Images

Diagram of frequency. The frequency is the number of times something happens in a certain period of time, such as the ground shaking up and down or back and forth during an earthquake.

Geodesy is the science of determining the size and shape of the earth and the precise location of points on its surface.

Map showing intensity for the New Madrid earthquake. (Image courtesy of the Central U.S. Earthquake Consortium)

A magnetic polarity reversal is a change of the earth's magnetic field to the opposite polarity. This has occurred at irregular intervals during geologic time. Polarity reversals can be preserved in sequences of magnetized rocks and compared with standard polarity-change time scales to estimate geologic ages of the rocks.

Person sitting and overlooking valley of snow-topped mountains with clouds in between mountains 

A stress vs time graph showing fault strength and an offset across fault vs time graph 

Seiche in Lake Geneva (Switzerland)

A seiche is the sloshing of a closed body of water from earthquake shaking. Swimming pools often have seiches during earthquakes.

The shadow zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves. The shadow zone results from S waves being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core.

Soil profile in hills of Manisa Province, Turkey, showing a distinct horizon of accumulated red-purple metallic (manganese and/or iron?) oxides.

The standard deviation is how much a set of data is different from the curve it should make when plotted on a graph. Or, the square root of the average of the squares of deviations about the mean of a set of data. Standard deviation is a statistical measure of spread or variability.

When the force trying to make the block (m) slip becomes greater than the frictional force causing it to stick, the block will slip.

The dots on the left make a regular pattern, but the dots on the right make a random, or stochastic, pattern.

Strain is the small changes in length and volume associated with deformation of the earth by tectonic stresses or by the passage of seismic waves.

Teleseismic is pertaining to earthquakes at distances greater than 1,000 km from the measurement site.

A velocity structure is a generalized regional model of the earth's crust that represents crustal structure using layers having different assumed seismic velocities.

Seismicity of Hawaii: earthquakes M>5 from the 1840-1899, 1900-1959, 1960-2019 catalogs shown separately. While earthquake activity remains high today, it seems to have decreased over the past 60 years, which could be related to less volcanic activity at Mauna Loa. 

Figure 1. Chance of minor or greater damaging earthquake shaking in the next 100 years. Population exposure estimates are rounded to the nearest 1000. 

Figure 2.

Debris flow caused by intense rainfall from Tropical Storm Fred in August 2021. Haywood County, NC. 

2018 Long-term National Seismic Hazard Map. Earthquake hazard map showing peak ground accelerations having a 2 percent probability of being exceeded in 50 years, for a firm rock site.  The map is based on the most recent USGS models for the conterminous U.S.

Debris flow deposits caused by intense rainfall in April 2020 block a highway in Macon County, NC.