Monitoring data from the Aleppo rockslide, Allegheny County, Pennsylvania, November 2013 - December 2018

Dates

Publication Date: 2021-06-01
Start Date: 2013-11-06
End Date: 2018-12-31

Citation

Ashland, F.X., 2021, Monitoring data from the Aleppo rockslide, Allegheny County, Pennsylvania, November 2013 - December 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9BHFXFS.

Summary

Upon reactivation, movement of deep-seated landslides in the Greater Pittsburgh region may persist for long periods of time. Monitoring equipment was located at two sites on a deep-seated rockslide in Aleppo Township, Pennsylvania to establish relationships between precipitation and changes in the state of activity and velocity. Precipitation, snow depth, and air temperature are monitored at a weather station (ARS_WS) located in a relatively flat, open area in the northern part of the rockslide. Displacement and soil moisture are monitored at a second site located in the southern part of a graben (ARS_GR) in the head of the rockslide. At ARS_WS, instrumentation includes a tipping bucket rain gauge, temperature probe, and a sonic ranging [...]

Summary

Upon reactivation, movement of deep-seated landslides in the Greater Pittsburgh region may persist for long periods of time. Monitoring equipment was located at two sites on a deep-seated rockslide in Aleppo Township, Pennsylvania to establish relationships between precipitation and changes in the state of activity and velocity. Precipitation, snow depth, and air temperature are monitored at a weather station (ARS_WS) located in a relatively flat, open area in the northern part of the rockslide. Displacement and soil moisture are monitored at a second site located in the southern part of a graben (ARS_GR) in the head of the rockslide. At ARS_WS, instrumentation includes a tipping bucket rain gauge, temperature probe, and a sonic ranging sensor, and at ARS_GR instrumentation includes two cable extension transducers and a soil moisture probe.

This data release presents the time series data from this instrumentation for an initial monitoring period starting on November 6, 2013 and ending on December 31, 2018. The data release generally presents the output for each sensor type as recorded on the datalogger, except in one case, for which the output requires conversion to engineering units and the factor necessary to make this conversion is provided.

ARS_WS instrumentation

Rain gauge: The rain gauge at ARS_WS has a resolution of 0.01 inch (in.) and an accuracy of 1 percent for rainfall intensities up to 2 in/hr. Initially, rainfall was recorded by a Hobo event datalogger and each event was equal to 0.01 in. Beginning on November 18, 2016, 15-minute (min) rainfall totals were recorded by a Campbell Scientific CR1000 datalogger. The rain gauge collector is subject to periodic clogging due to vegetative debris and insect activity. This type of rain gauge is not designed to accurately measure the snow water equivalent of snow fall and likely underestimates precipitation during the winter. Maintenance of the rain gauge is only performed periodically during site visits to retrieve data, install or maintain equipment, or perform other work. No field calibration was performed on the rain gauge.

Snow depth sensor: Snow depth is measured using a sonic ranging sensor that has a resolution of 0.25 millimeters (mm) (0.01 in.) and a stated accuracy of 1 centimeter (cm) based on the height of the sensor, which was installed 1.68 meters (m) above the ground. Measurements are recorded on an hourly interval. Quality numbers (Q) provide additional information about snow depth measurement certainty. An explanation of the quality number ranges is included as a separate text file (QualityNos_SnowDepth_ReadMe.txt). In May 2015, a square meter (m²), flat measurement area covered with locally derived claystone fragments was constructed beneath the sensor. Periodic maintenance of the site entails removing vegetation from this and the surrounding area in the fall prior to the initial snow fall.

Air temperature probe: Air temperature is measured using a temperature probe housed in 6-plate solar radiation shield. The probe consists of a thermistor in an epoxy-filled aluminum housing. The probe has a stated measurement range of -30^oC to +50^oC with no more than 0.01^oC error over this range. Average air temperature is recorded at 15-min intervals.

ARS_WS_DATA.xlsx contains three worksheets labeled EVENT, 15MIN, and 1HR. The EVENT worksheet contains the following fields: TIMESTAMP_EST - records the timestamp in the format mm/dd/yyyy hh:mm, Eastern Standard Time; and EVENT – records precipitation, where each event equals 0.01 in. The 15MIN worksheet contains the following fields: TIMESTAMP_EST - records the timestamp in the format mm/dd/yyyy hh:mm, Eastern Standard Time; AT_Avg – records the average air temperature in degrees Celsius; PRCP_Tot – records the total precipitation in inches; and BV_Avg – records the average battery voltage in volts. The 1HR worksheet contains the following fields: TIMESTAMP_EST - records the timestamp in the format mm/dd/yyyy hh:mm, Eastern Standard Time; AT_Avg – records the average air temperature in degrees Celsius; DT_Avg – records the average distance to target in meters; Q_Avg -records the quality number; TCDT_Avg – records the average temperature corrected distance to target in meters; and SD_Avg – records the snow depth (when snow is present) in meters.

