We performed hourly monitoring of conditions at the Two Towers landslide located in northern California near the town of Zenia. Monitored conditions included rainfall, groundwater head, horizontal total stress, horizontal effective stress, vertical soil deformation, and subsurface displacement. Data were acquired November 11, 2014–July 22, 2017, except for times during which power failure occurred; data for these times are given as “NAN” (not a number). Rainfall data are provided in millimeters during the past hour (mm/hr). Groundwater heads are provided in meters (m) above the landslide base. Horizontal stresses are provided in kilopascals (kPa). Vertical soil deformation data are provided in terms of length (centimeters, cm) of the sensor. Cumulative landslide displacement is provided in millimeters (mm). Rainfall was measured at the landslide middle monitoring location using a tipping-bucket rain gauge with resolution of 0.254 mm and accuracy of ±2% to 250 mm/hr (resolutions and accuracies stated herein are as specified by sensor manufacturers and accounting for datalogger resolution). A vibrating-wire total-stress plate sensor was installed with near-vertical orientation in the floor of an excavated pit at the middle monitoring location. This sensor measured total horizontal stress applied to its 230-mm-diameter surface with resolution of 0.014 kPa and accuracy of ±0.069 kPa. The sensor was installed within a slot slightly wider than the plate itself with its center at a depth of 1.83 m, and a vibrating-wire fluid pressure transducer with the same resolution and accuracy as the total stress sensor was installed adjacent to the cell to measure fluid pressure and therefore provide a means of calculating horizontal effective stress. The pit was backfilled after sensor installation with material removed during its excavation. The remaining sensors were installed within 6.35-cm-diameter holes bored using hand equipment. These included electronic, vibrating-wire fluid pressure transducers (piezometers) with resolutions of 0.014 kPa and 0.086 kPa, and respective accuracies of ±0.069 kPa and ±0.344 kPa. Boreholes were backfilled above transducers first with ~0.3 m of material obtained during boring followed by bentonite granules to the ground surface. Piezometers were installed at depths of 3.66 m and 6.07 m at the upper monitoring location, 3.95 m and 5.69 m at the middle monitoring location, and 2.62 and 3.66 m at the lower monitoring location. Landslide basal depths were identified at approximately 6.3 m, 7.9 m, and 3.6 m at the upper, middle, and lower monitoring locations, respectively. A 30.48-cm-long biaxial tilt sensor installed within PVC casing (slope inclinometer) was used to monitor landslide displacement at the lower monitoring location. The slope inclinometer has 0.003 mm displacement resolution and long-term displacement accuracy of ±0.23 mm. A vibrating-wire length sensor was installed in a borehole to measure near-surface vertical deformation at the middle monitoring location. This sensor measured length with 0.0375 mm resolution and ±0.15 mm accuracy. The sensor’s upper and lower ends were anchored within cement grout such that its length was measured over a depth range (at installation) of 0.20-1.72 m. All sensors contain thermistors and readings are temperature compensated, with the exception of the rain gauge. These data support a study described in Schulz, W.H., Smith, J.B., Wang, G., Jiang, Y., and Roering, J.J., 2018, Clayey landslide initiation and acceleration strongly modulated by soil swelling: Geophysical Research Letters, DOI:10.1002/2017GL076807.

We performed hourly monitoring of precipitation and soil moisture at the Two Towers landslide located in northern California near the town of Zenia. Data were acquired January 19, 2017 to April 29, 2020. Rainfall was measured near the center of the landslide using a tipping-bucket rain gauge with resolution of 0.254 mm and accuracy of ±2% to 250 mm/h (resolutions and accuracies stated herein are as specified by sensor manufacturers and accounting for datalogger resolution). Soil moisture (volumetric ratio of water volume to total volume; unitless) was measured near the center of the landslide using a dielectric sensor installed at 19-cm depth into the wall of a hand-excavated pit that was subsequently backfilled using material obtained during excavation. The soil-moisture sensor utilized factory calibration and has resolution of 0.001 and accuracy of +/- 0.03. These data support a study described in Liao, T.-H., Kim, S.-B., Handwerger, A.L., Fielding, E.J., Cosh, M., and Schulz, W.H., 2021, High-resolution soil moisture maps over landslide regions in northern California grassland derived from SAR backscattering coefficients: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 10.1109/JSTARS.2021.3069010.

