Program Name:
Utah Earthquake Ground-Shaking Maps, Which One Do I Use?
Administering Agency:
Geoscience Standing Committee, Utah Seismic Safety Commission
Contact:
Gary Christenson, Geologic Hazards Program Manager
Address:
1564 West North Temple, Salt Lake City, UT 84114-6100
Telephone:
801-537-3304
Fax:
801-537-3340
E-mail:
garychristenson@utah.gov
Program Summary
The Utah
Seismic Safety Commission (USSC) is an advisory commission established by
the Utah State Legislature to help reduce risks to the state and its
citizens from earthquakes. One of the USSC’s goals is outreach to the
technical community - mainly engineers, geoscientists, and building
officials - to promote risk reduction.
Utah adopted the International Building Code (IBC) in 2002, which uses the
USGS National Seismic Hazards Maps for earthquake design. Shortly after
adoption of the IBC, the Utah Geological Survey (UGS) published two sets of
earthquake ground-shaking maps, one showing earthquake scenario (M7.0) and
probabilistic ground-shaking maps for the Salt Lake City area, by URS
Corporation in conjunction with the UGS and University of Utah, and another
showing deterministic maximum peak bedrock acceleration maps for the entire
state by Utah State University. As a result of the near simultaneous
release of all of these products, and the various scales and levels of
detail of the maps, engineers and building officials needed guidance
regarding which maps to use for purposes of building, bridge, and dam design
and retrofit. Also, some of the maps incorporated site geology in mapped
ground-shaking levels, whereas others were strictly bedrock ground-shaking
maps, complicating their use.
The USSC Geoscience Committee recognized the need to clarify the purposes of
each set of maps, and define how each should be used. The Geoscience
Committee worked with the various authors of the maps (USGS, URS
Corporation, UGS, University of Utah, Utah State University) to prepare the
brochure “Utah Earthquake Ground-Shaking Maps, Which One Do I Use?” for use
by structural and geotechnical engineers, geoscientists, and building
officials to ensure that the maps were used properly, particularly with
respect to building code enforcement.
The need for the brochure arose from a unique situation in Utah, but
represents the importance of an organization stepping forward to fulfill a
recognized need in a timely manner. The brochure was completed in January
2003, and is distributed by the UGS and posted on the UGS and USSC
websites. It has been presented at various Utah earthquake and building
code conferences, and has contributed to proper earthquake-resistant design
in Utah.
Program Operational
Since
January 2003
Major Purposes
The main
purpose of the program was to clarify the purposes of the different
ground-shaking maps that were being released by the Utah Geological Survey
and Utah State University. The brochure educates the user to the different
applications of the ground-shaking maps.
Specific Activities and Operations
A press release was developed announcing the new maps, their purpose, and
the new brochure. The brochure was distributed to engineering
organizations, building officials and universities.
New Approaches and
Methods
The program was the result of a unique situation in the timing of the
release of similar products. Ground shaking maps are not usually
accompanied by a brochure. This would create a new approach in
understanding how these maps are used.
Program Funding
Start-up Costs:
$ 3500
Source:
Utah Geological Survey
Annual Budget:
$ 200
Source:
Utah Geological Survey
Program Staffing
2 FTE
Program Origins
The program has been fully implemented and appears to be unique to Utah.
Achievement of Stated
Purposes
The brochure’s effectiveness is measured by the distribution from the Utah
Geological Survey bookstore and requests from their website.
