Images

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).

Diagram of left-lateral motion on fault. If you were to stand on the fault and look along its length, this is a type of strike-slip fault where the left block moves toward you and the right block moves away. See also right-lateral. 

A Love wave is a surface wave having a horizontal motion that is transverse (or perpendicular) to the direction the wave is traveling.

Ripples on a pond are attenuated as they move away from the source. Q is the inverse of attenuation. A high Q means a low attenuation.

Geologic time scale showing eras, periods, and notable events in terms of millions of years ago.

Secular refers to long-term changes that take place slowly and imperceptibly. Commonly used to describe changes in elevation, tilt, and stress or strain rates that are related to long-term tectonic deformation.

The source is the term for the released forces that generate acoustic or seismic waves, also called the earthquake source.

The strike is the trend or bearing, relative to north, of the line defined by the intersection of a planar geologic surface (for example, a fault or a bed) and a horizontal surface such as the ground.

Tsunamigenic is referring to those earthquakes, commonly along major subduction zone plate boundaries such as those bordering the Pacific Ocean, that can generate tsunamis.

YBP is an abbreviation for "years before present".

Formation of Earth: 4.6x10^9 YBP

Dinosaur extinction: 6.5x10^7 YBP

First hominids: 2x10^6 YBP

Last great ice age: 1x10^4 YBP

Declaration of Independence: 2x10^2 YBP

Establishment of UWB: 1x10 YBP

High, medium, and low amplitude. The amplitude is the size of the wiggles on an earthquake recording.

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 2.

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

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. 

Debris flow caused by intense rainfall in April 2020 in Macon County, NC. 

Damage from a major post-wildfire landslide that occurred on 9 January 2018 near Montecito, Santa Barbara County as a result of the 2017 Thomas Fire.

Damage from a major post-wildfire landslide that occurred on 25 December 2003 near Devore, San Bernardino County as a result of the Old/Grand Prix fires that ran through the San Bernardino Mountains.

Alex Hatem stands in front of 1983 Borah Peak rupture with actual Borah Peak in the background.