of this island seemed to reveal that this was a kind of uh ejecta that may have been formed in the initial stages when lava was pouring into the lake a water lake and creating maybe small explosions but still we we don’t have um hand samples or uh or you know close views of the lake so it’s still its origin is still a little bit enigmatic

but you can see on this first day we see um uh first morning we could see lava from the fountains pouring into the lake and filling in the bottom of the crater so this is a time lapse of taken from the thermal camera um looking in halema and it starts off with the water leg here and we’ll see the whole month of the eruption just in this sequence so i’m going to start it and boom so there is the start of the lava lake and you can see it rises and fills the bottom very quickly we have this fountain on the north side and then that dies off and the fountain fountaining switches to the western fissure here and throughout this time you can see this island this cold island is kind of shifting around presumably carried by the currents in the lake and you also see these minor islands that are active in the east part of the lake again i should say that we’re looking towards the east so this area here the top of the image is the east and the bottom of the image is the west and then you can see around january 8th the eastern side of the lake starts to be kind of abandoned or starts to crust over and solidify and the active lava on the surface is really just limited to the western part of the lake watch that again so here we have this rapid emplacement of the lake of the lava lake we have this northern fissure that’s active we have this island that’s moving around in the currents then we have the shift to the western fissure here at the bottom of the image and then we’ll start to see just a little bit we’ll start to see the eastern side of the lake start to solidify this happens around the 8th of january so then we have active lava that’s more or less limited to the western part of the lake here okay so that’s kind of the state of what we have now and you know in the past week or so we’ve seen some minor changes in the vent activity at this western fissure which is the active vent area we see occasional small collapses that can trigger kind of minor switches in the vent location or cresting over the channel but overall relatively minor the western fissure remains active so one of the things that we track when we go out is is the elevation of the lava lake and this is important because we have the we know the topography of halemaumau crater before the eruption so by comparing the elevation of the lake to the pre-eruption topography we can figure out the volume and also the eruption rates we use the laser rangefinder for that anyway this is the results of all that data that hva geologists have collected over the past month and you can see this initial this is the depth of the lake in meters so you know roughly yards you can see the rapid rise or filling of the lake um in the initial days and then it kind of slows down and we’ve had been at this kind of slower rate in the past few weeks right now it’s it’s uh the lake is roughly 200 meters deep or about 650 feet deep that’s pretty deep um you know if you go online you can find points of comparison here is the closest one i could find is a space needle in seattle i’ve never been there but it’s about 184 meters so the lake is is deeper than um the space needle is tall the volume is about 30 million cubic meters so and that might not be necessarily very intuitive but point of comparison again 10 000 olympic swimming pools um and uh i’ve never been to the great pyramid of giza as another but i’ve always imagined it as a place that’s really enormous and uh this lava lake is almost 13 times the volume of of that pretty impressive so this is another view of that map of the summit caldera and we have uh this is the most recent thermal map that was made and we have again in the southwest portion of the caldera we have halemaumau crater and we have this lava lake that’s filling up you know portion of that crater and this is a thermal map so it the colors here the blue to the yellows to the reds show give a sense of the temperature on the surface and the blues that you see this eastern portion here is cooler and it’s actually solidified and the active lava here the hotter temperatures or the hotter colors are limited to the western side so as of today january 20th the eruptive activity is stable

we have seen there’s been a little bit of deflation over the past day and that’s uh associated with a slight decrease in the vigor of the eruption we’ve seen this pattern before we’ve seen how when we have these small deflation phases they’re followed by inflation so the eruptive activity can then pick up again so it’ll be interesting to see how eruption develops over the next few days with this kind of deflation inflation cycle but of course the bigger question is how will the eruption play out in the long run overall of course is the home of pele and this is very fitting because has such a long history of lava-lake activity we’ve had there were decades while almost 100 years of mavelic activity in the 1800s and early 1900s this is an example of one of the beautiful perched lava lakes that formed in halemaumau and of course we had 10 years of continuous lava lake activity from 2008 to 2018 but what we’ve seen is that you know these previous eruptions at holy mama there’s a there’s a wide range interruption durations they can last for a