资源环境科技发展态势分析平台

Lava flow thicknesses, volumes, and effusion rates provide essential information for understanding the behavior of eruptions and their associated deformation signals. Preeruption and posteruption elevation models were generated from historical stereo photographs to produce the lava flow thickness maps for the last five eruptions at Hekla volcano, Iceland. These results provide precise estimation of lava bulk volumes: V1947-1948 = 0.742 +/- 0.138 km(3), V-1970 = 0.205 +/- 0.012 km(3), V1980-1981 = 0.169 +/- 0.016 km(3), V-1991 = 0.241 +/- 0.019 km(3), and V-2000 = 0.095 +/- 0.005 km(3) and reveal variable production rate through the 20th century. These new volumes improve the linear correlation between erupted volume and coeruption tilt change, indicating that tilt may be used to determine eruption volume. During eruptions the active vents migrate 325-480 m downhill, suggesting rough excess pressures of 8-12 MPa and that the gradient of this excess pressure increases from 0.4 to 11Pas(-1) during the 20th century. We suggest that this is related to increased resistance along the eruptive conduit.

Plain Language Summary The sizes of volcanic eruptions are key parameters to understand eruption precursors and eruption hazard scenarios. Hekla is one of Iceland's most active volcanoes and erupted five times (1947-1948, 1970, 1980-1981, 1991, and 2000) during the 20th century. Here we use an archive of historical aerial photographs to reconstruct the topography before and after each eruption in order to provide the first precise lava thickness maps and volume estimates of Hekla volcano. Our results reveal that the last three eruptions ranged significantly in size unlike earlier estimates, indicating that the production rate at the volcano is more variable than previously thought. Furthermore, this suggests that geophysical measurements of the volcano deformation now correlate with the eruption size and therefore may be important to determine eruption size.