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Earth Matters

For more than two months, lava has been pouring from part of Hawaii’s Kilauea volcano, destroying homes and remaking the land surface. More data and imagery of the eruption is flowing in from satellites, drones, and ground-based sensors than Earth Observatory can cover, but here are a few striking images that we would be remiss not to share.

By The Lava’s Early Light
NASA Astronaut Ricky Arnold tweeted this nighttime photograph of lava on June 20, 2018. If the Star Spangled Banner had been composed in Hawaii rather than Baltimore, maybe “lava’s early light” would have made it into the lyrics. Credit: NASA


The Wrong Side of the Lava Flow


Notice the stark differences in landscapes on the northern and southern sides of the lava channel. With trade winds blowing heat and volcanic gases to the southwest, the north side remained green. Vegetation on the south side, yellowed and brown, took a battering. This aerial photograph was taken on July 10, 2018. Image Credit: USGS.


A Colorful Satellite Perspective on a Collapsing Caldera

As lava flows from some parts of Kilauea, other parts of the volcano have been sinking. In the case of the summit caldera, the rate of subsidence has been dramatic. This interferometric synthetic aperature radar (InSAR) image, or interferogram, shows surface movement at the summit caldera between June 9 and June 23. Each cycle of yellow-blue-purple indicates approximately 5 inches (13 centimeters) of movement. Areas where the colorful lines are the closest have shifted the most. The data was collected by Advanced Land Observing Satellite-2 (ALOS-2), a Japanese Aerospace Exploration Agency (JAXA) mission. Read more about this image and type of data from NASA’s Disasters Program. Image Credit: NASA/JAXA.

The Same Caldera Collapse Seen from the Ground


This sequence of images shows rapid subsidence of the caldera floor, along with the development of scarps. One photograph is shown per day between June 13 and 24. The photos were taken from the southern caldera rim, near Keanakāko‘i Crater, and face north. Image Credit: USGS.


Laze Billows into the Air as Lava Pours into the Sea


In this Sentinel-2 image,  a large plume of laze—steam, volcanic gases, and shards of glass—blows west over Hawaii as lava poured into the sea on June 27, 2018. Pierre Markuse created this image using data from Sentinel-2, a satellite managed by the European Space Agency. He regularly downloads and processes Sentinel and Landsat satellite data and has posted dozens of Kilauea images on Flickr. Image Credit: ESA/Sentinel-2/Markuse

Tracking the Kilauea Eruption

May 14th, 2018 by Adam Voiland

An active fissure in Leilani Estates subdivision. This photo shows fissure 7 on May 5, 2018. Image Credit: U.S. Geological Survey

You have probably seen dramatic images and videos of several new fissure eruptions cracking open the land surface in Hawaii, emitting plumes of gas, and spitting up fountains of lava in the middle of a residential neighborhood.

If you are tracking Kilauea’s eruptions, the U.S. Geological Survey Hawaiian Volcano Observatory (HVO) and Hawaii County Civil Defense are the best sources for the latest information. HVO releases status reports, photos, videos, maps, and near-real time data that are invaluable to understanding what is happening. Hawaii County issues frequent alerts with details about evacuations, road closures, and the status of utilities.

If you want to dig into the science of this eruption, HVO and the Smithsonian Global Volcanism Program both have informative summaries that synthesize what scientists know of Kilauea’s geologic history. There are also knowledgeable volcanologists tracking the eruption closely and offering science-based commentary. Janine Krippner of Concord University (@janinekrippner) is a trained volcanologist who tweets regularly about developments. Ken Rubin @kenhrubin), based at the University of Hawaii, does the same. Erik Klemetti, a volcanologist at Denison University, is reporting on the eruption on his Rocky Planet blog.

To extend the scientific conversation, Earth Matters reached out to a handful of researchers from NASA and elsewhere who are monitoring the volcano. Among those who responded were Simon Carn (Michigan Technological University), Ashley Davies (NASA Jet Propulsion Laboratory),  Jean-Paul Vernier (NASA Langley Research Center), Verity Flower (Universities Space Research Association/NASA Goddard Space Flight Center) and Krippner.

