Living with Earthquakes in Hawaii

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Detailed Description

Tens of thousands of earthquakes occur each year in Hawaii, making it one of the most seismically active places in the United States. Brian Shiro, USGS Hawaiian Volcano Observatory seismologist, talks about the different types of earthquakes in Hawaii and how they are monitored to help forecast volcanic eruptions and recounts the dramatic seismicity that happened during Kīlauea Volcano’s 2018 eruption. Learn about historic damaging earthquakes and seismic hazards in Hawaii, and how you can prepare for the next “big one,” as Brian addresses these topics and more, including how you can participate in the process of earthquake monitoring. This talk was presented as part of the Island of Hawai‘i's 11th annual "Volcano Awareness Month." Volcano Awareness Month is spearheaded by the USGS–Hawaiian Volcano Observatory, in cooperation with Hawai‘i Volcanoes National Park, the University of Hawai‘i at Hilo, and Hawai‘i County Civil Defense, and provides informative and engaging public programs about the science and hazards of Hawaiian volcanoes. Cover photo caption: Damage to the Kalāhikiola Congregational Church in Kapaʻau on the Island of Hawaiʻi caused by the magnitude-6.7 Kīholo Bay earthquake in October 2006. USGS photo.


Date Taken:

Length: 00:35:29

Location Taken: HI, US

Video Credits

Video Production: Katherine Mulliken, Geologist, Hawaiian Volcano Observatory,


[Speaker:  Brian Shiro, USGS Hawaiian Volcano Observatory]


Thanks for coming today. I'm really happy to see all of you. I'm glad that the turnout is so good on this lovely afternoon. Thanks for taking some time out of your day to be here to talk about earthquakes. This is in honor of Volcano Awareness Month, which we have every January. This is just one of a series of talks, as well as other programs that are going on throughout the month. At the end I'll share a few of the upcoming ones with you.


The purpose of the talk today is to discuss earthquakes here in Hawaii. Why do they happen? Where do they happen? What can you do about it? I'll give you a preview of some of our analyses from the 2018 eruption earthquakes, as well. And a little bit about what we do in the USGS. If you have questions or if I say any terms that you don't know, just raise your hand, let me know anytime. It’s fine to interrupt me. We’ll also have plenty of time at the end to ask more in-depth questions, too.


A little about myself first. My name is Brian Shiro. I've been with the Hawaiian Volcano Observatory now almost four years, where I coordinate the seismic group. We monitor the earthquakes here on the island. Prior to that, I spent almost 11 years at the Pacific Tsunami Warning Center on Oʻahu, where I was involved with monitoring earthquakes and tsunamis around the world. I've managed seismic networks in different places, including Fiji, Tonga, Antarctica, Mariana's, Canada, as well as here in Hawaii. The art and science of monitoring earthquakes is something that I find enjoyable. If you have questions about that, we’ll touch on it here, but just a little bit.


So, earthquakes in Hawaii….


Hawaii has thousands of earthquakes every year. In fact, on any given day, you may have hundreds. Here's an example of a station on the East Rift Zone of Kīlauea, which recorded, as you can see, each one of these blips on the graph is an earthquake. This is on May 2, 2018, in the lead-up to the eruption, which happened the next day in Leilani Estates. This example is highlighting the importance of monitoring earthquakes to forecast volcanic eruptions and to help keep people safe from volcanic hazards. This and other stations like it were used to track the earthquakes going down the rift zone as they travelled from the area of Pu‘u ‘Ō‘ō down to Leilani Estates, where the lava eventually came out.

I thought I'd start off with grounding you where we are right now today. This is a snapshot of earthquakes in the past week. If you want to know what's going on, you can also check out our website anytime and you'll see a different representation of this. But what you can see here is the island, and the circles are earthquakes. The color is how deep it is—the more blue or purple, the deeper it is. One thing you notice too, is if you took a big knife and sliced it like a cake, there's two cross-sections here: one going east-west, as if you had sliced it and are looking toward the north, and the other one is a cross-section going north-south, as if you sliced it and were looking towards the west. You can see the earthquakes don't just happen everywhere, they have a certain geographic pattern. They are mostly on the southern part of the island. They're mostly around the active volcanoes. And they're mostly shallow, with this exception here, this cluster that occurs around Pāhala.