day or they can last for decades so it’s still unclear how long this eruption will last there’s no indication of it stopping but it doesn’t necessarily have to last as long as these previous eruptions in any case we’re watching this very closely we’re out in the field on a daily basis we have a very robust monitoring network that’s keeping a very close eye on the eruption so thank you hi everyone i’m trisha nadeau and i will be giving you a bit of an update on what the gases have been doing during this recent kilauea eruption so before we get to what it’s doing now give you a little bit of background on what the gas was doing before the eruption so as many of you might know already so2 emissions or sulfur dioxide were very very low since the 2018 eruption and that meant all eruptive sites we were measuring about 30 tons a day at the summit but sites on the east rift zone were below detection and what that means is that magma was deep enough to keep that so2 dissolved so just like a bottle of soda that you might open we essentially had the cap on our magma chamber so no bubbling no gases leaking out until the eruption we did also have this water lake that you can see on the right and it is possible that some so2 that was escaping from the magma ended up dissolved in the lake water so we couldn’t measure it in the atmosphere now people might also be wondering if we saw anything in the degassing before the eruption that could have been a clue that interruption was coming and that’s a fair question because you do see signals like that at many volcanoes around the world and we’ve even seen it at kilauea in the past this is sulfur dioxide emission right here for a lot of 2007 so this is the lead up to the 2008 eruption and you can see that sulfur emissions were pretty low and pretty stable at only a few hundred tons of so2 per day until we hit december of 2007 when we started seeing this increase now nothing was erupting here yet but we were seeing an increase and then in the middle of march of 2008 that’s when the eruption started so here seeing that increase of so2 was a clue that there could have been an eruption coming and it did come this time we didn’t see that so this is a slightly different kind of unit this is so2 concentration this is measured at a site about a kilometer downwind of holy mountain low and it measures about half an hour every three hours so you can see this is the day of the eruption zero zero zero all zeros the eruption happened right about 9 30 just after our 9 o’clock sampling window we didn’t see any change even though the eruption was about to start you can see that the station definitely did measure more so2 after that once the eruption had started but no precursors this time around no no so2 showed up to clue us in that something was happening and now for gas emissions since the eruption started this is back to so2 emission rate again and this graph starts the day the eruption started and you can see right away we were we’re pretty high with so2 emission rates this is almost 40 000 tons per day of so2 it did start to decrease right away um and for context here we sort of crossed through this zone where we had um lava lake the previous lava lake level was um

so early in that emission early in that eruption so2 emissions around 2008 were close to 20 000 tons a day so we started higher than the previous lava lake crossed down through that and then most of the 28 uh 2008 to 2018 lava lake averaged around 5000 tons per day and we actually did with this new eruption see that for a while we’re a little bit lower than that right now um although there is variability um so we had this one point jump back up to almost uh 5 000 but our most recent point is two thousand five hundred so in general we’re slightly lower than emissions from the previous lava lake people may also be wondering about putu we did go check on it we took a helicopter out there on january 7th to make sure that there was no excess degassing out there and there’s not so2 remains below detection limits around putilo these sort of rainbow dots are measurements from along our flight track and if there was a significant degassing plume you would see all of the red dots concentrated in one place but you don’t you see it’s just noisy data there’s blues and reds and yellows all over the place so that’s telling us there’s essentially no plume coming out of in terms of sulfur dioxide what is out there is a little bit of h2s so hydrogen sulfide and human noses are actually more sensitive to hydrogen sulfide than they are to so2 so even though there’s just a tiny amount of that hydrogen sulfide if the winds change and blow that gas toward nearby communities people may smell a rotten egg smell so that’s not so2 that’s h2s and it’s only under certain wind conditions we can also see so2 emissions from space so tropomy is a satellite sensor that detects so2 once a day and you can see in this image from the day before the eruption there’s no plume this is just background noise once we had the eruption we see a a pretty big plume on december 22 but already by the 25th by christmas we were having a bit of a decrease there’s less of a plume and since then we’ve had even less it’s certainly still detectable by satellite but it is lower emissions than early in the eruption so it’s showing the same decrease in emissions that we’ve been seeing from our ground-based measurements people who may visit the national park or live here on the island of hawaii may be wondering about gas hazards and if you’ve lived here long enough you