PERSPECTIVES This is the first report of time-dependent of these has changed when changes in only track to realizing technological capabilities seismic tomography applied to an erupting two quantities (VP and VS) have been mea- resembling those of the fictional Virtual volcano. It builds on earlier work of the sured is not possible and requires the addi- Geophysical Laboratory by 2025. same kind done in geothermal areas in tion of other kinds of data. Both theoretical California and Iceland and the Long Valley advances and more data from different vol- References and Notes Caldera, California. But the seminal exam- canoes are needed before the potential of the 1. D. Patanè, G. Barberi, O. Cocina, P. De Gori, C. Chiarabba, Science 313, 821 (2006). ple of major changes in VP /VS comes from method can be fully assessed. 2. The compressional and shear waves are the fastest and The Geysers geothermal area in northern At present, monitoring of active volca- second-fastest waves to be radiated from an earthquake California. noes still rests mostly on relatively unso- source, so they arrive first and second on seismograms. Their ratio provides information about pressure and During the 1980s and 1990s, some phisticated seismic networks and the moni- about the presence of gas and liquid in the study volume. 13,600 tons of steam per hour were extracted toring of simple parameters, such as the Thus, changes in their ratio can tell us about changes in from The Geysers to generate electricity. As numbers of earthquakes and the amplitude pressure and gas/liquid, which are thought to accompany the buildup and occurrence of a volcanic eruption. a result of this overexploitation, the reser- of harmonic tremor. Patanè et al. show that 3. G. R. Foulger, C. C. Grant, A. Ross, B. R. Julian, Geophys. voir became progressively depleted as pore much more sophisticated methods can now Res. Lett. 24, 135 (1997). water was replaced by steam. Repeat seis- be used. Some of these methods only need to 4. R. C. Gunasekera, G. R. Foulger, B. R. Julian, J. Geophys. mic tomography showed the steady growth be automated—a critical factor if they are to Res. 108, 2134 (2003). 5. G. R. Foulger, B. R. Julian, Geotherm. Resour. Counc. of a reservoir-wide negative VP /VS anomaly be useful in situations where information is Bull. 33, 120 (2004). that coincided with the steam-production needed on an hourly basis. It is hoped that 6. G. R. Foulger et al., J. Geophys. Res. 108, 2147 (2003). zone. This anomaly was caused by the com- this automation work will be pushed for- Downloaded from bined effects of the replacement of pore liq- ward rapidly in the near future, putting us on 10.1126/science.1131790 uid with steam, the resulting decrease in pressure, and the drying of clay minerals. A remarkable series of snapshots showed the COMPUTER SCIENCE relentless growth of a volume of heavy depletion (3, 4). The work helped to increase http://science.sciencemag.org/ awareness of the nonsustainability of such high rates of fluid withdrawal. Production at Creating a Science of the Web The Geysers has now been reduced to sus- Tim Berners-Lee, Wendy Hall, James Hendler, Nigel Shadbolt, Daniel J. Weitzner tainable levels. Time-dependent tomogra- phy is currently used to monitor the Coso Understanding and fostering the growth of the World Wide Web, both in engineering and societal Geothermal Area, southern California (5). terms, will require the development of a new interdisciplinary field. Time-dependent seismic tomography was first applied to a volcano in a study of ince its inception, the World Wide lyzes the natural world, and tries to find Mammoth Mountain, a volcano on the rim Web has changed the ways scientists microscopic laws that, extrapolated to the of Long Valley Caldera, California. In 1989, Scommunicate, collaborate, and edu- macroscopic realm, would generate the on October 4, 2019 an intense swarm of hundreds of earth- cate. There is, however, a growing realiza- behavior observed. Computer science, by quakes accompanied an injection of new tion among many researchers that a clear contrast, though partly analytic, is princi- magma into the roots of this volcano, research agenda aimed pally synthetic: It is concerned with the con- and triggered the outpouring of some at understanding the struction of new languages and algorithms 300 tons of CO per day from the vol- Enhanced online at current, evolving, in order to produce novel desired computer 2 www.sciencemag.org/cgi/ cano’s surface. Several broad swaths content/full/313/5788/769 and potential Web is behaviors. Web science is a combination of of trees died as a result of high levels needed. If we want to these two features. The Web is an engineered of CO2 in the soil, and the CO2 model the Web; if we space created through formally specified also presented an asphyxiation hazard want to understand