Field investigations and aerial photography after the earthquake of May 12,2008 show a large number of geo-hazards in the zone of extreme earthquake effects.In particular,landslides and debris flows,the geo-hazards that most threaten post-disaster reconstruction,are widely distributed.We describe the characteristics of these geo-hazards in Beichuan County using high-resolution remote sensing of landslide distribution,and the relationships between the area and volume of landslides and the peak-discharges of debris flows both pre-and post-earthquake.The results show:1) The concentration(defined as the number of landslide sources per unit area:Lc) of earthquaketriggered landslides is inversely correlated with distance from the earthquake(DF) fault.The relationship is described by the following equation:Lc = 3.2264exp(-0.0831DF)(R2 = 0.9246);2) 87 % of the earthquake-triggered landslides were less than 15×104 m2 in area,and these accounted only for 50% of the total area;84% of the landslide volumes were less than 60×104 m3,and these accounted only for 50% of the total volume.The probability densities of the area and volume distributions are correlated:landslide abundance increases with landslide area and volume up to maximum values of 5 × 104 m2 and 30 × 104 m3,respectively,and then decreases exponentially.3) The area(AL) and volume(VL) of earthquake-triggered landslides are correlated as described with the following equation:VL=6.5138AL1.0227(R2 = 0.9131);4) Characteristics of the debris flows changed after the earthquake because of the large amount of landslide material deposited in the gullies.Consequently,debris flow peak-discharge increased following the earthquake as described with the following equation:Vpost = 0.8421Vpre1.0972(R2 = 0.9821)(Vpre is the peak discharge of pre-earthquake flows and the Vpost is the peak discharge of post-earthquake flows).We obtained the distribution of the landslides based on the above analyses,as well as the magnitude of both the landslides and the post-earthquake debris flows.The results can be useful for guiding post-disaster reconstruction and recovery efforts,and for the future mitigation of these geo-hazards.However,the equations presented are not recommended for use in site-specific designs.Rather,we recommend their use for mapping regional seismic landslide hazards or for the preliminary,rapid screening of sites. Field investigations and aerial photography after the earthquake of May 12,2008 show a large number of geo-hazards in the zone of extreme earthquake effects.In particular, landslides and debris flows, the geo-hazards that most threaten post-disaster reconstruction, are widely distributed.We describe the characteristics of these geo-hazards in Beichuan County using high-resolution remote sensing of landslide distribution, and the relationships between the area and volume of landslides and the peak-discharges of debris flows both pre-and post-earthquake The results show: 1) The concentration (defined as the number of landslide sources per unit area: Lc) of earthquaketriggered landslides is inversely correlated with distance from the earthquake (DF) fault.The relationship is described by the following equation: Lc = 3.2264exp (-0.0831DF) (R2 = 0.9246); 2) 87% of the earthquake-triggered landslides were less than 15 × 104 m2 in area, and these accounts only for 50% of the total area; 84% of the landsli de volumes were less than 60 × 104 m3, and these accounts only for 50% of the total volume. The probability densities of the area and volume distributions are correlated: landslide abundance increases with landslide area and volume up to maximum values ​​of 5 × 104 m2 and 30 × 104 m3, respectively, and then decreases exponentially.3) The area (AL) and volume (VL) of earthquake-triggered landslides are correlated as described with the following equation: VL = 6.5138AL1.0227 (R2 = 0.9131 ); 4) Characteristics of the debris flows changed after the earthquake because of large amount of landslide material deposited in the gullies. Reconstructed debris flow peak-discharge increased following the earthquake as described with the following equation: Vpost = 0.8421Vpre 1.0972 (R2 = 0.9821) (Vpre is the peak discharge of pre-earthquake flows and the Vpost is the peak discharge of post-earthquake flows) .We obtained the distribution of the landslides based on the above analyzes, as well as the magnitude of both t he landslides and the post-earthquake debris flows.The results can be useful for guiding post-disaster reconstruction and recovery efforts, and for the future mitigation of these geo-hazards. However, the equations presented are not recommended for use in site-specific designs Rather, we recommend their use for mapping regional seismic landslide hazards or for the preliminary, rapid screening of sites.