Wave Watchers: The Science of Tsunami Detection

Summary

Wave Watchers: The Science of Tsunami Detection – Detailed Summary

Off the Radar Episode released on January 14, 2025, hosted by Emily Gracey of The National Weather Desk, delves deep into the intricate world of tsunami detection and warning systems. In this episode, Gracey engages in an enlightening conversation with Dr. Stuart Weinstein, Deputy Director of the Pacific Tsunami Warning Center (PTWC) in Hawaii, to unravel the complexities involved in monitoring, detecting, and warning against one of nature's most formidable forces.

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1. Introduction to Tsunami Detection

Emily Gracey sets the stage by emphasizing the critical role of tsunami warning centers, highlighting the immense responsibility shouldered by scientists like Dr. Stuart Weinstein.

Emily Gracey [00:02]: "Millions of lives hang in the balance of their next decision. Send the alert too late and coastal communities won't have time to evacuate. Send it too early or too often and people might not take it seriously."

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2. The Pacific Tsunami Warning Center: Role and History

Dr. Weinstein provides an overview of the PTWC, its origins, and its evolution into a central hub for tsunami monitoring across the Pacific Basin.

• Establishment and Evolution:

  • Dr. Stuart Weinstein [03:54]: "A tsunami warning center has been in Hawaii since 1949."
  • The PTWC was initiated post the 1946 Alaska earthquake and further expanded after the 1960 Chile and 1964 Alaska earthquakes, establishing a Pacific-wide warning system in 1965.

• Organizational Structure:

  • The PTWC operates under the National Weather Service and collaborates with regional tsunami service providers globally, including centers in Japan, China, Nicaragua, and Australia.

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3. Understanding Tsunami Science

A comprehensive explanation of what constitutes a tsunami, its causes, and the mechanics behind these massive waves forms the crux of the discussion.

• Causes of Tsunamis:

  • Dr. Stuart Weinstein [06:54]: "Approximately 80% of the known destructive tsunamis are actually generated by earthquakes."
  • Other sources include:
    • Landslides: Both submarine and terrestrial landslides can displace significant ocean water.
    • Volcanic Explosions: Eruptions can trigger tsunamis.
    • Meteor Impacts: Rare but possible, as highlighted by a 2013 meteor-induced tsunami that affected the East Coast of the United States.

• Mechanics of Tsunami Generation:

  • Dr. Weinstein [06:54]: "Any phenomena that causes a sudden displacement of the ocean column can generate a tsunami."
  • Using the 2011 Japan earthquake as an example, he describes how tectonic movements displace vast amounts of water, leading to wave formation.

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4. The 2004 Indian Ocean Tsunami: A Turning Point

The catastrophic 2004 tsunami serves as a pivotal case study to discuss the shortcomings and subsequent advancements in tsunami warning systems.

• Impact and Lessons Learned:

  • Dr. Weinstein [12:11]: "The main problem was that there was really no functioning tsunami warning system in the Indian Ocean basin at that time."
  • The tragedy underscored the necessity for a global tsunami warning infrastructure beyond the Pacific Basin.

• Post-2004 Developments:

  • Establishment of tsunami service providers in Jakarta, Hyderabad, and Melbourne by late 2013.
  • Expansion of the warning system to other regions, including the Caribbean and the North Atlantic.

• Current Gaps:

  • Dr. Weinstein [14:07]: "We don't really have a tsunami warning system for the South Atlantic."
  • Highlighting vulnerabilities in regions like the South Atlantic, exposed by events like the 2021 South Sandwich Islands earthquake.

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5. Mechanics of Tsunami Warnings

An in-depth look at how tsunami warnings are generated, disseminated, and the technologies involved.

• Detection and Analysis:

  • Dr. Weinstein [18:53]: "Tsunami warning systems are really geared for tsunamis generated by earthquakes."
  • Utilization of seismic data to detect and assess earthquakes promptly.

• Technologies Employed:

  • DART Systems:
    • Dr. Weinstein [20:36]: "The DARTs are bottom pressure sensors maintained by the National Data Buoy Center."
    • These sensors monitor deep ocean tsunamis, providing real-time data on wave characteristics.
  • GNSS (Global Navigation Satellite Systems):
    • Enhancing ground displacement measurements to refine tsunami forecasts.
  • Infrasound:
    • Detecting low-frequency sounds to estimate explosive events like volcanic eruptions.

• Warning Dissemination:

  • Alerts are sent via wireless emergency alerts to mobile devices.
  • Dr. Weinstein [25:44]: "The earthquake early warnings and the tsunami warnings will pop up on the cell."

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6. Vulnerable Regions and Subduction Zones

Identifying and understanding the high-risk areas prone to generating destructive tsunamis.

• Subduction Zones:

  • Defined as regions where tectonic plates converge, leading to significant seismic activity.
  • Dr. Weinstein [22:34]: "Subduction zones are the areas where the Earth's plate is moving back into the Earth's interior."
  • Examples include the Japan Trench, Chile-Peru Trench, and the Cascadia Subduction Zone off the northwest coast of the United States and Canada.

