USGS Global Earthquake Alerts to Include Economic Loss and Casualty Information
The USGS PAGER system now produces rapid estimates of an earthquake's impact, a significant advancement in USGS earthquake information and alerting capabilities. PAGER stands for ‘Prompt Assessment of Global Earthquakes for Response’. Dr. David Wald describes the PAGER system and its new earthquake impact alerting capabilities.
Heidi Koontz: Hello and welcome to USGS CoreCast. I'm your host, Heidi Koontz. Today we're discussing a new twist to the USGS earthquake alert system called PAGER with one of its creators, Dr. David Wald. Thank you, Dr. Wald, for chatting with me today.
David Wald: My pleasure.
Heidi Koontz: PAGER is a new edition of an existing alert system. Can you tell me what PAGER stands for?
David Wald: PAGER stands for Prompt Assessment of Global Earthquakes for Response. And what PAGER does is it provides shaking and loss assessments following significant earthquakes anywhere in the world. And our loss alerts are generally available within about 30 minutes of an earthquake and they provide a first glance of whether an earthquake is deemed to be significant in terms of requiring response for attention.
Heidi Koontz: OK. So the present system has been revamped. How so?
David Wald: Well, the present system, the PAGER system that's online currently and has been running for several years, provides an estimate of the shaking intensity, the ShakeMap, and the population exposed at each level of shaking.
The new system actually converts that into an estimate of the impact, the losses both financial and in terms of casualties that we might expect from that particular earthquake.
Heidi Koontz: And I see with this edition of PAGER, there are color codes?
David Wald: That's right. So now that we can compute losses, there are uncertain estimates but we can estimate losses. We color-code those according to what we've seen in the past earthquakes in terms of response.
So the highest-level response, a red alert, we constitute what we would say from past earthquakes is an international-level response and the casualties are likely to be in the thousands, the damage is likely to be very widespread over a large area, and that would constitute the highest alert level.
Just below that would be an orange alert where the impact would be spread out but not as extensive and heavy as it would be for a red alert, although casualties could be in the hundreds.
Below that would be a yellow alert where we expect some casualties, maybe a few to dozens of casualties, and some significant financial losses but not over a very widespread area. And then the final, lowest level, the green alert, would constitute an earthquake that although the magnitude may be large wouldn't have any impact because the population exposure and the vulnerability of the population may be very low.
Heidi Koontz: And how many green alerts do you put out per year would you estimate?
David Wald: Well, you know, when we normally put out earthquake information it's in the form of magnitudes and locations. So we get about 200 earthquakes a year that would be magnitude 6 or larger. Of these, only a dozen or two would be earthquakes that are either fatal or have significant damage.
So what this system is doing is really filtering out the noise of the 200 events that might have magnitude 6 or larger and we determine which ones are likely to have significant impacts and we alert users based on those particular earthquakes.
Heidi Koontz: OK. So this explains why Haiti was a red and Christchurch, New Zealand was a green, correct?
David Wald: That's right. And this is very important distinction. We had two recent earthquakes this year, a magnitude 7 earthquake in Haiti and a magnitude 7 earthquake close to Christchurch, New Zealand. There were no fatalities in the latter, the New Zealand earthquake, which shook hard a sizable population but there were no fatalities. And there was quite the bit of damage to structures but no loss of life.
In contrast, the Haitian earthquake, also a magnitude 7 earthquake, struck a much higher population and a population that has extremely vulnerable structures. So that resulted in hundreds of thousands of fatalities, which of course would be a red alert in terms of fatalities.
So the magnitude, both being magnitude 7 in these cases, was not a good indication of the overall loss of life, and that's what the PAGER system does and it does analysis of the shaking, the population exposure as well as the vulnerability of the structures to determine how bad an earthquake it's going to be in terms of impact to society.
Heidi Koontz: OK. So essentially this tool is taking the guesswork out of whether or not a quake would be substantial?
David Wald: Yeah. It's very dangerous just to go on magnitude and location alone because it really doesn't tell you about the impact. One of the factors is you can have very strong shaking in an area that's very remote and it won't warrant much tension. And the PAGER system takes not only magnitude and location into account but where the shaking is with respect to the population and, very importantly, what kinds of buildings are there--
Heidi Koontz: OK.
David Wald: --because the most vulnerable structures will result from the most loss of life.
Heidi Koontz: OK. So how does the PAGER system estimate losses?
David Wald: The key ingredients for estimating losses are the ShakeMap. That's the map of the distribution of shaking that we estimate from basically the magnitude and location as well as seismic instruments that we have on the ground and estimates of shaking that come in through the internet for our "Did You Feel It?" system. It takes that shaking and it compares it with the population.
And then we look back at past earthquakes in each particular country and determine, given that shaking and population, what would have happened in terms of loss of life and economic impact based on what we've seen from past earthquakes in that country.
Heidi Koontz: Who are some of the system's key users?
David Wald: Well, our primary concern is getting impact assessments very rapidly to emergency responders, emergency managers, international aid organizations, and government agencies that are responsible for disaster relief. But there are other key users as well. In general, the media and the general population are very interested in getting more than just the magnitude and location and getting information about what might have happened in an earthquake.
It turns out that there's a lot of other interested parties including the financial world, the insurers, re-insurers, large organizations and companies that have exposure in the area that shook.
And then finally engineers and scientists, who may be responsible for response and for scientific information, get a quick heads-up on what the overall likelihood of the need for follow-up information.
Heidi Koontz: So you mentioned that this is publicly available. What is the URL where people can access this information?
David Wald: The PAGER information is available, along with all the other USGS earthquake information, at earthquake.usgs.gov. And for each earthquake that's significant, there's a separate page for that earthquake and the PAGER information is linked right there.
Heidi Koontz: Great. So ultimately, Dr. Wald, this is a tool that was built to help save lives.
David Wald: Well, that's right. Again, the primary concern is getting information out to first responders and to give them an assessment that an earthquake is very significant and where the likely impacts are to be. And so that will really speed up the process of getting off the ground and getting people in the areas that are most affected.
There's another aspect in terms of potentially saving lives, and that's the fact that we are able to look at structures around the world and understand what kinds of structures are the most vulnerable allows us to look forward and say, "How would things be different if we were able to mitigate the risks by improving these structures and building better structures in the future?"
Heidi Koontz: Well, Dr. Wald, this has been fascinating. Thank you so much for talking with us today about PAGER.
David Wald: Thank you.
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This CoreCast has been a product of the U.S. Geological Survey, Department of the Interior. Thank you for listening.