San Francisco Bay Area – SF Peninsula (BALT4) Site near Pacifica, CA Active
Landslides in the San Francisco Bay area (SFBA) of California impact people, infrastructure, and the environment, and are commonly induced by intense or prolonged rainfall associated with strong winter storms.
Recent Conditions
The instruments for this site were installed in the winter of 2012 and are used to monitor and detect changes in local conditions. Soil water content and ground water pressure are monitored at two nests on the same hillslope. Data for the site include:
- Rainfall
- Upper Nest Soil Water Content and Groundwater Pressure (Piezometer)
- Lower Nest Soil Water Content and Groundwater Pressure (Piezometer)
- Air Temperature, Relative Humidity, and Battery Voltage
Data are recorded every 5 minutes and updated on the graph every 30 minutes.
Project Background
Landslides in the San Francisco Bay area (SFBA) of California impact people, infrastructure, and the environment, and are commonly induced by intense or prolonged rainfall associated with strong winter storms. Both shallow (<3 meter) and deep (≥3 meter) landslides can occur. Typically, shallow landslides occur as a result of high-intensity precipitation when the ground is already nearly saturated with water from previous storms. These types of events can occur during the height of the rainy season, from December through February. Deep-seated landslides can also occur during these times, but are also often triggered during the spring months (March through May), when water from rainfall has had a chance to make its way to deeper soil and bedrock.
The U.S. Geological Survey, in cooperation with local and state government organizations, operates several shallow landslide monitoring sites in the SFBA for research purposes. The goal of this research is to identify thresholds for widespread shallow landsliding and related high-mobility debris flows based on in-situ soil moisture conditions. This information is being used to develop landslide warning criteria with the National Weather Service. Monitoring data includes cumulative rainfall, rainfall intensity, soil water content, groundwater pressure, air temperature, and relative humidity. Infiltration of water from rainfall increases soil water content, cumulatively saturating the soil profile. However, periods without rainfall can lead to drying of the soil. If the soil profile is nearly saturated, additional intense precipitation can increase groundwater pressures which can, in turn, induce landslide movement.
- Overview
Landslides in the San Francisco Bay area (SFBA) of California impact people, infrastructure, and the environment, and are commonly induced by intense or prolonged rainfall associated with strong winter storms.
Recent Conditions
The instruments for this site were installed in the winter of 2012 and are used to monitor and detect changes in local conditions. Soil water content and ground water pressure are monitored at two nests on the same hillslope. Data for the site include:
- Rainfall
- Upper Nest Soil Water Content and Groundwater Pressure (Piezometer)
- Lower Nest Soil Water Content and Groundwater Pressure (Piezometer)
- Air Temperature, Relative Humidity, and Battery Voltage
Data are recorded every 5 minutes and updated on the graph every 30 minutes.
Project Background
Landslides in the San Francisco Bay area (SFBA) of California impact people, infrastructure, and the environment, and are commonly induced by intense or prolonged rainfall associated with strong winter storms. Both shallow (<3 meter) and deep (≥3 meter) landslides can occur. Typically, shallow landslides occur as a result of high-intensity precipitation when the ground is already nearly saturated with water from previous storms. These types of events can occur during the height of the rainy season, from December through February. Deep-seated landslides can also occur during these times, but are also often triggered during the spring months (March through May), when water from rainfall has had a chance to make its way to deeper soil and bedrock.
The U.S. Geological Survey, in cooperation with local and state government organizations, operates several shallow landslide monitoring sites in the SFBA for research purposes. The goal of this research is to identify thresholds for widespread shallow landsliding and related high-mobility debris flows based on in-situ soil moisture conditions. This information is being used to develop landslide warning criteria with the National Weather Service. Monitoring data includes cumulative rainfall, rainfall intensity, soil water content, groundwater pressure, air temperature, and relative humidity. Infiltration of water from rainfall increases soil water content, cumulatively saturating the soil profile. However, periods without rainfall can lead to drying of the soil. If the soil profile is nearly saturated, additional intense precipitation can increase groundwater pressures which can, in turn, induce landslide movement.
Sources/Usage: Public Domain. View Media DetailsThe USGS “BALT4” monitoring site showing datalogger enclosures, solar panel (top right), air temperature and relative humidity sensor (far left, white), and rainfall gauge (left, silver and white). (Public domain.)
Sources/Usage: Public Domain. View Media DetailsThe USGS “BALT4” site is located in San Mateo County, south of San Francisco, and consists of dataloggers monitoring the hillslope in the central part of the image. This slope is typical for many in the San Francisco Peninsula region that have generated mobile debris flows in the past. The area consists of shrublands over an approximately 1-meter-deep sandy soil layer, underlain by sandstone. (Public domain.)