When it comes to disasters, though, EROS’ superpower is not to catch the first burst of lava from an erupting volcano—although that does happen—or floodwaters as they spill over a dam.

Instead, EROS’ 51-year archive of Landsat data reveals the land changes those disastrous events wreak. And observing that change over time unlocks another superpower: Helping to predict where the next flood, fire or drought might occur.

Of course, Landsat images from world-changing events, some of them manmade, are lodged in our collective memory as well, from the Chernobyl nuclear disaster to the World Trade Center attacks on 9-11.

But from the beginning, EROS’ response to catastrophic events quickly went beyond simply sharing imagery toward evaluating damage and observing recovery time. Later, the focus became tailoring data to each event, sometimes even with boots on the ground. Today, representing the USGS’ membership in the International Charter Space and Major Disasters, EROS is prepared to respond to disasters large and small through its Hazards Data Distribution System by sharing not only Landsat but also other satellite data as well as aerial imagery.

Flooding

An EROS press release on May 15, 1973, touted the pre- and post-flood change in the Mississippi River between October 1972 and March 1973, captured by Landsat 1 (called ERTS-1 at the time). The flooded area studied encompassed 600 miles of the Mississippi, from just north of St. Louis to the mouth of the Arkansas River, as well as a 150-mile stretch of the Ohio River. By June, EROS released a composite false-color map of the flooding extent as well as smaller maps of specific areas such as Memphis, Tennessee.

That was the first notable Landsat-observed flood, and it brought attention to EROS’ ability to map flooding. Response teams on the ground quickly learned to consult EROS to get a broader view in the aftermath of floods. In June and July 1975, for example, EROS assisted local and state officials in North Dakota and northwest Minnesota with understanding the flooding extent of the Red River.

While measuring individual floods is important, observing flooding patterns over time helps with prevention. The Missouri and Mississippi rivers flooded continuously from May to September in what came to be known as the Great Flood of 1993. In response, an 18-member Scientific Assessment and Strategy Team made up of scientists and engineers from federal and state agencies convened at EROS for two entire months in early 1994 to study watershed and floodplain issues related to the largest U.S. river system.

Today, two key tools at EROS for gauging the potential for flooding are Dynamic Surface Water Extent (DSWE) and Fractional Snow Covered Area (fSCA). Both are designated as Landsat Level-3 science products, which means that a lot of work and science are dedicated to ensuring their accuracy and ease of use. DSWE measures the existence and condition of surface water, essential information for anticipating where floods might occur. And the snowpack analyzed by fSCA is an important predictor of spring flooding.

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Drought

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Both DSWE and fSCA are also important leading indicators for drought, a disaster that came into focus for EROS in the mid-1980s when crops failed in Africa, causing devastating famine. In 1987, the U.S. Agency for International Development (USAID) asked EROS to review its Famine Early Warning Systems (FEWS) for some sub-Saharan countries. EROS today continues to provide USAID support with the FEWS Network, which is the longest-running continuous science project in EROS history.

EROS’ expertise was connected to greenness mapping made possible by the Advanced Very High-Resolution Radiometer antenna installed in 1987 by the National Oceanic and Atmospheric Administration (NOAA), which was in charge of EROS at the time. Analyzing vegetation health in Africa showed what a powerful tool it could be for agriculture in other places, so EROS began measuring greenness everywhere, starting with the Northern Great Plains in 1988 and the Western United States in 1989. By 1990, EROS started producing biweekly greenness maps of the conterminous United States, and in 1994, production on a global 10-day vegetation dataset began.

Drought modeling and monitoring contributions from EROS continued in the 2000s with the Vegetation Drought Response Index (VegDRI), which in 2009 reached the milestone of providing coverage of the entire conterminous United States at two-week intervals. When the governor of Montana declared more than a dozen emergency declarations for drought in 2017, VegDRI proved to be crucial, along with the Quick Drought Response Index (QuickDRI). EROS helped develop both drought monitoring programs.

And most recently, Landsat has been keeping a watchful eye on droughts with the potential to affect water availability across the West, especially by monitoring water levels at reservoirs such as Lake Powell and Lake Mead.

Fires

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Naturally, drought analysis also is a key indicator to know where dry vegetation creates tinder for fire. But in the early days of Landsat, it was a novelty just to be able to see a fire in remote areas where the landscape hadn’t previously been monitored regularly. On July 27, 1972, shortly after its launch, Landsat 1 acquired a vivid false-color image of an 81,000 acre blaze in Alaska.

