The 3 September 2016, Mw 5.8 Pawnee earthquake was the largest recorded earthquake in the state of Oklahoma. Seismic and geodetic observations of the Pawnee sequence, including precise hypocenter ...locations and moment tensor modeling, shows that the Pawnee earthquake occurred on a previously unknown left‐lateral strike‐slip basement fault that intersects the mapped right‐lateral Labette fault zone. The Pawnee earthquake is part of an unprecedented increase in the earthquake rate in Oklahoma that is largely considered the result of the deep injection of waste fluids from oil and gas production. If this is, indeed, the case for the M5.8 Pawnee earthquake, then this would be the largest event to have been induced by fluid injection. Since 2015, Oklahoma has undergone wide‐scale mitigation efforts primarily aimed at reducing injection volumes. Thus far in 2016, the rate of M3 and greater earthquakes has decreased as compared to 2015, while the cumulative moment—or energy released from earthquakes—has increased. This highlights the difficulty in earthquake hazard mitigation efforts given the poorly understood long‐term diffusive effects of wastewater injection and their connection to seismicity.
Key Points
The 3 September 2016, Mw 5.8 Pawnee earthquake is the largest event recorded in Oklahoma, rupturing along a previously unmapped basement fault
In 2016, the rate of M3 and greater earthquakes in Oklahoma has decreased, but the cumulative moment has increased
Observations from this and other Oklahoma earthquakes point to the difficulty in mitigation after years of fluid injection
The Mw 5.1 Fairview, Oklahoma, earthquake on 13 February 2016 and its associated seismicity produced the largest moment release in the central and eastern United States since the 2011 Mw 5.7 Prague, ...Oklahoma, earthquake sequence and is one of the largest earthquakes potentially linked to wastewater injection. This energetic sequence has produced five earthquakes with Mw 4.4 or larger. Almost all of these earthquakes occur in Precambrian basement on a partially unmapped 14 km long fault. Regional injection into the Arbuckle Group increased approximately sevenfold in the 36 months prior to the start of the sequence (January 2015). We suggest far‐field pressurization from clustered, high‐rate wells greater than 12 km from this sequence induced these earthquakes. As compared to the Fairview sequence, seismicity is diffuse near high‐rate wells, where pressure changes are expected to be largest. This points to the critical role that preexisting faults play in the occurrence of large induced earthquakes.
Key Points
One of the largest injection‐related earthquakes was likely induced by far‐field pressurization near Fairview, Oklahoma
Earthquakes occur in Precambrian basement, 6‐10 km below sea level, on a partially unmapped fault
Observations point to the critical role optimally oriented preexisting faults play in the occurrence of large induced earthquakes
Global seismographic networks (GSNs) emerged during the late nineteenth and early twentieth centuries, facilitated by seminal international developments in theory, technology, instrumentation, and ...data exchange. The mid‐ to late‐twentieth century saw the creation of the World‐Wide Standardized Seismographic Network (1961) and International Deployment of Accelerometers (1976), which advanced global geographic coverage as seismometer bandwidth increased greatly allowing for the recording of the Earth's principal seismic spectrum. The modern era of global observations and rapid data access began during the 1980s, and notably included the inception of the GEOSCOPE initiative (1982) and GSN (1988). Through continual improvements, GEOSCOPE and the GSN have realized near‐real time recording of ground motion with state‐of‐art data quality, dynamic range, and timing precision to encompass 180 seismic stations, many in very remote locations. Data from GSNs are increasingly integrated with other geophysical data (e.g., space geodesy, infrasound and Interferometric Synthetic Aperture Radar). Globally distributed seismic data are critical to resolving crust, mantle, and core structure; illuminating features of the plate tectonic and mantle convection system; rapid characterization of earthquakes; identification of potential tsunamis; global nuclear test verification; and provide sensitive proxies for environmental changes. As the global geosciences community continues to advance our understanding of Earth structure and processes controlling elastic wave propagation, GSN infrastructure offers a springboard to realize increasingly multi‐instrument geophysical observatories. Here, we review the historical, scientific, and monitoring heritage of GSNs, summarize key discoveries, and discuss future associated opportunities for Earth Science.