• The Cascadia Subduction Zone:

  • Dr. Weinstein [22:34]: "A particular concern is off the northwest coast of the United States and Canada."
  • Historical context: The 1700 earthquake and its associated tsunami highlight the recurring threat.

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7. Misconceptions and Media Portrayals

Addressing common misunderstandings about tsunamis, often perpetuated by media and popular culture.

• Tsunamis vs. Surfing Waves:

  • Dr. Weinstein [26:04]: "Tsunamis aren't surfing waves, they're drowning waves."
  • Clarifying that tsunamis are primarily destructive, unlike the often romanticized portrayal in films like The Poseidon Adventure.

• Tsunamis in the Open Ocean:

  • Dr. Weinstein [17:14]: "Tsunamis are not hazardous in the open ocean."
  • Emphasizing the minimal impact of tsunamis in deep waters due to their long wavelengths and low amplitudes.

• Meteor-Induced Tsunamis:

  • Dr. Weinstein [27:13]: "A meteorite can generate a tsunami."
  • Differentiating these rare events from typical earthquake-induced tsunamis.

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8. The Future of Tsunami Detection and Forecasting

Exploring advancements and future directions in improving tsunami warning systems and forecasting accuracy.

• Technological Innovations:

  • Dr. Weinstein [28:15]: "We are also looking at techniques that combine seismographs or GNSS."
  • Integrating multiple data sources for rapid and accurate tsunami characterization.

• Ionospheric Observations:

  • Dr. Weinstein [31:56]: "Ionospheric observations may become important in tsunami forecasting."
  • Investigating how tsunamis interact with the atmosphere to influence ionospheric conditions, potentially aiding in early detection.

• Enhanced Forecasting Models:

  • Developing more sophisticated models that account for complex coastal topographies and bathymetries to predict tsunami behavior upon reaching shorelines.

• Non-Seismic Tsunami Sources:

  • Greater emphasis on monitoring tsunamis generated by volcanic eruptions and meteor impacts.

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9. Public Education and Outreach

Highlighting the importance of community awareness and preparedness in mitigating tsunami risks.

• Safety Signage and Awareness:

  • Dr. Weinstein [33:25]: "If you come to Hawaii, you'll see on the beaches... how do you leave."
  • Implementation of hazard zones and evacuation routes in coastal areas.

• Natural Warning Signs:

  • Ocean Recession: Unnatural withdrawal of water signals an impending tsunami.
  • Earthquake Shaking: Strong ground movements indicate potential tsunami generation.
  • Dr. Weinstein [16:20]: Advises immediate inland evacuation upon noticing these signs.

• Evolution of Public Attitudes:

  • Post-2004, there has been a significant shift in public perception and adherence to tsunami warnings, aided by increased availability of real-time footage and information dissemination via social media.
  • Dr. Weinstein [36:30]: "People now can take a look and see for themselves... what a destructive tsunami looks like."

• Educational Initiatives:

  • Enhanced signage, community drills, and informational campaigns to educate both residents and visitors about tsunami risks and response protocols.

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Conclusion

The episode wraps up with Dr. Weinstein emphasizing the continuous efforts to refine tsunami detection and warning systems. He underscores the collaborative nature of this endeavor, involving technological advancements, scientific research, and public education to enhance resilience against future tsunami threats.

Dr. Stuart Weinstein [37:58]: "I think that's about it. It's been a pleasure."

Emily Gracey closes by thanking Dr. Weinstein and highlighting the ongoing commitment of The National Weather Desk to provide insightful and educational content on critical environmental phenomena.

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Notable Quotes:

• Dr. Stuart Weinstein [06:54]: "Approximately 80% of the known destructive tsunamis are actually generated by earthquakes."
• Dr. Stuart Weinstein [22:34]: "Subduction zones are the areas where the Earth's plate is moving back into the Earth's interior."
• Dr. Stuart Weinstein [26:04]: "Tsunamis aren't surfing waves, they're drowning waves."
• Dr. Stuart Weinstein [31:56]: "Ionospheric observations may become important in tsunami forecasting."

This episode of Off the Radar provides a thorough exploration of tsunami science, the evolution of warning systems, and the critical importance of public awareness in saving lives. Dr. Weinstein's expertise offers listeners a nuanced understanding of both the scientific and practical aspects of tsunami detection and response.