We can advance that to show the last month. You notice that the top, there were 400 earthquakes last week, magnitude-1 and greater—and here, the last month, 1600 magnitude-1 and greater earthquakes. Now you can see, we’re starting to have more scattered earthquakes in the northern part of the island and in the west side of the island, where we are. These earthquakes occur for different reasons—we’ll get into that in just a minute. But you can still see the same general pattern. Most of it happening in the south. Most of them shallow, with the exception of Pāhala.


In the last year, 10,000 earthquakes. The longer you go, the more you're going to cover up the island with dots. Everybody has probably felt an earthquake, right? Raise your hand if you felt one. Almost everyone, I’m sure, living here. We know it's earthquake country. Earthquakes happen all the time.


This video is 3 minutes long and gives you an overview of the different types of earthquakes—there are three types (there will be a quiz later). This video, by the way, you can find online. It's produced by an organization called IRIS, with cooperation from us. If you slice the volcano in two, you can see a cartoon view of the magma coming up. The first type of earthquake that happens here is related to the volcanoes directly—related to magma and gases moving underground. As the magma forces its way through these conduits, it breaks the rock, and anytime the rock breaks, you have an earthquake. Here’s an example where the magma just made its way up here and erupted.


These other lines here represent faults along the flank of the volcano. If you’ve been to the [Hawaiʻi Volcanoes National] Park and driven down Hilina Pali—you know those big faults…here’s a zoom in on that—that is slipping all the time, and as it slips, each time it does, it’s as an earthquake. Those are tectonic earthquakes, a second type of earthquake we have here—just along faults, not due to magma or the gas. It’s due to settling of the island. That's the most numerous type of earthquake in Hawaii, happens most commonly, and it's the most dangerous, potentially. If this lower section goes… This red line is the boundary between the volcanic material above that rests on the older ocean floor below. They’re made of different types of rock, and the two slide along each other easily. When this gets pushed, or when this moves like happened in the magnitude-6.9 earthquake on May 4, 2018, this could produce very big earthquakes, which we'll talk about a little bit more, including the 7.7 in 1975.


The third kind of earthquake happens deeper down. These are the earthquakes that are more common around here [West Hawaiʻi], as well as Pāhala and other areas of the island away from the active volcanoes. These are due to the bending of the plate beneath the weight of the island. If you imagine all this volcanic material from all the volcanoes piling up on top of the Pacific plate over many years, it pushes down and bends that plate. That produces stresses, and occasionally it causes the rock to break and make earthquakes.  We call those flexural earthquakes, or in this video, they're called mantle earthquakes. Those are the most common type of earthquakes up the [Hawaiian] chain as well, including these ones noted here: Lānaʻi, Maui, Molokai, etc., some of which have been quite damaging. So, the 3 types [of earthquakes] are volcanic, tectonic, and flexural.


We'll talk about hazards in just a minute. This is an older map, but this shows the hazard is high on the Big Island.

“Earthquakes in Hawaii” is available online and we’ll link to it once this gets posted on HVO’s website later.


Remember the quiz I told you about?  Who remembers one of the types? [audience responds]


Volcanic—here’s a little cartoon. This is showing… Imagine a little finger of magma underground, moving along—they call that a “dike.” As it's forcing its way into little cracks, it's making them bigger, widening them, and creating earthquakes as it goes. Usually, at the tip of that dike, you get what's called a “high-frequency” type of sharp earthquake. Behind it, once the conduit is open, you get this resonance that happens when magma degasses that just reverberates inside the pipe. That's often called “tremor.”


The second type, tectonic, could occur on small faults or this really big fault beneath the island. It has happened—and is the most numerous type.

Then the flexural, or the mantle, are the ones that occur deeper down. They’re due to the bending, and, in fact, it’s not only bending under the island, it could be bending away from the island, too, all the way out to Oʻahu.

That's why we have earthquakes here, that’s what causes them. Even though we're not on a plate boundary, like California is, we have a lot of earthquakes. In fact, in the U.S., we have the third highest rate of seismicity in the country due to these three processes.


That gets us to earthquake hazards. What do we do about that?


This map shows earthquakes magnitude-3 and higher that have happened in the past decade, just the last 10 years. You can see they are mostly on the Big Island. The biggest ones are on the south. The size of the circle is the magnitude of the earthquake. They're scattered up the island chain, and now you know why—because of the bending of the plate up there. Why 3 and higher magnitudes? Because that's generally what you might feel. Do you feel many earthquakes smaller than a magnitude-3? Maybe, if it’s nearby, but generally, it needs to be about that big to feel it widely.


