RELATIONSHIPS BETWEEN VOLCANIC CINDER CONE ANGLE AND AGES: A POTENTIAL DIAGNOSTIC TOOL FOR ESTIMATING QUATERNARY ERUPTION AGES AND VOLCANIC HAZARDS

The Potrillo Volcanic Field (PVF) is a 50 km² field located in southern Doña Ana County, New Mexico, and consists of maars, fissure flows, shield volcanoes, and over 150 cinder cones. Volcanic activity ranges from 916±67 ka to 20±4 ka. The study focuses on the correlation between cinder cone angle and age. In this arid climate, cone degradation is a product of mechanical weathering, and may be quantitatively modeled by diffusion equations. The quantitative model gives insight into eruptive characteristics and potential volcanic hazards for recent cinder cone fields. Data were obtained by overlaying digital topographic maps (DRGs), digital elevation models (DEMs), and a Landsat image into Global Mapper software. The average radius (for a closed contour on the slope of the cone) and height (the difference between the peak elevation and the elevation of the closed contour used for radius) were determined for each cinder cone. The expression Θ = tan^-1(h/r) was used to obtain the angle, where r is the radius and h is the height. 128 cinder cone angles were calculated; 95% of which have angles between 4 and 15 degrees. The remaining features were excluded due to complex geometries, such as nested clusters. The range of angles (4-15 degrees) is limited, and none are as steep as the angle of repose (35 degrees), which we estimate from Paricutin, Mexico (MEX), which last erupted in 1952. ³He and ⁴⁰Ar/³⁹Ar ages establish that the cones in the PVF represent volcanic activity from 350 ka to 100 ka. Other angle-age studies in arid climates contribute to our analysis because they reflect different time ranges. Capulin (NM) has been dated at 55 ka, the Chichináutzin Group (MEX) ranges from 38.59 to 8.44 ka, and the Colima Complex (MEX) from 16.5 to 1.5 ka. Combining the data from these fields with ours results in an exponential relationship between cone angle and age, reinforcing the viability of diffusion modeling. Future work will focus on utilizing data from other cinder cone fields where angle-age data exist to test the validity of our exponential power law. This can in turn be used as a predictive tool for cinder cone fields that lack age information. A space-time analysis will also be done for the Potrillo Volcanic Field by deconvoluting our current cumulative histogram.