Polar stratospheric clouds (PSCs) play a key role in ozone depletion. Surface-catalyzed reactions on PSC particles generate chlorine compounds that photolyze readily to yield radicals, which turn destroy very efficiently. The most prevalent PSCs form at temperatures several degrees above the ice frost point and are believed consist of HNO(3) hydrates; however, their formation mechanism is unclear. Results laboratory experiments presented indicate background H(2)SO(4)/H(2)O aerosols provide...

ABSTRACT Separating earthquake source spectra from propagation effects is challenging. The effect contains a site-dependent term related to the high attenuation of shallow sediments. Neglecting can cause large biases and scattering in corner-frequency (fc) estimates, resulting significant stress-drop deviations. In this study, we investigate at LArge-n Seismic Survey Oklahoma (LASSO) site-related parameter measurements due simplified models. We measure high-frequency spectral decay kappa on...

ABSTRACT The shear-wave velocity (VS) structure plays an important role in characterizing site amplification. Large-n Seismic Survey Oklahoma (LASSO; 1820 stations) revealed large vertical ground-motion variability a 25 km × 32 area northern Oklahoma. LASSO array has relatively simple and flat topography, typical sedimentary basin environment the central United States. In this study, we use dense to investigate under how ground motions relate shallow-to-deep structures. We extract...

The results of laboratory investigations the freezing behavior aqueous acid solutions indicate that in stratosphere H 2 SO 4 /H O aerosol droplets would not freeze at temperatures above ice frost point absence HNO 3 ; however, presence typical levels liquid sulfuric aerosols take up significant amounts and vapors much more readily. This is a consequence very rapid change composition as temperature drops to within two three degrees equilibrium which co‐condense form solution. In high latitude...

Deformation of all materials necessitates the collective propagation various microscopic defects. On Earth, fracturing gives way to crystal-plastic deformation with increasing depth resulting in a “brittle-to-ductile” transition (BDT) region that is key for estimating integrated strength tectonic plates, constraining earthquake cycle, and utilizing deep geothermal resources. Here, we show crossing BDT marble during experiments laboratory accompanied by systematic increase frequency acoustic...

Abstract We investigate the effects of site response on source parameter estimates using earthquakes recorded by LArge‐n Seismic Survey in Oklahoma (LASSO). While it is well known that near‐surface unconsolidated sediments can cause an apparent breakdown earthquake self‐similarity, influence laterally varying conditions remains unclear. analyze across 1825‐station array a river plain within area 40 km 23 vertical ground motions from 14 regional earthquakes. radiation pattern controls P‐wave...

Distributed acoustic sensing (DAS) has great potential for monitoring natural-resource reservoirs and borehole conditions. However, the large volume of data complicated wavefield add challenges to processing interpretation. In this study, we demonstrate that seismic interferometry based on deconvolution is a convenient tool analyzing wavefield. We also show limitation technique, in it still requires good coupling extract signal interest. coherent waves from observation DAS system at Brady...

ABSTRACT To investigate the sensitivity of slip inversions to station distribution and choice empirical Green’s function (EGF), we examine three microearthquakes that occurred within high-density LArge-n Seismic Survey in Oklahoma (LASSO) nodal seismic array. The LASSO array’s dense 1825 geophones provides an exceptional level spatial azimuthal coverage, allowing for more accurate than are possible with typical distributions. highly inversions, turn, allow exploration parameter choices. We...

ABSTRACT: The strength of the lithosphere is limited by pressure-dependent, "brittle" deformation upper crust and temperature- strain-rate-dependent "ductile" in lower mantle. From a simplified mechanistic point view, intersection these two envelopes can be used to estimate depth region known as brittle-to-ductile transition (BDT) where rocks deform semi-brittle flow. This BDT key for estimating integrated tectonic plates, constraining earthquake cycle, utilizing deep geothermal resources....

The distributed acoustic sensor (DAS) has great potential for monitoring natural-resource reservoirs. In this study, we investigate the DAS borehole data at Brady geothermal field. We analyze seismic velocity perturbations of waves propagating along during an eight-day period and variations across depth, time, temperature, pressure. results suggest that reverberation is caused by poor coupling between cable well-casing, reverberations provide useful information to measure time-lapse changes...

Modern high-performance computing (HPC) tasks overwhelm conventional geophysical data formats. We describe a new schema called HDF5eis (read H-D-F-size) for handling big multidimensional time series from environmental sensors in HPC applications and implement freely available Python application programming interface (API) building processing files. augments the popular Hierarchical Data Format 5 with minimal set of additional conventions that facilitate fast flexible input output protocols...

Telecommunication dark fibers with distributed acoustic sensing (DAS) are a useful survey tool for site characterization in urban environments. In this paper, we introduce our five-day student-led DAS experiment using at the Massachusetts Institute of Technology campus city Cambridge. The has been identified as an area that is highly susceptible to seismic hazards due subsurface structure and soil properties. included planning, data acquisition, analysis, characterization, site-response...

We have recently created an age-dependent hypertensive-mono-arthritic animal model from the stroke-resistant spontaneously hypertensive rat to populations with autoimmune disease who are and prone stroke. The exhibits signs of hemorrhagic stroke (HS) subsequent chronic inflammation hypertension. HS is also associated inability middle cerebral arteries undergo pressure dependent constriction (PDC). investigated alterations in cerebrovasculature our mono-arthritic animals that develop Animals...

Earth and Space Science Open Archive Presented WorkOpen AccessYou are viewing the latest version by default [v1]Quantifying earthquake source parameter uncertainties associated with local site effects using a dense arrayAuthorsHilaryChangiDRachelAbercrombieiDNoriNakataColinPenningtonKilianKemnaiDElizabethCochraniDRebeccaHarringtonSee all authors Hilary ChangiDCorresponding Author• Submitting AuthorMassachusetts Institute of TechnologyiDhttps://orcid.org/0000-0002-9402-6089view email...

The distributed acoustic sensing (DAS) has great potential for monitoring natural-resource reservoirs and borehole conditions. However, the large volume of data complicated wavefield add challenges to processing interpretation. In this study, we demonstrate that seismic interferometry based on deconvolution is a convenient tool analyzing wavefield. We extract coherent wave from observation DAS system at Brady geothermal field in Nevada. Then, analyze reverberating waves, which are used...

The distributed acoustic sensing (DAS) has great potential for monitoring natural-resource reservoirs and borehole conditions. However, the large volume of data complicated wavefield add challenges to processing interpretation. In this study, we demonstrate that seismic interferometry based on deconvolution is a convenient tool analyzing wavefield. We extract coherent wave from observation DAS system at Brady geothermal field in Nevada. Then, analyze reverberating waves, which are used...

Earthquake stress drop values estimated from ground-motion spectra commonly vary by several orders of magnitude, particularly for small earthquakes (~M < 3). Stress-drop have been found to with faulting style, type (intraplate, interplate), depth, and exhibit differences between natural induced earthquakes. Nevertheless, distinguishing uncertainties real trends across data sets is challenging, in part due the variation methodological approaches observational constraints. However,...