This data release provides datasets supporting research on landslides triggered by a series of storms in the San Francisco Bay Area, California, that occurred between December 25, 2022, through January 19, 2023. During this period, eight atmospheric river storms delivered intense and prolonged rainfall across the region, leading to significant hydrological responses and widespread landsliding. Statewide, over 700 landslides were initially reported, with the total count likely exceeding 10,000. This release includes detailed observations from three landslide-prone monitoring sites in urbanized areas of the San Francisco Bay Area, capturing high-resolution time series data on rainfall, soil moisture, and subsurface pore water pressure. These datasets can be used for analyzing the subsurface hydrologic conditions preceding and during landslide events, thereby providing insight into storm-induced landslide triggers and informing future landslide prediction models. The data also support ongoing efforts to improve early warning systems for rainfall-induced landslides in California and other vulnerable regions. The data package includes the following files: 1. CSV Files: Time-series data capturing rain, soil moisture and piezometer measurements for each monitoring site. These files track key variables such as soil volumetric water content and pore water pressure, essential for understanding the hydrologic triggers of landslides. 2. PDF: Geotechnical Properties of Sites: This document presents detailed results from soil classification and hydromechanical testing conducted at each site. The data provide the physical properties of the soil, such as its composition and behavior under stress, which influence landslide susceptibility. 3. PDF: Site Images and Cross-Sections: This file contains a photograph and cross-sectional diagram of each site, offering visual context and structural details for the monitoring locations. These diagrams help illustrate the subsurface geological characteristics relevant to landslide risks. 4. PDF: Location Maps: This document includes a map showing the precise geographic location of each monitoring site within the San Francisco Bay Area, providing context for the collected data regarding regional landslide hazards. 5. CSV Files: Landslide location data for landslides mapped to have occurred during the December 25, 2022, to January 19, 2023, storm sequence near the BALT1 (East Bay), BALT2 (Marin County), and BALT3 (San Francisco Peninsula) monitoring sites. Each dataset includes a unique landslide identifier and the corresponding easting and northing referenced to the North American Datum of 1983 (NAD83) (EPSG:26910) and projected to Universal Transverse Mercator (UTM) Zone 10 North coordinates. These locations represent general landslide locations and should not be misconstrued as the precise headscarp location.

The West Hills of Portland, in the southern Tualatin Mountains, trend northwest along the west side of Portland, Oregon. These silt-mantled mountains receive significant wet-season precipitation and are prone to sliding during wet conditions, occasionally resulting in significant property damage or casualties. In an effort to develop a baseline for interpretive analysis of the groundwater response to rainfall, an automated monitoring system was installed in 2006 to measure rainfall, pore-water pressure, soil suction, soil-water potential, and volumetric water content at 15-minute intervals. The data show a cyclical pattern of groundwater and moisture content levels—wet from October to May and dry between June and September. Saturated soil conditions tend to last throughout the wet season. This release presents data collected from January 10, 2006, through January 23,2017.

This data release includes 2014 time-series data from three debris-flow monitoring stations at Chalk Cliffs in Chaffee County, Colorado, USA. The data were collected to help identify the triggering conditions, magnitude, and mobility of debris flows at the site. The three stations are located sequentially along a channel draining the 0.3 km^2 study area. The Upper, Middle, and Lower stations have respective drainage areas of 0.06, 0.16, and 0.24 km^2. The location (UTM zone 13) of each station is: 396826E/4287851N (Upper), 396893E/ 4287815N (Middle), and 396929E/4287712N (Lower). See also “ChalkStationLocations.jpg” in the README.zip file. The 2014 data includes three types of time series: (1) 1-minute time series of rainfall recorded by tipping bucket rain gages at each station, (2) 10-Hz time series of flow stage recorded by laser distance meters at each station, and (3) 333-Hz time series of ground vibrations and basal normal force at the Upper station only. Ground vibrations were recorded by two 4.5 Hz triaxial geophones separated by 18 m along the channel. Basal normal force was recorded by a 232 cm^2 force plate installed in the bedrock channel bed directly beneath the laser distance meter. The 10-Hz stage data is collected only when it is raining due to data storage limitations. Similarly, the 333-Hz ground motion and force data are provided only during significant flow events. These events occurred on 4 July 2014, 31 July 2014, 1 August 2014, 4 August 2014, and 6 August 2014. The first three events are primarily debris flows and the last two events are debris floods. Note that the rain gage at the Lower station, which is partially shielded by a near-vertical cliff, is used primarily as a trigger for sampling 10-Hz stage data rather than providing an accurate representation of rainfall at the station. Details of the sensors and photos of each station are contained in the “README.zip” file. The file also contains formulas for (1) converting the distance between the laser and the flow surface (or stationary bed surface) to stage above the datum for each station, and (2) converting the raw voltage readings from the geophones and force plate transducer into engineering units of ground velocity and normal force, respectively. Additional details of the study are provided in the journal articles: McCoy, S. W., J. W. Kean, J. A. Coe, G. E. Tucker, D. M. Staley, and T. A. Wasklewicz (2012), Sediment entrainment by debris flows: In situ measurements from the headwaters of a steep catchment, J. Geophys. Res., 117, F03016, doi:10.1029/2011JF002278. Kean, J. W., J. A. Coe, V. Coviello, J. B. Smith, S. W. McCoy, and M. Arattano (2015), Estimating rates of debris flow entrainment from ground vibrations, Geophys. Res. Lett., 42, doi:10.1002/2015GL064811.