likely know all about vog so the vog is back unfortunately and it can be a hazard but as i mentioned the emission rates right now are actually a bit lower just a little lower than that 2008 to 2018 lava lake level of emissions and there’s actually much less fog than there was during the 2018 eruption that released far more so2 than we’re measuring right now so the fog is not as bad as during that eruption if people are wondering more about fog you can head to this website called the vog dashboard and there you can get information from the hawaii department of health about how the vog and the so2 might affect your health you can get forecasts about where the bug will go on any given day and that’s what this image on the right is showing and you can also get real-time air quality data if you’re curious about whether the vlog is near you at any given time so i’ve talked a lot about just sulfur dioxide but we can actually monitor other gases in some other ways so one of the ways we get a better picture of gas chemistry is by unoccupied aircraft system or drones as most people call them so we have permission from the national park service to do some of those gas measurement flights within the park and this picture on the left is just showing sort of a slice through the plume and the red is where we encountered sulfur dioxide and i could have also just as easily put this profile showing where we encountered carbon dioxide or hydrogen sulfide and then on the right is showing where the gas concentrations were highest when we flew actually in and over the erupting crater so that’s a place that we cannot go ourselves but that’s where the drones come in handy they can go places that we can’t so we are able to measure the chemistry right in the erupting plume right close to the vent we can also get gas chemistry using what’s called infrared spectroscopy so there we don’t have to go so close to the vent we can just measure the gas that’s in between our infrared source which when there’s an eruption we can use lava as our infrared source and our spectrometer we can also just physically go grab some of the gas and send it off to the lab to analyze the

so again we can’t go in the erupting crater to do any of this but there are some degassing sites in public areas of the national park at sulfur banks so we do this sort of sampling with this bottle to sample the gases every three months anyway and we added some extra sampling because we had an eruption now we can learn things about the eruption by looking at the gas chemistry and the combinations of gases so both of our multi-gas sensors meaning our ground base station and our drone mounted multi-gas sensors plus that infrared spectroscopy all of those methods are telling us the same thing there’s a low ratio of carbon dioxide to sulfur dioxide so sulfur dioxide is dominating the degassing during this eruption and what that means is that this lava that’s erupting right now sat around in a magma chamber for a while before it erupted so like in this top panel if we had brand new magma coming right up from deep in the mantle all of its dissolved carbon dioxide and sulfur dioxide would all come out during this one eruption and that would mean there’s a higher proportion of carbon dioxide or a higher c to s ratio but we don’t see that so we’re actually down in the second picture here where the magma comes up sits in a magma chamber for a while and while it’s sitting there it is able to lose or degas some of that carbon dioxide it just comes up without erupting it leaks out through cracks in the ground and then once it finally does erupt we end up with that sulfur dioxide coming out so that’s what we see right now so the gas chemistry is telling us that the lava that’s erupted so far in this eruption did not come quickly from deep in the mantle this is magma that was sitting in a magma chamber for a while so it’s sort of pre-degassed it lost its carbon dioxide already so that’s one of the things that gas chemistry has shown us we still have a lot of data to look at and interpret and understand and we’ll certainly keep making measurements both for these sorts of chemistry issues that we can figure out and to make sure we’re keeping an eye on hazards for all of you in the public thanks for listening my name is ingrid johansen i’m a geophysicist with the hawaiian volcano observatory and i’m going to talk about deformation during the december 2020 eruption at kilauea volcano and show you some of the data that we collected during that time first i want to introduce you to two of the data types that i’m going to show these are the primary ways in which we monitor the volcano in real time at least via deformation measurements the first is continuous gps the gps antenna is underneath this gray dome here it’s fixed firmly to a monument which is itself fixed firmly to the ground it operates not too dissimilarly from the gps in your phone or in your car but instead of measuring the position of something that’s freely moving around we’re very precisely tracking the change of position of the ground to which this antenna is attached the other instrument is a borehole tilt meter which is this long cylinder here inside this cylinder are two bubble levels uh one oriented north south the other oriented east-west so not too different from bubble levels you might have used around your own house except that they’re extremely sensitive capable of measuring tilt down to a fraction of a micro radian and for comparison one micro radian is about 50 millionths of a degree so very very small amounts of tilt these cylinders are lowered down into a hole where they’re kept a little bit protected from temperature changes and other noise sources at the surface when magma starts to move into a reservoir it bulges the ground above it this has the effect of tilting the surface outward uh and moving points on the ground up and and outward from the magma reservoir so this is what we’re measuring and how we’re interpreting these data when an eruption happens taps into that magma reservoir moves material out of it and we see the opposite type of motion so now the ground is moving downward on top of the magnet reservoir tilt the ground is tilting inwards and points on the surface are moving down and inwards towards the magma