the architectural princi- languages and protocols. However, because to humans. A comparison of VP /VS tomo- ples that have provided for its growth; and if humans are the creators of Web pages and graphic images calculated for 1989 and we want to be sure that it supports the basic links between them, their interactions form 1997 showed changes that correlated well social values of trustworthiness, privacy, emergent patterns in the Web at a macro- with areas of tree death on the surface above, and respect for social boundaries, then we scopic scale. These human interactions are, and were attributed to migration of CO2 in must chart out a research agenda that targets in turn, governed by social conventions and the volcano (6). the Web as a primary focus of attention. laws. Web science, therefore, must be inher- By showing that time-dependent seismic When we discuss an agenda for a science ently interdisciplinary; its goal is to both tomography can be used to monitor struc- of the Web, we use the term “science” in two understand the growth of the Web and to cre- tural changes directly associated with a vol- ways. Physical and biological science ana- ate approaches that allow new powerful and canic eruption cycle, Patanè et al. take a crit- more beneficial patterns to occur. ical step toward developing a useful volcano- Unfortunately, such a research area does T. Berners-Lee and D. J. Weitzner are at the Computer Science hazard-reduction tool based on seismic and Artificial Intelligence Laboratory, Massachusetts Institute not yet exist in a coherent form. Within tomography. As with all good experiments, of Technology, Cambridge, MA 02139, USA. W. Hall and computer science, Web-related research has N. Shadbolt are in the School of Electronics and Computer however, it ushers in new challenges. VP /VS largely focused on information-retrieval is affected by several factors, including pore Science, University of Southampton, Southampton SO17 algorithms and on algorithms for the routing 1BJ, UK. J. Hendler is in the Computer Science Department, fluid phase, pressure, mineralogy, and frac- University of Maryland, College Park, MD 20742, USA. of information through the underlying Inter- ture density. However, determining how each E-mail: [email protected] net. Outside of computing, researchers grow www.sciencemag.org SCIENCE VOL 313 11 AUGUST 2006 769 Published by AAAS PERSPECTIVES ever more dependent on the Web; but they given topic. Conventional information- modeling. Imagine being able to query the have no coherent agenda for exploring the retrieval techniques are insufficient at the Web for a chemical in a specific cell biology emerging trends on the Web, nor are they scale of the Web. However, it turns out that pathway that has a certain regulatory status fully engaged with the emerging Web human topics of conversation on the Web as a drug and is available at a certain price. research community to more specifically can be analyzed by looking at a matrix of The engineering challenge is to allow inde- focus on providing for scientists’ needs. links (7, 8). The mathematics of information pendently developed data systems to be con- Leading Web researchers discussed the retrieval and structure-based search will nected together without requiring global scientific and engineering problems that certainly continue to be a fertile area of agreement as to terms and concepts. The sta- form the core of Web science at a workshop research as the Web itself grows. However, tistical methods that serve for the scaling of of the British Computer Society in London in approaches to developing a mathematical language resources in search tasks and the September 2005 (1). The participants consid- framework for modeling the Web vary data calculi that are used in scaling database ered emerging trends on the Web and debated widely, and any substantive impact will, queries are largely based on incompatible the specific types of research needed to again, require a new approach. The process- assumptions, and unifying these will be a exploit the opportunities as new media types, oriented methodologies of the formal sys- major challenge. data sources, and knowledge bases become tems community, the symbolic modeling Despite excitement about the Semantic “Webized,” as Web access becomes increas- methodologies of the artificial intelligence Web, most of the world’s data are locked in ingly mobile and ubiquitous, and as the need and semantics researchers, and the mathe- large data stores and are not published as an increases for privacy guarantees and control matical methods used in network analyses open Web of inter-referring resources. As a of information on the Web. are all relevant, but no current mathematical result, the reuse of information has been Downloaded from The workshop covered a wide range of model can unify all of these.