Piton de la Fournaise, elasto-plastic models of stresses and deformation accounting for the topographic load and a magmatic injection
<p><span>Building on previous work aimed at identifying and characterizing the potential mechanical </span><span>trigger</span><span> controlling eruptions and destabilization at Piton de la Fournaise, we study the mechanical behavior of the </span><span>volcanic edifice</span><span> on a crustal scale. Do </span><span>the</span> <span>recurrent </span><span>earthquake </span><span>pattern</span><span> correspond to a destabilization structure, precursor </span><span>of</span><span> a large-scale flank slid</span><span>ing</span><span>? </span><span>Or instead to a</span><span> reactivated </span><span>area of </span><span>magma storage (partially crystallized &#8220;sill&#8221;)? To answer these questions, we design numerical models which estimate the stress field associated with the volcanic complex. We use the ADELI finite element method in three dimensions, which handles</span> <span> elasto-visco-plastic rheolog</span><span>ies</span><span>. In these models, we take into account 1) the topographic </span><span>load</span><span>, 2) the major density and resistance heterogeneities within the volcano obtained from previous studies, and 3) the </span><span>overpressure induced by the </span><span>in</span><span>tr</span><span>usion of a dike of arbitrary geometry.<br>The model</span><span>ed dike </span><span>injection generates deformation and stress fields such that their </span><span>isocontours</span><span> highlight an ellipsoidal cup structure </span><span>extending </span><span>from the central cone to a depth close to 0 and reaching the ends of the eastern flank. This zone could be assimilated to the zone of seismicity observed and described previously. </span><span>Toget</span><span>h</span><span>er with several systematic test cases, w</span><span>e will discuss the significance of these results, </span><span>such as whether</span><span> it </span><span>reveals</span><span> a rheological delimitation zone of the hydrothermalized </span><span>bed</span><span>rock, </span><span>resulting from</span><span> the combin</span><span>ed</span><span> influence of the topographic load and that of a magmatic injection.</span></p>