NASA astronaut Drew Feustel tweeted this photograph of a volcanic plume at the summit of Kilauea on May 13, 2018. Image Credit: NASA

Can you briefly describe the steps that happen in an eruption like we’re seeing with Kīlauea?
“First, USGS HVO tiltmeters recorded inflation of the volcano. This was caused by magma moving up from depth, causing the volcano to bulge outwards.  The lava lake level in the summit caldera (Halema’uma’u) rose, an indication of the influx of magma into the volcanic plumbing system. Local seismic activity increased due to rock breaking as magma forces its way upwards, and as the broader volcanic edifice adjusted and reacted to the changing stress field.  As magma rose, more volcanic gas (including sulfur dioxide) was released. As magma moved into the near surface East Rift Zone, the summit started to deflate, and the lava lake level dropped. There were structural adjustments along the rift, from the summit, to Pu’u O’o, and along the rift, causing earthquakes. Then lava erupted, the whole system began to depressurize, and deflation continued.”
– Ashley Davies

Starting on the afternoon of Monday, April 30, 2018, magma beneath Pu‘u ‘Ō‘ō drained and triggered the collapse of the crater floor. Within hours, earthquakes began migrating east of Pu‘u ‘Ō‘ō, signaling an intrusion of magma along the middle and lower East Rift Zone. Map credit: U.S. Geological Survey. More maps here.

How would you describe the significance or scope of this eruption?
“This eruption is part of the normal life cycle of Kilauea volcano and is comparable to past activity. In fact, 90 percent of the surface of Kilauea is less than 1,000 years old  very young on a geologic time scale. The significance of this eruption is that it is directly occurring in the Leilani community. These people need help and support. Even though we all live with natural hazards, no matter where we are, we don’t often imagine it happening to us.” Janine Krippner

What can we expect to happen next? Is the fissure eruption likely to persist for a long time?
“It could be a major risk to the Leilani Estates area if the eruption continues. So far, the lava flows have not traveled very far from the eruptive fissure. If this changes or the fissure extends in length, then more property will be destroyed and major roads could be cut.”
Simon Carn

This map overlays a georegistered mosaic of thermal images collected during a U.S. Geological Survey helicopter overflight of the fissures in Leilani Estates on May 9, 2018. The base is a copyrighted satellite image (used with permission) provided by Digital Globe. Temperature in the thermal image is displayed as gray-scale values, with the brightest pixels indicating the hottest areas (white shows active breakouts). Image: Courtesy of USGS, Copyright Digital Globe, NextView License.

“This eruption could persist for quite a while, but it is impossible to tell how long. This is a dynamic situation, and new fissures could start and stop with little to no warning. The risk of lava inundation is real and significant, depending on where lava is extruded at the surface and how much.” Janine Krippner

Can you address the health hazards associated with sulfur dioxide?
“The problem with sulfur dioxide is that if you breathe it in, it can combine with water in the lungs to create an acid. With sulfur dioxide issuing from the fissures in an inhabited area, it makes for unhealthy concentrations locally. HVO has more on this here.” Ashley Davies

This false-color ASTER image was acquired on May 6, 2018. It shows the sulfur dioxide plume in yellow and yellow-green coming from new activity in Leilani Estates. A smaller, but thicker, sulfur dioxide plume can be seen coming from Kilauea’s main vent. Image Credit: NASA/ASTER

“Sulfur dioxide is a common occurrence in Hawaii, as vog (volcanic smog), which is a mixture of sulfur and aerosols. Sulfur dioxide and/or vog can cause irritation to eyes and airways, causing coughing, wheezing, headaches, and sore throats. People with preexisting conditions, such as asthma, are more at risk. Sulfur dioxide levels have been measured at dangerous and deadly levels near the fissures.”  Janine Krippner

Volcanic gases rise from a fissure on Nohea Street, Leilani Estates. An HVO geologist measured a temperature of 103 degrees C (218 degree F). The asphalt road was describes as “mushy” from the heat. Image Credit: U.S. Geological Survey.

Which satellites sensors are making observations of Kilauea’s plume?
There are several. The Multi-angle Imaging SpectroRadiometer (MISR) can measure the height of plumes from stereo imagery, and makes observations of the size and shape of the particles, which is useful for determining the degree to which the plume is rich in liquid sulfate and water particles versus solid, angular ash particles. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) are collecting daily snapshots of the amount of particulate matter in the plume as well as making observations of the sulfur dioxide plumes based on their thermal bands. The Operational Land Imager (OLI) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) provide more detailed images, though overpasses are less frequent. Finally, synthetic aperture radar on Sentinel 1 is tracking how much the land deforms as the eruption progresses.
— Verity Flower

To what degree are satellites sensors like OMPS and OMI useful for monitoring sulfur dioxide emissions?
Satellites provide unique information on the total sulfur dioxide mass and spatial distribution in a plume ‘snapshot’, but provide minimal information on sulfur dioxide at ground level. Other techniques provide more localized measurements but can detect surface concentrations. Simon Carn

The Ozone Mapping Profiler Suite (OMPS) detected increasing concentrations of sulfur dioxide over Hawaii in May 2018. Image Credit: NASA Earth Observatory. Learn more about this map.

