How old is the wasatch fault

The relatively minor Magna earthquake was a rare chance to catch the fault in the act. Moschetti, M. Seismological Research Letters. Utah Seismic Safety Commission Putting down roots in earthquake country—Your handbook for earthquakes in Utah. Wald, L. Wong, I. Major roads, pipelines and communications networks also could be disrupted in a big quake. He was speaking from his office in the Rio Grande Depot, which sustained among the worst damage of any large building and is still undergoing repairs.

A massive crack was apparent in the wall behind Merritt, a testament to the destructive power of an earthquake that would hardly hold a candle to the magnitude 6. Clare Collard, a Magna resident, was showering on the morning of the quake, and braced herself as she heard glass breaking and objects fall.

That experience prompted her to champion legislation last session aimed at boosting public awareness about the dangers of unreinforced masonry and what homeowners can do to mitigate the risks. HB would have funded a public education campaign, while fellow Democratic Rep. Francisco Kjolseth Tribune file photo Masonry buildings on Magna's historic Main Street took a beating in last year's magnitude 5.

To her disappointment, both bills failed, but she plans to resurrect these proposals in interim sessions. Collecting data at the Flat Canyon site. The trench log is a map of the trench wall drawn on a small-scale paper print out of the trench photo mosaic. Paleoseismologists record details of the trench walls onto the trench logs.

These details include the location and type of geologic contacts between layers of sediment a. Careful descriptions of color, grain size, moisture, and density are recorded for each geologic unit. Samples of important geologic units are collected and sent to a laboratory to be age-dated. The geologic age of a sample is determined by various age-dating techniques, such as carbon dating and luminescence dating.

The deformation of sediment, faults, and other features in the trench walls tell the sequential story of past earthquakes at that location, and age-dating informs paleoseismologists when the past earthquakes happened. Collecting all the data to reconstruct the story takes a team of scientists about two weeks in the trench, carefully recording everything onto the trench log. When the job is done they celebrate with a "trench party", where interested scientists and local citizens are invited to tour the trench and discuss the geologic interpretations before it is filled in.

As part of this Wasatch fault zone project, an airborne LiDAR topographic survey was conducted of the entire Wasatch fault zone. The LiDAR survey along the length of the fault took approximately 8 weeks of flying time between the Fall of and Spring of LiDAR data provides a very high-resolution picture of Earth's surface so subtle features like fault scarps that may be missed during ground mapping can be identified from a bird's eye view.

The laser scanner that does all the work is slightly larger than a large coffee can and is mounted to the underside of a small plane that flies back and forth over an area until the entire fault zone has been surveyed. The laser pulses are able to penetrate vegetation and bounce off Earth's surface, so even if an area is covered with a dense forest, LiDAR is able to measure the surface elevation beneath the tree canopy.

The red lines on the interpreted maps are faults that could be identified with the LiDAR images. Several of these faults are newly identified, revealed for the first time with this LiDAR data. The point data collected from the LiDAR survey are processed to create a digital elevation model DEM , a digital representation of the ground surface, similar to a topographic map.

Shining a "digital light" onto the DEM, which simulates the early morning or late afternoon sun, creates a digital hillshade model that includes "fake shadows," which can reveal subtle topographic features such as fault scarps. USGS scientists use these hillshade models to identify several new fault traces that had never been noticed before. The trench logs are also turned into a digital picture to illustrate the geologic relationships and to measure fault offset of geologic layers. Once the age-dating laboratory determines the ages of the geologic samples from the trench, that data is used to figure out when paleo-earthquakes occurred at that location.

In this Wasatch fault zone study, scientists are looking for paleo-earthquakes near the end of one fault segment that happened at the same time as paleo-earthquakes on the adjacent fault segment, indicating that the earthquake occurred on both fault segments.

Such information would support that the paleo-earthquake could have been larger and probably less frequent than if it had happened only on a single fault segment. Skip to main content. Search Search. Earthquake Hazards. Where is the Wasatch Fault? Download Video. Trench log top and photo mosaic bottom from the Alpine trench site.

Gold Ryan D. GSA Bulletin : 43— Article history received:. Abstract The Wasatch fault zone defines the eastern boundary of the actively extending Basin and Range Province Utah, western United States and poses a significant seismic hazard to the metropolitan areas along the Wasatch Range. You do not currently have access to this article. You could not be signed in.

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