What is Mendocino triple junction and Cascadia subduction zone?
The Mendocino Triple Junction (MTJ) region straddles the transition between two of the most important segments of the North American plate boundary, separating the Cascadia subduction zone from translational tectonics of the San Andreas plate boundary.
What type of triple junction is the Mendocino?
The Mendocino Triple Junction (MTJ) joins three active boundaries: extending North, the Cascadia subduction zone, where the Gorda plate (oceanic plate) is subducting under the North American Plate (continental plate); extending South, the San Andreas Transform Fault and to the West, the Mendocino Transform Fault.
Does the Mendocino Triple Junction show low or high rates of seismic activity?
The Mendocino Triple Junction is located in the Pacific Ocean near Cape Mendocino in northern California. This area is the most seismically active active regions of the San Andreas transform system [1].
What type of plate boundary is the Mendocino fault?
Mendocino fault zone is a 260-km-long east-west striking fundamental structure that forms the transform boundary between the Pacific plate to the south and the Juan de Fuca plate to the north (Dengler and others, 1995 #4873).
Why north of the Mendocino triple junction the seismic hazard is very high?
Because of the different directions and the various rates of movement of the three plates, the area under Cape Mendocino and a region immediately off-shore has to absorb a lot of mechanical strain. That makes this area one of the most seismically active regions in the state.
Where is the triple junction located today?
FFR, FFT: The triple junction type is found at the San Andreas Fault and the Mendocino Transform Fault in the Western U.S. RTF: This type of triple junction is found at the southern end of the Gulf of California.
How fast is the Gorda plate moving?
The Pacific Plate is moving to the northwest at a speed of between 7 and 11 centimeters (cm) or ~3-4 inches a year. The North American plate is moving to the west-southwest at about 2.3 cm (~1 inch) per year driven by the spreading center that created the Atlantic Ocean, the Mid Atlantic Ridge.
What is a triple junction of plate boundaries?
A triple junction is a point where the three plates, A, B, and C, meet. It is also the intersection of the boundaries between the three pairs AB, BC, and AC. The velocity of any point moving along one of these boundaries will lie on a line in velocity space (Box 3-1).
Where is the Mendocino Fracture Zone?
Mendocino Fracture Zone, submarine fracture zone in the eastern Pacific Ocean, defined by one of the major transform faults dissecting the spreading centre of the Gorda Ridges. The Mendocino Fracture Zone extends west from immediately offshore of Cape Mendocino, California, for at least 2,500 miles (4,000 km).
Is Eureka CA on a fault line?
Eureka lies at a ‘tectonic triple junction,’ where three tectonic plates meet. At many other triple junctions, the three fault systems are perpendicular to each other, and so all of the action can be taken up along the major faults. But here, Eli Silver discovered in 1971 that there is a space problem (Silver, 1971).
Will the Cascadia earthquake affect California?
While the most significant impacts of a Cascadia rupture would be felt in far Northern California, Oregon and Washington, the Alaska earthquake scenario would direct ocean wave energy farther south, flooding much of California’s low-lying coastline and requiring the evacuation of 300,000 to 400,000 people.
Which triple junction is always unstable?
transform-transform- transform triple junctions
Because the sides of a triangle never intersect in a single point, transform-transform- transform triple junctions are always unstable.
What happened at the triple junction?
In plate tectonics theory during the breakup of a continent, three divergent boundaries form, radiating out from a central point (the triple junction). One of these divergent plate boundaries fails (see aulacogen) and the other two continue spreading to form an ocean.
Is California drifting away?
No, California is not going to fall into the ocean. California is firmly planted on the top of the earth’s crust in a location where it spans two tectonic plates.
What happens at triple junctions?
What is a triple junction Why are they important?
A triple junction is ideally a point at which boundaries of three lithospheric plates come together. At such a point, geological processes belonging to one plate boundary abruptly give place to others belonging to the other two boundaries.
How long is the Mendocino Escarpment fracture zone?
2500 miles
The Mendocino Fracture Zone is a fracture zone and transform boundary over 4000 km (2500 miles) long, starting off the coast of Cape Mendocino in far northern California.
How old is Mendocino ridge system?
As the Pacific and Gorda plates move apart due to plate tectonics, the resulting spreading center created the ridge approximately 30 million years ago, and continues to cause volcanic and seismic activity in the region.
When was the last big earthquake in Eureka California?
The 2010 Eureka earthquake occurred on January 9 at 4:27:38 pm PST offshore of Humboldt County, California, United States. The magnitude was measured 6.5 on the Mw scale, and its epicenter was located offshore in the Pacific Ocean 33 miles (53 km) west of the nearest major city, Eureka.