Stein, S., and A. Newman (2004). But they also create the beautiful mountain ranges and valleys on our planet. Northwest of Hovey Lake, the Wabash Island fault comprises several branches in a quasi-planar fault zone that dips about 65° east-southeast. Structural complexity on the graben floor also decreases to the south. Deformation of the land surface directly over a fault that moves may manifest as very localized uplift or subsidence, or lateral distortions of up to several meters (for a very large earthquake). Vertical displacement on the floor fault increases with increasing depth and is about 120 m at the Upper Cambrian Eau Claire Formation. Share sensitive information only on official, secure websites. Correlation of these faults with steep potential field gradients suggests that the fault positions are controlled by major lithologic contacts within the basement and that the faults may extend into the depth range where earthquakes are generated, revealing a potential link between specific faults and recently observed low-level seismicity in the area. Normal faults are the result of extension when tectonic plates move away from each other. Nature 462, 87–89. Stein, S., and M. Liu (2009). Reverse faults look like two rocks or mountains have been shoved together. According to the Indiana Geological Survey, while there was minor damage associated with the earthquake, the tremor was a warning to residents of the Wabash Valley Seismic Zo… The largest faults in the system bound the 22-km wide 40-km long Grayville Graben. Right: Illinois Basin (has lots of shale oil potential) 1800-1995 quakes - click map for Indiana Geological Survey site. United States. A fault that moves to the left is a sinistral transcurrent fault, and a fault that moves to the right is a dextral transcurrent fault. This constant lithospheric motion results in surface fractures in the Earth’s crust, which are called faults. Vernon and West Franklin in Posey County, in an area that is known as the Wabash Valley Seismic Zone. They are most common at the base of large mountain ranges. Wabash Valley Seismic Zone - relation to New Madrid Seismic Zone. Structural trends north of 38?? Secure .gov websites use HTTPS Faults consist of two rock blocks that displace each other during an earthquake or regular tectonic movement. latitude and south of 38.35?? Strike-slip faults include transform (which end at another plate boundary) and transcurrent (which end before reaching another plate boundary) fault lines. It is responsible for a number of smaller fault systems across the western United States. Earthquake activity in the Wabash Seismic Zone has a history of affecting the St. Charles and the St. Louis metropolitan area and its residents. Official websites use .gov Interpretations of newly available seismic reflection profiles near the center of the Illinois Basin indicate that the Wabash Valley Fault System is rooted in a series of basement-penetrating faults. latitude are offset laterally across several large faults, indicating strike-slip motions of 2 to 4 km. The most famous example of a strike-slip fault is the San Andreas Fault. Centered in the Wabash River Valley, the Wabash Valley Seismic Zone straddles the state line between southeastern Illinois and southwestern Indiana and spreads into part of western Kentucky. … The Wabash Valley Seismic Zone (also known as the Wabash Valley Fault System or Zone) is a tectonic region located in the Midwest of the United States, centered on the valley of the Lower Wabash River, along the state line between southeastern Illinois and southwestern Indiana. The Wabash Valley seismic zone (WVSZ) along the southeastern Illinois–southwestern Indiana border is the shaded, elliptical-shaped area. Left image: Indiana quakes. If you’d like to learn more about landforms and earth science, check out an article that lists examples of landforms around the world. One block is called the hanging wall, and the other is the footwall. You may see additional examples of normal faults in these places: Although reverse faults are also dip-slip faults, they behave the opposite way that a normal fault does. Wabash Valley Seismic Zone Last updated April 22, 2019 Locations of quakes magnitude 2.5 or greater in the Wabash Valley (upper right) and New Madrid (lower left) Seismic Zones. This suggests that the graben is not a NE extension of the structural complex composed of the Rough Creek Fault System and the Reelfoot Rift as previously interpreted. The fault system is composed predominantly of north-northeast-trending high-angle normal faults. But if you’re looking at a strike-slip fault, it may look like the land on either side has moved in opposite directions. The behavior of each of these parts helps earth scientists identify faults as normal, reverse, or