Plain Language Summary
Global seismographic networks (GSNs) record information‐rich ground motion signals that allow scientists and nations to identify and quantify global earthquakes and other seismic sources, and to rapidly assess their significance and impacts on society. In addition to providing a global standard for the monitoring and assessment of such events, these networks provide unique high‐quality data that are fundamental to revealing Earth's structure and dynamic behavior. Scientific applications of GSNs, supplemented by regional data, include imaging the deep interior of the Earth and its plate tectonic system, modeling the structure and dynamics of the inner core, imaging and understanding the rupture of earthquake faults, detecting, discriminating, and characterizing nuclear and other explosions, and improving our general understanding of Earth's ubiquitous seismic wavefield and the unique information that it conveys from the deep interior to the surface and atmosphere of the planet. Leveraging the extensive and hardened infrastructure at these global observatories facilitates the recording of other signals of geophysical interest, such as the magnetic field, low frequency sound waves, and meteorological observations. We review the heritage of GSNs, including their history and resulting scientific achievements, and summarize future opportunities for these networks to contribute further to improved advancements in Earth science.
Key Points
Long running globally distributed seismographic networks are fundamental to understanding Earth's interior structure and processes
Networks have expanded beyond initial mid‐twentieth century design which were focused on recording signals from earthquakes and explosions
Global seismic data combined with data from nearby geophysical instrumentation continue to facilitate new discoveries in Earth science
The Gorkha earthquake on April 25th, 2015 was a long anticipated, low-angle thrust-faulting event on the shallow décollement between the India and Eurasia plates. We present a detailed multiple-event ...hypocenter relocation analysis of the Mw 7.8 Gorkha Nepal earthquake sequence, constrained by local seismic stations, and a geodetic rupture model based on InSAR and GPS data. We integrate these observations to place the Gorkha earthquake sequence into a seismotectonic context and evaluate potential earthquake hazard.
Major results from this study include (1) a comprehensive catalog of calibrated hypocenters for the Gorkha earthquake sequence; (2) the Gorkha earthquake ruptured a ~150×60km patch of the Main Himalayan Thrust (MHT), the décollement defining the plate boundary at depth, over an area surrounding but predominantly north of the capital city of Kathmandu (3) the distribution of aftershock seismicity surrounds the mainshock maximum slip patch; (4) aftershocks occur at or below the mainshock rupture plane with depths generally increasing to the north beneath the higher Himalaya, possibly outlining a 10–15km thick subduction channel between the overriding Eurasian and subducting Indian plates; (5) the largest Mw 7.3 aftershock and the highest concentration of aftershocks occurred to the southeast the mainshock rupture, on a segment of the MHT décollement that was positively stressed towards failure; (6) the near surface portion of the MHT south of Kathmandu shows no aftershocks or slip during the mainshock. Results from this study characterize the details of the Gorkha earthquake sequence and provide constraints on where earthquake hazard remains high, and thus where future, damaging earthquakes may occur in this densely populated region. Up-dip segments of the MHT should be considered to be high hazard for future damaging earthquakes.
•We present a detailed multiple-event hypocenter relocation analysis of the Mw 7.8 Gorkha Nepal earthquake sequence.•We compute a geodetic rupture model of the Mw 7.8 Gorkha earthquake based on InSAR and GPS data.•The distribution of aftershocks surrounds the mainshock maximum slip.•The near surface portion of the MHT south of Kathmandu shows no aftershocks or slip during the mainshock.•Up-dip segments of the MHT should be considered to be high hazard for future damaging earthquakes.
