PRELIMINARY INVESTIGATION OF MUD VOLCANISM USING SPRUCE TREES: KLAWASI GROUP, COPPER RIVER BASIN, ALASKA

Mud volcanism, or eruptions of water-laden mud and gases, is a comparatively benign geological phenomenon, which occasionally impacts the human environment. As a result, multiple methods have been introduced to monitor and forecast eruption activity, such as discharge measurements and remote-sensing techniques to track volume and thermal changes to these edifices. Because of their restricted settings, there is very little information on eruption history—tree-ring science may prove useful in providing some temporal depth to eruption frequency. Three samples of dead, mud-encased, white-spruce (Picea glauca) snags were collected from Lower Klawasi (LK), Upper Klawasi (UK), and Shrub (Sh) mud volcanoes (Klawasi Group) on the western flank of Mt. Drum, Copper River Basin of the Wrangell-St. Elias National Park and Preserve in southcentral Alaska. Samples were prepared for analyses and processed using a combination of Cybis.se, XDateR, COFECHA, and ARSTAN computer programs. The resulting floating, master chronology spanned 109 years. Dating (1859-1957) was corroborated with five Picea sp. published master chronologies (i.e., AK11, AK15, AK20, AK73, AK77) and revealed death dates: LK_d=1918, UK_d=1933, and Sh_d=1957. Each sample exhibits suppressed terminal growth rings approximately five years before death. This suppression may indicate that death dates represent death after a period of senescence due to encasement of the tree bole by eruptive muds and/or changes in groundwater temperature and/or gas composition(s). Eruptive dates, therefore, are likely: LK_e=1914, UK_e=1929, and Sh_e=1951. All projected eruption dates antedate observations by multiple years. Additional work needs to be completed where the master chronology is compared to the non-eruptive chronologies to tease out even earlier eruptive activity. If conditions allow, tree-ring science can provide chronological depth to mud-volcanic activity; thereby, increasing confidence in the monitoring and forecasting efforts underway at many of these unique geological sites.