strike-slip. Tectonic plates are always moving under your feet. The fault system is composed predominantly of north-northeast-trending high-angle normal faults. LockA locked padlock Copyright © 2020 LoveToKnow. Recent earthquakes have reinforce that the New Madrid Seismic Zone isn’t the only ‘hot spot’ for earthquakes in the central U.S. On June 18, 2002, a M4.6 earthquake struck near Evansville, Indiana with an epicenter between Mt. The hanging wall slides up over the footwall during tectonic movement in these faults. Footwall - the rock block that occurs below the fault plane. The fault scarp may be visible in these faults as the hanging wall slips below the footwall. In 2008 in the nearby Wabash Valley Seismic Zone, a similar magnitude 5.4 earthquake occurred with its epicenter in Illinois near West Salem and Mount Carmel. Reverse faults with a 45 degree dip (or less) are known as thrust faults, while faults with over 45 degree dips are overthrust faults. Wabash and NM faults map. Earthquake activity in the Wabash Seismic Zone has a history of affecting the St. Charles and the St. Louis metropolitan area and its residents. Since then, more than 4,000 earthquakes have been recorded, most of which were too small to be felt. Many strike-slip faults are found on the ocean floor. The Wabash Valley Seismic Zone consists largely of vertically oriented ("normal") faults deeply buried under layers of sediment. beneath the Wabash Valley fault zone. Normal faults, or extensional faults, are a type of dip-slip fault. latitude. Some of the major faults are interpreted to penetrate to depths of 7 km or more. This movement may cause offset rivers, parallel valleys, and abrupt ends to mountain chains. Once you know what type a fault is, you can predict what can happen there during an earthquake. Characteristic and uncharacteristic earthquakes as possible artifacts: Applications to the New Madrid and Wabash seismic zones. The area spanning the Wabash Valley fault system (WVFS) is indicated by thin solid line. Moderate damage was reported in St. Charles and other parts of Missouri. They are found in areas of geological compression. the Wabash Valley fault in Illinois and Indiana: and the East Tennessee Seismic Zone that runs into Alabama: These are not like the faults in California , which last had a major earthquake in 1994, when the magnitude 6.7 Northridge temblor killed 57 people and caused $20 billion in damages. The Eastern Tennessee Seismic Zone (ETSZ), a zone of small seismic faults stretching from northeastern Alabama to southwestern Virginia, may have generated earthquakes of … They occur when the hanging wall drops down and the footwall drops down. Other examples of transcurrent faults include: Faults mark the edges of tectonic plates and points of lithospheric stress. Large faults also appear in the boundaries between tectonic plates. Interpretations of newly available seismic reflection profiles near the center of the Illinois Basin indicate that the Wabash Valley Fault System is rooted in a series of basement-penetrating faults. Reverse Faults Although reverse faults are also dip-slip faults, they behave the opposite way that a normal fault does. Normal faults create space. Explore recent publications by USGS authors, Browse all of Pubs Warehouse by publication type and year, Descriptions of US Geological Survey Report Series, Seismic interpretation of the deep structure of the Wabash Valley Fault System, The Publications Warehouse does not have links to digital versions of this publication at This gives the mountain a leaning, sloping look. These faults may look like large trenches or small cracks in the Earth’s surface. A lock ( After a major earthquake in the New Madrid or Wabash Valley seismic zone, what changes to the landscape would we most likely see? Structure contour maps drawn on the base of the Mount Simon Sandstone (Cambrian System) and a deeper pre-Mount Simon horizon show dip-slip displacements totaling at least 600 meters across the New Harmony fault. 2002 Caborn, Indiana, earthquake is plotted with a star. Scientists … In a flat area, a normal fault looks like a step or offset rock (the fault scarp). So how can you tell if you’re looking at a strike-slip fault? Seismologists believe that the Wabash Valley fault dates from Precambrian times, the oldest era of the Earth's history, and that the fault has been reactivated. This fault system is about 90 km long and 50 km wide in southeastern Illinois, southwestern Indiana, and northwestern Kentucky near the deepest part of the Illinois Basin (fig. A .gov website belongs to an official government organization in the Instruments were installed in and around the area in 1974 to closely monitor seismic activity.
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