ARS_GR Instrumentation

Cable extension transducers: Displacement and ground surface rotation is monitored at two locations near the margins of the graben using cable extension transducers (CETs) that have a 152-cm (60-in.) range and an accuracy of 0.1 percent of full stroke (potential deviations may range up to 1.5 mm). Both CETs are mounted above the ground surface on a 5.1-cm (2-in.) diameter stainless steel pole that is grouted approximately 90 cm deep into the slope colluvium and uppermost weathered/fractured claystone. An Invar wire attached to the factory-installed cable on each CET provides the required additional length to reach the anchor point. At the first location (CET01_MS), the anchor point consists of a stainless-steel eyebolt grouted into the sandstone exposed in the main scarp free face. At the second location on the western margin of the graben (CET02_AS), the cable is anchored to a stainless-steel pole grouted into the antithetic (upslope-facing) scarp slope. The CET data may be affected by falling tree limbs throughout the year and cable icing in winter. The average eyelet position (or amount of cable extension), measured in cm, is recorded at 15-min intervals.

Soil moisture probe: The volumetric water content (VWC) of the shallow colluvial deposit is measured using water content reflectometer. The probe derives VWC from its sensitivity to dielectric permittivity and has an accuracy of approximately ±3 percent. The probe was inserted into the upslope wall of shallow hand-excavated test pit using an insertion guide tool to create two parallel holes for the probe rods. The probe was installed at a depth of 20 cm, a depth approximately half the total thickness of the colluvium at that location. The pit is located approximately 4 m downslope from the stress relief joint that is the main scarp free face. The average slope of the ground surface is about 18 percent (10 degrees). Average volumetric water content in meters³/meters³(m³/m³), electrical conductivity in deciSiemens/meter (dS/m), and soil temperature (°C) are recorded at either 15-min or hourly intervals.

ARS_GR_DATA.xlsx contains two worksheets labeled 15MIN and 1HR. The 15MIN worksheet contains the following fields: TIMESTAMP_EST - records the timestamp in the format mm/dd/yyyy hh:mm, Eastern Standard Time; CET01_MS_Avg – records the average extension at cable extension transducer CET01_MS in cm; CET02_AS_Avg – records the average extension at cable extension transducer CET02_AS in cm; VWC_20_Avg – records the average volumetric water content at a depth of 20 cm in m³/m³; EC_20_Avg – records the average electrical conductivity at a depth of 20 cm in dS/m; ST_20_Avg – records average soil temperature at a depth of 20 cm in °C; and BV_Avg – records the average battery voltage in volts. The 1HR worksheet contains the following fields: TIMESTAMP_EST - records the timestamp in the format mm/dd/yyyy hh:mm, Eastern Standard Time; VWC_20_Avg – records the average volumetric water content at a depth of 20 cm in m³/m³; EC_20_Avg – records the average electrical conductivity at a depth of 20 cm in dS/m; and ST_20_Avg – records average soil temperature at a depth of 20 cm in °C.

Details of this study are described in the journal article: Ashland, F. X., and Delano, H. L., 2015, Continuous monitoring of meteorological conditions and movement of a deep-seated, persistently moving rockslide along Interstate Route 79 near Pittsburgh: Pennsylvania Geology, v. 45, no. 2, p. 22–26.

Liability

Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), 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. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Contacts

Point of Contact :: Francis Ashland, Florence Bascom Geoscience Center
Originator :: Ashland, Francis X.
Metadata Contact :: Francis Ashland, Florence Bascom Geoscience Center
Publisher :: U.S. Geological Survey
Distributor :: U.S. Geological Survey - ScienceBase
SDC Data Owner :: Florence Bascom Geoscience Center
USGS Mission Area :: Natural Hazards

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MetadataARSmonitoring.xml Original FGDC Metadata	View	23.9 KB	application/fgdc+xml
ARS_GR_DATA.xlsx		5.93 MB	application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
ARS_WS_DATA.xlsx		7.66 MB	application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
QualityNos_SnowDepth_ReadMe.txt		270 Bytes	text/plain

Related External Resources

Type: Related Primary Publication

Ashland, F.X. Critical shallow and deep hydrologic conditions associated with widespread landslides during a series of storms between February and April 2018 in Pittsburgh and vicinity, western Pennsylvania, USA. Landslides 18, 2159–2174 (2021). https://doi.org/10.1007/s10346-021-01665-x	https://doi.org/10.1007/s10346-021-01665-x

Purpose

Data were obtained to establish relationships between precipitation and changes in the state of activity and velocity of a deep-seated rockslide. Data on soil moisture in the shallow colluvial deposit on the rockslide also provided information on the hydrologic response to rainfall and snowmelt.

Monitoring data from the Aleppo rockslide, Allegheny County, Pennsylvania, November 2013 - December 2018

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