Of these, some of them are larger and damaging. This is showing magnitude-6 and greater earthquakes since 1868, which predates instrumentation in seismology, but we have ways to figure out magnitudes for older earthquakes. You can see a number of large, damaging earthquakes—all these caused various amounts of damage. In fact, by taking data like that, scientists have figured out the probability of the next damaging earthquake. Generally speaking, we have a damaging, if you define that as 6.5 or greater, earthquake, every 10 years or so. We just had one in 2018, but who knows the prior one before that?

Kīholo Bay in 2006. So, 2006-2018 it's roughly that much [10 years]. But you can see that the probability gets higher and higher the longer you wait. In fact, remember I mentioned our relative risk compared to other places in the U.S. Here's a map of the country. You can see the red color along the west coast, Alaska, southern Hawaii, as well as Puerto Rico. Those are the areas with the highest [earthquake] hazard.


When these big earthquakes happen, they rupture a fault. A fault is the place underground where the rocks slip to make the earthquake. If you've ever bent or broken a pencil, you know the phenomenon of bending it a little bit, and it won't break. It just bends and it goes back to where it started. That's what's happening in the earth all the time—there's a little stress bending the rock a little bit, but it doesn't break. But if it bends it long enough, and pushes persistently enough, eventually the rock can't sustain that anymore and it snaps. That's a brittle process and that’s what happens in the earth, as well. When it happens, it happens along a surface we call a fault. In the case of the pencil, the width of the pencil.


This is showing the bulk areas of some of the largest earthquakes that have affected the island. A lot of them are just rectangles because we're roughly guessing, based on the energy released, how big the fault would have to be to produce that energy. In the case of the 1868 earthquake, which is this odd shape here, we think it ruptured this whole section of the island, which is almost the whole south flank of the volcano. Based on that, seismologists think the largest earthquake that could happen in Hawaii is about a magnitude-8. That [1868] was a 7.9 earthquake and was almost the whole south flank. Just a little bit more rupture maybe to get up to an 8, but not any more. That's due to the physical geometry of the island, how big it is.


Again, remember the red line in the video showing that surface between that big fault between the upper material that's younger and older material below? This is that area.


I’m going to go through a few examples of these historic events to give you a feel for what they were like. The 1868 earthquake, the great Ka‘ū earthquake, is showing here. This is a Shakemap, which depicts the intensity away from the earthquake. The earthquake happened down here, and the intensity is how much ground shaking you get going away from the earthquake. It’s measured with these Roman numerals. Traditionally, it was qualitative based on reports that people did about what it was like, what fell down, what kind of damage there was. Today, we augment that with actual measurements of deceleration of the ground swell. You can see it rattled all the way to Oʻahu. In fact, there were reports on Kaua‘i, as well. Here’s a picture of a church [in Ka‘ū] that was destroyed. Certainly, this is the biggest earthquake that has been recorded in Hawaii. This one was also notable because it created a local tsunami. The tsunami, unfortunately, killed a number of people, as well as some landslides, so it's also the deadliest earthquake that we've had modern times, or recent times. Also notable for this earthquake, it's the only time it's been documented that it induced an eruption. So, eruptions Kīlauea and Mauna Loa were affected by the earthquake. It's pretty interesting that there is an interplay that happened.

Since this is a Kona audience, I thought I’d talk about the 1951 earthquake. This was the biggest earthquake since the Ka‘ū earthquake. The 1868 earthquake happened, and then the next biggest one was the 1951 one, here in South Kona. This one was quite severe. It also produced a really small local tsunami that was not damaging. There were no fatalities recorded for this, but it was damaging. You can see here, a picture of a water tank that was destroyed nearby.


The 1975 earthquake. Who was around and felt that earthquake? The one that happened in 2018 was in almost the exact same place, almost a repeat of that earthquake, just not as big. You can see some [1975] photos here, things thrown on the floor in a store in Hilo, cracks in the National Park, and the tsunami that it produced destroying a house, in this case. That tsunami was famous, too, for killing two Boy Scouts who were camping in the National Park.

Finally, the 2006 Kīholo Bay earthquake, as well as the Māhukona earthquake. This is interesting because they were twin earthquakes that occurred, not from movement along that fault at the base of the island, but this is due to that third type of earthquake on the video—the flexure or bending earthquakes. On this little diagram below, you can see that it's showing that the Kīholo Bay, the first earthquake, was actually in this lower part of the plate that was bent down and had this stress that’s pushing it more outward. Then the second earthquake, the Māhukona earthquake, was in the upper part, which had the stress that’s pushing inward on it. We can tell that from the seismic waves that came from them. We can tell which way the fault moved, whether it was pressure or extension. It was just a textbook example of that. Basically, the first earthquake triggered the second earthquake. They were pretty close together in time. Who felt that earthquake? Most of you here. I was on Oʻahu and didn't feel it because I was running. But I saw a tree fall down on Oʻahu from that earthquake.

