October 20th, 3:59 am

USGS Volcanoes

Alaska Volcano Observatory
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October 19th, 11:36 am

USGS Volcanoes

A Kīlauea hazard assessments include analyses of salts on volcanic ash! This week's HVO Volcano Watch article discusses why. volcanoes.usgs.gov/observatories/hvo/hvo_volcano_watch.html?vwid=1387

Sulfur dioxide (SO2)-rich emissions have long been a feature of Kīlauea Volcano's summit activity. However, vigorous volcanic ash production during the 2018 eruption raised new concerns about potential impacts for downwind communities.

During an eruption, chemical reactions that occur between volcanic ash and the SO2-rich plume form salt coatings on the surfaces of ash particles. These coatings contain a wide range of components that are soluble (easily dissolved).

Upon contact with water, either through ash falling into water catchments or by rain falling on ash, the soluble components are washed from the ash. This can impact human and agricultural activities, both positively (if ash supplies nutrient elements, such as sulfur, to soil) and negatively (if ash can release potentially toxic species, such as fluoride).

The composition of the ash coating can be measured in the laboratory through ash leaching experiments. This is performed by mixing samples of freshly erupted volcanic ash with ultrapure water and measuring the change in the water chemistry.

These "leachate" results from the laboratory can then be scaled with the amount of ashfall to evaluate the potential impact on water resources, agriculture, and human health. If the ash coating poses a hazard, then appropriate protective actions can be communicated.

Determining the composition of ash surface coatings through ash leaching is a valuable part of the volcanic hazard assessment carried out by the U.S. Geological Survey. With the help of citizen scientists, the USGS collected and analyzed almost 30 ash samples produced by collapse events at the summit of Kīlauea in 2018. All data are available online from the USGS (doi.org/10.5066/P98A07DC).

Ash from an explosive event at Halema‘uma‘u on May 15, 2018, was blown by trade winds to the southwest, where it fell from the plume and blanketed the Ka‘ū Desert landscape. Samples of this ash were collected for ash leachate analyses as part of the assessment of hazards from Kīlauea Volcano's eruption. USGS photo by S. Brantley.

Contamination of drinking water by fluoride is of primary concern for human health. Some good news is that recent ashfall at Kīlauea did not contribute sufficient fluoride to water catchment systems to cause adverse health effects. In fact, it was determined to be at least ten times lower than the maximum contaminant level (MCL) goal set by the U.S. Environmental Protection Agency (EPA). This is the level at which no known adverse human health effects occur.

The concentration of fluoride on ash from the recent activity of Kīlauea is below 100 milligrams of fluoride per kilogram of ash. This is lower than the average for other eruptions worldwide (129 mg F per kg ash).

Leachates from Kīlauea ash contain a tremendous amount of sulfur, exceeding anything measured at previous eruptions from volcanoes around the world. This may not be surprising given the massive output of SO2 throughout Kīlauea's eruption.

Some of the Kīlauea ash samples had nearly 25,000 milligrams of sulfur per kilogram of ash, which is over 2 teaspoons of native sulfur for every pound of ash! The impact of this sulfur on drinking water in Hawaii is largely aesthetic, affecting taste only. Concentrations were still below the EPA MCL despite the remarkable amount of sulfur on the ash surfaces.

Only manganese, aluminum, and iron were measured on the ash at concentrations that may reach defined EPA thresholds for causing undesirable taste and color of water. However, the concentrations are not a threat to health.

Although the hazard to humans is low, grazing animals can experience nutritional deficiencies from ingesting high amounts of sulfur, and fluoride exposures can result in the erosion of teeth, loss of bone, and other growth abnormalities. Accordingly, recommendations for protecting livestock were issued by the University of Hawai‘i at Mānoa's College of Tropical Agriculture and Human Resources (cms.ctahr.hawaii.edu/er/volcanicEmissions).

Advice on maintaining water catchments systems and guidance on living with ashfall, in general, are available on the Hawai‘i Interagency Vog Information Dashboard (vog.ivhhn.org/).

Previous Volcano Watch articles have addressed protecting yourself from Kīlauea ash (June 7, 2018, volcanoes.usgs.gov/observatories/hvo/hvo_volcano_watch.html?vwid=1368) and the many forms of sulfur found on Kīlauea (July 13, 2018, volcanoes.usgs.gov/observatories/hvo/hvo_volcano_watch.html?vwid=1373).

