{"ID":1224,"name":"Long Valley","location":[{"name":"Canada and Western USA","url":"https:\/\/comet.nerc.ac.uk\/location\/canada-and-western-usa\/","slug":"canada-and-western-usa","id":43,"api_endpoint":"https:\/\/comet.nerc.ac.uk\/wp-json\/volcanodb\/v1\/location\/43"}],"volcano_number":"323822","country":"United States","geodetic_measurements":"Yes","deformation_observation":"Yes","duration_of_observation":"1975 - present","characteristics_of_deformation":"
In the last ~35 years, over 75 cm of uplift has been observed at Long Valley Caldera at an average rate of 3 cm\/yr. Deformation within the caldera is dominated by episodic, symmetrical inflation of the resurgent dome, with no periods of subsidence. Uplift occurred\u00a0in\u00a01978-1983, 1990-1995, 1996, and 1997-1998. This ground deformation has been monitored using an array of ground based instruments including\u00a046 GPS receivers and 9 tiltmeters that make up the network monitoring Long Valley Caldera (http:\/\/earthquake.usgs.gov\/monitoring\/gps\/LongValley\/). Tiltmeters were installed in the early 1980s, with additional instruments added in 2009. The first GPS receiver was installed in\u00a01995, with the network then being updated and modernised between 2006 and 2008. More recently deformation measurements have been made using InSAR. Gravity\u00a0<\/span>surveys reveal a positive anomaly centered on the resurgent dome with peak amplitude of 66 \u00b1 11 \u03bcGal.<\/p>\n Best fitting source models vary between studies: most of the deformation field can be explained by a\u00a0spatially compact inflation source in the form of a near-vertical, pipe-like, prolate ellipsoid, but\u00a0can be equally well fitted by a spatially distributed inflation source. However,\u00a0all datasets suggest that the source is located beneath the resurgent dome at depths 5 – 8 km.\u00a0<\/span>The 1978\u20132004 unrest is associated with the addition of ~0.3 km\u00b3 of material (probably a combination of magma and hydrous fluids) into the brittle crust from the subjacent magma body at a depth of 6 –\u00a07 km beneath the resurgent dome.\u00a0Gravity results indicate a mass increase beneath the resurgent dome with a density in the range 1180 to 2330 kg m\u22123.<\/p>\n","latitude":"37.7","longitude":"-118.87","images":[{"path":"\/nas\/content\/live\/cometnerc\/wp-content\/uploads\/figures_sentinel\/long_valley\/long-valley_137A_05266_171717.jpg","url":"https:\/\/comet.nerc.ac.uk\/wp-content\/uploads\/figures_sentinel\/long_valley\/long-valley_137A_05266_171717.jpg","width":501,"height":668,"mime":"image\/jpeg","size":175939,"filename":"long-valley_137A_05266_171717.jpg"},{"path":"\/nas\/content\/live\/cometnerc\/wp-content\/uploads\/figures_sentinel\/long_valley\/long-valley_144D_05298_131313.jpg","url":"https:\/\/comet.nerc.ac.uk\/wp-content\/uploads\/figures_sentinel\/long_valley\/long-valley_144D_05298_131313.jpg","width":501,"height":660,"mime":"image\/jpeg","size":156360,"filename":"long-valley_144D_05298_131313.jpg"},{"path":"\/nas\/content\/live\/cometnerc\/wp-content\/uploads\/figures_sentinel\/long_valley\/long-valley_064A_05211_131313.jpg","url":"https:\/\/comet.nerc.ac.uk\/wp-content\/uploads\/figures_sentinel\/long_valley\/long-valley_064A_05211_131313.jpg","width":501,"height":669,"mime":"image\/jpeg","size":180446,"filename":"long-valley_064A_05211_131313.jpg"}],"uri":"https:\/\/comet.nerc.ac.uk\/volcanoes\/long-valley\/","api_endpoint":"https:\/\/comet.nerc.ac.uk\/wp-json\/volcanodb\/v1\/volcano\/1224","measurement_methods":"InSAR, GPS - continuous, Levelling, Tiltmeter, EDM, Gravity","inferred_causes":"Hydrothermal, Magmatic","references":["U.S. Geological Survey California Volcano Observatory (CalVO)
\nhttps:\/\/volcanoes.usgs.gov\/volcanoes\/long_valley\/long_valley_monitoring_1.html","Tizzani, P., Battaglia, M., Zeni, G., Atzori, S., Berardino, P., & Lanari, R. (2009). Uplift and magma intrusion at Long Valley caldera from InSAR and gravity measurements. Geology, 37(1), 63-66.","Battaglia, M., & Vasco, D. W. (2006). The search for magma reservoirs in Long Valley Caldera: single versus distributed sources. Geological Society, London, Special Publications, 269(1), 173-180.","Hill, D. P. (2006). Unrest in Long Valley Caldera, California, 1978\u20132004. Troise, C., De Natale, G. & Kilburn, C. R. (Eds.) , Mechanisms of Activity and Unrest at Large Calderas , 269, 1-24 pp. http:\/\/www.geolsoc.org.uk\/gsl\/publications\/bookshop\/page1251.html","Newman, A. V., Dixon, T. H., & Gourmelen, N. (2006). A four-dimensional viscoelastic deformation model for Long Valley Caldera, California, between 1995 and 2000. Journal of volcanology and geothermal research, 150(1), 244-269."],"date_added":"2015-04-10 14:07:31","last_modified":"2015-04-10 14:07:31"}