reservoir so here we’re now looking at three tilt meter plots for tilt meters around the summit uwe sdeh and iki this is a map of kilauea’s summit showing the locations of these tilt meters here’s uwe at the uakuhuna vaults sdh sandhill and iki near kilauea these plots are showing 12 hours of data around the onset of the december 20th eruption you’ll see two lines here blue line and a green line and as i mentioned before the tilt meters have two bubble levels north south and east west but we often find it convenient to mathematically rotate those uh into different azimuths in order to emphasize different signals so for example uh the blue line here for uwe has been rotated to 310 degrees and this emphasizes deformation from the shallow holley magma reservoir and and this direction has been chosen specifically so that downward motion of this blue line is consistent with deflationary type motion and upward uh movement of the line would be consistent with inflationary motion and the same is true for sdh and iki even though they’re rotated to different azimuths those azimuth were chosen such that upward motion of the blue line is consistent with uh inflation and downwards is consistent with deflation of that shallow holy mathematical reservoir if the source is different than we can expect uh different patterns of tilt that might not all resolve onto the blue line we first started seeing changes in tilts on december 20th at about 8 30 pm this was only an hour before the fissure opened at around 9 30. so you can see this period this about this period of um one hour prior to the eruption we saw a mix here of deflationary and inflationary motion somewhat complicated pattern was probably caused by the opening of the fissures after the onset of eruption we see on all of our summit meters um data that’s very consistent with just gradual steady deflation of the shallow holy mountain reservoir it’s interesting to note that um the changes here prior to the eruption were very modest only a couple micro radians uh it was actually not enough to trip our tilt alarms so that this was an event that happened um with very little precursory deformation it did trip other alarms so it was the swarm alarms and the thermal alarm that really alerted us to what was going on uh you might be interested to know that you know this spike that you can see on on several of these tilt meters um this is when the magnitude uh 4.4 earthquake on the south flank occurred and what’s happening here these are really noise what’s happening is uh the shaking from that event it really sets up sloshing in the bubble level in the days following the onset of the december 20th eruption we continue to see a steady deflationary motion this plot is showing gps positions for station caln calm is located centrally in kilauea caldera on what we call the down drop block this plot is showing its vertical motion so you can see it moved very steadily downward following the onset of the eruption but then had a change in behavior uh on around december 26th this was when the the north vent in uh holly mountain crater was drowned by the lava lake after this time period saw a little bit of uplift um but overall deformation was much lower amplitude following december 26th than it was in the days before with a nice time series like this we can start to model the decay using different kinds of curves in this case i’ve fit an exponential curve to this time series uh we can do this for all of the gps stations around the summit region and come up with a sense of the the spatial pattern of this deflationary component which is what i’m showing in this plot so these arrows are representing the amplitude of an exponential curve fit to the time series uh for all of these gps stations in kilauea summit region

the size of the arrow corresponds with the magnitude of the exponential how how much uh deformation happened and here’s the key here and the direction uh indicates the the direction that this exponential decay was oriented towards so as you can see uh the the the vectors here and the summit are all pointing inwards very consistent with deflation of a source uh here in in the summit which um could very well be the shallow halloween mountain on source there’s a little bit of asymmetry here in the sizes of the arrows which might indicate something more complicated than just a simple sphere here at the sun one of the interesting observations from this eruption was um the the observation of contraction out into the east rift zone so here i’ve expanded the the size of the map to show gps stations out around the east rift so you can see some inward direction motion up around makapuuy crater uh and also some motion here near where uh stations are being drawn uprift this is a unique observation this hasn’t been observed in other events that have