Transcript

[Emily Gracie]

Every minute counts. In a tsunami warning center in Hawaii, Dr. Stuart Weinstein's team monitors a network of deep ocean sensors scanning for telltale signs of an approaching tsunami. When they detect one, millions of lives hang in the balance of their next decision. Send the alert too late and coastal communities won't have time to evacuate. Send it too early or too often and people might not take it seriously. It's a responsibility few of us could imagine shouldering. Yet for the scientists at the Pacific Tsunami Warning center, it's just another day in the office. Their work represents humanity's best defense against a force that can move oceans and reshape coastlines in minutes. Today we're going off the radar and stepping inside the nerve center of tsunami detection to understand how a handful of scientists got guard our coastlines from one of nature's deadliest forces. From the advanced technology they use to track waves across vast oceans to the split second decisions that can save thousands of lives. I'm meteorologist Emily Gracey and you're listening to off the Radar, a production of the National Weather Desk. On the show, we dig deep into topics about weather, climate, the ocean, space, and much more. Our goal is to help you better understand the weather and to love it as much as we do.

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[Emily Gracie]

Welcome to the first new episode of off the radar in 2025. A couple of weeks ago, we talked about the devastating 2004 tsunami and spoke to a survivor, Duane Meadows. Experience. Today we're diving deep into the science of tsunamis and the changes that resulted from that tsunami 20 years ago. And for that I'm speaking to Dr. Stuart Weinstein, Deputy director of the Pacific Tsunami Warning center in Hawaii. We'll discuss the science behind tsunamis, their causes, because they are not caused by earthquakes and the evolution of tsunami warning systems. He'll also explain how tsunami warnings are issued and the importance of public awareness and the future of tsunami forecasting and education. Here's my conversation with Dr. Weinstein.

[Interviewer]

Dr. Weinstein, let's talk about tsunamis. We recently spoke to a tsunami survivor.

[Emily Gracie]

And so we learned all about his.

[Interviewer]

Experience and how traumatizing it was. But I want to hear about tsunamis themselves. I think there's a lot misunderstood about them and things have come a long way too, as far as the warning system, from what I understand, over the past couple of decades. So can you tell me what your position is and where you work?

[Dr. Stuart Weinstein]

Well, I am the science officer for the Pacific Tsunami Warning center. And the Pacific Tsunami Warning center is based on Ford island in the middle of Pearl Harbor.

[Interviewer]

Okay, so you live in Hawaii?

[Dr. Stuart Weinstein]

I live in Hawaii, yes.

[Interviewer]

How long has the Pacific Tsunami Warning center been there?

[Dr. Stuart Weinstein]

A tsunami warning center has been in Hawaii since 1949. The tsunami warning System got started in Hawaii following the 1946 earthquake in Alaska that generated a tsunami that caused over 150 fatalities in the then territory of Hawaii. So the Tsunami warning System became operational in 1949. And following the 1960 Chile earthquakes, in 1964 Alaska earthquake, which also generated destructive tsunamis, a Pacific wide Tsunami Warning System was created in 1965. And the center in Hawaii became the center for the Pacific Basin Tsunami Warning System.

[Interviewer]

And you guys fall under the National Weather Service, correct?

[Dr. Stuart Weinstein]

That's right.

[Interviewer]

Okay, so it's a little confusing. And then also you have a specific territory.

[Emily Gracie]

Right.

[Interviewer]

So sometimes warnings come out of different offices depending on where they are.

[Dr. Stuart Weinstein]

There are what we call regional tsunami service providers. For example, now all, most of, if not all the countries in the Pacific Basin have what we call a national Tsunami Warning Center. There are what we would call tsunami service providers. For example, in the Northwest Pacific, Japan operates the Northwest Pacific Tsunami Warning System. And in the South China Sea, China operates, you know, the South China Sea Tsunami Warning System. And Perhaps later in 2025, Nicaragua will operate a regional center for Central America, the National Tsunami Warning center in Palmer, Alaska. They provide warnings for all, all the coastlines of, of North America.

[Interviewer]

Okay, gotcha.

[Emily Gracie]

I think.

[Dr. Stuart Weinstein]

And Right. And so, and we, we have basin wide responsibility. Basically. What happens if, let's say there's an earthquake in the South China Sea? China will issue whatever products they deem required for that event, and then PTWC will follow suit using their parameters if the earthquake occurs outside those regions, like if there's a great earthquake off the coast of Ecuador or something. Like that, then we will provide the initial tsunami message products for, for that earthquake.

[Interviewer]

Okay, let's go back to tsunami basics for those who don't understand, and I think it's even confusing to people who do kind of understand how tsunamis work. What causes a tsunami? And it's not all earthquakes. Right. Can you give me some basics here on tsunami science and how they happen?