Are there other reasons to monitor volcanic plumes aside from health hazards?
The particles in volcanic ash have sharp, angular edges that can abrade aircraft windows hindering the pilots ability to navigate. Where these ash particles enter aircraft engines the high temperatures cause ash to melt, coating the rotors, air intakes and casings that can lead to engine failure. Plumes can also have effects—sometimes even positive effects—on the wider environment. Ash falls can destroy crops and damage infrastructure during an eruption, but they can also add nutrients to the ocean that fuel phytoplankton blooms and nutrients to the soil that make farmland more fertile on longer timescales. — Verity Flower

Can you tell me anything about the wind patterns around Hawaii?
So far, northwesterly trade winds, which are common in this area, have kept the plume over the ocean. The winds do occasionally shift for short periods, which could bring more volcanic pollution over populated areas. — Verity Flower

What has NASA been doing in response to the eruption?
“The NASA Disasters Program is working with several teams to assess the eruption and make information available to first responders and others. We are working with several instrument teams to monitor the sulfur dioxide plume. We are also looking at thermal imagery from VIIRS to detect the position of the new fissures. The VIIRS thermal anomaly is usually used for fire detection, but it appears to be a useful tool for detecting the fissure events in Leilani Estates. We are also using ASTER thermal anomaly data in near-real time to detect the fissures. You can find imagery and data from several sources showing different aspects of the eruption here.” Jean-Paul Vernier

A screenshot from a repository of maps and images related to the eruption compiled by the NASA Earth Science Disasters Program. Image Credit: NASA

 

Help NASA Create the Largest Landslide Database

April 18th, 2018 by Kasha Patel

This landslide occurred on June, 1, 2007 on a mountain near Canmore in Alberta, Canada. The Flickr photo was taken by Sheri Teris (Creative Commons)

Landslides cause thousands of deaths and billions of dollars in property damage each year. Surprisingly, very few centralized global landslide databases exist, especially those that are publicly available.

Now NASA scientists are working to fill the gap—and they want your help collecting information. In March 2018, NASA scientist Dalia Kirschbaum and several colleagues launched a citizen science project that will make it possible to report landslides you have witnessed, heard about in the news, or found on an online database. All you need to do is log into the Landslide Reporter portal and report the time, location, and date of the landslide—as well as your source of information. You are also encouraged to submit additional details, such as the size of the landslide and what triggered it. And if you have photos, you can upload them.

Kirschbaum’s team will review each entry and submit credible reports to the Cooperative Open Online Landslide Repository (COOLR) — which they hope will eventually be the largest global online landslide catalog available.

Landslide Reporter is designed to improve the quantity and quality of data in COOLR. Currently, COOLR contains NASA’s Global Landslide Catalog, which includes more than 11,000 reports on landslides, debris flows, and rock avalanches. Since the current catalog is based mainly on information from English language news reports and journalists tend to cover only large and deadly landslides in densely populated areas, many landslides never make it into the database. Landslide Reporter should help change this because it makes it possible for people to submit reports, including first-hand accounts, from anywhere in the world.

This map shows 2,085 landslides with fatalities as reported in the Global Landslide Catalog, which is currently included in the Cooperative Open Online Landslide Repository (COOLR). NASA Earth Observatory images by Joshua Stevens, using landslide susceptibility data provided by Thomas Stanley and Dalia Kirschbaum (NASA/GSFC).

Kirschbaum plans to use this database to improve the algorithm for her team’s landslide prediction model. The model, known as the Landslide Hazard Assessment for Situational Awareness (LHASA) model, analyzes rainfall and land characteristics in an area that might make a landslide more susceptible. The model produces forecasts of potential landslide activity every 30 minutes. In some cases, however, the model predicts more or less potential activity.

