Continuous GPS monitoring at Long Valley Caldera

Long Valley Stations

Figure. This map shows the locations of of GPS receivers that are operating within and near the Long Valley Caldera. Also shown are the outlne of the caldera, the resurgent dome, Mammoth Mountain, and the Inyo and Mono chain. The sites of the GPS receivers are colored. In addition, two other sites are monitored, MUSB and CMBB located southwest of the caldera by 50 KM and West-Northwest of the caldera by 100 KM respectively.

The data are processed using the GIPSY software. Common-mode signals are identified and removed. Prior to plotting, "bad" measurements of position are identified and removed that are deviate significantly relative to position measurements made within a 3 month window. In addition, the average position and its velocity is removed prior to plotting.

Plots of the data

Plots of displacements are made relative to the Sierra Nevada block.

Displacement vector map of the data

Follow the links below to look at maps of displacement vectors determined from the continuous GPS network. The vectors show the magnitude and direction of displacement of each continuous GPS site. Those plotted in gray without an error ellipse are not statistically significant. Otherwise, the error ellipse represents the 95% confidence region assuming that the measurement error statistics are known completely. Those displacements that are not significant either have very small displacements or, the error in the measurement is high. High measurement error can be due to lack of data.

Rate changes

Most recent 10 days

The following plots explore rate changes in these GPS data. Rate for each component of GPS data is estimated for the previous 1.5 years and a change in rate is estimated for the previous 10 days. The vectors of the rate changes are shown below. For those rate changes that exceed its 95% confidence interval, those vectors are plotted in black with an error ellipse; otherwise the rate changes are shown in gray.

The time series over the past 1.5 years are shown below. They have been detrended. The estimated rate change over the past 10 days is highlighted either as a black or a red line. If red, then the estimated rate change exceeds its 95% confidence level.

Most recent 30 days

The following plots explore rate changes in these GPS data. Rate for each component of GPS data is estimated for the previous 1.5 years and a change in rate is estimated for the previous 30 days. The vectors of the rate changes are shown below. For those rate changes that exceed its 95% confidence interval, those vectors are plotted in black with an error ellipse; otherwise the rate changes are shown in gray.

The time series over the past 1.5 years are shown below. They have been detrended. The estimated rate change over the past 30 days is highlighted either as a black or a red line. If red, then the estimated rate change exceeds its 95% confidence level.

Most recent 90 days

The following plots explore rate changes in these GPS data. Rate for each component of GPS data is estimated for the previous 2.5 years and a change in rate is estimated for the previous 90 days. The vectors of the rate changes are shown below. For those rate changes that exceed its 95% confidence interval, those vectors are plotted in black with an error ellipse; otherwise the rate changes are shown in gray.

The time series over the past 2.5 years are shown below. They have been detrended. The estimated rate change over the past 90 days is highlighted either as a black or a red line. If red, then the estimated rate change exceeds its 95% confidence level.

For plots of raw data and the data themselves:

Long Valley GPS data

For more details, contact:

John Langbein (langbein at usgs.gov)