We have a lot of earthquakes in Hawaii, including a history of damaging earthquakes. If you look at the magnitudes and energy releases of these earthquakes, they’re on par with the biggest ones in the country, including the 1906 San Francisco earthquake, for example, which was devastating for that city, as well as Loma Prieta and Northridge, famous earthquakes in California. Hawaii’s earthquakes are just as big. The hazard here is equivalent to that. What's different is the population—a lot lower population, a lot less infrastructure [in Hawaii]. So, there's less vulnerability, if you will, but just as much probability of the hazard.

Kīlauea eruption 2018 was remarkable in many ways. Most notably, of course, the volume of lava that came out. This is fissure 8 and its lava channel, which fed a very vigorous eruption, covering so many [716] homes and creating 800-something acres of new land to the island. Associated with that were a lot of earthquakes, although not associated with this process itself.


Most of the earthquakes were earlier on, due to the creation of that magma pathway in the ground that I showed in cartoon form, and also at the summit, which we'll talk about. If you break down the earthquakes—this is a map of earthquakes during the eruption, magnitude 2.7 and higher. I like to break it down to three main types, three main categories: Ones that occur in the lower East Rift Zone and associated with that eruption. Ones at the summit associated with the collapse of the caldera… Has anybody gone and seen that in the Park? It’s very different.  And [ones] at the south flank. All these south flank ones are associated with the magnitude-6.9 earthquake and its aftershocks. They have distinct characteristics about them. If you want to hear more about this, I have an “After Dark in the Park” talk in the [Hawaiʻi Volcanoes] National Park at the end of the month where I’ll delve into this more. If you look at these colors here, it shows the amount of earthquakes over time. This is starting in January 2018. In May, everything takes off. By August, it shuts off. So, May to August [2018], those three months, is when it was active. If you look at the red ones first, they pick up for only three weeks, when the area down here was really active. For three weeks, when all those fissures were forming, covering up those homes, creating new lava flows—that’s when all the earthquakes happened. But once that was established and fissure 8 took dominance of the system, notice how those earthquakes just dropped off, tailed off to a low level. It was pretty interesting. Only 1500 of those recorded at this magnitude level.


The south flank is another story. The magnitude-6.9 earthquake happens, takes it longer to die down, lots of aftershocks, which are still going to this day. Notice how it's not quite going back down to the level it was before. That's another interesting observation. This is basically showing that the south flank of Kīlauea Volcano, and we can measure this with GPS, is more mobile now than it was before the eruption. It's more free to move—and in the process, sometimes creates these smaller earthquakes—than it was prior to the eruption.

Finally, the big story seismically was the summit. We'll talk about this in the next slide. But notice how the blue color didn't pick up at the beginning. Slightly, but it didn't really start until about a month into it, then it started to pick up. Once enough magma had drained away beneath the summit, that's when the caldera started to collapse. That’s when all these earthquakes really started to take off.


The 6.9 earthquake was large—the biggest in more than 40 years—and had very severe shaking. I remember diving under my desk. It was a really exciting day, and it certainly made the news. Here's a [Hawaiʻi] Tribune-Herald article about it, talking about some of the effects. But it didn't make a big splash, for obvious reasons, because the eruption began just the day before. People were evacuating their homes, there was lava on the ground. It's a triage situation, in a certain sense, so the public's attention did not dwell on this very long. But it's definitely a very major earthquake in the grand scheme of things for Hawaii. It’s hard to see here… this is a figure from a paper that came out in ‘Science’ last year. It's showing how the magma underground actually pressed sideways on the flank of the volcano. That’s what caused this fault to give, we think. It might have been ready to go anyway, but this is the push it needed.


