Publications by authors named "P J Gregg"

As the volume of data collected at monitored volcanoes continues to expand, researchers will need quick, reliable, and automated methods of inverting those data into useful models of the underlying magma systems. Recently adapted from other fields for use in volcanology, the Ensemble Kalman Filter (EnKF) is one such inversion technique that has been used to produce several successful forecasts and hind-casts of volcanic unrest, correlating geodetic deformation with mechanical stresses around the magma reservoir. However, given the similarity in which changes to a reservoir's size and pressure are expressed at the surface, the filter can have trouble fully resolving magmatic conditions.

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Understanding the stress evolution of extinct volcanoes can improve efforts to forecast flank eruptions on active systems. Field, petrographic, and seismic data are combined with numerical modeling to investigate the paleo-stress field of New Zealand's Akaroa Volcano, or Akaroa Volcanic Complex. Field mapping identifies 86 radially oriented dikes and seven lava domes found only within a narrow elevation range along Akaroa's erosional crater rim.

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Using recent advancements in high-performance computing data assimilation to combine satellite InSAR data with numerical models, the prolonged unrest of the Sierra Negra volcano in the Galápagos was tracked to provide a fortuitous, but successful, forecast 5 months in advance of the 26 June 2018 eruption. Subsequent numerical simulations reveal that the evolution of the stress state in the host rock surrounding the Sierra Negra magma system likely controlled eruption timing. While changes in magma reservoir pressure remained modest (<15 MPa), modeled widespread Mohr-Coulomb failure is coincident with the timing of the 26 June 2018 moment magnitude 5.

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Article Synopsis
  • - In Australia, managing resistance to Bt toxins in transgenic cotton involves destroying overwintering pupae of certain pests (Helicoverpa spp.), traditionally done through a costly method called tillage, also known as "pupae busting."
  • - An alternative method using attract-and-kill technology, which involves applying plant volatile formulations, showed promise in reducing moth populations and egg-laying during trials—particularly a preventive approach that cut egg numbers by about 90%.
  • - This preventive strategy is now an optional part of resistance management for cotton, especially in southern New South Wales, and was adopted on about 60% of eligible fields during the 2020-2021 season after collaboration between technology providers, the cotton
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Understanding the impact that heat stress has on critical life stages of an organism is essential when assessing population responses to extreme events. Heat stress may occur as repeated small-scale events or as a single prolonged event, which may cause different outcomes to the organism. Here, we subjected Helicoverpa punctigera (Wallengren) pupae to two temperatures (44.

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