“With more ground data to validate the model, we can create a better tool for improving situational awareness and research for this pervasive hazard. We could better anticipate and forecast where landslides may impact populations,” said Kirschbaum.

Check out posts by Caroline Juang on Discover magazine’s citizen science blog and by David Petley on American Geophysical Union’s Landslide Blog to find out more. You can also follow the project on Twitter (@LandslideReport) and Facebook.

Why the SoCal Fires are So Fierce

December 7th, 2017 by Adam Voiland

NASA Earth Observatory image by Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response.

With thousands of homes threatened by intense wildfires burning in southern California, NASA Earth Observatory checked in with Jet Propulsion Laboratory scientist Natasha Stavros to learn more about the destructive blazes.

Earth Observatory (EO): Why have these fires been so fast-moving and destructive? Are fierce Santa Ana winds the key factor? Are anomalous temperatures, rainfall, ENSO conditions, bark beetle activity, or other factors playing an important role?

There are absolutely other factors. Santa Ana winds definitely played a role in spreading the fires, but the late fire season is a more complex story. Last year, we had a lot of heavy rains, and this increased fuel connectivity by enabling grasses and annual shrubs to flourish (hence the green hills last spring). However, we had a lot of record-breaking heat waves this year.

In fact, a recent study we conducted with NASA DEVELOP and the National Park Service in the Santa Monica Mountains showed that the number of days over 95 degrees Fahrenheit stressed established vegetation and contributed to massive die-off. Even though the drought is over, the trees are still recovering from the stress of reduced water availability for such an extended period. They are in a fragile state and their defenses are down. This means that they are even more susceptible to infestation, mortality, and ultimately fire danger.

EO: We have published MODIS (top of the page), Sentinel-2 (below), and nighttime VIIRS (bottom of the page) satellite imagery of these fires. Is there anything that you find particularly interesting or notable about these images?

To me, the noteworthy thing is that the plume is going over the ocean and not the continental United States (as we saw earlier this year). This has to do with the Santa Ana winds coming from the desert and pushing particulates, ozone, carbon monoxide, and other toxic pollutants away from where people live.

NASA Earth Observatory image by Joshua Stevens, using modified Copernicus Sentinel data (2017) processed by the European Space Agency.

As for the Sentinel-2 image, this is a great shot in that it really shows the value of remote sensing in monitoring fire. Flames that look like that are tens of meters tall. The flame length is proportional to the heat released from the flame, so these fires are very hot. Just like you would not want to stand too close to a bonfire with flames tens of meters tall, fire management does not want to put personnel in the path of those flames.

Images like these and fire behavior models help inform how we think the fire will move across the landscape. There is still a lot we do not know; our models are based on what we do know, so as fires become more intense, the models do not work as well, so this is an area of active research.

NASA Earth Observatory images by Joshua Stevens using VIIRS day-night band data from the Suomi National Polar-orbiting Partnership.

EO: Is there anything to say about how these fires fit into longer term trends and/or changing climate patterns?

Fire regimes are changing. There is no question about that, and there are a lot of things contributing to it: climate change, a century of fire exclusion, and a growing wildland urban interface (WUI). As we move into the future, we expect there to be an increase in very large fire events. Also, and this is relevant for the events happening now, there will be longer fire seasons. Also, note that many of the fires that ignite close to where people live are actually caused by people. This is particularly true in Southern California.

As we move forward, we need to think about how to support smart fire management practices. By that I mean: what can we proactively do to reduce fire risk (i.e. the threat to valuable resources)?

Most fires on the coasts are lit by people. NASA Earth Observatory map by Joshua Stevens, using fire data courtesy of Balch, J. et al. (2017).

EO: What about JPL’s response to these fires? I was intrigued by the megafire project described here. Will your group be responding to this fire in any way?

We just received approval from NASA Headquarters to fly the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over these fires. This sensor has been useful for investigating fuel load type and subsequent effects on emission types, fire behavior, and post-fire analysis (e.g., safety, erosion, area burned, fire severity or the amount of environmental change caused the fire, etc.) and is often analyzed in interagency and federal-academic coordination to improve our understanding of fire.

Another effort to support fire management includes work being done from JPL in coordination with the National Interagency Fire Center (NIFC) to help them develop metrics of fire danger using NASA satellites that provide hydrologic variables (e.g., soil moisture and vapor pressure deficit—the difference between the amount of moisture in the air vs how much it can hold). These metrics have a one-month forecast to help allocate fire management resources nationally, which is particularly important as our fire seasons extend throughout the year in multiple places at the same time.

