Challenges and opportunities for the 21st century
Preceding chapters have described various geodetic and modeling tools that can be used to monitor volcano deformation, discussed examples of how those tools have been used to infer what might be happening beneath a few well studied volcanoes, and explored some emerging links between geodesy and other disciplines in volcanology. In this final chapter, I take a step back to consider some basic questions about the current state of volcano geodesy and try to glimpse its future — a future bright with the promise of real time, global surveillance but also clouded by increasing risk as populations continue to encroach on many of the world’s dangerous volcanoes.
KeywordsGlobal Position System Lava Dome Magma Body Global Position System Station Volcanic Explosivity Index
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- 3.Although relatively rare, there have been several recent discoveries using interferometric synthetic-aperture radar (InSAR) of deformation at otherwise quiescent andesite-dacite volcanoes, including Mount Peulik, Alaska (Lu et al., 2002a) and Three Sisters, Oregon (Wicks et al., 2002a, b) (Chapter 5). Deformation at active basaltic shields such as Kīlauea, Hawai’i, and at restless silicic calderas such as Yellowstone, Wyoming, and Long Valley, California, is relatively common.Google Scholar
- 5.VEI is a measure of the size of volcanic eruptions akin to the Richter magnitude scale for earthquakes. The VEI is a 0-to-8 index of increasing explosivity, each interval representing an increase of about a factor of ten. It combines total volume of explosive products, eruptive cloud height, descriptive terms, and other measures (Newhall and Self, 1982).Google Scholar
- 6.All calculations assume Poisson’s ratio v = 0.25, which means the uplift volume is 1.5 times the injected volume. For a discussion of the dependence of surface displacements on v, see Section 8.4.1 or Delaney and McTigue (1994).Google Scholar
- 8.The Goats Rocks eruptive period began about 1800 CE with the explosive eruption of dacitic pumice layerT (Mullineaux and Crandell, 1981), which produced a recognizable ash layer as far downwind as northern Idaho. From the 1830s to the mid-1850s, many minor explosive eruptions were observed by explorers, traders, and settlers in the area. Extrusion of the andesitic Floating Island lava flow was followed by growth of the dacitic Goat Rocks dome on the volcano’s north flank, which ended in 1857 When the volcano reawakened in 1980, the Goat Rocks dome was deformed by the famous north-flank bulge and destroyed by the catastrophic landslide and eruption on May 18.Google Scholar
- 9.The Mount St. Helens Emergency Response Plan defines three alert levels that differ from normal background activity: Level 1, Notice of Volcanic Unrest (unusual activity detected); Level 2, Volcano Advisory (eruption likely but not imminent); and Level 3, Volcano Alert (eruption imminent or in progress).Google Scholar
- 10.The USGS David A. Johnston Cascades Volcano Observatory (CVO) and the USFS Johnston Ridge Observatory (JRO) commemorate USGS geologist Dave Johnston, who died in the 18 May 1980, eruption of Mount St. Helens near the current site of JRO.Google Scholar
- 12.Mount St. Helens had been selected earlier as one of several volcanoes where PBO instrument clusters would be deployed, in this case to include ~20 CGPS stations and 5 borehole strainmeters.The first deployments were scheduled for summer 2005, but in response to the earthquake swarm 9 CGPS stations were installed on the volcano in October 2004 and 2 more in February 2005.Google Scholar
- 13.Among the distinctive features of the 2004–2006 eruption are persistent seismicity (~1 event per minute, many with similar waveforms, continuing for several months), and a ubiquitous layer of fault gouge, ~1 m thick, at the surface of a piston-like extrusion.Google Scholar
- 15.The Catalog of Active Volcanoes of the World (CAVW), a regional series of publications by the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI), developed a volcano numbering system in the late 1930s that has been retained, where possible, by the Smithsonian Institution’s Global Volcanism Program (Simkin and Siebert, 1994). The numbering scheme is geographic and hierarchical. The first two numerals identify the region, the next two identify the subregion, and the last two or three (after the hyphen) identify individual volcanoes in that subregion. For example, Mount St. Helens is the fifth volcano, numbered from North to South, in the first subregion (USA, west coast states) of the twelfth region (Canada and western USA) of the world. Its volcano number is therefore 1201–05.Google Scholar