Page 11 - Ragg_et_al-1999-Tectonics

RACK}ET AL.: TECTONIC STRESSIN SICILY 679

10' 12'- 14' 16' 18'

42' 42"

Method:

focal mechanism

40' 40'

D -- .d •,R '•..."..•.•.:.•:.•.. /

• macinollisfrion[ t • 38'

38' Ionian Sea

/

• Malta36' 36'

34' "..•.•.."."..•.•.'.•..•.•.•.•..•.•..... 34'
........•.........,•.•..•... .••••

10' 12' 14' 16' 18'

__

Figure 10. Map of the maximum horizontalcrustal stress(SHmax) orientationin the central Mediterranean
(datatakenfromtheEuropeanStressMap (Miiller et al. [1992],Rebaiet al. [1992], andfromthisstudy).The
differentsymbolsstandfor differenttypesof stressindicatorswhile the lengthof the arrowsis linkedto the
dataquality [Zoback,1992]. NF, normalfaults;SS, strikeslip faults;TF, thrustfaults;U, unknowntectonic
regime.The insetshowsthe locationmap of the areawithin the Mediterranean.

Seismicprofilessuggesta subdivisionof the cru'stinto four andTyrrhenianSeas,(3) thickenedcrust(about35 km) under
different crustaltypes (see Figure 11) [Ben-Avrahamet al., Sicily through continent-continent collision and under
1995; Liischenet al., 1992]. We distinguish(1) a thinned Calabria throughsubduction,and (4) normal continentalcrust
continentalcrust (under 25 km) in the Strait of Sicily, (2) (between 25 and 35 km).
normal oceanic crust (10-15 km) in the center of the Ionian
Vertically, the continental crust is subdivided into