also caused deflation at kilauea summit with the exception of 2018 where there was deformation all over the volcano what this might mean is that magma may have actually been drawn backwards out of the rift into the summit typically what happens is that magma comes first up to the summit and then is transported down the rift but this might be telling us that in some cases in fact um magma can can flow backwards and be drawn from the rift back into the summit which would be a an interesting and unique observation i should point out that that no contraction or inflationary type motions were observed down rift of puu including uh at the site of the the 2018 eruption so these data the gps stations in these areas uh didn’t show anything that that looked clearly related to the december 20th eruption so now i’m looking at the a tilt plot again this is again the the uwe tilt meter uh which is the uae kahuna vault not that far from jagger museum here we’re looking at two months of tilts in order to put the eruption of december 20th in context of what happened after and what happened before so you can see here at december 20th in the days after until the drowning of the north bends there’s about 50 micro radians here of depletionary motion since december 26th we’ve seen modest inflation and deflation but um much lower rates overall prior to december 20th we saw a lot of these events where there’d be deflation and then inflation we call these di events deflation inflation events and they are extremely common at kilauea’s summit so in fact these di events are part of the background activity at kilauea but the most prominent signal prior to december 20th was this inflationary signal on december 2nd this was associated with a small magma intrusion in the southern portion of kilauea caldera so it’s worth pointing out that but this intrusion happened in a different part of the caldera than the eruption and so it’s unlikely that the eruption is actually tapping into the magma from the intrusion instead it’s more likely that both the intrusion and the eruption are being fed from a slightly deeper uh more central reservoir the size of this tilt excursion as you can see is about 20 micro radians both of these events dwarf are dwarfed by the 2018 eruption and collapse signals during that time period uh we recorded tilt changes over three months uh of on the order of 600 micro radians so still compared to what happened in 2018 you know which was a centuries centuries-level event these are relatively modest now we’re zooming out to the past year of tilt data tilt from tilt meter uwe at the top and then vertical motion from gps station calm

at the bottom you can see in the tilt record the repeated di events which are very common at the summit um you can also start to see this this steady slow inflationary deformation this actually started not long after the end of the 2018 eruption and has been this signal has been very typical of the summit in the years since uh you can see that here at the calm as well where the station was slowly moving upwards uh throughout 2020 and this sort of gives you an idea of what a departure both the intrusion and the eruption were from the pattern that had been established in the previous year the the sizes of the motions that we have seen in the last month and a half can maybe be compared to tilt changes that were observed in the 60s and 70s so in the era before the eruption started there were eruptions at multiple locations throughout kilauea volcano that would cause deflation at the summit this record here is from um a water tube tilt meter so this is the era before borehole tilt meters before gps so tilts during this time was recorded um using an instrument called water tube tilt meter and those of you who have been to jaguar museum may remember that this was on display there this was read manually once per day which is what gives us this nice continuous two decade long record however so you can see here many instances the scale goes from minus 400 to 400 many instances of 100 micro red 50 micro rad type motions both deflationary and sometimes inflationary um what this means is that you know it’s not unreasonable to think that as we go into the future we may see more events similar to um the eruption on december 20th um we’re still learning you know what this new regime at kilauea volcano is going to be like and this era of the 60s and 70s might be um what we’re moving into to summarize throughout the december eruption we saw deformation consistent with that summer reservoir deflating magma moving out and feeding the eruption in holy mountain crater we also observed contraction in the nearby portions of the east rift zone and this was a unique observation that suggested that magma might have actually been flowing backwards towards the summit overall the levels of deformation were low compared to 2018 but not too different from what was observed in the 60s and 70s so we’re continuing to learn how kilauea volcano is different and similar to the era and and very much looking back at previous times in kilauea’s history in order to learn what we might be moving into thanks my name is peter dotray and i’m a seismologist here at the hawaiian volcano observatory and i’m here today to talk to you about the most recent seismic activity uh so the activity over the past month and we’ll focus on some of the events that led up to and occurred during the december 20th kilauea summit eruption so first we’ll take a look at this island map of the earthquake locations and you can see they’re colored