Dfyjkt

I would like the numbers to be aligned by multiplication signs on this table. I have tried to use the option table-format in what it looks like the right way to me, but actually I haven't found any explanation about it in the booktabs documentation.

Are there other options I could use? And do you also know where to find a good documentation about them?

documentclassarticle
usepackagebooktabs
usepackagesiunitx

begindocument
begintable[h!]
 centering
 begintabularlS[table-format=-1.1e-1]S[table-format=-1.1e-1]
 toprule
 & $m$ & $q$ \
 midrule
 Total death toll & num-9.8e-5 & num2.0e-1 \
 Climatic hazards & num-1.0e-4 & num2.1e-1 \
 Earthquakes & num6.0e-6 & num-1.1e-2 \
 Mass movements & num-1.8e-8 & num5.1e-5 \
 Volcanic hazards & num-2.7e-7 & num5.4e-4 \
 bottomrule 
 endtabular
captionFit parameters for death toll per population and per year for the classes of geohazards.
labelt1
endtable

enddocument

You have nearly got it! You need to remove the num... and just have the number.
See example below. For package documentation I like to use CTAN

documentclassarticle
usepackagebooktabs
usepackagesiunitx

begindocument
begintable[h!]
 centering
 begintabularlS[table-format=-1.1e-1]S[table-format=-1.1e-1]
 toprule
 & $m$ & $q$ \
 midrule
 Total death toll & -9.8e-5 & 2.0e-1 \
 Climatic hazards & -1.0e-4 & 2.1e-1 \
 Earthquakes & 6.0e-6 & -1.1e-2 \
 Mass movements & -1.8e-8 & 5.1e-5 \
 Volcanic hazards & -2.7e-7 & 5.4e-4 \
 bottomrule 
 endtabular
captionFit parameters for death toll per population and per year for the classes of geohazards.
labelt1
endtable

enddocument