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Ivan G. Wong

Publications and source records attributed to Ivan G. Wong.

3 recordsLinked to original sources
USGS2016

Earthquake probabilities for the Wasatch front region in Utah, Idaho, and Wyoming

In a letter to The Salt Lake Daily Tribune in September 1883, U.S. Geological Survey (USGS) geologist G.K. Gilbert warned local residents about the implications of observable fault scarps along the western base of the Wasatch Range. The scarps were evidence that large surface-rupturing earthquakes had occurred in the past and more would likely occur in the future. The main actor in this drama is the 350-km-long Wasatch fault zone (WFZ), which extends from central Utah to southernmost Idaho. The modern Wasatch Front urban corridor, which follows the valleys on the WFZ’s hanging wall between Brigham City and Nephi, is home to nearly 80% of Utah’s population of 3 million. Adding to this circumstance of “lots of eggs in one basket,” more than 75% of Utah’s economy is concentrated along the Wasatch Front in Utah’s four largest counties, literally astride the five central and most active segments of the WFZ.

Utah, Idaho, Wyoming↗
USGS2011

Shear-wave velocity characterization of the USGS Hawaiian strong-motion network on the Island of Hawaii and development of an NEHRP site-class map

To assess the level and nature of ground shaking in Hawaii for the purposes of earthquake hazard mitigation and seismic design, empirical ground-motion prediction models are desired. To develop such empirical relationships, knowledge of the subsurface site conditions beneath strong-motion stations is critical. Thus, as a first step to develop ground-motion prediction models for Hawaii, spectral-analysis-of-surface-waves (SASW) profiling was performed at the 22 free-field U.S. Geological Survey (USGS) strong-motion sites on the Big Island to obtain shear-wave velocity ( V S ) data. Nineteen of these stations recorded the 2006 Kiholo Bay moment magnitude (M) 6.7 earthquake, and 17 stations recorded the triggered M 6.0 Mahukona earthquake. V S profiling was performed to reach depths of more than 100 ft. Most of the USGS stations are situated on sites underlain by basalt, based on surficial geologic maps. However, the sites have varying degrees of weathering and soil development. The remaining strong-motion stations are located on alluvium or volcanic ash. V S 30 (average V S in the top 30 m) values for the stations on basalt ranged from 906 to 1908 ft/s [National Earthquake Hazards Reduction Program (NEHRP) site classes C and D], because most sites were covered with soil of variable thickness. Based on these data, an NEHRP site-class map was developed for the Big Island. These new V S data will be a significant input into an update of the USGS statewide hazard maps and to the operation of ShakeMap on the island of Hawaii.

Hawai'i↗