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A liquefaction susceptibility map – excerpt of USGS map for the San Francisco Bay Area. Many areas of concern in this region are also densely urbanized. The other common observation is land instability – cracking and movement of the ground down slope or towards unsupported margins of rivers, streams, or the coast.
Locations of quakes magnitude 2.5 or greater in the Wabash Valley (upper right) and New Madrid (lower left) Seismic Zones. The Wabash Valley seismic zone (also known as the Wabash Valley fault system or fault zone) is a tectonic region located in the Midwestern United States, centered on the valley of the lower Wabash River, along the state line between southeastern Illinois and southwestern ...
The New Madrid seismic zone (NMSZ), sometimes called the New Madrid fault line (or fault zone or fault system), is a major seismic zone and a prolific source of intraplate earthquakes (earthquakes within a tectonic plate) in the Southern and Midwestern United States, stretching to the southwest from New Madrid, Missouri.
Seismic microzonation is defined as the process of subdividing a potential seismic or earthquake prone area into zones with respect to some geological and geophysical characteristics of the sites such as ground shaking, liquefaction susceptibility, landslide and rock fall hazard, earthquake-related flooding, so that seismic hazards at different locations within the area can correctly be ...
Surface motion map for a hypothetical earthquake on the northern portion of the Hayward Fault Zone and its presumed northern extension, the Rodgers Creek Fault Zone. A seismic hazard is the probability that an earthquake will occur in a given geographic area, within a given window of time, and with ground motion intensity exceeding a given threshold.
The San Jacinto Fault Zone and the San Andreas Fault (SAF) accommodate up to 80% of the slip rate between the North American and Pacific plates.The extreme southern portion of the SAF has experienced two moderate events in historical times, while the SJFZ is one of California's most active fault zones and has repeatedly produced both moderate and large events.
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
Map showing regional tectonic plates and the Middle America Trench. Much of Mexico's volcanic and seismic activity stems from the movement of the North American plate against the Cocos and Pacific plates and it is one of the most active trenches in the world. [3] Each year more than 90 tremors above magnitude 4.0 are recorded in this zone. [5]