[Dr. Stuart Weinstein]

Well, basically, any, any phenomena that causes a sudden displacement of the ocean column can generate a tsunami. Approximately 80% of the known destructive tsunamis are actually generated by earthquakes. In the aftermath, let's say, of the Japan earthquake back in 2011, you know, we had the Pacific plate subducting beneath Japan. You know, the Earth's surface is cut in pieces that we call plates, and where they collide, this is where the major fault boundaries are. And so off the coast of Japan, you know, the Pacific plate is subducting beneath Japan. And over time, stress builds up and the overriding plate where Japan is sitting on slowly buckles. But then at some point, the stress that accumulates becomes large enough that it breaks and then pops back up, and then all the water that's on top is lifted upwards. So after the Japan 2011 earthquake, imagine that you've had a prism of water that was about 350 kilometers long, 75 to 100 kilometers wide, and perhaps as much as 10 kilometers thick. And you now have picked up this whole prism by like 10 to 15 meters, as you might imagine. That's a, that's a lot of, that's a lot of water in there. And the amount of energy needed to pick and displace all that water is, is quite, quite enormous. And, and so in the immediate aftermath of the earthquake, you've created this mound of water. And water doesn't hold itself, so it collapses. And so all the energy that was used to pick up this water is then released in a series of traveling waves that we call tsunamis. And that's why they can be so very destructive.

[Interviewer]

So you said 80% of tsunamis are caused by earthquakes. What are the other 20% caused by?

[Dr. Stuart Weinstein]

Well, landslides. You can have landslides falling into the ocean or what we call submarine landslides. Sometimes these happen by themselves, or sometimes they're triggered by earthquakes, another mechanism for generating earthquakes as well. This occurred relatively recently. Volcanic explosions, well, different ways that nature can generate tsunamis.

[Interviewer]

You said submarine landslide, right?

[Dr. Stuart Weinstein]

Yeah. Beneath the ocean.

[Interviewer]

Oh, okay, yeah, yeah.

[Dr. Stuart Weinstein]

I don't mean submarines. I mean.

[Interviewer]

And I've heard of meteos. Tsunamis. Is that, Am I saying that right?

[Dr. Stuart Weinstein]

Yes.

[Interviewer]

So are those ever, like, really destructive, like regular tsunamis, or are they a whole different class?

[Dr. Stuart Weinstein]

Well, they can produce hazardous waves. In general. No, they're not as destructive as tsunamis caused by great earthquakes. But back in, I think it was 2013, a meteor tsunami did strike the east coast of the United States and hurt, like, a dozen people or so. So they, they can be destructive. They. They can be hazardous. And meteor tsunamis don't just occur in the oceans, but they can also occur in the Great Lakes in the United States. And there is some consideration about developing a meteor tsunami warning system for the Great lakes in the U.S. oh, interesting.

[Interviewer]

Okay, so let's talk about what makes, like, the kind of perfect storm of a tsunami. What kind of earthquake, how deep, how far from land? Is there, like, an equation for a really destructive tsunami?

[Dr. Stuart Weinstein]

Well, basically, the kinds of earthquakes are what we call, what we call thrust earthquakes. This is where the motion along the fault is vertical. You know, for example, the San Andreas fault in California, that's where motion along the fault is horizontal. And the recent earthquake off the coast of California was also due to horizontal motion. In general, those aren't particularly efficient at generating tsunamis because most of the ground motion is horizontal, and therefore you're not really displacing the water column. And in a thrust earthquake, the plates are either moving up or down, displacing the water vertically.

[Interviewer]

Did the plates stay up? Like, is that land permanently higher?

[Dr. Stuart Weinstein]

For the time being. But the sub. But as long as subduction keeps going, then eventually it gets pulled back down again.

[Interviewer]

I was curious, like, if sea level rise, if there, if there's like a change in sea level because of that, I guess it would just be temporary.

[Dr. Stuart Weinstein]

There is, yes. Yes. So after, after the land rebounds? Well, actually, it's not a sea level rise, it's a sea level rise drop.

[Interviewer]

Okay, so let's talk about the 2004 Indian Ocean tsunami. This is one that obviously stands out to a lot of people. It's been 20 years since this happened, but this one is the one I think of as, like, just ridiculous. How many people died? I mean, we're talking a quarter million people. So many countries affected. What about that particular tsunami made it so impactful to so many people and then also so deadly to so many people?

[Dr. Stuart Weinstein]

Well, it was generated by perhaps the third largest instrumentally recorded earthquake.

[Interviewer]

So number one big earthquake was the starting point.

[Dr. Stuart Weinstein]

Yes, but the main problem was that there was really no functioning tsunami warning system in the Indian Ocean basin at that time, only the Pacific Basin had a tsunami warning system. There is also very little seismic information and sea level information coming from that area of the world. I mean, the Pacific Tsunami Warning center, that they did what it could. The world learned a very hard lesson that a tsunami warning system can't be stood up in a few hours. It takes years. Following the Sumasha earthquake, we became the interim tsunami warning center for the Indian Ocean Basin. That started in like 2005 and continued till around 2013 when we passed that responsibility off to the three tsunami service providers in the Indian Ocean. One is in Jakarta, another Hyderabad, India, and the third in is in Melbourne, Australia. So they became operational, I think in late 2013 as a result of. As a result of that. In fact, it was a wake up call pretty much for the rest of the world because, oh yeah, it's not just the Pacific Basin that has destructive earthquakes and tsunamis. The Indian Ocean has them, the Caribbean Sea has them. So there is a tsunami warning system in the Caribbean Sea. The PTWC is the warning center for the Caribbean Sea. And tsunamis do happen in the Mediterranean and North Atlantic. So there is a North Atlantic and Mediterranean Tsunami Warning center system that actually has five tsunami service providers, one in Turkey, Greece, Portugal, France and Italy.

