Calculate the rates of resurfacing by lava in km^2/year (to 3 significant digits

Question

Calculate the rates of resurfacing by lava in km^2/year (to 3 significant digits) for Regions 1 and 2 in Fig. 2 and their average, using your answer from Q7 and the data in Table 2. Calculate the time needed to resurface all of lo (radius = 1821 km) by volcanic flows, assuming that the average rate you show in Table 3 is representative. Show values to 3 significant digits. Surface area of lo = 4(3.142) (1821 hm)^2/=4.17 times 10^7 km^2 Time needed to resurface lo by volcanic flows = ___ (years) Give a reason why the global resurfacing rates you calculated in Table 3 may not be representative for lo as a whole. In your answer, specify whether the actual resurfacing rate be higher or lower than you calculated. Provide an alternative argument showing how the resurfacing rates in Table 3 could be representative for lo as a whole.

Explanation / Answer

(10) Active volcanism from mid-sized hot spots is responsible for about 10% of Io’s heat flow, representing a volume of ~43 km3 of magma erupted per year. Much of that lava is emplaced effusively within paterae, or emplaced on older lava flows. This analysis assumes little or no heat loss by conduction through the lithosphere, a factor strongly dependent on the resurfacing rate. Io is being resurfaced at a prodigious rate, great enough to erase any impact crater to the limit of detection. If the resurfacing rate is 1 cm year-1. It may be that most resurfacing comes not from lava flows but from plume deposits. Even so, if an outburst eruption takes place outside of a patera, then a large area can be covered by lavas. The values derived at table 3 are lower than the actual. Small hot spots, even assuming a number as high as 250 and with an average thermal output of 10 GW, contribute only ~2.5% to Io’s total emission. The rest of the thermal emission, 70% of Io’s heat flow, comes from a) a suite of eruptions conceivably emplaced over the last century resulting in a distribution of cooling flows down to Io’s ambient temperature additional, as yet not quantified, conductive heat transport in and around volcanically active centers.

(11) Active volcanism from mid-sized hot spots is responsible for about 10% of Io’s heat flow, representing a volume of ~43 km3 of magma erupted per year. Much of that lava is emplaced effusively within paterae, or emplaced on older lava flows so there was little contribution to global resurfacing. Io’s surface shows some large flow fields, the Amirani lava flow in solar system. The resurfacing rates are low. The plumes it creates exhibit significant variability. They range from < 100 km to > 460 km in height. Large plumes are associated with high temperature thermal anomalies. This may produce annular deposits more than 1230 km in diameter. The color may be reddish to black color.

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