Rates and factors of stratovolcano degradation in a continental climate: a complex morphometric analysis for nineteen Neogene/Quaternary crater remnants in the Carpathians

The systematic age progression of the Neogene/Quaternary volcanic chain in the Carpathians, manifested in progressively degraded stratovolcanoes from south to north, offers a great opportunity to calculate erosion rates and the factors that control degradation in a moderate continental climate. Using available and newly determined KAr ages for the cessation of volcanism of nineteen stratocones, a great number of morphometric variables, including crater diameter and perimeter, intracraterial valley length, valley order and density, dip of internal and external crater rim, cone diameter, relative height/cone diameter, height above and distance from base level, etc., has been examined by regression and factor analyses. On the one hand, the erosion rates which are calculated from the regression equations of a given characteristic versus age seem to answer the question of to what extent the stratovolcanoes are degraded: numerical values of crater enlargement (109 m/Ma), internal valley growth (1.3 km/Ma), average cone lowering (31.5 m/Ma), etc., are given. Moreover, using multiple regression equations as “age equations”, the age of any volcano in the same climate can be estimated from the measured characteristics. On the other hand, there are morphometric characteristics (e.g., dip of crater rim, crater circularity, intracraterial valley density) which are not functions of time. Three major factors, i.e., the “time factor” (about 40%), the “size-depth” factor (about 24%), and the “erosional distance” factor (about 10%) account for about 75% of the stratovolcano characteristics variance, and two additional factors (eruption style-magma viscosity, and the central manifestation of volcanism) may be responsible for a further 13%.