Upper crust beneath the central Illinois basin, United States

Abstract The variation of phase and group velocity dispersion of Love and Rayleigh waves was determined for the continental United States and adjacent Canada. By processing ambient noise from the broadband channels of the Transportable Array (TA) of USArray and several Program for the Array Seismic Studies of the Continental Lithosphere experiments and using some earthquake recordings, the effort was focused on determining dispersion down to periods as short as 2 s. The relatively short distances between TA stations permitted the use of a 25 km×25 km grid for the four independent tomographic inversions (Love and Rayleigh and phase and group velocity). One reason for trying to obtain short-period dispersion was to have a data set capable of constraining upper crust velocity models for use in determining regional moment tensors. The benefit of focusing on short-period dispersion is apparent in the tomography maps—shallow geologic structures such as the Mid-Continent Rift, and the Michigan, Illinois, Anadarko, Arkoma, and Appalachian basins are imaged. In our processing, we noted that the phase velocities were more robustly determined than the group velocities. We also noted that the inability to obtain dispersion at short periods shows distinct regional patterns that may be related to the local upper crust structure.

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Shear velocity structure beneath the central United States: implications for the origin of the Illinois Basin and intraplate seismicity

Geochemistry Geophysics Geosystems ◽

10.1002/2015gc006206 ◽

2016 ◽

Vol 17 (3) ◽

pp. 1020-1041 ◽

Cited By ~ 23

Author(s):

Chen Chen ◽

Hersh Gilbert ◽

Christopher Andronicos ◽

Michael W. Hamburger ◽

Timothy Larson ◽

...

Keyword(s):

United States ◽

Velocity Structure ◽

Shear Velocity ◽

Illinois Basin ◽

Intraplate Seismicity ◽

Central United States

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Survival of Cercospora sojina on Soybean Leaf Debris in Illinois

Plant Health Progress ◽

10.1094/php-rs-14-0005 ◽

2014 ◽

Vol 15 (3) ◽

pp. 92-96 ◽

Cited By ~ 1

Author(s):

Guirong Zhang ◽

Carl A. Bradley

Keyword(s):

United States ◽

Southern Illinois ◽

Cercospora Sojina ◽

North Central ◽

East Central ◽

The North ◽

Central United States ◽

Soybean Leaf ◽

Soybean Leaves ◽

Central Illinois

Historically, frogeye leaf spot (FLS, caused by Cercospora sojina) of soybean has been observed more frequently in the southern United States than the north-central United States. However, in recent years, FLS field observations have increased in the north-central United States. To better understand the survival rate of C. sojina in Illinois, a field study was conducted at three locations: Monmouth (west-central Illinois), Urbana (east-central Illinois), and Dixon Springs (southeastern Illinois). At each location, soybean leaves affected by FLS were placed at depths of 0, 10, and 20 cm and retrieved at different durations up to 24 months. To determine the viability of C. sojina in the collected leaves, a greenhouse bioassay was used. Survival of C. sojina declined equally with time at all three locations through 19 months. After 24 months, C. sojina from leaves that had been placed at Monmouth and Urbana were no longer viable, whereas leaves that had been placed at Dixon Springs produced viable inoculum. Depth of leaf placement had no effect on survival of C. sojina at any of the locations. These results suggest that planting a nonhost crop for two years in central Illinois will reduce levels of C. sojina inoculum to a negligible amount; however, soybean farmers in southern Illinois may need a longer rotation for FLS management. Accepted 10 May 2014. Published 23 July 2014.

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