#volcanoes #volcano #usgs #hvo #hawaiianvolcanoobservatory #volcanicash #volcanichazards
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October 18th, 11:35 am

USGS Volcanoes

So, it's Thursday (or Friday, depending upon what side of the date line you are on)...let's take a little geologic tour of some U.S. volcanoes. arcg.is/0Te4rK

#Yellowstone #ThreeSisters #CraterLake #MedicineLake #LassenPeak #MammothMountain

#volcanoes #usgs #CalVO #YVO #CVO
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October 16th, 12:33 pm

USGS Volcanoes

Low sulfur dioxide gas emissions on Kīlauea have resulted in greatly diminished vog (volcanic air pollution) in Hawaii, giving rise to spectacular views on the island. Here, looking across the field of lava erupted from Kīlauea's lower East Rift Zone this past summer, the shield-shaped profiles of Mauna Loa (left) and Mauna Kea (right) can be clearly seen in the far distance.

#Kilauea #volcanoes #usgs #HVO #LERZ #MaunaLoa #MaunaKea
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October 15th, 4:00 am

USGS Volcanoes

Maintaining instruments in #Yellowstone requires constant sleuthing, as well as resourcefulness. The vast distances, limited access, and harsh winter weather all pose particular challenges to keeping data flowing day after day and season after season. Specialized state of health monitoring tools combined with prior knowledge helps engineers remotely diagnose any problems before they arrive onsite, to be as efficient as possible with limited resources. But sometimes the damage is so extensive that entire stations need to be replaced. What can cause such havoc? Bison? Wind? Snow? Yes, but lightning can wreck equipment so completely that nearly all of the instrumentation needs to be replaced!

In the latest edition of Yellowstone #CalderaChronicles, read all about how UNAVCO engineers keep deformation monitoring stations running at Yellowstone all year long!

volcanoes.usgs.gov/volcanoes/yellowstone/article_home.html

(Photo: UNAVCO field engineer Dylan Cembalski replaces damaged antennas on the communications tower at Sawtell Peak. The tower is shared by multiple groups that use this regional high point to relay data. UNAVCO Photo by Summer Rhoades.)
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October 12th, 7:03 am

USGS Volcanoes

All volcanoes in the Cascade Range of Washington and Oregon are at normal background levels of activity this week.
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN
Weekly Update: on.doi.gov/2hwAiRm

Recent observations and activities: A few small earthquakes occurred at Mount Rainier, Mount St. Helens, and Mount Hood over the past week, which is typical activity for these volcanoes. Crews were busy at Mount Rainier conducting maintenance on seismic and deformation monitoring stations prior to the onset of winter conditions.

The image shows a CVO scientist directly sampling volcanic gases from the fumaroles on the north side of Mount Hood's Crater Rock (Oregon). As reported, gas flow was relatively strong for this site and a light hissing sound was evident from the hole. Overall, conditions were very dry in the area, but wet and muddy near the site (as usual). The samples were sent to the lab for analysis of the gases' chemical composition. By routinely collecting gas samples and comparing their composition to past measurements, scientists can become aware of subtle changes that might indicate a rekindling of eruptive activity. USGS image taken August 31, 2018, by Wes Thelen.

#usgs #cvo #cascadesvolcanoobservatory #volcanoupdate
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October 12th, 6:17 am

USGS Volcanoes

Aftershocks of the 2018 magnitude-6.9 earthquake expected to continue - read more in this week's #HVO #VolcanoWatch.

On May 4, 2018, a powerful magnitude-6.9 earthquake on the south flank of Kīlauea Volcano shook the Island of Hawai‘i. It was the largest quake in Hawaii in 43 years. Today, more than five months later, smaller-magnitude earthquakes in the same area are still occurring.

What causes these earthquakes, and how long will they last?

Most earthquakes are caused by patches of rock slipping along a fault plane within the Earth's crust. The area and the distance of slip relate directly to the energy release (magnitude) of the earthquake.

