When was the wasatch fault formed

These geologists prepared maps that show where ground failures fracturing, slumping, and sliding from Wasatch Fault earthquakes are expected to be most severe. Such hazard maps assist public officials in evaluating requests for construction approval and urban planners in recommending suitable land-use practices. Using the information provided by scientists, Utah residents and their representatives have embarked on several courses of action to prepare for earthquakes.

They have:. Although no powerful earthquake has occurred on the Wasatch Fault for the past years, future such events are certain. In the past decade, the people of Utah have become more aware of the threat of a catastrophic earthquake.

Strong bonds between residents, their church communities, and public agencies have created an effective network for disaster preparation unequaled in the United States. Taking action today reduces the loss of life and property in future earthquakes.

The Utah experience exemplifies what can be achieved in earthquake-prone regions of the United States through the cooperation of scientists and engineers, government, and the local community. For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader , free of charge.

More information about viewing, downloading, and printing report files can be found here. Machette, M. Geological Survey Fact Sheet —95, 2 p.

Geologic studies show that at least 22 surface-faulting earthquakes shown as starbursts on this generalized diagram have occurred on the Wasatch fault during the past 6, years. Together, these contributions led to the subdivision of the WFZ into 10 structural fault segments, each approximately km miles long.

The central five fault segments have been active during Holocene time the last 10, years and produce large magnitude 7. The most recent earthquake on fault segments near Weber, Provo, and Nephi occurred years ago. The most recent earthquake on the Salt Lake City segment occurred years ago. It has been years since the most recent earthquake on the Brigham City fault segment. Paleoseismologic studies have provided a detailed record of Holocene earthquakes on the WFZ.

This record generally suggests that individual magnitude 7. However, in a few cases, the data could also be interpreted as multi-segment ruptures on the WFZ, where rupture spanned a segment boundary. Multi-segment earthquake ruptures on the WFZ may have produced longer surface ruptures and generated larger magnitude 7. The extent and frequency of ruptures that span segment boundaries remain poorly known, adding uncertainty to seismic hazard models for this populated region of Utah.

Active faults of the segmented Wasatch fault zone are next to the largest and growing population centers of central Utah. Structural fault segment boundaries play an unknown role in limiting large earthquakes Public domain.

These new datasets will help researchers to understand if past surface-rupturing earthquakes have spanned fault segment boundaries. They are also analyzing new high-resolution airborne LiDAR topographic data to characterize previously unmapped fault traces and to measure how vertical displacements vertical offset of the ground surface from faulting vary, both in space from north to south and time the last 20, years. These trenches near fault segment boundaries can provide critical information about the length and displacement of past earthquakes.

These data will also allow the researchers to figure out if past earthquakes repeatedly stop at a fault segment boundary or sometimes break through. Preliminary observations include evidence for four to seven Holocene earthquakes at each trenching site. Ongoing geochronologic analysis will help determine the timing of these earthquakes.

The timing of these earthquakes will be compared to earthquakes observed in trenches on adjacent fault segments to help identify through-going ruptures across segment boundaries. Lidar , which stands for Li ght D etection A nd R anging, is a remote sensing method that uses laser pulses, usually from a specially-equipped airplane, to create detailed topographic maps of Earth's surface. Lidar is able to "see through" the vegetation to record ground elevations and is a much faster and more precise way to gather topographical data than collecting data with a ground survey.

These data are available to the public. Detailed bare-earth digital elevation models DEMs and hillshade models of these LiDAR data allow the scientists to identify previously unmapped fault traces, providing a more complete story of Holocene earthquake ruptures on the WFZ. Analysis of the lidar data helps quantify fault displacements and slip rates, allows scientists to estimate the extent of fault ruptures associated with most recent earthquakes, and documents spatial and temporal slip patterns near fault segment boundaries.

Preliminary observations identify numerous previously undocumented fault scarps, including recent scarps north of Ogden, UT that may correspond with a late Holocene rupture that spanned the Brigham City-Weber fault segment boundary, as previously suggested from nearby paleoseismic trench studies.

Oblique photo looking north across Utah Valley. Segment boundaries yellow arrows separate fault segments e. Salt Lake City, Provo, Nephi. Previous trenches white stars ; new trenches from this study yellow stars. The photo was taken at approximately 10, m altitude. A typical, benched paleoseismic trench exposure across the Wasatch fault scarp. The fault scarp at this Flat Canyon site is about 13 m high and formed as a result of several surface-faulting earthquakes.

Photo by Scott Bennett, Credit: Scott Bennett. What's really involved in planning and completing a paleoseismology project like this one on the Wasatch fault zone? It's more time-consuming and interesting than you might think. The first order of business is selecting a trench site. The trench site location depends on the scientific questions to be answered and the ability to gain permission to dig a trench at the site. In this Wasatch fault zone study, the scientists needed to select site locations that were near the end of known fault segments, so a good bit of staring at maps and wandering around in the field preceded site selection.

The circulatory system includes large arteries and smaller veins. Because of this research, we have now been able to zoom in more closely on smaller sections of the [Wasatch Front] fault systems, which significantly improves our understanding of the entire zone.

The study harnessed airborne light detection and ranging or lidar elevation data to improve the accuracy, resolution and detail of current fault maps. A fairly recent technology, l idar is a surveying method that illuminates a target with laser light and measures the reflected light, recording differences in laser return times and wavelengths.

These differences are used to render digital three-dimensional representations of the ground. The new study also helped locate previously unmapped fault traces and find potential sites for future investigations into earthquakes that occurred in the distant past, known as paleoseismic events.

The special study zones and fault mapping will soon be available on a hazards app that the UGS is beta testing. The agency has already posted an interactive map illustrating faults and folds that produced earthquakes exceeding magnitude 6. These geological structures are those that are most likely to produce large quakes in the future. Not covered in the study is the fault that shifted near Magna on March 18 , damaging dozens of homes and scores of historic buildings.

That quake and a previous temblor in the same area in were not strong enough to breach the surface, so that fault remains hidden underground. University of Utah seismologists have deployed dozens of portable seismometers around the northern parts of the Salt Lake Valley to record hundreds of aftershocks stemming from that magnitude 5.

This research is hoped to help map the lesser faults underlying the valley with great precision. Images courtesy of the Utah Geological Survey These images compare an aerial photograph, left, with recently acquired lidar slope-shade images, center and right, from the Levan segment of the Wasatch fault zone.