Images

A map showing the epicenter of the M 3.5 quake that occurred 3.7 miles (6 km) east of Elgin, South Carolina on June 29, 2022. The quake is part of an ongoing sequence in central South Carolina. The sequence started on December 27, 2021, with an M3.3 earthquake near Lugoff, South Carolina.

Alex Hatem observes surface deformation from the 2020 Monte Cristo, Nevada, earthquake eroding away, June, 2022.

In June 2022, Mendenhall Fellow Sabine Loos (Research Civil Engineer in the Geological Hazards Science Center) presented a seminar to USGS's Earthquake Science Center at Moffett Field, CA, where Max Schneider (Research Statistician) works as a Mendenhall Fellow.

Rich Briggs and Alex Hatem make geologic observations within Nevada’s Monte Cristo Range, June, 2022.

The geologic time scale showing each eon, era, period, epoch, and their associated ages.

Photo of Zion Canyon located in Zion National Park in Utah, United States. (Image courtesy of Justin Gould)

Photo of the Grand Canyon located in Grand Canyon National Park, Arizona, Untied States.

Photo of GPS site with instrument on a tripod and a solar panel. (Photo by John Galetzka, U.S. Geological Survey)

Photo of bridge.  Geotechnical means referring to the use of scientific methods and engineering principles to acquire, interpret, and apply knowledge of earth materials for solving engineering problems.  

Horst and graben diagram. A graben is a down-dropped block of the earth's crust resulting from extension, or pulling, of the crust. 

Diagram of great circle. The shortest path between two points on the surface of a sphere lies along a great circle.

Liquefaction and lateral spreading occurred along the west side of Sunset Lake trailer park in Tumwater.

Liquefaction potential map of the San Francisco Bay Area, California. (Image courtesy of the Association of Bay Area Governments-ABAG)

The natural frequency is the frequency at which a particular object or system vibrates when pushed by a single force or impulse, and not influenced by other external forces or by damping. If you hold a slinky by one end and let it hang down and then give it one push up from the bottom, the rate of up-and-down motion is its natural frequency.

Cartoon of half-space model. A half space is a mathematical model used to approximate the earth when performing some calculations in seismology. The model is much simpler than the real earth.

Plot showing 440 Hertz and 880 Hertz. Hertz (Hz) is a unit of measurement named in honor of Heinrich Hertz, the German physicist who in 1887 first produced electromagnetic waves. Expresses the frequency in cycles per second; 1 Hz = 1 cycle of rise and fall of a wave per second .

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

The earthquakes (colored dots) in the middle of the continent are intraplate events. Those near the ocean boundary are at the boundary between two plates (interplate).

Iceland and plate motions. Kinematic refers to the general movement patterns and directions of the earth's rocks that produce rock deformation.

Strike-slip, normal, and reverse faults. A reverse fault with a small dip angle is called a thrust fault.

Photo of fault gouge. Fault gouge is crushed and ground-up rock produced by friction between the two sides when a fault moves.