The Gemmi Fault has offset moraine scree deposits, indicating Quaternary fault activity; this observation was also made during trenching. It has been active in post-glacial time. Luminescence dating has yielded ages of 8,700±2,000 and 2,400±500 years, which have been interpreted as either two earthquakes or as an upper limit to the age of the last fault movement. This implies that the Gemmi Fault was active during the Holocene. Earthquakes frequently cause multiple rock slides during each event, and a number of such rockslides are documented from Switzerland. Rock slides in the Kander valley and at Rinderhorn appear to be contemporaneous about 9,800-9,600 years ago within dating uncertainty, and sediment deposits within Lake Lucerne and Lake Seelisberg indicate that an earthquake with magnitude exceeding 6 took place 9,870-9,960 years ago. The Gemmi Fault is located within the area and has an earthquake that took place 8,700±2,000 years ago; however earthquakes in Switzerland often are not bound to specific fault systems. Climatic triggers of clustered rockslides are possible but speculative. The movement direction of the Gemmi Fault is congruent with the regional tectonic stress field, which is supported by the kinematics of regional earthquakes which form a cluster that lies south of the fault. The magnitude of earthquakes associated with the Gemmi Fault may have reached 5.5-5.8, intensities comparable to these of other earthquakes in Switzerland. References Sources Geology of Switzerland Earthquakes in Switzerland Natural history of Switzerland Seismic faults of Europe Strike-slip faults