based on depths and size based on their magnitudes and you can really see some of these seismogenic regions that we’re used to seeing being very active continue to be quite active over the past month so here we have the east rift south flank activity um that’s been occurring and then we can focus on mauna loa and the northwest flank and then kawiki fault system continues to stay very active and then of course this deep hall activity that has been very relevant over the past couple of years we’ll dig into that a little bit as well and then we’ll focus on this activity at keyway summit and you can see here it looks very quiet and we’ll talk about what we’re seeing there and maybe why it’s been quiet over this past month period and then over here to the left we have a histogram so this is a two-year plot a bar graph that shows you the number of earthquakes per week so each bar is a single week and it’s showing you the number of earthquakes so up here we you know we had a week of island-wide seismicity of over a thousand counts and then the

next week we dropped down below 600. and we’ll take a look at a lot of other histograms as well um so these histograms are actually focused just on kilauea summit so this activity at kilauea summit over the past two years and you can see these weekly counts really fluctuate and kilauea is very dynamic so it’s expected we have weeks of swarms and the next week will be event counts under 100 in a week october 20th to january um 18th activity we can see there’s a few spikes here so now we’re actually looking at earthquakes per day so each bar is a single day and you can see there’s a few spikes here in late october late november and then this little spike with a drop off in mid-december so we’ll take a look at those independently so first that first little spike here’s the video of that activity and you’ll notice there’s a couple of episodes of a lot of earthquakes that focus up in these lower kawaiki faults we call these the namakani piyo swarms and a storm of earthquakes is just a group of earthquakes that occur very closely in space and time tiny platforms because um on this density plot that they occur very close to the namakani pile campgrounds and here this density plot is showing you different squares of concentrations of earthquakes in that square so your cooler colors are going to be lower concentrations while your warmer colors are higher concentrations so you can see we have some of these uh grids of these warm dark reds which are very high counts of earthquakes so most of that swarm was occurring right there on these lower kawaiiki faults and again this is that first spike we are looking at in these daily counts and if we take a different look at this same storm now we’re looking at this histogram which is earthquakes per hour over this two-day period and you can see it really flared up right after midnight and it produced the highest rate of earthquakes at 25 earthquakes in an hour before it really quieted down and then picked up for its second episode and if we come over here and look at this map so this map is now showing you um colors based on time so your cooler colors actually happened early on october 22nd while your warmer colors were more on october 24th and size based on magnitudes again you can see this large earthquake right here it was a magnitude 3.5 and this map has these depth panels so these longitudinal and longitudinal depth panels and you can think of those as just if we took a slice out of this map and were able to look north at the um at the sort of subsurface activity we would see where these events are occurring which is a great way to look at where the depths are clustering and you can see here um so these are the same events all looking at different views and the latitude again is you’re going to cut this way and look west and this is what you’d be seeing and you can see these events all really cluster in this two to four kilometer depths um and this is in regards to sea levels so two to four kilometers below sea level you can see both of these episodes um very concentrated right there and at these debts and in these kawiki faults we expect these events um as the there’s some stress redistributions between the kilauea volcano and the mount aloha volcano two volcanoes pressed up against each other and produce all these faults and that activity is is it occurs there relatively often um and now we’ll jump into this um second spike that we’re looking at which is more sort of focused in the kilauea caldera and a breeze rift you’ll see a lot of activity in this upper east rift connector so you see a little flare up there some activity and then it’ll sort of focus in the southeastern part of the caldera before a few large events occur on this upper east rift connector and if we sort of take that same look we’re looking at the namakani pile swarms and look at it for these caldera swarms we’re going to look at this density plot again there’s a slightly longer time span november 29th to december 3rd but we can see again some of these darker colors are occurring in where most of the earthquakes were concentrated which was the southeastern part of the caldera in this western part of the caldera with some blues and greens these moderate colors uh forming on this the down drop block so the shelf of the caldera that fell during the 2018 eruption and a lot of activity up here in this upper east rift connector as we saw in that video i mean now we’ll go take another look at these histograms these hourly histograms to see this swarm really had two episodes as well you had this first episode flare up um and it peaked out about 17 earthquakes in an hour and then it quieted down and then it picked up again and this time it topped out at 23 earthquakes in an hour