Natasha Stavros. Image courtesy of N. Stavros.

Taking Stock of a Smoky Fire Season

October 10th, 2017 by Adam Voiland

NASA Earth Observatory images by Jesse Allen, using VIIRS data from the Suomi National Polar-orbiting Partnership.

You have probably heard or read that it has been rather smoky out West this year. Dozens of large wildfires have raged through forests in British Columbia, Alberta, Washington, Oregon, Idaho, California, and other states this fire season. Intense blazes are lofting up so much smoke that huge plumes have been blowing across the country—and even turning up in Europe. We checked with a few scientists who specialize in studying wildfires for an update on what is going on.

EO: How does this fire season compare to past years?
The western fire season has been quite active this year. British Columbia has surpassed its greatest burned area in the modern era. While its unlikely that this season will be record-breaking in the western U.S., it is above normal relative to the past decade, which has seen abundant fire activity.
— John Abatzoglou, University of Idaho

EO: Is climate change exacerbating these fires?
Because we have let fuels build up in the western U.S., it is difficult to tell in many ecosystems what is weather-driven vs. climate-driven until we get back to normal fuel loads. This 2013 PNAS paper tries to answer the climate question given the artificially increased fuel loadings. They found that climate change is responsible for 55 percent of the observed increasing fuel aridity.  — Jessica McCarty, Miami University

EO: Are bark beetles making these fires worse?
No, the bark beetle outbreaks have little-to-no relationship with trends in area burned or the ecological severity of fires. I think this continues to be a big misconception with the public, which is understandable because climate is a key driver of both bark beetle outbreaks and wildfires. Many people jump to the conclusion that bark beetle outbreaks are causing fires. But it is likely a classic case of correlation without causation.  — Brian Harvey, University of Washington

EO: If there was one thing you wished Americans understood about wildfires in the West, what would it be?
Be careful with fire. Smokey the Bear is trying to educate you on the risk—listen. Heed fire risk and fire weather warnings. Don’t build campfires unless you have to. Don’t go off-roading during droughts and heat waves. Be careful with your cigarette butts.  — Jessica McCarty, Miami University

Even though no one is a fan of widespread smoke, wildfires aren’t inherently “bad” [when they are in unpopulated areas]. One continuing challenge is figuring out how to live with fire as part of the system as more people settle in the region during an era of changing environmental conditions. — John Abatzoglou, University of Idaho

NASA Earth Observatory images by Jesse Allen and Jeff Schmaltz, using Suomi NPP OMPS data provided courtesy of Colin Seftor (SSAI).

A June snowstorm just topped off the already thick layer of white stuff atop the Sierra Nevadas. California’s snow water equivalent rose to a heaping 170 percent of normal. But not so long ago, the state was in the midst of a deep drought; its mountains were bare and brown, and water levels plummeted in reservoirs.

Throughout, satellites were watching. Check out the California drought and its aftermath in a video from NASA Earth Observatory:

 

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Image by the NASA GSFC Landsat/LDCM EPO Team using Landsat 5 data from the U.S. Geological Survey.

Twenty years ago this month, a hundred-year flood inundated cities along the Red River. The waters rose through April and May 1997, inundating 2,200 square miles (5,700 square kilometers) of North Dakota and Minnesotaa footprint twice as big as Rhode Island. The river spilled over its banks in Winnipeg, Canada, as well.

The false-color Landsat 5 image above shows Grand Forks, North Dakota, as it appeared on May 4, 1997. At that point, flood waters had mostly retreated, but the river still appeared swollen, with water lingering in floodplains just north of the city. Water appears dark blue, while structures are off-white.

There have been a several other notable floods since 1997. The river also overflowed its banks in 2006, 2009, and 2011.

In early May 2017, the river’s levels are average, and its water output holds steady, according to ground-based measurements taken at Grand Forks. Yet, the country as a whole just experienced its second-wettest April on record, with severe floods along the Mississippi River.

The U.S. Geological Survey has additional satellite imagery and a gallery of ground photographs of the flood. The Star Tribune has a good story that looks at how Grand Forks has fared since 1997.

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Blizzard 2017: Not In Denver, but in Hawaii

March 10th, 2017 by Pola Lem

In Hawaii, land of palm trees, pineapples, and year-round surfing, a full-blown blizzard hit last week. The early March storm brought more than 8 inches (20 centimeters) to the top of Mauna Kea volcano, leading authorities to shut the road to the peak.