[Interviewer]

Are there any holes in the world when it comes to tsunami warning? Where? And if so, where are they?

[Dr. Stuart Weinstein]

Yeah, I think the South Atlantic. We don't really have a tsunami warning system for the South Atlantic. And the need for one was Highlighted by the 2021 South Sandwich Islands earthquake sequence, which did generate a tsunami that produced the hazardous waves in South Africa, for example.

[Interviewer]

Okay, so first giant earthquake, no tsunami warning system. And then something else I noticed when watching, because I've watched a lot of videos of, you know, tourists and survivors, and a lot of them said the same thing in the videos over and over again.

[Emily Gracie]

What is that? What is that?

[Dr. Stuart Weinstein]

Yeah, lack of tsunami awareness.

[Interviewer]

Right. So people not knowing what it was and then also how it works. And one, the survivor I spoke to said he was shocked at the number of people he saw walking out when the water receded. So can you tell me about what happens there? Why the water recedes before a tsunami? And does it always.

[Dr. Stuart Weinstein]

No, it depends on where you are relative to where the tsunami was generated and how it was generated. So what happens is sometimes the trough of a tsunami arise first. And so that's a depression of the sea surface. So as the trough arrives to the seashore, then the water along the coast starts draining into that trough. And so you see the recession of the ocean and so all of a sudden you see a section of the sea floor that you've never seen before because the ocean has receded. And fortunately a lot of people were like, oh, this is interesting. And they went out to take a look.

[Emily Gracie]

Yeah.

[Interviewer]

He said fish were flopping around in the sand.

[Dr. Stuart Weinstein]

That's right, yeah. They could be left to us at the water. If the ocean recedes quick enough, of course, then at some point the crest of the wave arrives, then that's when the inundation happens and the destruction. That's a, that's an important warning sign. If you're, if you're on the coastline, you see the water start receding in a kind of like unnatural way. Run inland and uphill. Don't wait for the tsunami warning.

[Interviewer]

What typically is the time period once you see that.

[Dr. Stuart Weinstein]

Kind of depends, but it, but once you see the water receding, you may have anywhere from five minutes to 20. 20 or 25 minutes. Yeah. Sort of depends on how big the tsunami is. You know, the bigger the tsunami typically. Well, for an ocean crossing tsunami, they, they will have periods anywhere from like 30 minutes to an hour. In other words, the, the period is the time elapsed between successful arrival of the, of, let's say, the crest of the wave. If you see the water receding, then you know the trough has arrived and then the crest of the wave will approach about a half a period later. So that could be anywhere. For an ocean crossing tsunami, that could be anywhere from 10 minutes to 30 minutes.

[Interviewer]

How fast can they travel? So if there's an earthquake hundreds of miles away, how long will it take for that tsunami to reach a shoreline?

[Dr. Stuart Weinstein]

Well, in deep water, a tsunami can travel the speed of a jetliner. The deeper the water, the faster the tsunami travels. So for example, if you left Narita Airport on The same time 2011 earthquake struck Japan, you'd probably arrive in Honolulu Airport, you know, within, I don't know, 30, 30 minutes to 45 minutes of when the tsunami would arrive. Now, the thing is, even though that's pretty scary, what the tsunami is traveling at the speed of a jetliner in open ocean, the fact of the matter is, tsunamis are not hazardous in the open ocean. They're not hazardous in deep water. That's because the, it has to do again with the period of the tsunami and the amplitude of the tsunami in deep water. Even for a tsunami like the destructive 2004 tsunami, maybe it's amplitude in deep water, that is from normal sea level to the highest point of the wave was maybe about a meter you know, around a little more than three feet. So if you were in an ocean liner while this, while the Sumatra tsunami was passing under you, your ship would have gone up and down by a couple of meters over the course of, you know, 45 minutes. You would not have felt anything.

[Emily Gracie]

That's wild.

[Dr. Stuart Weinstein]

Yeah.

[Interviewer]

Okay, so take me through a tsunami warning kind of from start to finish, and what you guys are doing at the Tsunami Warning center, and then how you come up with, do we warn, do we not warn? What's the warning time? How does all of that work?