before it really fell off um and again these are colored based on the time so cooler colors are earlier warmers later and they’re size based on magnitude so you have this large 3.1 event right here and this map is interesting because you see the colors are actually quite separate you can see these blue these early episodes happen in this down drop block and western part of the caldera before you get these oranges and yellows and the uppers rift connector and then finally it moved into these darker reds up here in the southeastern part of the caldera and we’ll take a look at these longitudinal and latitudinal depth panels again if we cross cut and look in you can see these depths are actually quite a bit more shallow we’re looking at about zero to one and a half to two kilometers below sea level um and these uh swarms really had different implications with with the shallow depths and them occurring right under the caldera along with some geodetic signals we are seeing with the second episode especially these are believed more to have um the results of some shallow magma intrusions under the volcano and which is very different from those namakani pile storms which was really more just stress redistribution on some faults this had some more magmatic implications and then finally about a a month not quite a month later we have this eruption activity so this is a longer time span video and you’re gonna see it builds up there’s just some micro seismicity really nothing obvious until the day of the eruption we get a little flare right there and then we get this large south flank event that i think most of us felt on the east side of the island and then a very interesting part of this video actually is after a few days after the eruption began activity got very very quiet you see occasional micro seismic events popping up but for the most part time is still running and i mean the map it looks empty and we’ll get into that a little bit of why we’re seeing such uh little earthquakes at the summit and what we are seeing since the eruption began so again we’ll take a look at this final little um spike in the drop off which occurred you know the eruption began on the 20th uh through the night and in early december 21st and you can see on this density plot you have a very different scale only one to four mostly light blues with just a couple of these warm colors occurring on the south uh part of the caldera on this sort of this rain fault around and still some upper east rift can east rift connector activity as well and so now i’m actually going to show a slightly different view so here we’re looking at waveforms from different stations which i’ve highlighted on this map to get nice coverage around the caldera and this map is is still the the earthquakes are colored based on time size based on magnitude and this plot down here is slightly different because we’re showing depth in regards to time so this is no longer a cross-cutting view simply where the depths were were occurring over time and you can see this red dotted line is when lava was seen at the surface when it broke the surface and up to before that and even after that we have this slight shallowing of located activity which would make sense even after lava breaks the surface the the conduit and the path that the magma’s taking is still trying to um establish itself and sort of get a stable path that it can pour lava out of um so we see some of this shallowing later as well so now we’ll focus on some of these waveforms um but i actually want to shift this view to spectrogram view so this is the same stations the same time except now we’re looking at the frequency content so you can see some of these darker colors um are the events these darker reds i mean and the darker the red and the more red you see you’re generally the stronger the events so you can see sort of this hour leading up to the eruption we have these these spikes these sort of broadband you know they have low frequencies and up to 20 25 high frequencies these broad signals that are really signature of earthquakes you know rock breaking rock fracturing um you can see some of these high frequencies attenuate over time which is very classic for any sort of volcano tectonic earthquake i mean you can see these are occurring you know every minute every 30 seconds leading up to about 10 minutes before lava broke the surface and then you can clearly see these sort of volcano tectonic events start coming in more rapidly and more strongly and becoming not even single events anymore it’s almost multiplets many events stacked on top of each other and then the lava breaks the surface about 10 minutes after that activity picks up and then even you know 15-20 minutes