Slip is not uniform during a major earthquake—some patches move more than others, and some do not move at all. This unevenness in motion within the Earth's crust puts higher stresses on the patches that did not move than on the ones that did.

As the crust readjusts with time, these higher stresses give way to smaller earthquakes—called "aftershocks"—that occur on adjacent fault patches. The effect can cascade in avalanche-like fashion until the stresses caused by the major earthquake (known as the "mainshock") even out.

Generally, larger mainshocks produce larger, more numerous, and longer periods of aftershock activity. Aftershock sequences can last from days to centuries.

Not all earthquakes that happen after a major earthquake are smaller. Statistically, there's about a 5 percent chance that a larger earthquake will occur within a day after a major earthquake. If that happens, the larger earthquake gets labeled as the "mainshock," and the previous one is instead labeled a "foreshock."

During periods of intense seismic activity, there is no way to predict which earthquakes will be foreshocks, the mainshock, and aftershocks. These labels are applied retrospectively.

Prior to the 2018 Kīlauea eruption that started in Leilani Estates on May 3, migrating magma pushed through the East Rift Zone of the volcano. This compressed the south flank and caused slip along the island's basal fault, resulting in thousands of earthquakes near the coast and offshore.

The sequence of larger events started with a magnitude-5.1 earthquake at 10:30 a.m. local time on May 3. A day later, at 11:32 a.m. on May 4, a magnitude-5.4 earthquake then claimed the titled as mainshock. One hour later, at 12:32 p.m., the eventual mainshock of the sequence occurred—the magnitude-6.9 earthquake that rattled the island with enough intensity to knock items off the shelves in Hilo stores. It was also felt statewide and produced a modest tsunami along nearby coastlines.

The first large aftershock occurred later that day—a magnitude-5.3 earthquake at 3:37 p.m. local time. So far, 15 aftershocks of magnitude-4 and higher, along with thousands of smaller events, have occurred in the sequence.

Plotting these earthquakes on a map reveals an area that extends offshore and spans about 800 square kilometers (300 square miles). We can infer this as the total fault area that ruptured during the sequence.

The statistical relationship between aftershock activity and time was first formulated by the pioneering seismologist Fusakichi Omori in 1894. In what is now known as Omori's Law, the formula gives an inverse relationship between the probability of aftershocks and time. In other words, the longer the time since the mainshock, the less likely it is that an aftershock will occur. Omori's formula helps inform aftershock seismic hazard assessment.

In the case of the 2018 magnitude-6.9 earthquake, Omori's Law forecasts a decreasing frequency of aftershocks continuing in the area over the next year or more, including a small chance of a magnitude-6 earthquake during that time.

Interestingly, Omori had ties to the Hawaiian Volcano Observatory (HVO). In 1912, he supplied Thomas Jaggar, HVO's founder, with the observatory's first two seismographs. These instruments were housed in the Whitney Laboratory of Seismology at HVO's original site near the present-day Volcano House hotel in Hawai‘i Volcanoes National Park.

Given today's focus on earthquakes, we take this opportunity to remind you of the upcoming 2018 Great Hawaii ShakeOut on October 18 at 10:18 a.m. HST. Please join over 70,000 Hawaii residents and more than 50 million people worldwide and practice "Drop, Cover, and Hold On"—the appropriate actions to take whenever you feel strong shaking. You can learn more about earthquake safety at www.shakeout.org/hawaii/.

Map Caption: The inferred rupture area (white dashed line) of the May 4, 2018, magnitude-6.9 earthquake, with its foreshocks and first 10 days of aftershocks, spans an area of about 800 sq km (300 sq mi). Circle size indicates earthquake magnitude; color indicates earthquake depth. Magnitudes for some of the larger events are labeled. Inset graph shows the aftershock decay rate for May 4-15, 2018. USGS graphic.

volcanoes.usgs.gov/observatories/hvo/hvo_volcano_watch.html

#volcanoes #usgs #kilauea #maunaloa #hawaii #earthquakes #aftershock
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October 12th, 4:07 am

USGS Volcanoes

October 11th, 8:29 am

USGS Volcanoes

Did you know….