I promised to talk about the summit earthquakes a little bit. This was one of the more surprising, or novel, things about the eruption from an earthquake standpoint. No one had ever observed this incremental caldera collapse in such great detail. The Hawaiian Volcano Observatory has a really dense seismic network of monitoring stations around the summit where we could record all these earthquakes very well. Here, these blue lines are the number of earthquakes per hour throughout that period of the eruption, these three months of the eruption. Sometimes you'd have as much as 150 earthquakes an hour happening in this region. But notice how it would rise high, to a peak. That's when, basically, this roof of the caldera is wiggling. As the magma is drained away, it's not supported very well. It’s wiggling a little bit, creating all these earthquakes. It can't hold itself up any longer and falls. Falls down several meters, 10 feet, something like that. Then everything goes quiet. It's happy again. It's stable. It's on more solid ground. That's when this rate drops off until … the magma is still draining away… it's not supported as well and starts to wiggle again, starts to create the earthquakes, rises back up to the rate of earthquakes, until it falls again. This happened 62 times. Each one of these measured about a magnitude-5 energy release—a 5-point-something, on average. Very remarkable.

This is a time-lapse video of the caldera, showing from April through August [2018] what was going on. That’s one photo per day, I believe. We’ll watch it one more time to see what it was like before. You see the explosions happening with all the gas and ash early on. Then it just falls in on itself. The crater increased in volume by about 15 times; depth by about 6 times; width by 3 times. If you have not seen it, go see it.

How unusual was the seismicity in the summer of 2018? This is one way to look at it. This is showing 20 years of earthquake counts from our catalog. I asked our earthquake catalog how many earthquakes are happening per month. That's what these blue lines are. You can hardly see here, but normally we have a few 100 earthquakes, up to maybe 1000 earthquakes, a month. Remember the plot in the beginning of this talk, when I showed the last month of earthquakes, it was 1600, I think. Then, here is the summer of 2018. This is how unusual it was. We got about 3 years-worth of earthquakes in 3 months. We haven't looked at all of them—it’s going to take us years to look at all those earthquakes and analyze them. You can see, though… notice how now, over the past year and a half, we're at a higher level of seismicity, in terms of number of earthquakes, than we were before the eruption. So, the volcano, the island, is still adjusting, still creating a lot of earthquakes, relatively speaking.

How do we monitor these earthquakes?


At HVO, we have a number of ways to monitor the volcanic activity. My piece of it is just one of many. My piece is monitoring the earthquakes, but we have other scientists who monitor other things. By taking all these types of data into account, we have a good picture of what the volcano is doing. This includes the shape of the volcano, how it’s inflating. It includes the gases that are coming out. It even includes the sounds that it makes, etc. Increasingly, we're using satellites and drones more, to monitor from the air and space.


This is just one piece of the picture. But from the seismic side, I broke it down into about 4 or 5 steps. First, you have to record the earthquakes on your instruments—your seismometers. You have to get the data back, and have to be able to use it. Then, you analyze the data so you can learn about it, what's going on. And, you tell people about it. Then, of course, do something about it if it's a “Drop, Cover, and Hold.”


This map shows where our stations are. All the red triangles are the locations of a majority of our stations. There’s about a 100 sites on the island. You can see they're concentrated on Kīlauea, as well as Mauna Loa, but they're scattered around as well. This is what I take care of, and this is what we use to monitor the earthquakes.

This has changed a lot over time. Thomas Jaggar, who founded the Hawaiian Volcano Observatory—the [NPS] museum is famously named after him, was one of the people at the forefront of seismology back in the early part of the 1900s, developing the instruments for the first time. This is a photo of him in the Whitney Vault, which is behind the Volcano House in the National Park, developing some of the very first seismometers ever made. Here is an example of what one of our stations looks like today, up on the summit of Mauna Loa in the snow, with solar panels and ethernet radios and batteries. Very modern telecommunications infrastructure at our stations. The instruments are all digital and computer-based.


Speaking of telemetry… The next cog in our wheel is getting the data back. HVO operates its own private area network, if you will. It's like a cell network that's just for our data. It uses radios, microwave range radios. This is what one of the telemetry hubs looks like. Our data is shooting around the island, getting collected at places like this, and then comes back to the observatory where we analyze it.

How do we analyze it? Well, we have to triangulate where the earthquake occurred. We have a team of seismologists whose main job is to look at all the data streams coming in every day, to verify that the computer has found the arrival times of the earthquakes properly. Then adjust this, as necessary, the time the earthquake occurred. If you want to know the details, at least roughly, here here's how it works. You want to find when the P-wave, the first wave, arrives at a station. When did the shaking begin at the station? We can measure that, and that's a time. If we multiply a time by a velocity, which is the speed that sound travels in rock, you can measure that lag. You can knock on a rock and listen on the other side, and you can figure out the velocity that it took that wave to travel through that medium. Scientists have done that, so we know the velocity of the rock. If you multiply those, you get distance. Same phenomena as if you’re driving your car and trying to figure out how long it's going to take you to get somewhere. You know your speed, how much time you have, how far can you get, do you want to get gas, etc. That's the basic idea. These distances are circles. They become the radius of how far away an earthquake could have been from that station. If you do that at enough stations, where the circles overlap is your earthquake. So, in principle, this is how we locate earthquakes. The computers help a lot. The computers do the number crunching, and we just provide the eyes, the expertise to see when this happened.