[Dr. Stuart Weinstein]

The tsunami warning systems are really geared for tsunamis generated by earthquakes. That doesn't mean we don't pay attention to tsunamis generated by other means. But the thing is, tsunamis generated by earthquakes are the kind of like, the easiest to detect and warn for, because as fast as the tsunami travels, seismic waves are much faster. They, they can travel several. They travel several miles a second. If there's a big earthquake, we're going to know about that earthquake within a few minutes, you know, we'll have it located. We will have an estimate of the magnitude of the earthquake, and depending on that information, we will issue our initial message product. And depending on the magnitude, depth, and location. You know, so, for example, for the recent event that occurred off the coast of San Francisco, the criteria for the National Tsunami Warning center basically is any, any earthquake above 7 0, they're going to put a certain section of the coastline within a warning. You know, depending how big the earthquake is, then the greater the earthquake, the larger section of the coastline that will be placed in a warning. And that was done within a few minutes. And then after, after that, we will do, we will continue to evaluate the earthquake, refine the location, come up with better estimates of the magnitude, and then we're going to keep track of what's happening in the ocean. What was the amplitude of the tsunami recorded on the dart? What was the amplitude of the tsunami recorded on coastal sea level stations?

[Emily Gracie]

What's the dart?

[Dr. Stuart Weinstein]

Okay, the Darts, they are bottom pressure sensors. They are maintained by the National Data Buoy Center. Very good information to have. Bottom pressure sensor tells us what are the characteristics of the tsunami in very deep water. And if we generate tsunami forecast, we can use that information to validate the forecast or tell us, oh, we're under forecasting or over forecasting, et cetera. Likewise, you know, there we can also generate a forecast for what we see along the coastline. However, the forecasting, what a tsunami is going to be like along the coastline is a lot more complicated than Forecasting what it's going to be in deep water because the topography and bathymetry along the coastline is very complicated. So you need much more sophisticated modeling. But nonetheless, if we have an idea of what's going on in the deep water, that'll tell us, oh, is this going to be a destructive tsunami as a propagates across the ocean, you know, those kinds of things. And the coastal sea level stations, they give us the facts on the ground. Okay, what, what actually is happening on the coastline? So after that warning went out and no hazardous tsunami was observed, I mean, tsunami did strike California like an Arena Cove, but it was small and non destructive, fortunately. And so the tsunami warning that was put in effect was canceled.

[Interviewer]

Yeah, pretty quickly I noticed it was, yeah. Do you think there are any spots that perhaps are most vulnerable to a large destructive tsunami? You mentioned how the west coast, the way, you know, the faults are situated, it's not as big of a risk of a big tsunami. Are there, are there situations that are at greater risk though?

[Dr. Stuart Weinstein]

Well, yeah, basically what geophysicists call subduction zones. These are the areas where the Earth's plate is moving back into the Earth's interior. And the Pacific Rim is basically subduction zones for the most part. You have, you have the Japan Trench, the subduction zone, Chile, Peru Trench, you have a seduction zone off the coast of New Zealand, etc. Off the coast of, off the, in front of the Aleutians, just to the south of the Aleutians, for example, Kamchatka, et cetera, most of the Pacific Rim is the subduction zone. And the subduction zone is what I like to call the triple threat. Because at a subduction zone you can have great earthquakes, you will have volcanoes and you will have tsunamis. And for the United States, a particular concern is off the northwest coast of the United States and Canada that is known as the Cascadia subduction zone. And back in 1700, there was a great earthquake there that we know from history produced a destructive tsunami in Japan. And at some point this is going to happen again.

[Interviewer]

I think, you know, many people don't know about the forecasting strength or weaknesses when it comes to tsunamis and don't know that earthquakes can't be forecasted. Do you think we'll ever get to that point where we can forecast an earthquake, therefore increasing this warning time of tsunami?

[Dr. Stuart Weinstein]

I don't think so. Let me, let me put it to, let me put it to you this way. The idea that, oh, in the year 2030 on April 14th at 10 in the morning there's going to be a 9.1 in the Chile Trench. That's not happening. The best we can do, I think is we're, we're hoping and there's still some active research around this. The hope is, is that at some point we will uncover certain phenomenon that indicate that a great earthquake might be coming within a few minutes or so. So I think the best we can do is give a bit of a heads up. Earthquake early warning systems, while they don't give you a heads up in advance of the great earthquake, once a great earthquake has been detected, the earthquake early warning system can then tell you that a great earthquake occurred. And you may, depending on how far away you are from the epicenter or so you may have anywhere from a few seconds to several tens of seconds to take cover and hold. So at least that'll give you a little bit of warning. But as far as some sort of warning prior to great earthquake, that's going to take some research, but it's not going to be done. You know, like for hurricane warnings, you know, we have like days in advance.

[Interviewer]

12 days.

[Dr. Stuart Weinstein]

Yeah, that's not going to happen. That's not going to happen for earthquakes. Wish it could, but, but no, that's, I don't, I don't see that happening.

[Interviewer]

So if there was an early warning or if there was a tsunami warning, is that something like a weather warning that would pop up on our phone? Is it a wireless emergency alert?

[Dr. Stuart Weinstein]

Yes. Yeah. The earthquake early warnings and the tsunami warnings will, will pop up on, on the cell.

[Interviewer]

Is there anything that you often hear as a misconception when it comes to tsunamis or earthquakes that the public really gets wrong or even something you see in movies where you're like, well, yeah.

