Filtering by Subject: Planetary Geophysics and Seismology

Stress and Strain during Shock Metamorphism

Auriol S. P. Rae, Michael H. Poelchau, Thomas Kenkmann

Published: 2021-04-15
Subjects: Geology, Planetary Geology, Planetary Geophysics and Seismology, Tectonics and Structure

Shock metamorphism is the process by which rocks, and the minerals within them, transform during the passage of a shock wave. Shock effects, such as shatter cones, are critical for the identification of impact structures and have commonly been used to infer mechanical and structural information on the cratering process. To make these inferences, the mechanics of shock wave behavior must be [...]

No cryosphere-confined aquifer below InSight on Mars

Michael Manga, Vashan Wright

Published: 2021-02-24
Subjects: Planetary Geophysics and Seismology, Planetary Hydrology, Planetary Sciences

The seismometer deployed by the InSight lander measured the seismic velocity of the Martian crust. We use a rock physics model to interpret those velocities and constrain hydrogeological properties. The seismic velocity of the upper ~10 km is too low to be ice-saturated. Hence there is no cryosphere that confines deeper aquifers. An increase in seismic velocity at depths of ~10 km could be [...]

Bias correction of global climate model using machine learning algorithms to determine meteorological variables in different tropical climates of Indonesia

Juan Nathaniel

Published: 2020-12-11
Subjects: Applied Statistics, Atmospheric Sciences, Planetary Geophysics and Seismology, Statistical Models

Accurate and localized forecasting of climate variables are important especially in the face of uncertainty imposed by climate change. However, the data used for prediction are either incomplete at the local level or inaccurate because the simulation models do not explicitly consider local contexts and extreme events. This paper, therefore, attempts to bridge this gap by applying tree-based [...]

Seismic electric signals (SES) and earthquakes: A review of an updated VAN method and competing hypotheses for SES generation and earthquake triggering

Daniel S. Helman

Published: 2020-04-07
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Studies, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences, Social and Behavioral Sciences

Electromagnetic phenomena are sometimes associated with seismic events, but earthquake prediction using seismic electric signals (SES) has not been seriously considered since the early 1990s. There are several causes: (1) false alarms that have created panics in Greece, and (2) a strong critique of the Varotsos-Alexopoulos-Nomicos (VAN) method used there. An updated VAN method that includes time [...]

Analytical prediction of seismicity rate due to tides and other oscillating stresses

Elias Rafn Heimisson, Jean-Philippe Avouac

Published: 2020-03-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences, Tectonics and Structure

Oscillatory stresses are ubiquitous on earth and other solid-surface bodies. Tides and seasonal signals perpetually stress faults in the crust. Relating seismicity to these stresses offers fundamental insight into earthquake triggering. We present a simple model that describes seismicity rate due to perpetual oscillatory stresses. The model applies to large amplitude, non-harmonic, and [...]

Linking the evolution of terrestrial interiors and an early outgassed atmosphere to astrophysical observations

Dan J. Bower, Daniel Kitzmann, Aaron S. Wolf, Patrick Sanan, Caroline Dorn, Apurva V. Oza

Published: 2019-10-17
Subjects: Astrophysics and Astronomy, Earth Sciences, Geophysics and Seismology, Other Astrophysics and Astronomy, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences

A terrestrial planet is molten during formation and may remain molten due to intense insolation or tidal forces. Observations favour the detection and characterisation of hot planets, potentially with large outgassed atmospheres. We aim to determine the radius of hot Earth-like planets with large outgassing atmospheres. Our goal is to explore the differences between molten and solid silicate [...]

Thermal and magnetic evolution of a crystallizing basal magma ocean in Earths mantle

Nicolas Blanc, Dave Stegman, Leah B. Ziegler

Published: 2019-10-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences

We present the thermochemical evolution of a downward crystallizing BMO overlying the liquid outer core and probe its capability to dissipate enough power to generate and sustain an early dynamo. A total of 61 out of 112 scenarios for a BMO with imposed, present-day $Q_{BMO}$ values of 15, 18, and 21 TW and $Q_r$ values of 4, 8, and 12 TW fully crystallized during the age of the Earth. Most of [...]

Core Formation and Geophysical Properties of Mars

Matthew C Brennan, Rebecca A. Fischer, Jessica C. E. Irving

Published: 2019-02-25
Subjects: Earth Sciences, Geochemistry, Mineral Physics, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences

The chemical and physical properties of the interiors of terrestrial planets are largely determined during their formation and differentiation. Modeling a planet’s formation provides important insights into the properties of its core and mantle, and conversely, knowledge of those properties may constrain formational narratives. Here, we present a multi-stage model of Martian core formation in [...]

Ocean Drilling Perspectives on Meteorite Impacts

Christopher Lowery, Joanna V. Morgan, Sean P. S. Gulick, Timothy J. Bralower, Gail Christeson, Expedition 364 Scientists

Published: 2018-08-08
Subjects: Earth Sciences, Geophysics and Seismology, Oceanography and Atmospheric Sciences and Meteorology, Paleobiology, Paleontology, Physical Sciences and Mathematics, Planetary Geomorphology, Planetary Geophysics and Seismology, Planetary Sciences, Stratigraphy

Extraterrestrial impacts are a ubiquitous process in the solar system, reshaping the surface of rocky bodies of all sizes. On early Earth, impact structures may have been a nursery for the evolution of life. More recently, a large meteorite impact caused the end-Cretaceous mass extinction, causing the extinction of 75% of species known from the fossil, including non-avian dinosaurs, and clearing [...]

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