A5020164628- Seismic Waves and Analysis
- Earthquake Detection and Analysis
- Seismology and Earthquake Studies
- Landslides and related hazards
- earthquake and tectonic studies
- Cryospheric studies and observations
- Pulsed Power Technology Applications
- Seismic Imaging and Inversion Techniques
- Geological and Tectonic Studies in Latin America
- Geophysical Methods and Applications
- Geophysics and Sensor Technology
- Meteorological Phenomena and Simulations
- Particle accelerators and beam dynamics
- Structural Engineering and Vibration Analysis
- Geological and Geochemical Analysis
- Lightning and Electromagnetic Phenomena
- High-pressure geophysics and materials
- Structural Health Monitoring Techniques
- Gyrotron and Vacuum Electronics Research
- Underwater Acoustics Research
- Railway Engineering and Dynamics
- Hydrology and Sediment Transport Processes
- Laser-Plasma Interactions and Diagnostics
- Electrostatic Discharge in Electronics
- Ionosphere and magnetosphere dynamics
Boise State University
2016-2025
Michigan State University
2007-2024
New York University Press
2024
Yale University
2024
Institut für Stadtforschung und Strukturpolitik
2024
Grand Valley State University
2014-2020
Los Alamos National Laboratory
1994-2019
New Mexico Institute of Mining and Technology
2007-2013
Instituto Geofísico de la Escuela Politécnica Nacional
2008
University of New Hampshire
2004-2006
Secondary emission is measured from single crystals of MgO cleaved along the (100) plane. The maximum ratio secondary to primary current, ${\ensuremath{\delta}}_{max}$, about 7 at 1 000 volts and room temperature. cross-overs are 33 far above 5 volts. Most probable energy ev or less. A definite effect temperature established, $\ensuremath{\delta}$ decreasing with increasing temperature, in accord expectations for an insulator.
A sensitive cathode ray oscillograph tube is described which operates at a low voltage. The electron stream comes from thermionic cathode, and focused by the action of ionized gas in tube. Illustrations show examples use
Infrasonic airwaves produced by active volcanoes provide valuable insight into the eruption dynamics. Because infrasonic pressure field may be directly associated with flux rate of gas released at a volcanic vent, infrasound also enhances efficacy hazard monitoring and continuous studies conduit processes. Here we present new results from Erebus, Fuego, Villarrica highlighting uses for constraining quantitative parameters, such as duration, source mechanism, explosive flux.
[1] The field of seismoacoustics is emerging as an important discipline in its own right, owing to the value colocated seismic and infrasound arrays that sample elastic energy propagating both solid Earth atmosphere. The fusion infrasonic data provides unique constraints for studying a broad range topics including source physics natural man-made events, interaction mechanical waves Earth's crust atmosphere, location characterization, inversion atmospheric shallow subsurface properties. This...
Abstract The implementation, characterization, and evaluation of a low-cost infrasound sensor developed at the Infrasound Laboratory New Mexico Institute Mining Technology (Infra-NMT) are described. This is based on commercial micromachined piezoresistive differential pressure transducer that uses mechanical high-pass filter to reject low-frequency outband energy. features low-noise, 2.02-mPa rms (0.5–2 Hz), 5.47-mPa (0.1–20 or 5.62-mPa (0.05–20 flat response between 0.01 least 40 Hz; inband...
Abstract Open‐vent volcanic systems with active degassing are particularly effective at producing infrasound that exhibits resonant tones controlled by the geometry of volcano's crater. Changes in character can thus provide constraints on a crater's lava level, which may vary dynamically lead‐up to an eruption. Here we show increasing frequency content and damping characteristics Volcán Villarrica (Chile) relate lake position its crater/conduit preceding 2015 We model acoustic response...