We monitored displacement of the Slumgullion landslide located in Hinsdale County, Colorado. We measured displacement at the ground surface between 12 August 2011 and 10 October 2018, and in the subsurface between 4 September 2016 and 7 December 2016. Both types of data were acquired at irregular time intervals. Displacement at the ground surface was measured at locations within the upper, middle, and lower parts of the landslide using electronic cable extension transducers (extensometers) with stated ±0.7 mm accuracy (Extensometer_data.csv). Subsurface displacement was measured near the middle of the landslide using a 16-sensor array of 30.48-cm-long tilt sensors (inclinometer) installed within a PVC-cased borehole. Each tilt sensor has stated 0.003 mm displacement resolution and long-term displacement accuracy of ±0.23 mm. Tilt sensor readings are provided (Inclinometer_data.csv) in terms of horizontal position relative to the array bottom. Sensors were oriented so that position values increased in the general direction of landslide movement and decreased in the opposite direction; the tilt sensor array did not penetrate the landslide base so measurements indicate potential differential displacement within the landslide body. Sensors are numbered from 1 to 16 with 1 being the deepest sensor and 16 being the shallowest. The inclinometer was installed within a depth range of 4.93-9.81 m from 4 September 2016 to 17 October 2016 and within a depth range of 0-4.88 m from 19 October 2016 to 7 December 2016. Data from the deeper installation of 4 September 2016 to 17 October 2016 revealed that differential displacement occurred there, with material at shallower depths having moved farther downslope than deeper material. However, data from the shallower installation of 19 October 2016 to 7 December 2016 revealed a general lack of differential displacement with depth, other than relaxation of backfill around the array that permitted tilting of some sensors in the direction opposite the landslide movement direction. These data support a study described in Hu, X., Bürgmann, R., Schulz, W.H., and Fielding, E.J., 2020, Four-dimensional surface motions of the Slumgullion landslide and quantification of hydrometeorological forcing: Nature Communications, v. 11, 2792, doi:10.1038/s41467-020-16617-7.

This inventory was originally created by Harp and others (1984) describing the landslides triggered by a sequence of earthquakes, with the largest being the M 6.5 Mammoth Lakes, California earthquake that occurred on 25 May 1980 at 19:44:50 UTC. Care should be taken when comparing with other inventories because different authors use different mapping techniques. This inventory includes landslides triggered by a sequence of earthquakes rather than a single mainshock. Please check the author methods summary and the original data source for more information on these details and to confirm the viability of this inventory for your specific use. With the exception of the data from USGS sources, the inventory data and associated metadata were not acquired by the U.S. Geological Survey (USGS) and thus have not been reviewed for accuracy and completeness by the USGS. They are presented as part of this data series for convenience of the user only, as part of an effort to make published ground-failure inventories more accessible from a single aggregated site. No warranty, expressed or implied, is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.

