PENINSULA GEOLOGICAL SOCIETY
Jake Lowenstern , U.S. Geological Survey, Scientist In Charge, Yellowstone Volcano Observatory
Intrusion, Deformation and Degassing at the Yellowstone Caldera
- DINNER MEETING – Tuesday, May 8, 2007
Location: Stanford University
- 5:30 PM-Social (3/4) Hour: . . . GeoCorner Room 320-109
- 6:15 PM-Dinner: . . . GeoCorner Room 320-109
- 7:30 PM-Meeting: . . . GeoCorner Room 320-105see Map showing Mitchell and GeoCorner Room 320
Anyone wishing to attend the lecture only is welcome at no cost.
This will be the 389th meeting since 1954
Map of Yellowstone National Park and vicinity. Thick black line is the boundary of the Yellowstone Caldera. Thin black lines are roads. Gray outline is park boundary. Red regions are thermal areas. Dashed line shows state boundaries (from USGS SIR-2006-5276).
The Yellowstone caldera is well known for its cycles of uplift and subsidence over both historic and geologic timescales. Most models for deformation assume sources due to transport of magma or hydrothermal brine streaming through ruptured permeability barriers. Recent investigations of chemical mass balance at Yellowstone provide critical insights into potential sources of both deformation and heat. Volatile fluxes from the Yellowstone caldera have been calculated by summing the flux of Cl–, F, SO42–‚ and HCO3– through the major rivers leaving the Yellowstone Plateau. Long-term studies show that Cl–, the primary non-H2O component of geothermal brines has not changed appreciably in output during recent periods of subsidence and uplift. Instead, Cl– flux is dominated by recharge constraints, increasing during periods of greater precipitation. Carbon is much more abundant than sulfur in Yellowstone’s waters, but is even more dominant when combined with data on gas flux from fumaroles and diffuse degassing. In fact, CO2 is about 300 times more abundant than Cl– on a molar basis as an effluent from the Yellowstone hydrothermal system. Similarly sulfur flux exceeds Cl– by about 25 times what one would expect from the concentrations in degassed volcanic rocks that could be leached. Phase equilibrium constraints imply that the shallow subsurface at Yellowstone (the upper two km) should be saturated with a CO2-rich vapor phase under most conceivable P-T conditions. This volumetrically significant (even dominant) phase should have an important role in pressurization of the hydrothermal system and may contribute to ongoing cycles of deformation within the caldera. The volatile “signature” from Yellowstone strongly suggests that gas discharge is controlled not by the crustal granitic magma chamber but by subjacent basaltic intrusions that provide both heat and mass to the overlying system
- [gview file=”http://pubs.usgs.gov/of/2007/1071/of2007-1071.pdf”%5D
About the Speaker
Jake Lowenstern is a Research Geologist with the U.S. Geological Survey in Menlo Park and is the Scientist-in-Charge of the Yellowstone Volcano Observatory. He received his B.A. in Earth Sciences in 1986 from Dartmouth College and his Ph.D. in 1992 from Stanford University. In 1986-87 he spent a year as a Fulbright Fellow in Sicily studying the volcanic rocks of Mt. Etna. He also worked as a research scientist near Tokyo with the Geological Survey of Japan during 1992-93.
Lowenstern specializes in the gases that come off magmas and the influence these gases have on volcanism and on the geothermal and ore-forming systems that surround magma chambers in the earth’s crust. Besides Yellowstone, he has worked on volcanoes and geothermal systems in California, Alaska, Italy and the African nation of Eritrea.
Reservations: The preferred way to make reservations is simply to email Janice Sellers at firstname.lastname@example.org by May 4, tell her you will attend, commit to pay, and bring your payment to the meeting. Janice always emails a confirmation; if you don’t get one, assume email crashed yet again and email her a second time. A check made to “PGS” is preferred, payable at the meeting.
If you want to pay in advance:
Stanford faculty and students: Please make dinner reservations by May 4. Contact Dr. Elizabeth Miller via her mailbox (and leave check), Geological and Environmental Sciences Office, Geocorner – Bldg. 320 (Rm. 205). Make checks out to “PGS.”
All others, including faculty and students from other Bay Area universities and colleges and USGS: Please make dinner reservations by April 6. Contact Janice Sellers, at 1066 28th Street, Oakland, CA 94608-4547, (510) 268-8254. Send check made out to “PGS” to Janice.
Dinner is $30.00. Includes wine (5:30 to 6:15 PM.) and dinner (6:15-7:30 PM.).
For students from all universities and colleges, the dinner, including the social 3/4-hour, is $5.00 and is partially subsidized thanks to the School of Earth Sciences, Stanford University (Note, no-show reservations owe the full price).
Doris, whose wonderful crew prepares our meals, asked that we let you know that people who are late RSVP’ing and people who show up without a reservation will be welcome but that they will be eating on paper plates with plastic utensils (food supply permitting).
