We present a detonating failed deflagration model of Type Ia supernovae .
In this model , the thermonuclear explosion of a massive white dwarf follows an off-center deflagration .
We conduct a survey of asymmetric ignition configurations initiated at various distances from the stellar center .
In all cases studied , we find that only a small amount of stellar fuel is consumed during deflagration phase , no explosion is obtained , and the released energy is mostly wasted on expanding the progenitor .
Products of the failed deflagration quickly reach the stellar surface , polluting and strongly disturbing it .
These disturbances eventually evolve into small and isolated shock-dominated regions which are rich in fuel .
We consider these regions as seeds capable of forming self-sustained detonations that , ultimately , result in the thermonuclear supernova explosion .

Preliminary nucleosynthesis results indicate the model supernova ejecta are typically composed of about 0.1 - 0.25 ~ { } M _ { \odot } of silicon group elements , 0.9 - 1.2 ~ { } M _ { \odot } of iron group elements , and are essentially carbon-free .
The ejecta have a composite morphology , are chemically stratified , and display a modest amount of intrinsic asymmetry .
The innermost layers are slightly egg-shaped with the axis ratio \approx 1.2 - 1.3 and dominated by the products of silicon burning .
This central region is surrounded by a shell of silicon-group elements .
The outermost layers of ejecta are highly inhomogeneous and contain products of incomplete oxygen burning with only small admixture of unburned stellar material .
The explosion energies are \approx 1.3 - 1.5 \times 10 ^ { 51 } erg .