This data release includes time-series data and qualitative descriptions from a monitoring station on a steep, landslide-prone slope above the City of Sitka, Alaska. On August 18, 2015, heavy rainfall triggered around 60 landslides in and around Sitka. These landslides moved downslope rapidly; several were damaging, and one demolished a home on South Kramer Avenue and killed three people. On September 16-18, 2019, the U.S. Geological Survey installed instrumentation at a site near the initiation zones of these landslides and other previous landslides on the west face of Harbor Mountain. The station consists of an electronics enclosure, a mounted rain gage, and two instrumented soil pits. Instruments record continuous measurements of precipitation, air temperature, volumetric water content, pore-water pressure, soil temperature, and soil matric potential at five-minute intervals. Soil pits were dug as deep as possible into the soil mantle for installation of the hydrologic monitoring instruments. Extensive probing with a 1.2-m-long piece of rebar to the point of refusal confirmed that the bottom of each hole was near the top of bedrock or compact till. The first soil pit (SP1), located at N 57.08551, W 135.35936, is about 1 m downslope from the north rim of the drainage hollow. SP1 is about 60 cm deep with the upper 12-15 cm in dark brown, moist, silty sand with large concentration of plant roots. Below 15 cm, to bottom of hole, consists of abundant gray sandstone clasts in silty sand matrix, which ranges in color from orange-brown, brown, to gray. The SP1 sensor array consists of a water potential sensor and soil moisture sensor at 25 cm depth, a second soil moisture sensor at 50 cm depth, and a pressure transducer near bottom of hole with a port at ~55 cm depth. The second soil pit (SP2), located at N 57.08548, W 135.35933, is about 5 m downslope from the north rim of the drainage hollow and is 65 cm deep. The top of hard material (bedrock or till) was about 70 cm deep, but there was free water at a depth of about 50-55 cm. Material throughout the depth of the hole was moist sandy silty clay of a gelatinous consistency. Color ranged from orange-brown to dark brown. Very few stones were present. These soils were interpreted as transported/mixed, weathered volcanic ash (Jacqueline Foss, USDA Forest Service, personal communication, 2019). The SP2 sensor array consists of soil moisture sensors at 25 and 40 cm depth, and a pressure transducer lying on the bottom of the hole, with a port at about 60 cm depth. A Campbell Scientific CR1000 datalogger is used to collect continuous data from these sensors. The datalogger and modem are contained in a sealed, weather-resistant fiberglass enclosure. The CR1000 datalogger contains an internal thermistor that continuously measures temperature. Additionally, an air temperature sensor was installed to collect continuous air temperature data. A tipping bucket rain gage installed in a clearing about 10 m northwest of the logger enclosure collects precipitation data. The maximum resolution of the rain gauge is 0.2 mm; that is, one tip of the bucket represents 0.2 mm. Four METER ECH20 EC-5 sensors are used to collect soil moisture data. Pore-water pressures are measured using two Campbell Scientific CS-451 pressure transducers. A METER MPS-6 water potential sensor in SP1 is used to collect soil matric potential. This sensor’s measurements range from -100,000 to -9 kPa was exceeded for the duration of the monitoring period. Recorded values appear to hover around the sensor’s upper limit (-9 kPa), with the exception of September 2019 when the station was first installed and a few brief periods in July 2022 when conditions were sufficiently dry for matric potentials to drop below -9 kPa. The water potential sensor and pressure sensors have integrated thermistors and the associated temperature readings are included. Several factors that may influence data consistency and/or quality should be

This data release contains (1) geotechnical reports describing colluvium strength and grain size distribution, (2) hydrological monitoring data (rainfall and soil volumetric water content), and (3) shapefiles of mapped landslides from 1996 and 2021 that occurred in the Columbia River Gorge, Oregon. The geotechnical reports describe test results from a sieve and hydrometer analysis (ASTM D422) to characterize the grain size distribution and from consolidated drained direct shear tests (ASTM D3080) to characterize soil shear strength. Hydrological data includes a time history of rainfall and volumetric water content from a monitoring station in the Columbia River Gorge, spanning 10/28/2022 to 2/13/2023. The mapped landslide shapefiles represent shallow landslide source areas, assumed to have failed during storms in 1996 and 2021.

This data release includes time-series data of rock temperature, air temperature, wind speed, and humidity at the Chalk Cliffs debris-flow monitoring site in central Colorado (Latitude: 38.73330, Longitude: -106.18704). The data were collected to help identify the environmental controls on rates of rockfall, which is the primary source of debris-flow material at the site. Data were recorded at 1-minute intervals between November 2011 and August 2015. Data collection was occasionally interrupted during maintenance periods or when there was a problem with the power supply. Two probes measured profiles of rock temperature at depths of 0, 1, 2, 4, 8, 16, 24, 32, and 42 cm below the rock surface. One probe was placed on a south-facing rock slope, the other probe was on a north-facing rock slope. See photo “SensorLocations.jpg” for layout of sensors. Occasional malfunctions in the temperature sensor are identified by “NAN” readings or anomalous low temperatures (<-50 degrees Celsius). Time stamps are in standard Mountain time. Details of this study are described in the journal article: Rengers, F. K., Kean, J. W., Reitman, N. G., Smith, J. B., Coe, J. A.,and McGuire, L. A. ( 2020). The Influence of Frost Weathering on Debris Flow Sediment Supply in an Alpine Basin. Journal of Geophysical Research: Earth Surface, 125, e2019JF005369. https://doi.org/10.1029/2019JF005369