Florence Bascom was the first woman hired by the USGS in 1896. She combined teaching with field and laboratory work to become an authority on the rocks of the Piedmont. Julia Gardner followed, using her experience as a paleontologist during World War II to help pinpoint the Japanese military’s launch sites for balloonborne incendiary bomb attacks against the Pacific Northwest by analyzing seashells in the sand ballast of balloons.

Since then, many women have followed in their footsteps, pursuing careers in science, technology, engineering, or math (STEM), with an ever-increasing diversity of backgrounds, education, and interests.

This new publication highlights the work of 91 scientists at the USGS—women who have been pathfinders as scientists, cartographers, editors, and more, showing career options and pathways not typically pursued. The publication will inspire you to be part of the STEM future.

Read USGS Circular 1443, "A Snapshot of Women of the U.S. Geological Survey in STEM and Related Careers," available at pubs.er.usgs.gov/publication/cir1443.

#usgs #WomenInScience #STEM #DayOfTheGirl
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October 11th, 7:06 am

USGS Volcanoes

Today’s #ThrowbackThursday takes us back four months to watch fissure 8 construct its cinder cone.

In this series of images taken on June 23, 2018, the lava fountain within fissure 8 pulses, sending showers of hot lava fragments over the rim. The fragments (cinders) cool, building the cone higher and broader. The spatter cone at the time was about 55 m tall (180 ft). The cone has since settled and slumped inward.

The USGS–Hawaiian Volcano Observatory set up a temporary research camera looking into the fissure 8 cone, available at volcanoes.usgs.gov/observatories/hvo/webcam.html?webcam=LQcam.

A chronology of events from April 17 to October 5, 2018, at Kīlauea Volcano’s summit and lower East Rift Zone is available at volcanoes.usgs.gov/vsc/file_mngr/file-179/Chronology%20of%20events%202018.pdf.

#usgs #hvo #hawaiianvolcanoobservatory #kilauea #volcano #KilaueaErupts #LERZeruption #LERZ #KilaueaEruption
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October 10th, 4:42 am

USGS Volcanoes

October 10th, 4:38 am

USGS Volcanoes

Small hydrothermal (steam) explosions are the most likely type of volcanic hazard at Yellowstone National Park. volcanoes.usgs.gov/volcanoes/yellowstone/hazard_summary.html

This new video from Woods Hole Oceanographic Institution (WHOI) provides a nice visual explanation of how they can occur.
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October 8th, 4:00 am

USGS Volcanoes

#Yellowstone #CalderaChronicles this week is all about rivers!

We often talk about monitoring Yellowstone. To most people, this implies tracking earthquake activity over time, or how the ground moves up and down, or how temperatures change due to thermal activity. But did you know that the river systems are also monitored? It turns out that tracking changes in river chemistry is a good way to identify overall changes in Yellowstone's hydrothermal system.

Learn more at volcanoes.usgs.gov/volcanoes/yellowstone/article_home.html!

(Map shows locations of river morning stations in the Yellowstone region.)
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October 5th, 10:51 am

USGS Volcanoes

All volcanoes in the Cascade Range of Washington and Oregon are at normal background levels of activity this week.
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN
Weekly Update: on.doi.gov/2hwAiRm

Observations: Earthquakes were located at Mount Rainier, Mount St. Helens, and Mount Hood over this past week. Field crews installed infrasound on the Puyallup River Rainier Lahar Detection System stations, as well as relocated antennas at a critical data repeater station in that network.

USGS image shows field crews working on the Lahar Detection System seismic/camera site PR05 on the Puyallup River, near Mount Rainier (Washington).

#usgs #cvo #cascadesvolcanoobservatory #volcanoupdate
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October 3rd, 4:50 am

USGS Volcanoes

Before and After - Kīlauea's lower East Rift Zone eruption dramatically changed the landscape of the lower Puna district on Hawaiʻi Island. These satellite image comparisons from before and after speak many more words than we could ever put down on this screen. The juxtaposition of lush, tropical landscape against the parched and paved over land (and sea) depicts the dramatic changes to the landscape.

For a map of the 2018 lower East Rift Zone eruption fissures and surrounding area, see the HVO web site: volcanoes.usgs.gov/volcanoes/kilauea/multimedia_maps.html

#LeilaniEstates #LanipunaGardens #Kapoho #VacationLands #Fissure8 #KilaueaEruption
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Big Island Learning