Laboratory friction experiments on natural samples from IODP site U1520

The northern Hikurangi subduction margin hosts slow slip events (SSEs), which are exceptionally shallow (<15 km). The sedimentary sequence on the incoming plate is therefore representative of the shallow fault material where the SSEs will take place once they enter the subduction zone. Knowledge about the frictional behavior of these sediments is required to know which lithologies are capable of hosting SSEs, and what mechanisms are causing them. Frictional behavior is material-specific and depends on sliding velocity, but it is unknown how these natural sediments behave at plate-rate velocities. We performed laboratory shearing experiments testing the major lithologies sampled during IODP Expedition 375, at velocities ranging from the plate convergence rate at the Hikurangi margin (5 cm/year), up to those characteristic of the shallow SSEs (160 and 530 cm/year), under simulated in-situ as well as standardized conditions. We observe spontaneous laboratory SSEs in the calcareous pelagic sediments, which show partial locking in between sliding events consistent with the interpretation of SSEs within the spectrum of slow to fast earthquakes. This dataset includes the frictional parameters needed to assess the frictional stability of the tested materials, as well as details about the laboratory slip events.