How fluids affect volcanos

Eos, Vol. 7 2 , No. 3 7 , September 1 0 , 1 9 9 1

sion, a jokullhaup flowed down the Huemules valley to the coast. A 2-m-thick de­ posit o f ash- to lapilli-sized sand, and 0 . 2 5-m diameter ice blocks, was randomly dispersed near the delta. These ice blocks probably floated in the mudflow. "Direct observations at 1250 showed an explosion from a new vent (crater 2 ) about 2.5 km south-southeast of the first vent (cra­ ter 1 ) . The new white and black explosion cloud was smaller and spread laterally, de­ veloping black, cold pyroclastic-ice flows around the vent, similar to the original. White-grey columns, reaching 3 km height, were observed up to the last direct observa­ tion at 1630 on August 11. "A s e c o n d , larger eruption started at about 1200 on August 12. Bad weather pre­ vented aerial observation, but heavy ashfall was reported at Rio Murta (60 km SSE) at 1245, and 7 minutes later at Rio Tranquilo, 20 km further south. The ashfall was a c c o m ­ panied by intense lightning and a sulfur odor. At 1300, ashfall was reported at Puerto Guadal (105 km S ) . The eruption was di­ rectly observed on a commercial flight at 1430. The dense, brown-grey cauliflowershaped cloud carried to the southeast was visible from 4 km altitude, but clearly reached > 1 0 km with more than a 5-km thickness. "Since August 12 the eruption continued without variation, and the plume has been carried to the southeast." Although weather clouds obscurred the eruption plume to visi­ ble and infrared satellite images on the 12th and much of the 13th, preliminary data from the Nimbus-7 satellite's Total Ozone Map­ ping Spectrometer (TOMS) indicated 250,000 metric tons of S 0 within a disconnected section of the eruption cloud near the Falk­ land Islands at about 1100 on the 13th. [A paper describing TOMS data from this erup­ tion has b e e n submitted to Eos.] Beginning at about 2000, a continuous, narrow, eruption plume was visible in AVHRR (NOAA 9 and 11) and GOES satellite images gradually extending 1200 km south­ east, beyond the Falkland Islands, at an alti­ tude of about 12 km. The plume b e c a m e disconnected from the volcano at about 1200 on August 14, by which time, Naranjo re­ ported, the eruptive column reached a stable altitude of 16 km. Intense seismic activity was felt at 1630 60 km south-southeast where 3-cm-diameter pumice was falling. Continuous eruption be­ gan again at about 2000, when satellite im­ ages (GOES and NOAA 9 and 11) showed that the plume was carried southeast at 185 km/hr at stratospheric altitudes of 1 7 - 1 8 km. Seismicity increased, with felt earthquakes at Coyhaique (80 km NE) beginning at 2200, and a series of five large earthquakes ( M > 5 ) detected near Hudson by the Worldwide Standardized Seismic Net beginning at 2238. Early on the 15th the plume extended 1500 km southeast, past the Falkland Islands, where it divided into two components, one travelling east, the other south, both quickly becoming diffused. At its widest point (the Falkland Islands), the plume was 370-km wide. Infrared satellite imagery showed the 2

plume before it disconnected from the vol­ c a n o at 1130. TOMS data from 1100 on the 15th showed the plume already discon­ nected from the volcano. No additional emissions have b e e n reported as of August 23. The eruption plume of August 1 4 - 1 5 was rapidly carried by the "Roaring Forties" winds to the east, as shown by TOMS satel­ lite data, reaching Australia (15,000 km east) on August 2 0 .

Information Contacts J o s e Antonio Naranjo, Servico Nacional de Geologia y Mineria, Casilla 10465, Santiago, Chile; Hugo Moreno Roa, Departamento de Geologia y Geofisica, Universidad de Chile, Casilla 1 3 5 1 8 - 2 1 , Santiago, Chile; Gustavo Fuentealba C. and Pedro Riffo A., Universidad de La Frontera, Casilla 54-D, T e m u c o , Chile; Peter R. Bitschene, Patagonia Volc a n i s m Project, Depto. Geologia UNPSJB, km 4, 9 0 0 0 C o m o d o r o Rivadavia, Argentina; Norman Banks, USGS C a s c a d e s Volcano Observatory, 5 4 0 0 MacArthur Blvd., Vancouver, WA 98661; Synoptic Analysis Branch, NOAA/NESDIS, 5 2 0 0 Auth Road, Camp Springs, MD 2 0 2 3 3 ; Scott Doiron, NASA Goddard S p a c e Flight Center, Greenbelt, MD 2 0 7 7 1 ; Bruce Presgrave, National Earthquake Information Center, U.S. Geological Survey, Stop 9 6 7 , Denver Federal Center, B o x 2 5 0 4 6 , Denver, CO 8 0 2 2 5 ; Charles Stern, Dept. of Geological Sciences, Uni­ versity of Colorado, Campus B o x 2 5 0 , Boulder, CO 8 0 3 0 9 ; A.J. Prata, CSIRO, Division of Atmospheric Reasearch, Private Bag No. 1, Mordialloc, Victoria 3 1 9 5 , Australia; International Civil Aviation Organi­ zation, Suite 4 0 0 , 1000 Sherbrooke St. W, Montreal, Q u e b e c H3A 2R2 Canada; Radio Nacional de Chile; Associated Press.