In this thesis, I use passive source seismic data to image the crust and upper mantle in an effort to better understand how the lithosphere deforms. First, I examine how crustal shortening was ...accommodated during the Laramide orogeny in the Bighorn Mountain region of Wyoming. Second, I examine crustal and upper mantle deformation surrounding the Pacific-Australian plate boundary in the South Island of New Zealand. Laramide basement-cored foreland arches make up many prominent ranges in the eastern Rocky Mountains (USA). While thick-skinned Laramide shortening is easily observable at the surface, how shortening was accommodated at depth remains a first order question. A diverse variety of kinematic shortening models each predict a unique, modern-day crustal geometry and are therefore testable. I use teleseismic P-wave receiver functions to image basin and Moho structure in the Bighorn Mountain region. First, I develop and test a sequential H-k (thickness-Vp/Vs) stacking algorithm to account for error introduced by low velocity sedimentary basins. Crustal thickness observations rule out models in which a ductile lower crust undergoes pure shear thickening, forming a crustal root, and models in which faults penetrate the Moho. A mismatch between the geometry of the Bighorn Arch at the surface and that of the Moho suggest that the upper and lower crust are poorly coupled and therefore casts doubt on models in which the whole lithosphere buckles. Kinematic models that invoke a major detachment fault remain feasible and suggest a pre-Laramide origin for the modern Moho structure. I use Rayleigh phase and group velocity observations from ambient noise to construct a regional 3D shear-velocity model and find that high-velocity lower crust appears absent beneath the Bighorn Mountains. Next, I focus on the modern day boundary between the Australian and Pacific plates on the South Island of New Zealand. I use continuous waveform data from ocean bottom seismometers to examine the anisotropic Rayleigh group velocity structure on and offshore of the South Island. Fast directions align sub-parallel to the Alpine Fault. Observations suggest distributed deformation of the lower crust and correlate well with seismic anisotropy observations of the mantle, suggesting the lower crust and mantle are well coupled.
We present a 24-30-GHz 256-element dual-polarization transceiver (TRX) phased array based on a 16-element beamformer integrated circuit (BF-IC), 2-element frequency conversion integrated circuit ...(FC-IC), liquid crystal polymer (LCP)-based combiners and filters, and a tileable package with 64 embedded dual-polarized (dual-pol) antennas. The phased array presented in this work overcomes three key challenges in current 5G millimeter-wave (mmWave) antenna arrays: 1) it supports a dramatic increase in the number of supported fast-access beams; 2) it offers improved power efficiency; and 3) it provides a path to lower solution cost. 1) We enable fast switching among >30000 beams-orders of magnitude improvement over prior work-by employing an on-chip beam calculator in the BF-IC, achieving 200-ns beam setup and 8-ns over-the-air (OTA)-switching time. 2) We enable a module-level transmitter (TX) mode peak power added efficiency (PAE) of 20% using a modular architecture that preserves power amplifier (PA) linearity and efficiency as well as receiver (RX) mode low noise amplifier (LNA) noise figure (NF). The module achieves Psat effective isotropically radiated power (EIRP) of 68.5 dBm and BF-IC NF < 3.9 dB. 3) We lower the solution cost by enabling a wider steering range to reduce the number of phased arrays required in a sectorized coverage scheme, by reducing the IC and package area, and by avoiding calibration. The wider steering range is enabled by using an in-package magnetoelectric dipole antenna (for the first time in silicon-based phased arrays), resulting in steering over ±70° in H- and V-pol in both E- and H-planes without requiring any calibration. Moreover, the module achieves >20-dB cross-polarization isolation across the entire ±70° beam steering range.
A scalable, non-multiplexed cryogenic 14-nm FinFET quantum bit (qubit) state controller (QSC) for use in the semi-autonomous control of superconducting transmon qubits is reported. The QSC includes ...an augmented general-purpose digital processor that supports waveform generation and phase rotation operations combined with a low-power current-mode single sideband upconversion I / Q mixer-based RF arbitrary waveform generator (AWG). Implemented in the 14-nm CMOS FinFET technology, the QSC generates control signals in its target 4.5-5.5-GHz-frequency range, achieving an spurious free dynamic range (SFDR) <inline-formula> <tex-math notation="LaTeX">></tex-math> </inline-formula> 50 dB for a signal bandwidth of 500 MHz. With the controller operating in the 4 K stage of a cryostat and connected to a transmon qubit in the cryostat's millikelvin stage, measured transmon <inline-formula> <tex-math notation="LaTeX">T_{1}</tex-math> </inline-formula> and <inline-formula> <tex-math notation="LaTeX">T_{2}</tex-math> </inline-formula> coherence times were 75.7 and 73 <inline-formula> <tex-math notation="LaTeX">\mu</tex-math> </inline-formula>s, respectively, in each case comparable to results achieved using conventional room temperature (RT) controls. In further tests with transmons, a qubit-limited error rate of 7.76 <inline-formula> <tex-math notation="LaTeX">\times</tex-math> </inline-formula> 10<inline-formula> <tex-math notation="LaTeX">^{-4}</tex-math> </inline-formula> per Clifford gate is achieved, again comparable to the results achieved using RT controls. The QSC's maximum RF output power is <inline-formula> <tex-math notation="LaTeX">-</tex-math> </inline-formula>18 dBm, and power dissipation per qubit under active control is 23 mW.
