Videos

On the remote western coast of Australia lies a UNESCO World Heritage Site above and below the sea. Researchers from the U.S. Geological Survey and University of Western Australia convened here at Ningaloo Reef and Jurabi Coastal Reserve to embark on the most extensive study EVER done into how coral reefs shape our coasts.
 

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

A time-lapse video of the excavation of the trench for a paleoseismology research project at Flat Canyon, Utah, along the Wasatch fault zone.
 

Barter Island sits at the top of the Arctic National Wildlife Refuge in Alaska, and with the Arctic facing quickly rising temperatures, USGS wants to investigate what’s causing the North Slope bluffs to erode so quickly.

In 2014, the Silverado Fire burned approximately 4 km^2 in Orange County, California. After the fire, the USGS installed an automated rain-triggered camera to monitor post-wildfire flooding and debris flow at the outlet of a small 0.6 km^2 basin within the burn area.

Title: A Sight "Fearfully Grand" Eruptions of Lassen Peak, California, 1914 to1917

• A summary of the eruptions and their effects
• Illustrated with historical photographs

The Hawaiian Islands’ beautiful ocean and beaches attract more than 8.5 million tourists each year. The USGS aims to help Hawaii preserve its underwater natural resources by tracing how oceanography may influence coral disease outbreaks.

Volcano gas geochemistry has been around for a long time. Scientists can make gas measurements using very large, very expensive Correlation Spectrometers or collect samples in the field and bring them back for analysis in the lab. But it’s possible we’re missing out on a lot of information because our monitoring capabilities don’t include continuous observation.

A thrust fault that does not rupture all the way up to the surface so there is no evidence of it on the ground. It is buried under the uppermost layers of rock in the crust.

Aftershocks are earthquakes that follow the largest shock of an earthquake sequence. They are smaller than the mainshock and within 1-2 fault lengths distance from the mainshock fault. Aftershocks can continue over a period of weeks, months, or years.

Elastic rebound is what happens to the crustal material on either side of a fault during an earthquake. The idea is that a fault is stuck until the strain accumulated in the rock on either side of the fault has overcome the friction making it stick.

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

The wavefront is the instantaneous boundary between the seismic waves in the earth material, and the material that the seismic energy has not yet reached. As a seismic wave propagates through the earth, the wavefront moves.

When you throw a pebble in a pond, it makes waves on the surface that move out from the place where the pebble entered the water. The waves are largest where they are formed and gradually get smaller as they move away. This decrease in size, or amplitude, of the waves is called attenuation.

Normal, or Dip-slip, faults are inclined fractures where the blocks have mostly shifted vertically. If the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed a Reverse fault.

Directivity is an effect of a fault rupturing whereby earthquake ground motion in the direction of rupture propagation is more severe than that in other directions from the earthquake source.

A thrust fault is a reverse fault with a dip of 45° or less, a very low angle. This animation shows a reverse fault which is a steeper-angle fault, but it moves the same way.

The shortest path between two points on the surface of a sphere lies along a great circle. On a 2-dimensional map, this looks like a line, but when it's on a 3-dimensional sphere, it's an arc... part of a circle.

Shaking at a site may be increased, or amplified, by focusing of seismic energy caused by the materials in basins or by surface topography such as mountains.

An asperity is an area on a fault that is stuck. The earthquake rupture usually begins at an asperity.

A divergent boundary is where two adjacent tectonic plates are moving away from each other.