Coastal America Program Going Forward PAGE 3 9 5 Coastal America, a new multiagency ini­ tiative developed by the Bush administration to address coastal resource problems, s e e m s to b e ignoring the fact that Congress did not fund it for FY92. Although $23 million was requested by Bush for four agencies for FY92, Congress zeroed the funding for the National O c e a n i c and Atmospheric Adminis­ tration, the U.S. Army Corps of Engineers, and the Department of the Interior. The ap­ propriations bill that covers the Environmen­ tal Protection Agency has not b e e n voted on by its joint conference committee. Until they are federally funded, Coastal America will use money from the agencies that has al­ ready b e e n authorized in specific areas, such as dredging for the Corps of Engineers. They will also rely on state and private sup­ port. Announcing the project in February, Pres­ ident Bush said "the new initiative will en­ able federal agencies to work more closely with e a c h other and with states, local elected officials, and private citizens . . . to protect, preserve, and restore our living coastal heritage." The main areas that Coastal America fo­ c u s e s on are nonpoint source pollution, loss and degradation o f habitat, and contam­ inated sediments. Projects will have to ad­ dress one of these topics in order to b e ac­

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cepted. T h e s e problems are the result of increased population in coastal areas and increased demand on natural resources. Fac­ tors that contribute to these problems in­ clude dredging and dredged material dis­ posal, changes in salinity, shoreline modification, toxic pollutants, and pollution. Proposals to the Coastal America pro­ gram are developed at the regional level and then submitted to the national office. Projects will also b e managed at the regional level, where administrators will decide the role e a c h agency will have in a particular project. Calling the program "revolutionary," its strength, said Virginia Tippie, acting director of Coastal America, lies in the integrated approach by the agencies. She added that "The task of restoring the nation's coast and our resources cannot be done by one agen­ cy." In an article published in Sea Technol­ ogy in August, she commented on the grow­ ing importance of interagency partnerships such as Coastal America to a c c o m m o d a t e increasing controversial management issues, complicated technical needs, and limited financial resources. The goal of Coastal America, said Norm Edwards, assistant to the acting director, is not to create more laws but to find solutions to coastal problems. "This is not a research program," he said. "It is 'do oriented' rather than 'study oriented.'" Each of the agencies involved has ample authority on which Coastal America will rely, and e a c h is an equal partner. The seven regional areas set up by Coastal America are the Northeast, South­ east, Gulf of Mexico, Pacific Southwest (in­ cluding Hawaii), Pacific Northwest, Great Lakes, and Alaska. Different parts of the United States have unique coastal problems, noted Tippie. For example, the Northeast region is most concerned with habitat prob­ lems, while s o m e proposed projects in the Southeast region are Swift Creek nonpoint source pollution, restoration of tidal creeks, post hurricane restoration in tropical ecosys­ tems, and nonpoint source sediment and nutrient reduction. S o far, about 110 proposals have b e e n submitted to the national office in Washing­ ton, and a decision on them is expected sometime in October, said Tippie. Projects funded will serve as models for managing coastal resources. For now, said Edwards, Coastal America will focus on short-term projects of 1-2 years. As the initiative re­ ceives funding, it may b e able to have longer term projects, he added. Coastal America administrators are also developing a Na­ tional Education program to educate both the agencies and the public.—Susan Bush

How Fluids Affect Volcanos PAGES 3 9 5 - 3 9 6 An interdisciplinary session entitled "Flu­ id-Volcano Interactions" was held at the 1990 AGU Fall Meeting to draw together re­ searchers from volcanology, geochemistry,

Eos, Vol. 7 2 , No. 3 7 , September 1 0 , 1 9 9 1 hydrogeology, tectonophysics, and geophys­ ics. Forty-seven papers were presented dur­ ing a two-day poster session followed by an open discussion period. The session provided a forum to discuss how circulating fluids influence the thermal, c h e m i c a l , m e c h a n i c a l , and hydrologic pro­ c e s s e s that contribute to the evolution and behavior of v o l c a n o s . Papers presented dur­ ing the poster session covered a broad range of topics, including measurements o f heat, fluid, and solute fluxes at volcanos; volcano deformation and internal dynamics; waterrock interaction and the role of magmatic volatiles; structural controls on fluid flow and heat transfer; and approaches for model­ ing fluid, heat, and solute transport in volca­ nos. The diversity of topics illustrates the importance o f fluid circulation to a wide va­ riety o f volcanic p r o c e s s e s . It also highlights the difficulty o f integrating the observations and theories generated within disparate dis­ ciplines into robust models. Field observations s e e m to require c o m ­ prehensive models o f volcano evolution to a c c o u n t for the coupling between deforma­ tion, fluid flow, solute transport, and heat transfer. Most o f the papers, however, dealt with o n e or two couplings at most. One au­ thor, for example, described how microseismicity might b e related to boiling within a volcano, whereas the patterns and rates o f fluid circulation and heat transport that con­ trol the onset o f boiling could b e con­ strained only through geochemical and isotopic studies. Geoscientists do not yet simulate the entire set o f relevant processes. Not only are computational resources inade­ quate, but quantitative descriptions o f the