Dues for Academic Year 2006-2007 ($10.00) should be sent to Janice Sellers, 1066 28th Street, Oakland, CA 94608-4547. Janice’s phone: (510) 268-8254.
Officers: Ray Wells, President; Dwight Harbaugh and Elizabeth Miller, Co-Vice Presidents; Mike Diggles, Secretary; Janice Sellers, Treasurer; Bob Coleman, Field-Trip Czar
Volcano Update from Archive
44°25’48” N 110°40’12” W, Summit Elevation 9203 ft (2805 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREENSeismicity
During March 2014, the University of Utah reports 277 earthquakes were located in the Yellowstone National Park region. More events will be added as the University of Utah Seismograph Stations, responsible for the operation and analysis of the Yellowstone Seismic Network, processes the remaining March events. The largest event was a light earthquake of magnitude 4.7 on March 30, at 06:34 AM MDT, located four miles north-northeast of Norris Geyser Basin in Yellowstone National Park, Wyoming. The M4.7 main shock was reported felt in Yellowstone National Park, in the towns of Gardiner and West Yellowstone, Montana and throughout the region. This is the largest earthquake at Yellowstone since the early 1980s. Initial source analysis of the M4.7 earthquake suggests a tectonic origin (mostly strike-slip motion).March 2014 seismicity was dominated by two earthquake clusters in the Norris Geyser Basin region and are described below.1) A north-south trending series of earthquakes, over seven miles in length, began in September, 2013 and persisted throughout March with 130 events. The largest earthquake (magnitude 3.5) occurred on March 26, at 05:59 PM MDT, located 13 miles south-southwest of Mammoth, WY.
2) The earthquake series containing the March 30 magnitude 4.7 event began on March 27 and continues into April. At the end of March the series consisted of 70 located earthquakes, including the largest earthquake of the month, four magnitude 3 earthquakes, and numerous magnitude 2 and smaller earthquakes.
Earthquake sequences like these are common and account for roughly 50% of the total seismicity in the Yellowstone region.
Yellowstone earthquake activity in March is elevated compared with typical background levels.
The ground deformation occurring in north-central Yellowstone continues. Since August 1, 2013, the NRWY GPS station has moved about 1.5 cm east, 2 cm north, and 5.5 cm up.
Further south, the caldera subsidence, which began in 2010, has ceased. Since the beginning of 2014, the caldera has been slowly rising at a rate of about 2 cm/yr. All the deformation currently occurring in Yellowstone remains well within historical norms.
The Yellowstone GPS network recorded no deformation associated with the March 30, 2014 M4.7 earthquake. Earthquakes of this size and depth do not typically produce ground displacements large enough to detect with GPS.
The GPS field crew at Yellowstone has traveled around the Park over the past week and has not observed any effects from the earthquake. If any subtle changes have occurred, they are most likely to be found after the snow melts.
YVO’s real time temperature data in Norris Geyser Basin indicate no significant changes to the thermal features that are monitored.(http://volcanoes.usgs.gov/volcanoes/yellowstone/yellowstone_monitoring_32.html)
The Yellowstone Volcano Observatory (YVO) provides long-term monitoring of volcanic and earthquake activity in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.
YVO Member agencies: USGS, Yellowstone National Park, University of Utah, University of Wyoming, UNAVCO, Inc., Wyoming State Geological Survey, Montana Bureau of Mines and Geology, Idaho Geological Survey
|This article needs additional citations for verification. (November 2007)|
Volcanic gases include a variety of substances given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating directly from lava or indirectly through ground water heated by volcanic action.
The sources of volcanic gases on Earth include:
- primordial and recycled constituents from the Earth’s mantle,
- assimilated constituents from the Earth’s crust,
- groundwater and the Earth’s atmosphere.
Substances that may become gaseous or give off gases when heated are termed volatile substances.
Magmatic gases and high-temperature volcanic gases
Gases are released from magma through volatile constituents reaching such high concentrations in the base magma that they evaporate. (Technically, this would be described as the exsolution and accumulation of the gases upon reaching excess supersaturation of these constituents in the host solution (magmatic melt), and their subsequent loss from the host by diffusion and phase separation into bubbles). Molten rock (either magma or lava) near the atmosphere releases high-temperature volcanic gas (>400 °C). In explosive volcanic eruptions, sudden release of gases from magma may cause rapid movements of the molten rock. When the magma encounters water, seawater, lake water or groundwater, it can be rapidly fragmented. The rapid expansion of gases is the driving mechanism of most explosive volcanic eruptions. However, a significant portion of volcanic gas release occurs during quasi-continuous quiescent phases of active volcanism.
