Silverthrone Caldera - Monitoring

Monitoring

Currently Silverthrone is not monitored closely enough by the Geological Survey of Canada to ascertain how active the volcano's magma system is. The existing network of seismographs has been established to monitor tectonic earthquakes and is too far away to provide a good indication of what is happening beneath the caldera. It may sense an increase in activity if the volcano becomes very restless, but this may only provide a warning for a large eruption. It might detect activity only after the volcano has started erupting.

A possible way to detect an eruption is studying Silverthrone's geological history since every volcano has its own pattern of behavior, in terms of its eruption style, magnitude and frequency, so that its future eruption is expected to be similar to its previous eruptions. But this would likely be abandoned in part because of the volcano's remoteness.

While there is a likelihood of Canada being critically effected by local or close by volcanic eruptions argues that some kind of improvement program is required. Benefit-cost thoughts are critical to dealing with natural hazards. However, a benefit-cost examination needs correct data about the hazard types, magnitudes and occurrences. These do not exist for volcanoes in British Columbia or elsewhere in Canada in the detail required.

Other volcanic techniques, such as hazard mapping, displays a volcano's eruptive history in detail and speculates an understanding of the hazardous activity that could possibly be expected in the future. At present no hazard maps have been created for the Silverthrone Caldera because the level of knowledge is insufficient due to its remoteness. A large volcanic hazard program has never existed within the Geological Survey of Canada. The majority of information has been collected in a lengthy, separate way from the support of several employees, such as volcanologists and other geologic scientists. Current knowledge is best established at Mount Meager and is likely to rise considerably with a temporary mapping and monitoring project. Knowledge at the Silverthrone Caldera and other volcanoes in the Garibaldi Volcanic Belt is not as established, but certain contributions are being done at least Mount Cayley. An intensive program classifiying infrastructural exposure near all young Canadian volcanoes and quick hazard assessments at each individual volcanic edifice associated with recent seismic activity would be in advance and would produce a quick and productive determination of priority areas for further efforts.

The existing network of seismographs to monitor tectonic earthquakes has existed since 1975, although it remained small in population until 1985. Apart from a few short-term seismic monitoring experiments by the Geological Survey of Canada, no volcano monitoring has been accomplished at the Silverthrone Caldera or at other volcanoes in Canada at a level approaching that in other established countries with historically active volcanoes. Active or restless volcanoes are usually monitored using at least three seismographs all within approximately 15 kilometres (9.3 mi), and frequently within 5 kilometres (3 mi), for better sensitivity of detection and reduced location errors, particularly for earthquake depth. Such monitoring detects the risk of an eruption, offering a forecasting capability which is important to mitigating volcanic risk. Currently the Silverthrone Caldera does not have a seismograph closer than 124 kilometres (77 mi). With increasing distance and declining numbers of seismographs used to indicate seismic activity, the prediction capability is reduced because earthquake location and depth measurement accuracy decreases. The inaccurate earthquake locations in the Garibaldi Volcanic Belt are a few kilometers, and in more isolated northern regions they are up to 10 kilometres (6 mi). The location magnitude level in the Garibaldi Volcanic Belt is about magnitude 1 to 1.5, and elsewhere it is magnitude 1.5 to 2. At "carefully monitored volcanoes both the located and noticed events are recorded and surveyed immediately to improve the understanding of a future eruption. Undetected events are not recorded or surveyed in British Columbia immediately, nor in an easy-to-access process.

In countries like Canada it is possible that small precursor earthquake swarms might go undetected, particularly if no events were observed; more significant events in larger swarms would be detected but only a minor subdivision of the swarm events would be complex to clarify them with confidence as volcanic in nature, or even associate them with an individual volcanic edifice.

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