[1] The shortening between the African and the Iberian plates is absorbed by a number of faults distributed over a very wide zone with very low slip rates and long periods of seismic loading. Thus a seismotectonic map based only on faults associated with seismicity or with expressive geomorphic features is incomplete. It is possible to characterize seismogenic faults using paleoseismology. First, paleoseismological results based on trenching analysis in the eastern Betics (Lorca-Totana segment of the Alhama de Murcia fault) are presented. The main paleoseismic parameters of this fault segment are (1) a minimum of two to three M w 6.5-7 earthquakes in the last 27 kyr (shortly before 1650 A.D., between 830 and 2130 B.C. and shortly before 16.7 ka, respectively), with a mean recurrence period of 14 kyr, and a very short elapsed time, and (2) a net slip rate of 0.07-0.6 mm/yr during the last 30 kyr. These results were extrapolated to the rest of the known active faults in the eastern Betics and were added to the slip rates of the active faults at the African margin. The total slip rate of the transect, which crosses de Alhama de Murcia fault in Spain and reaches the Cheliff basin (Algeria), would represent 21-82% of the total shortening between Africa and Eurasia estimated from plate motion models and seismic moment summation. A number of factors could account for this discrepancy: (1) hidden seismogenic faults in the emerged areas, (2) absence of correlation between current and late Pleistocene slip rates, (3) extensive small faults that are undetected and that absorb a significant amount of the deformation, and (4) possible overestimation of the convergence rates.

The northeast-striking, dextral-reverse Alpine fault transitions into the Marlborough Fault System near Inchbonnie in the central South Island, New Zealand. New slip-rate estimates for the Alpine fault are presented following a reassessment of the geomorphology and age of displaced late Holocene alluvial surfaces of the Taramakau River at Inchbonnie. Progressive avulsion and abandonment of the Taramakau fl oodplain, aided by fault movements during the late Holocene, have preserved a left-stepping fault scarp that grows in height to the northeast. Surveyed dextral (22.5 ± 2 m) and vertical (4.8 ± 0.5 m) displacements across a left stepover in the fault across an alluvial surface are combined with a precise maximum age from a remnant tree stump (≥1590-1730 yr) to yield dextral, vertical, and reverse-slip rates of 13.6 ± 1.8, 2.9 ± 0.4, and 3.4 ± 0.6 mm/yr, respectively. These values are larger (dextral) and smaller (dip slip) than previous estimates for this site, but they refl ect advances in the local chronology of surfaces and represent improved time-averaged results over 1.7 k.y. A geological kinematic circuit constructed for the central South Island demonstrates that (1) 69%-89% of the Australian-Pacifi c plate motion is accommodated by the major faults (Alpine-Hope-Kakapo) in this transitional area, (2) the 50% drop in slip rate on the Alpine fault between Hokitika and Inchbonnie is taken up by the Hope and Kakapo faults at the southwestern edge of the Marlborough Fault System, and (3) the new slip rates are more compatible with contemporary models of strain partitioning presented from geodesy.

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Most catastrophic earthquakes occur along fast-moving faults, although some of them are triggered by slow-moving ones. Long paleoseismic histories are infrequent in the latter faults. Here, an exceptionally long paleoseismic record (more than 300 k.y.) of a slow-moving structure is presented for the southern tip of the Alhama de Murcia fault (Eastern Betic shear zone), which is characterized by morphological expression of current tectonic activity and by a lack of historical seismicity. At its tip, the fault divides into a splay with two main faults bounding the Góñar fault system. At this area, the condensed sedimentation and the distribution of the deformation in several structures provided us with more opportunities to obtain a complete paleoseismic record than at other segments of the fault. The tectonic deformation of the system was studied by an integrated structural, geomorphological, and paleoseismological approach. Stratigraphic and tectonic features at six paleoseismic trenches indicate that old alluvial units have been repeatedly folded and thrusted over younger ones along the different traces of the structure. The correlation of the event timing inferred for each of these trenches and the application of an improved protocol for the infrared stimulated luminescence (IRSL) dating of K-feldspar allowed us to constrain a paleoseismic record as old as 325 ka. We identifi ed a minimum of six possible paleoearthquakes of M w = 6-7 and a maximum mean recurrence interval of 29 k.y. This provides compelling evidence for the underestimation of the seismic hazard in the region.