Low-temperature volcanic gases and hydrothermal systems
So, if the magmatic gas traveling upward encounters meteoric water in an aquifer, steam is produced. Latent magmatic heat can also cause meteoric waters to ascend as a vapour phase. Extended fluid-rock interaction of this hot mixture can leach constituents out of the cooling magmatic rock and also the country rock, causing volume changes and phase transitions, reactions and thus an increase in ionic strength of the upward percolating fluid. This process also decreases the fluid’s pH. Cooling can cause phase separation and mineral deposition, accompanied by a shift toward more reducing conditions. At the surface expression of such hydrothermal systems, low-temperature volcanic gases (<400 °C) are either emanating as steam-gas mixtures or in dissolved form in hot springs. At the ocean floor, such hot supersaturated hydrothermal fluids form gigantic chimney structures called black smokers, at the point of emission into the cold seawater.
Non-explosive volcanic gas release
The gas release can occur by advection through fractures, or via diffuse degassing through large areas of permeable ground as Diffuse Degassing Structures (DDS). At sites of advective gas loss, precipitation of sulfur and rare salts forms sulfur deposits and small sulfur chimneys, called fumaroles. Very low-temperature <100 °C) fumarolic structures are also known as solfataras. Sites of cold degassing of predominantly carbon dioxide are called mofettes. Hot springs on volcanoes often show a measurable amount of magmatic gas in dissolved form.
The principal components of volcanic gases are water vapor (H2O), carbon dioxide (CO2), sulfur either as sulfur dioxide (SO2) (high-temperature volcanic gases) or hydrogen sulfide (H2S) (low-temperature volcanic gases), nitrogen, argon, helium, neon, methane, carbon monoxide and hydrogen. Other compounds detected in volcanic gases are oxygen (meteoric), hydrogen chloride, hydrogen fluoride, hydrogen bromide, nitrogen oxide (NOx), sulfur hexafluoride, carbonyl sulfide, and organic compounds. Exotic trace compounds include mercury, halocarbons (including CFCs), and halogen oxide radicals.
The abundance of gases varies considerably from volcano to volcano. Water vapor is consistently the most common volcanic gas, normally comprising more than 60% of total emissions. Carbon dioxide typically accounts for 10 to 40% of emissions.
Volcanoes located at convergent plate boundaries emit more water vapor and chlorine than volcanoes at hot spots or divergent plate boundaries. This is caused by the addition of seawater into magmas formed at subduction zones. Convergent plate boundary volcanoes also have higher H2O/H2, H2O/CO2, CO2/He and N2/He ratios than hot spot or divergent plate boundary volcanoes.
Sensing, collection and measurement
Volcanic gases can be sensed (measured in-situ) or sampled for further analysis. Volcanic gas sensing can be:
- within the gas by means of electrochemical sensors and flow-through infrared-spectroscopic gas cells
- outside the gas by ground-based or airborne remote spectroscopy (e.g., COSPEC, FLYSPEC, DOAS, FTIR)
Volcanic gas sampling is often done by a method involving an evacuated flask with caustic solution, first used by Robert W. Bunsen (1811-1899) and later refined by the German chemist Werner F. Giggenbach (1937-1997), dubbed Giggenbach-bottle. Other methods include collection in evacuated empty containers, in flow-through glass tubes, in gas wash bottles (cryogenic scrubbers), on impregnated filter packs and on solid adsorbent tubes.
Analytical techniques for gas samples comprise gas chromatography with thermal conductivity detection (TCD), flame ionization detection (FID) and mass spectrometry (GC-MS) for gases, and various wet chemical techniques for dissolved species (e.g., acidimetric titration for dissolved CO2, and ion chromatography for sulfate, chloride, fluoride). The trace metal, trace organic and isotopic composition is usually determined by different mass spectrometric methods.
Volcanic gases and volcano monitoring
Main article: Prediction of volcanic activity
Certain constituents of volcanic gases may show very early signs of changing conditions at depth, making them a powerful tool to predict imminent unrest. Used in conjunction with monitoring data on seismicity and deformation, correlative monitoring gains great efficiency. Volcanic gas monitoring is a standard tool of any volcano observatory. Unfortunately, the most precise compositional data still require dangerous field sampling campaigns. However, remote sensing techniques have advanced tremendously through the 1990s.
Volcanic gases were directly responsible for approximately 3% of all volcano-related deaths of humans between 1900 and 1986. Some volcanic gases kill by acidic corrosion; others kill by asphyxiation. The greenhouse gas, carbon dioxide, is emitted from volcanoes, accounting for nearly 1% of the annual global total. Some volcanic gases including sulfur dioxide, hydrogen chloride, hydrogen sulfide and hydrogen fluoride react with other atmospheric particles to form aerosols. 
- H. Sigurdsson et al. (2000) Encyclopedia of Volcanoes, San Diego, Academic Press
- N. Morello (editor) (1998), Volcanoes and History, Genoa, Brigati
- Royal Society Climate Change Controversies, London, June 2007
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