[Dr. Stuart Weinstein]

Glad you put that up, brought that up. Yeah. I remember a movie that I saw when I was a kid, the Poseidon Adventure. And basically in the Beside Adventure was a disaster movie in the early 70s. And you had this cruise ship that basically got that, that basically got knocked over by a tsunami in the middle of the ocean. That's, that's not going to happen.

[Emily Gracie]

Little bop.

[Dr. Stuart Weinstein]

Yeah, a little, little bump. The tsunami will propagate. The ship will go up and down over the course of tens of minutes. Not going to get knocked over by, by the tsunami wave in the middle of the ocean. The other thing is a tsunami is also kind of like a scientific term. So a tsunami wave doesn't have to be big. A scientist will still call it a tsunami if it's gener, if It's a wave that's generated by a displacement due to the sea column. So the tsunami that arrived, let's say in Arena Cove in California, due to the recent off the coast of California quake, it was, I don't know, like 14 and 15 centimeters maybe trough to peak. I mean that's, that's small. It's still a tsunami.

[Interviewer]

Is it a tsunami if something falls from the sky or space and displaces water?

[Dr. Stuart Weinstein]

Well, a meteorite can generate a tsunami. That's another mechanism. Okay, yeah, I think that was also in a science fiction movie.

[Interviewer]

Well, the reason I ask is I interviewed an astronaut recently and he was talking about them bringing down the International Space Station and how they're just going to crash it into the ocean. So is that seems like it would generate a wave, right?

[Dr. Stuart Weinstein]

Well, yeah, if you're nearby. But it's, it's, it's, it's not going to displace the, the, the water column proper and generated tsunami. It'll make a mess. But it's not going to generate anything that you'll detect on a coastal sea level station unless it, unless it lands relatively close to the coast. But a meteorite, you know, a big, a big meteorite, yeah. Different. Little bit of a different story.

[Interviewer]

What's the future of tsunami warning look like? What are some goals for the next. I'd say maybe a couple of decades. When it comes to tsunami warning, we.

[Dr. Stuart Weinstein]

Want to try and get better and better. We want to try and be able to characterize, come up with more accurate tsunami forecasts, better characterize great earthquakes, do it quicker and sooner. Also there's more emphasis now on us dealing with tsunamis generated by non seismic sources like volcanoes. For example. One of the problems with for example the Hugatunga explosion was how do we quickly assess the energy release of this explosion. Science didn't at that time didn't really have a way to do it quickly, but that's changed. So for example, when I went to an SSA meeting a few months after the Hugatanga explosion, that's the size, that's the medium of the Seismological Society of America, there are a number of talks regarding what, what transpired in Hakatanga and at that time estimates of the energy yield of the explosion range from like 30 to 60 megatons of TNT was the equivalent of detonating 30 to 60 megatons of TnT. Well then a few months later it was okay, maybe it's like 60 megatons to 90 megatons. And now okay, yeah, it seems to be on par with Krakatoa back in the 1880s. Anywhere from 150 to 200. You know, mind blowing. There have been studies using what's known as infrasound. This is like low frequency sound sound that you can't hear, but nonetheless it can be detected by instruments. And based on analysis of infrasound, if we were able to do this back at Hongatango using infrasound, we might have been able to roughly estimate the size of the explosion within like 20 to 30 minutes. We are also looking at using GNSS. GPS tells us how the ground actually was displaced until fairly recently. Seismologists would just tease how much of the ground was, how much the ground was displaced by now by analyzing the seismic waves generated by the earthquake. But now we can get some information from how much the ground was displaced due to gps. And we're also looking at techniques that combine seismographs or gnss. What that allows us to do is perhaps rapidly estimate the size of even the greatest earthquakes, like the Japan earthquake in three minutes, in three to three and a half minutes. And that can tells us, okay, we need to get out a warning for like this entire coastline to start. And as we get the particulars later, then we can generate a more. Then we can generate a forecast and using gnss that helps us determine what was displacement along the fault. And if we get more information about the displacement along the fault, that we can generate more accurate forecasts. Also we have to really realize that tsunamis are examples of air sea interaction because tsunamis have relatively long periods. As the tsunami propagates across the ocean, even though the amplitude isn't that great, it's still a long enough period, still a long enough wavelength. The wavelength of the tsunami is many times the thickness of the atmosphere. So as the tsunami is propagating across the ocean, it's moving the atmosphere up and down. And that affects things like GPS transmissions.

[Interviewer]

Whoa, I didn't even think about that.

[Emily Gracie]

That's wild.