The last step is getting the word out. This goes to the website. You can subscribe to something called the Earthquake Notification Service. Who gets that on your phones? If you haven't heard of it, you can go to the USGS website, look for Earthquake Notification Service, or ENS. That’s the link. You can set up how to get it on your phone. You'll be one of the first to know. As well as the HVO website—there's also earthquakes on the website.


What about the response step? That’s what this section is about. What do you do with that information? If it's a small, magnitude-2 earthquake, you don’t need to do anything. But what if it's a bigger one? As we know, it’s not “if” but “when” the next big earthquake’s going to happen. We know every roughly 10 years there’s going to be a day when there’s a damaging earthquake. Here are some of them we talked about, as well as models that we talked about.

The main thing is “Drop, Cover and Hold on.” If the earthquake is so strong you have trouble standing up, that’s your cue to drop down because you might fall down. You’d rather get down yourself rather than fall down and get hurt. So, dropping down is really important. Stand on your knees, get on the ground, however you want to, however you can. Ideally, cover up. Get under a table, under a desk, or something like that, so that if the roof starts to fall, especially things like ceiling tiles, anything that’s weak could fall down. You don't want it to hit you on the head. So, have a shield over yourself. That's why you cover up. The reason you hold on is because the shaking can be violent enough that the table you’re under might tip over or it might shake its way out from over you. It might shake its way sideways, and then you wouldn't be under it anymore. So, hold it over yourself. This will be tens of seconds and it will be done. Once it's happened, once it's all done, you can go. Usually we say go outside because there could be aftershocks and weakened material could fall down, if it didn't already. Drop, Cover and Hold on.


Of course, if you’re at the beach get away from the water. If it's one of these earthquakes that’s strong enough you can't stand, it may be strong enough to make a local tsunami. Just get away from the water. Walk about quarter mile, walk for 10-20 minutes, if you want to be extra safe. There's more information… [question from audience: “What would be the time that it could generate a local tsunami? Let's say from a M6.”]  The tsunami itself will be generated right away. The speed of the tsunami is dependent on the depth of the water—the deeper the water, the faster it travels. So, when it occurs close to shore in shallow water, the speed is somewhat slower, which buys you some time. If the earthquake occurs on the south flank of Kīlauea, the tsunami would have to wrap around the island to get here [West Hawaiʻi], which could take about 15 minutes, 10 or 15 minutes, depending on at what depth it occurred away from the coast. If the earthquake were a South Kona or southwest flank of Mauna Loa earthquake, on this side of the volcano, you might have as little as 5 minutes before it would reach you. That gives you a rough idea. Folks on Oʻahu would have about 30, to 35 or 40 minutes.

There's a pamphlet in the back called “Earthquakes in Hawaii” that you’re all welcome to take home with you. Of course, you can learn a lot more on our website. The “Great Hawaii ShakeOut” website, if you’ve not heard of this, go check it out. There's a lot of material there on preparedness, on safety, on different scenarios—what if you're disabled, what if you're at a school, what if it’s in an office. A lot of “what if” scenarios are there, and there are good materials to review for all sorts of situations. The Great ShakeOut coordinates the world's largest earthquake drill every October. You and your business organization can sign up to be counted in the earthquake drills with tens of millions of people nationwide participating every October to practice Drop, Cover and Hold on.


The other thing I want to remind everyone today is to please submit “Did you feel it?” reports. Who knows what “Did you feel it?” is? I see a few hands. It's a service on the USGS website. You can go to for “Did you feel it?” If you feel an earthquake, it asks a question—did you feel it? Say ‘yes’ or ‘no.’ If you want to, you can answer a few additional questions—did things fall off the wall? did it form cracks? And additional questions if you want to answer those. It helps to make maps like this that show the amount of shaking. We can't have seismometers everywhere. Remember my map of the red triangles of where we have instruments. They're not everywhere, but there's a lot more people, so you guys can be little seismometers filling in the gaps on our maps. It's really valuable to us to help us do that.


Thank you very much for your time. If you have questions, let me know.