Humboldt County, CA, is located in a seismically active region, influenced by several significant fault zones capable of generating earthquakes. Here's an overview of the faults in the area and their characteristics:
Among these faults, the most active ones currently monitored include the Mad River Fault Zone, Little Salmon Fault Zone, Table Bluff Fault Zone, and others with ongoing seismic activity detected through monitoring systems.
In a major earthquake, Humboldt County could face various hazards, including:
Areas near the active fault zones, especially those with softer soils prone to amplifying seismic waves, would likely experience the strongest shaking during a large earthquake.
Over the past 600 years, Humboldt County has experienced several significant earthquakes, although historical records are less detailed compared to more densely populated areas. Notable events include those associated with the Cascadia Subduction Zone and local faults.
Humboldt County faces a potential tsunami risk from offshore earthquakes, particularly those associated with the Cascadia Subduction Zone. Depending on the magnitude and location of such an earthquake, coastal communities could experience tsunami waves, necessitating preparedness and evacuation plans.
In summary, Humboldt County is located in a seismically active region with multiple fault zones capable of generating significant earthquakes. Understanding these hazards is crucial for preparedness and mitigation efforts to enhance community resilience against future seismic events.
USGS 2014 Significant Earthquakes Archive
List of the strongest California earthquakes
NAME is an 80-character field for the name of the fault (including section name, i.e., Denali fault, Holitna section). Fault and section are lower case.
CODE is a three-integer field that defines certainty or reliability of field mapping (integer one), time of most recent movement (integer two), and amount or rate of slip (integer three). CODE is a composite of the single integer fields ACODE, SLIPCODE, and FCODE and determines the line type (fault trace) to be plotted.
NUM is a six-character unique USGS identifier that defines a fault or section ID. Simple fault IDs are only numeric; section IDs are alphanumeric.
AGE is the upper bounding time of the most recent surface-deforming earthquake. The allowable choices are provided in a pull-down menu.
ACODE is the second integer in CODE and defines the upper bounding time of the most recent surface-deforming earthquake. Permissible values are between 1 and 6: 1 = historic «150 years; red = cmyk 1096680); 2 = post glacial (15,000 years; orange = cmyk 1 38 1000); 3 = late Quaternary «130,000 years; green> cmyk 1002500); 4 = middle and late Quaternary «750,000 years: blue > cmyk 1004440); 5 = Quaternary «1,600,000 years; black 5); 6 = Class B (black halftone). In the text documentation, Quaternary faults (integer two, 1-5) are Class A structures. Questionable or suspected structures are Class B (integer two, 6).
SLIPRATE is the assigned slip rate category.
SLIPCODE is the third integer in CODE and defines the assigned slip rate category. Permissible values are between 1 and 4 and determine line width: 1 = >5 mm/year (extra wide; .048); 2 = 1-5 mm/year (wide; .0325); 3 = 0.2-1 mm/year (medium; .025); 4 = <.2 mm/year (thin; .015).
SLIPSENSE is normal, reverse, strike slip, thrust.
DIPDIRECTION is one of the eight quadrant dip directions for the entire fault or section, not the individual arc. C = center, E = east, N = north, NE = northeast, NW = northwest, S = south, SE = southeast, SW = southwest, W = west.
SLIPDIRECT (we are not using that field anymore and can be left empty) FCODE is the first integer in CODE and defines how well the fault is located and expressed in the landscape. Permissible values are between 1 and 3: 1 = fault landforms are more continuous than discontinuous and mapping is accurate at given MAPPEDSCALE (solid); 2 = fault landforms are more discontinuous than continuous and mapping is accurate at given MAPPEDSCALE (dashed); 3 = location of fault is inferred (dotted).
FTYPE is one of three allowable choices provided in a pull-down menu: Well constrained (FCODE 1), Moderately constrained (FCODE 2), and Inferred (FCODE 3).
MAPPEDSCALE is one of four allowable choices provided in a pull-down menu. Mapped scale will control visualization of the fault at various scales. 1:24,000, fault should be more continuous than discontinuous and mapping is accurate at <10,000 scale. 1:50,000, fault should be more continuous than discontinuous and mapping is accurate at <25,000 scale. 1:100,000, fault could be more discontinuous than continuous and mapping is accurate at <50,000 scale. 1:250,000, fault location may be inferred or is poorly constrained.
Click on the fault lines for more information. Note* The earthquake faults are color-coded by unique name and section not type.
Data source: USGS
CCCarto is not responsible for data errors or omissions, use as reference only.
copyright cccarto.com