It was in Alaska, as well, that the ability of Landsat data analysis to help with fire management was first demonstrated. In August 1977, a dry summer resulted in more than 500 forest fires, with the total acreage burned estimated at 2 million acres. Because a reindeer range inventory of northwest Alaska had previously been completed with the help of EROS, the Bureau of Land Management knew which rangeland to protect and which areas should be left to burn. In addition, the EROS Applications Assistance Facility (AAF) in Alaska provided imagery of fires in progress and made a standing request for imagery of all fire areas. In a foreshadowing of what would become standard practice for later fire management efforts such as Monitoring Trends in Burn Severity (MTBS), the AAF mapped the perimeters of the 1977 burn areas.

In December that same year, 11 representatives from the Northern Forest Laboratory in Missoula, Montana, and other Forest Service units traveled to the EROS Center to study the potential for using Landsat to map and inventory forest fire fuels, model fire behavior, and reduce residual fire from logging, prefiguring similar goals taken up in later years by the Landscape Fire and Resource Management Planning Tools (LANDFIRE) program, among others.

Other EROS fire milestones include:

• 1988: Yellowstone National Park fires that created a haze across much of the United States were monitored by Landsat imagery.

• 1997: EROS and the U.S. Forest Service developed a Fire Potential Index to assess the probability of a fire at 1 km resolution on a real-time daily basis.
• 2001: EROS began working with the U.S. Forest Service to map significant wildfires on Department of Interior and Forest Service lands for Burn Area Emergency Response (BAER) teams using satellite imagery.
• 2004: The LANDFIRE program hosted at EROS was chartered by the Wildland Fire Leadership Council after a prototype began in 2002.
• 2006: EROS and the U.S. Forest Service began the initial MTBS project to map and assess the burn severity of all large fires in the United States between 1984 and 2010 using Landsat scenes. This initial effort was completed in 2012, with 14,900 fires mapped, but updates continue today. 
• 2020: LANDFIRE released its Remap for the Conterminous United States, marking the first full-scale update of the program’s base map in its 15-year history, improving its accuracy and boosting its value to the research community.

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Cataclysmic Events

When it comes to less predictable events such as volcanoes, hurricanes or tsunamis, the value of Landsat’s continuous monitoring of land is helpful for observing the extent of damage—and perhaps even more so for recording the months- or years-long recovery in the aftermath.

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Volcanoes

The May 18, 1980, Mount St. Helens eruption in Washington killed 57 people, flattened forests for miles around the mountain, choked rivers with ash and created a haze as far east as the Dakotas. While the volcano was still erupting, it was difficult to catch clear views of how widespread the damage was, but once the billowing clouds of ash settled, Landsat 4, from its 438-mile-high orbit, was in a unique position to reveal the full extent of damage. Equally important, the satellite and its successors tracked the gradual recovery of the surrounding ecosystem, which is still ongoing and has been slowed at times by minor eruptions of the still-active volcano.

Imagery and data from other volcanic eruptions monitored by Landsat and stored at EROS include Pinatubo in the Philippines in 1991 and Kilauea and Mauna Loa in Hawaii, including this rare image of a dual eruption in December 2022.

Hurricanes

EROS’ remote sensing archive is good at highlighting land disturbances such as the rapid coastal changes caused by storm surges and other damage caused by hurricanes.

After Hurricane Mitch wreaked havoc in Central America in October 1998, EROS personnel were able to customize information for the affected countries, creating a template for future work with hurricanes. A team of EROS scientists traveled to Honduras for six weeks of geographic information system (GIS) support to USAID and the data distribution and training center in Honduras. EROS experts built a geospatial data library and organized data layers for reconstruction work in towns and cities. EROS also traveled throughout six countries to lay the foundation for an Internet Clearinghouse to provide access to geospatial data for reconstruction, land management and disaster mitigation work. Crucially, the EROS team trained Central American scientists, both on the ground there and back in South Dakota at EROS, so they could maintain and use the database in case of future disasters.

Landsat also tracked the aftermath of other devastating hurricanes, from Katrina in 2005 to both Harvey and Irma in 2017. And once in a while, a Landsat satellite captures a stunning view of a hurricane, like this one of Hurricane Ian from September 28, 2022. In fact, with the help of artificial intelligence and a consistently maintained algorithm, scientists are beginning to use harmonized data from multiple satellite programs to aid response in real time for storms like Ian and other events.

