E arthquakes cause immediate damage to mountain forests 1 , 2 , largely through earthquake-triggered landslides 2 , 3 which can completely strip hillsides of vegetation and soil 4 . Earthquakes have thus been viewed as a potential source of carbon dioxide (CO 2 ) over the years that follow, owing to the direct forest damage and subsequent degradation of organic matter 1 , 2 , 5 . However, in steep mountain catchments, landslide debris can be transported rapidly to rivers 6 and buried within lake, delta or marine deposits 7 – 9 . Active mountain belts are therefore thought to play an important role in setting the global discharge of biospheric organic carbon derived from vegetation and soil (OC biosphere ) by rivers of ~ . −. +. 01 6 00 5 00 7 PgC yr − 1 (refs 10 , 11 ) and promote efficient organic carbon burial owing to high sediment loads, thereby contributing to sequestration of CO 2 over geological timescales 8 , 10 , 12 . It has proved difficult to quantify the long-term role of earthquakes in OC biosphere export because they are unpredictable and infrequent, and sediment export after large earthquakes occurs over decades or longer 13 , 14 . If large earthquakes are not accounted for, then short-term measurements of OC biosphere export by rivers 10 , 11 may be underestimated and fail to capture large transient changes in carbon fluxes over decadal timescales. The immediate impacts of earthquake-triggered landslides have been observed in the sediment loads of numerous rivers 13 – 15 . Comparison with longer-term denudation rates shows that earth - quake-triggered landslides can account for a significant part of total denudation over 10 2 –10 6 years (refs 16 – 18 ). The only quanti - tative study of OC biosphere fluxes comes from the 2008 Wenchuan earthquake 19 , mainly owing to the need for river samples before and after the event. There, OC biosphere discharge by the Sanping River doubled in the 4 years after the earthquake 19 , but the brevity of the historical record meant that the roles of multiple earthquakes in driving OC biosphere export and CO 2 sequestration over longer times - cales could not be determined. We address this using the sedimen - tary archive in Lake Paringa (Fig. 1 ), western Southern Alps, New Zealand 20 . The tectonic and geomorphic setting 21 – 23 , climate 24 and extensive vegetation cover 25 make this an ideal location to quantify the impact of repeated earthquakes on biogeochemical cycles.