The snow was all the more surprising given how little has fallen in more traditionally snowy locales. Hawaii received more snow that day than Denver has accumulated over the past seven weeks. The Colorado city got 1.6 inches (4 centimeters) in the past 51 days, according to local news.

The island archipelago also got more white stuff than Chicago. That city, famed for its bitter winters, is currently in the midst of a snow drought, with a mere 0.6 inches (1.5 centimeters) falling in 2017. That’s the least on record since the late 1800s. To put that into perspective: Chicago averages 37 inches (94 cm) of yearly snowfall. By contrast, Hawaii gets a yearly average of 3.7 inches (9 cm).

Thanks to their height, the peaks of Mauna Kea and Mauna Loa volcanoes do receive a dusting now and again. But that snow rarely sticks around for more than a few days, according to Ken Rubin, an assistant professor of geology and geophysics at the University of Hawaii.

Mauna Kea in December 2016. Image: NASA Earth Observatory/Jesse Allen, using Landsat data from the U.S. Geological Survey.

 

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Is That The Best You Can Do?

March 2nd, 2017 by jallen

Regular readers of our site may have noticed our recent piece on the Antarctic Peninsula. That Aqua MODIS shot was made possible by a weather pattern that brings clearer skies to the peninsula in January or February most years. You can see the same pattern in finer detail with a mosaic of Landsat scenes from early 2016.

But that was last year: what are things like this year?

Here’s the best shot of the peninsula this year during the “clear skies” season. It comes from the Aqua MODIS instrument and was acquired on February 7, 2017.

You can quickly see that it is not as clear as the best view from early 2016. The western side of the Peninsula and its neighboring islands are clouded in. On the other side, there’s a clearer edge to the eastern ice shelves because the wind has been blowing the loose sea ice in the Weddell Sea away from the coast, leaving a narrow gap of open water along the edges of the shelves. The distinction between the Larsen C and D shelves and the sea ice is much more clear than it was last year.

In a closer view, you can also see the crack in the Larsen C ice shelf.  In August 2016, the crack extended from the Gipps Ice Rise northward for 130 kilometers (80 miles), and the crack has continued to grow since.

Something Swirling in the Sea

January 20th, 2017 by Kathryn Hansen

Almost every volcano is interesting from a scientific perspective, but there are just too many eruptions for us to cover every single one. Instead we tend to focus on eruptions that have the potential to affect people. Or, occasionally our satellites return images that simply look so unique that we find the time to cover them. The plume recently ejected from Alaska’s Bogoslof Volcano was noteworthy for both reasons.

Bogoslof, which has been erupting since mid-December 2016, gave rise to a compelling two-tone plume. Are materials being ejected from a vent that is still under water? (Most of the volcano is below the surface of the sea.) The volcano’s interaction with seawater explains the white steam. But if the vent is not yet above water, then how did such a large, dark plume of ash reach so high in the atmosphere? Scientists at the Alaska Volcano Observatory continue to monitor the remote volcano and perhaps answers will be forthcoming as the eruption evolves.

Also intriguing are the swirls of blue visible in the image above. The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured the image on January 7, 2017. My first thought was that the color was caused by a bloom of phytoplankton. The milky blue color looked about right. And iron from eruptions have previously been shown  to provide the nutrients needed for blooms to flourish. But when I asked the experts, the general consensus was that while you can’t rule out a bloom, there was another more likely explanation for the swirls.

According to ocean scientist Norman Kuring of NASA’s Goddard Space Flight Center:

“Phytoplankton don’t normally bloom in the Bering Sea during winter because there’s not a lot of sunlight and because winter storms deepen the mixed layer which also keeps the plankton more in the dark. Wave action can resuspend bottom sediments, and that may be happening farther east along the Aleutian chain in the January 7 image where the water is relatively shallow. Bogoslof Island is beyond the shelf break, however, so bottom resuspension is less likely. Ash in the water seems most probable…. I wouldn’t expect the Bering Sea to be nutrient limited in the winter, so I don’t expect an ash-based phytoplankton boost.”

In short, the swirls are probably ash in the water. The phenomenon is not unprecedented. We have previously published images of the occurrence here and here. But as Kuring reminds us, “the only way to know for sure would be to sample the water directly.”