Abstract The paroxysmal 2015 eruption of Volcán Villarrica (Chile) produced a 2.5 h long lahar, which descended more than 20 km within the Rio Correntoso/Turbio drainage and destroyed two small bridges. A three‐element infrasound array 10 from summit, 4 lahar's closest approach, was used to study flow's progression. Array processing using cross‐correlation lag times semblance places constraints on dynamics, including detection an initial flow pulse that traveled 2 12 at average speed 38 m/s....
When sound of high amplitude is transmitted into a liquid by means mechanical driving device, the ultimate limitation to power that can be transferred cavitation or breakdown under internal stresses. A study has resulted in establishing following results. Under steady-state conditions, light liquids filled with air cavitate when negative acoustic pressure reaches atmospheric pressure. are degassed, their natural cohesive becomes effective and they will withstand It found total required cause...
The exposed top of the conduit system at Mount Erebus Volcano, Ross Island, Antarctica, is a convecting lava (magma) lake hosting Strombolian eruptions caused by explosive decompression large (up to 5 m radius) gas slugs. Short‐period (SP; f ≥1 Hz) seismoacoustic eruption seismograms are accompanied oscillatory very long period (VLP) signals observed in near field broadband seismometers 0.7 2.5 km from lake. A variable VLP onset, preceding several seconds, followed repeatable coda that...
We describe a multiparameter experiment at Erebus volcano, Antarctica, employing Doppler radar, video, acoustic, and seismic observations to estimate the detailed energy budget of large (up 40 m‐diameter) bubble bursts from persistent phonolite lava lake. These explosions are readily studied crater rim ranges less than 500 m present an ideal opportunity constrain dynamics mechanism magmatic that can drive Strombolian Hawaiian eruptions. first second typical explosion as function time type....
Secondary emission by electron bombardment has been measured for single crystals of Ge with $p\ensuremath{-}n$ junctions. Maximum yield was found in the range $\ensuremath{\delta}=1.15\ifmmode\pm\else\textpm\fi{}0.03$, at ${V}_{p}\ensuremath{\approx}500$ volts and room temperature. Increasing temperature decreased because a small interaction between internal secondaries lattice. The most probable energy 1-2 ev. There no change donor or acceptor concentration up to...
The secondary electron yield of (BaSr)O has been studied, as induced by microsecond pulses primary electrons with energy up to 2000 ev. $\ensuremath{\delta} \mathrm{vs}. {V}_{p}$ curves have the usual form, maximum $\ensuremath{\delta}$ near 1200 At room temperature, and before surface charges build up, ${\ensuremath{\delta}}_{max}$ is order 12, but it may be reduced 6 less than 0.1 atomic layer Ba evaporated from a nearby thermionic cathode. With increasing temperature decreases an apparent...
Abstract Over the past two decades (2000–2020), volcano infrasound (acoustic waves with frequencies less than 20 Hz propagating in atmosphere) has evolved from an area of academic research to a useful monitoring tool. As result, is routinely used by observatories around world detect, locate, and characterize volcanic activity. It particularly confirming subaerial activity remote eruptions, it shown promise forecasting paroxysmal at open-vent systems. Fundamental on providing substantial new...
[1] Monotonic infrasound with stable peaked frequency of 0.77 Hz was recorded at Volcan Villarrica in January 2010. Similar monotonic had been previously reported (e.g., Ripepe et al. [2010]). Using joint and visual observations from a suspended camera we demonstrate that the likely source is Helmholtz resonance produced cavity volume 105 m3 separates active convecting lava lake an overhanging spatter roof. Spatter roof dimension (65 m diameter) vent diameter (10 m) are constrained video...
Abstract On 19 January 2012, a large D3 avalanche (approximately 10 3 t) was recorded with an infrasound array ideally situated for observing the velocity. The crossed Highway 21 in Central Idaho during largest cycle 15 years of history and deposited approximately 8 m snow on roadway. Possible source locations along path were estimated at 0.5 s intervals used to calculate velocity 64 event. Approximately prior main signal, small signal originated from direction start zone. We infer this be...