Commissioning of the St. Benedict RF carpet Davis, C.; Bualuan, R.; Bruce, O. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2022, Letnik:
1042
Journal Article
Recenzirano
Odprti dostop
The Superallowed Transition BEta NEutrino Decay Ion Coincidence Trap (St. Benedict) aims to measure the beta-neutrino angular correlation parameter for superallowed mixed beta decay transitions ...between mirror nuclei in order to conduct precision tests of the Standard Model. St. Benedict will include a gas catcher, a differentially pumped extraction system, a radio-frequency quadrupole (RFQ) cooler and buncher, and a Paul trap to utilize radioactive ion beams produced at the Nuclear Science Laboratory of the University of Notre Dame. The two-part differentially pumped extraction system contains a RF carpet at a helium gas pressure of around 3 mbar, and a radio-frequency quadrupole (RFQ) ion guide at a pressure of around 2×10−3 mbar. Transport efficiency of potassium ions in the first part of the extraction system using the RF carpet in the presence of gas flow was determined to be near 100% in the 0.75 to 5 mbar pressure range using the ion surfing transport method.
The 6 February 2023 Mw 7.8 Pazarcik and subsequent Mw 7.5 Elbistan earthquakes generated strong ground shaking that resulted in catastrophic human and economic loss across south-central Türkiye and ...northwest Syria. The rapid characterization of the earthquakes, including their location, size, fault geometries, and slip kinematics, is critical to estimate the impact of significant seismic events. The U.S. Geological Survey National Earthquake Information Center (NEIC) provides real-time monitoring of earthquakes globally, including rapid source characterization and impact estimates. Here, we describe the seismic characterization products generated and made available by the NEIC over the two weeks following the start of the earthquake sequence in southeast Türkiye, their evolution, and how they inform our understanding of regional seismotectonics and hazards. The kinematics of rupture for the two earthquakes was complex, involving multiple fault segments. Therefore, incorporating observations from rupture mapping was critical for characterizing these events. Dense local datasets facilitated robust source characterization and impact assessment once these observations were obtained and converted to NEIC product input formats. We discuss how we may improve the timeliness of NEIC products for rapid assessment of future seismic hazards, particularly in the case of complex ruptures.
In this article, we present a low-power, small form-factor, 60-GHz packaged radio featuring broad beam coverage. We increase angular coverage by beam switching between two orthogonally pointed low ...directivity beams that are created using two different antennas integrated in package. The resulting wide angular coverage of the radio makes radio links robust to movement and rotation; this improvement overcomes a key challenge for millimeter-wave (mmWave) deployment in portable electronics. We incorporate a 3.2 mm <inline-formula> <tex-math notation="LaTeX">\times </tex-math></inline-formula> 3.2 mm 32-nm CMOS radio integrated circuit (IC) in the package for radio functions. The IC includes TX and RX RF front ends, up- and down-conversion mixers, TX and RX analog baseband circuits, a common PLL, TX and RX LO chains, and ADCs and a micro-controller for built-in self-test (BIST). The IC is flip-chip packaged on a four-layer organic package comprising two TX antennas and two RX antennas. In board-level over-the-air measurements of the half-duplex packaged radio, 17.1-dBm effective isotropic radiated power (EIRP) and 6.1-dB noise figure are achieved in the TX and RX modes respectively, with power consumption below 250 mW in either mode. We characterized the radio over the air using 802.11ad waveforms; the radio is 802.11ad compliant in both TX and RX modes at data rates up to the maximum 802.11ad PHY rate of 4.62 Gb/s (raw data rate >7 Gb/s) with a TX EVM < −22 dB and RX sensitivity < −54 dBm. To measure angular coverage, we characterized 802.11ad compliance in 3-D over 3<inline-formula> <tex-math notation="LaTeX">\pi </tex-math></inline-formula> steradians in first-of-a-kind measurements. The radio maintains 802.11ad compliance over 2.9<inline-formula> <tex-math notation="LaTeX">\pi </tex-math></inline-formula> steradians solid angle.
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