volcano vary in time and s p a c e in response to intrusive or eruptive activity and variations in geochemical regimes? How do temporal variations in permeabil­ ity influence eruption cycles and the evolu­ tion o f hydrothermal systems? What are the sources o f fluids and sol­ utes in volcanic systems and what methods are available to distinguish their origins? Can temporal variations in the discharge of "magmatic" components be related to eruptive cycles, and are there measurable precursors? What influence does meteoric recharge have on eruption cycles, microseismicity, and thermal regimes? How important is knowledge of a volca­ no's hydrology to mitigating volcanic haz­ ards?—Craig Forster, Dept. of Geology and Geophysics, University of Utah, Salt Lake City, and Steve Ingebritsen, US. Geological Survey, Menlo Park, Calif. The Penrose Con­ ference convenors are Ingebritsen (primary contact), Forster, Bruce Christenson (DSIR, Taupo, New Zealand), Grant Heiken (Los Alamos Natl. Lab., New Mex.), and Craig Manning (Dept. of Earth and Space Sciences, UCLA).

physical parameters controlling e a c h process are incomplete. Several papers, however, illustrated good agreement between quantita­ tive modeling results and thermal and chem­ ical observations. T h e s e results imply that simulating a subset o f the coupled processes can provide useful insight into transport phe­ nomena. Obtaining a better understanding of spa­ tial and temporal changes within active vol­ c a n o s will require integrating observations and theory developed within several disci­ plines o f the Earth s c i e n c e community, ex­ panding existing observation networks, and developing the conceptual and numerical models needed to link and evaluate observa­ tion-based inferences. The existing database is likely to b e expanded by scientific drilling at Katmai (Alaska) and White Island (New Zealand) and by observations of fluid, heat, and m a s s fluxes from various other volca­ nos. Developing a clear understanding o f the linkages between primary processes requires enhanced communication among scientists from different disciplines. To this end, a Pen­ rose Conference entitled "Fluid-Volcano In­ teractions" is scheduled for October 4 - 9 , 1992. The convenors would w e l c o m e sug­ gestions regarding possible venues and top­ ics. Questions currently proposed for discus­ sion arise in part from the AGU session on fluid-volcano interactions and include: What pressure, temperature, and fluidsaturation conditions are found between magma and the land surface? How are these conditions related to heat and m a s s transfer between magma and the shallow subsur­ face? How does the permeability structure of a

Bibliography Giggenbach, W. F., J . W. Hedenquist, B. F. Hough­ ton, P. M. Otway, and R. G. Allis, Research drill­ ing into the volcanic hydrothermal system on White Island, New Zealand, Eos Trans. AGU, 70, 98, 1989. Torgersen, T., Crustal-scale fluid transport: Magni­ tude and mechanisms, Eos Trans. AGU, 71, 1, 1990. Williams, S. N., and H. Meyer, A model of Nevado del Ruiz volcano, Colombia, Eos Trans. AGU, 69, 1554, 1988.

SECTION NEWS GEOMAGNETISM & PALEOMAGNETISM

Table 1. Spherical H a r m o n i c Coefficients of the 1 9 9 0 Magnetic Models for the Conterminous States a n d Alaska

Field at 1990.0 Alaska

Conterminous States

Editor: Kenneth P. Kodama, Department of Geol­ ogy, Williams Hall # 3 1 , Lehigh University, Bethle­ hem, PA 18014; tel. 215-758-3663

1990 Magnetic Models for the United States PAGE 397 New mathematical models o f the mag­ netic field in the United States have been developed by the U.S. Geological Survey. T h e models describe the direction and inten­ sity o f the field at the beginning o f 1990, and

n

m

1 1 2 2 2 3 3 3 3 4 4 4 4 4

0 1 0 1 2 0 1 2 3 0 1 2 3 4

Q

m

-27885 1123 -6769 388 3400 6441 -3374 -496 -1392 -604 2308 685 399 -145

m

h„

0 5864 0 -2245 4585 0 -1671 -4118 1326 0 2116 599 -1404 -1011

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Q

Annual Change

m

-27327 -1916 -5186 6887 6075 886 -8771 -6379 -1724 2167 4128 4038 -380 -789

m

h„

0 1577 0 5954 -892 0 -6245 2131 -1668 0 1399 -1029 518 -1065

m 23.8 -12.6 -15 54.0 -11.8 -25.1 -43.6 182 -11.4 17.4 8.1 -172 -12 -13.1

m

K

0.0 -345 0.0 26.8 -6.5 0.0 -33.7 115 1.0 0.0 163 -53 2.6 3.5