after we had that strong strong vt multiplex occurring uh before things really got sort of mixed together so you still see in this in this time period you know about 15 minutes after lavabre surface you can see these sort of um pulsing vt volcano tectonic multiplets on top of this band of tremor that began i mean we had geologists on the ground at that point i mean they’re seeing different vents pop up there weren’t just one vent where everything came out there’s different vents and the path is really trying to establish itself this magma needs to establish a nice least low resistance path to reach the surface and then you can see about 40 minutes after it was first seen on the surface it really did establish its path and you can see that nicely because you have less of this pulsing broadband sort of rock breaking activity and more of this steady low frequency sort of humming this tremor which is a signature sort of signal you expect um with material pouring out or or liquid movement in here we have an open vent that lava was pouring out of the crater and then we’ll focus on this this event that occurred about an hour after lava reached the surface that most of us felt i i remember being slightly concerned when we first felt the shaking of this event but then we saw that it was it was a south flank event um which is expected and occurs often on this event you can see this map it shows where the felt the did you feel it reports were submitted from uh very strongly on the east side of the island really all around the big island and then maui i had a maximum mercalli intensity of four which indicates light shaking and really no damage and had about 620 did you feel it or reports um it occurred at 6.3 kilometers depth and that along with the sort of a shallow dipping fault plane really indicate uh it occurred on the day come on which is the detachment fault of the island sitting on top of the ocean floor and we get a lot of events there and here if we sort of zoom in and focus on the east rift you can see a lot of these events occurring these are now colored based on depths and they’re occurring you know from 5 to 13 kilometers below the surface so um that’s that’s about what we would expect for these day coal mine events and you can see you know the rift is pretty clear right here the east rift of kilauea these events are happening south of that um and which is is a pretty clear indicator they’re not migrating through the rift these are really south flank sort of that detachment um faulting events and then here if we sort of focus and look at the lower east rift you see it’s very quiet it’s really been known migrating activity out there few micro seismic events a couple of moderately sized events which had a handful of fellow reports but very small and very quiet i mean over here you can see we have this histogram these are weekly counts it stayed pretty consistent until the recent activity and with kilauea summit being as quiet as it is it’s really just mostly the south flank activity we’re seeing over the past month and then finally the pahola seismicity catches a lot of attention including ours um we’re focused on this area because the the activity has really picked up uh but the activity stays at these 25 to 40 kilometers dense you see some of the shallow activity up here but it’s a very separate activity you don’t really see any migrating or shallowing right under bahala it’s really just these deep events which past studies have linked that to sort of deep magma uh upwelling maybe uh where it comes into the volcanic edifice that the big island where first enters from the sort of upper mantle area to the crust um and if you you can read more about that at this um volcano watch that was written in 2019 we’ll talk slightly more about that but again this activity has been observed for decades and it did pick up in august 2019 um but it stayed pretty consistent since then so thank you very much if you have questions please feel free to email and we’ll get back to you as soon as possible and stay safe thank you hello again i hope you enjoyed that presentation about what’s happening at kilauea volcano just a reminder activity is ongoing and things likely evolved from when this presentation was recorded in mid-january until the time that you’re watching it so please visit the hvo website for the latest information about the activity at kilauea there are regular updates on the activity we have photo and video chronologies for some unique perspectives on the activity and the interpretations as well as live webcam feeds so you can

see what things are like in real time i would also like to say that at this time all activity from the current eruption is taking place within hawaii volcanoes national park the lava lake itself is not currently visible from any safe viewing locations within the park so please carefully follow the park’s guidelines uh to have the best and safest experience that you can hvo is performing our critical monitoring activities within the closed area of the park and we’re doing this with permission and in close collaboration with park authorities hvo field crews are also equipped with a full complement of specialized personal safety equipment and communications equipment while we perform the volcano monitoring work as part of hbo’s mission again i would like to acknowledge janet babb for initiating volcano awareness month and we wish her a very happy and healthy retirement i would also like to acknowledge tina neal who served as hbo scientist in charge up until this past june and she was in charge of hvo and the response throughout the dramatic events of 2018 and tina sends her aloha from the alaska volcano observatory where she is now and uh finally i’d like to acknowledge the uh the tremendous efforts and talents of katie mulligan who organized and made this year’s uh hbo volcano awareness month activities possible so thank you very much katie a lot of work goes into these especially in the middle of a pandemic and in the middle of interruption so mahalo katie happy volcano awareness month to everyone happy new year in general please stay safe take care and stay aware aloha you