[Dr. Stuart Weinstein]

And it also affects the ionospheric afterglow. So the ionosphere is currently always sending radiation back into space. And as a wave propagates through it, that changes the intensity of that radiation. So in the future. Yeah, Ionospheric observations may become important in tsunami forecasting. Yeah, that's probably a bit ways down the line. But if you're seeing like over the next 20 years. Yeah, I'd be surprised if that doesn't happen over the next 20 years. When we incorporate ionospheric observations. Now that won't help for like locally destructive tsunamis, you know, tsunamis generated by earthquakes in the Sevens, for example, because those tsunamis won't have, let's say, a long enough wavelength or propagate far enough to cause displacement of, much displacement of the atmosphere. But for the ocean crossing destructor tsunamis like Tohoku, like Sumatra, like Chile, et cetera, yeah, those will help.

[Interviewer]

What about education and outreach? As simple as like people going on vacation to a place that might be prone to it, like in Hawaii. Are there, I've never been to Hawaii. Are there, is there like educational resources? Kind of in the way that like when you go to a tornado prone area, it says tornado shelter here, right?

[Dr. Stuart Weinstein]

Yeah. If you come to Hawaii, you'll see on the beaches of Hawaii, it'll tell you you are entering a tsunami hazard zone. It will also give you some ideas of, okay, you know, where do you, how do you leave, you know, what's the, what's the quickest route out of here? So there, there'll be some of that information. Prior to 2004, there was a little bit of resistance in that regard. Oh, we don't want to scare people, but following the Sumasha earthquake and tsunami. Yeah, okay. You know, people understand that. I mean that was one of the major things that tsunami really profoundly increased public awareness of the tsunami hazard and risk because there was so much video made available of what that tsunami did that people got the message. When I first came to Hawaii as a postdoc at the University of Hawaii, and in, I think it was 1994, there was an earthquake in the Coral Islands and a tsunami warning was issued to the state of Hawaii. It was issued in the morning. The sirens went off in the morning, woke me up. I was living in Waikiki at the time. The tsunami wasn't going to get here for a few more hours. But I got in my car and drove to uh, and along with all my colleagues we were watching TV and, and the news media were interviewing the local tsunami expert, Professor Gerard Fryer, talking about tsunamis. And in the background they had a screenshot of the North Shore of Hawaii and all these surfers waiting for the wave to arrive. And I was like, are these people crazy? Because if a destructive tsunami did arrive, most of them would have been drowned. You know, tsunamis aren't surfing waves, they're drowning waves. And I was just like dumbfound. Almost 30 years later, 20 years later. Excuse me. Back in 2011 when we issued the tsunami warning for tsunami generated by the great Tohoku earthquake in 2011. And there was nobody this time, there was nobody on the North Shore waiting to surf the waves. Everybody got the message. There is so much video of coming out of Sumatra, Thailand, all the places in the Indian oceans that, oh, yeah, it's not the smart thing to stay on the coastline during a tsunami warning. And the public got the message and today they, they like, okay, yeah, if there's a, there's a tsunami coming. Yeah, we definitely want to know about it. I think the public attitude has definitely changed following the 2004 event. Yeah.

[Interviewer]

And if you think about just like the kind of social media between then and now over the past 20 years, what's changed there and YouTube and just the availability of video, not just the fact that it was taken, but the fact that people can post it, share it.

[Dr. Stuart Weinstein]

Right. So people now can take a look and see for themselves. Oh, my God. This is, this is. What are the. A destructive tsunami looks like.

[Interviewer]

Is there anything else you want to share about tsunami education to the general public or anything else you want people to know?

[Dr. Stuart Weinstein]

Yeah, just a couple of things. Safety signs. So we already talked about, if you see the ocean receding unnaturally, that's a heads up that a tsunami is coming. But there are actually other warning signs too. For example, if you're on the coastline and you feel strong ground shaking, like you have a little trouble maintaining your balance, don't wait for the tsunami warning. Don't wait for the tsunami to get there. Inlet and uphill as soon as possible. Likewise, if you feel kind of like gentle shaking or whatever, but it lasts for like tens of seconds. It could mean one of two things. One, that we're dealing with a slow, or what's called a tsunami earthquake. Or it could mean that there's a great earthquake maybe a couple hundred miles away or further. Don't wait for the warning. Just inland and uphill. The worst that happens is you gotta. You. You took a walk for. For nothing. The best that happens is you just saved yourself. So there are some natural warning signs. Take heed of those. If you're in a coastal area and you're in a seismically active area. Keep those in mind.

[Interviewer]

Stuart, anything else you want to share?

[Dr. Stuart Weinstein]

I think that's about it. It's been a pleasure.

[Emily Gracie]

Off the Radar is a production of the National Weather Desk. Make sure you're following the show on Apple podcasts, Spotify or wherever you listen to podcasts. New episodes publish every Tuesday.

[Interviewer]

If you like today's show, please share it with a friend.

[Emily Gracie]

And make sure you check out some.

[Interviewer]

Of our past episodes.

[Emily Gracie]

We have some really exciting episodes coming out in the next couple of months. Thank you to Dr. Stuart Weinstein for his expertise today. And also thank you to my assistant associate producer, Brian Petrus for his help with this episode. For the National Weather Desk, I'm meteorologist Emily Gracie. Make it a great day.