 Tsunamis

On December 26, 2004, a 9.1 magnitude earthquake in the Indian Ocean near Sumatra, Indonesia, sent a tsunami roaring onto the coasts of several countries in South and Southeast Asia. At least 225,000 people died in one of the deadliest natural disasters in the modern era. The waves, 30 meters high in some cases, altered coastlines and stripped vegetation away. EROS rapidly responded by providing relief organizations with pre- and post-tsunami satellite images, including Landsat, and image-derived products through the Hazards Data Distribution System. More than 517,000 files were downloaded during the eight weeks following the tsunami.

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Manmade Disasters

Arguably the most famous Landsat scenes are the before-and-after images of the nuclear disaster at Chernobyl. The nuclear power plant in Ukraine, then part of the Soviet Union, experienced a core meltdown in April 1986 followed by an open-air fire that released radioactive contaminants across Europe, killing dozens and prompting evacuations in the immediate area, including the towns of Chernobyl and nearby Pripyat.

In the Cold War era, the Soviet claim that just one reactor core had melted could only be assessed by remote observation. Landsat 5 thermal imagery in May verified only one of the three reactors showed a telltale glow—landing EROS director Al Watkins on the CBS Evening News with Dan Rather. EROS followed up in 1987 by assessing radiation damage to pine trees in the area.

EROS’ has responded to other manmade events as well, including, among other things, petroleum spills and conflict.

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Petroleum

EROS learned about responding to petroleum disasters starting in September 1979, when several Landsat scenes of a Gulf of Mexico oil spill were examined to determine the spectral characteristics of the oil slick. Image classification techniques were applied to determine area estimates of the slick size. EROS’ Alaska Field Office supported cleanup efforts after the Exxon Valdez oil spill in Prince William Sound in 1989. More recently, Landsat 7 captured images after the Deepwater Horizon oil platform explosion caused a large oil spill in the Gulf of Mexico in 2010.

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Conflict

One of the first instances where EROS data was used during conflict was in 1981 when the United Kingdom invaded the Falkland Islands. Since then, the focus of conflict has mainly been in the Middle East, except when it hit close to home in the 9-11 attacks:

• In 1990-91, EROS supplied the U.S. Department of Defense and intelligence agencies with AVHRR and Landsat imagery during Operation Desert Shield and Desert Storm, notably including Landsat imagery of oil fields burning in Kuwait and the Persian Gulf oil slick during Desert Storm.
• After the September 11, 2001, terrorist attacks, EROS provided support for different federal and state agencies’ requests, processing and providing access to satellite, aerial and lidar imagery. Landsat 7 captured the smoke still rising above Ground Zero in a September 12 image.
• In 2017, ISIS terrorists set fire to oil wells as they retreated before Iraqi forces in eastern Iraq. The flames, dark smoke and resulting oil spill were monitored by Landsats 7 and 8 as well as Europe’s Sentinel-2A satellite.   

International Charter

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Today, EROS’ response to disasters around the world has become more structured. It started in October 2000, when European and Canadian space agencies created the International Charter Space & Major Disasters to make it easier to access satellite data to help with disaster management. To participate, all that government relief agencies have to do is sign up to become authorized users. When disaster strikes, members activate the charter and provide the satellite data quickly at no cost. For example, just in the past few weeks, the charter has been activated for a typhoons in Russia and South Korea and landslides in Vietnam and the country of Georgia.

The USGS became a member of the International Charter in 2005 and provided data for the effort even before that. Within USGS, it was a natural fit for EROS to provide the imagery support. To do so, EROS hosts the Hazards Data Distribution System, which acquires and delivers disaster-relevant satellite, aerial and radar imagery from myriad sources, including but not limited to Landsat and commercial data.

What a contrast from when EROS started as the only Earth-observing satellite and press releases about the disaster-caused land changes were the main option for letting the world know of the capabilities of remote sensing for disaster relief!

EROS’ collection of imagery and data related to disasters were a matter of coincidence at the very beginning, and then the vigilance of scientists and the deliberate creation of tools to help measure the extent of disasters and even predict them, sometimes at the request of other agencies or governments. Now, as part of a worldwide network maintained by the International Charter, EROS is better poised than ever to provide assistance as well as striking imagery in the aftermath of disastrous events.