Geological and geobotanical studies of Long Valley Caldera, CA, USA utilizing new 5m hyperspectral imagery

In May of 1989, a six month-long small magnitude earthquake swarm began beneath the Pleistocene-aged dacitic cumulovolcano Mammoth Mountain. The following year, increased mortality of trees in the Horseshoe Lake region was observed. Their deaths were initially attributed to the Sierran drought of the 1980s. In 1994 however, soil gas measurements made by the USGS confirmed that the kills were due to asphyxiation of the vegetation via the presence of 30-96 % CO/sub 2/ in ground around the volcano. Physiological changes in vegetation due to negative inputs into the ecological system such as anomalously high levels of magmatic CO/sub 2/, can be seen spectrally. With this phenomena in mind, as well as many other unanswered geological and geobotanical questions, seven lines of hyperspectral 5-meter HyMap data were flown over Long Valley Caldera located in eastern California on September 7, 1999. HyMap imagery provides the impetus to address geobotanical questions such as where the tree kills are currently located at Mammoth and other locales around the caldera as well as whether incipient kills can be identified. The study site of the Horseshoe Lake tree kills serves as a focus to the initial analyses ofthis extensive HyMap dataset due to both the tree kill's geologically compelling origins and its status as a serious volcanic geohazard.