Kinematic Rupture and 3D Wave Propagation Simulations of the 2019 Mw 7.1 Ridgecrest, California, Earthquake

ABSTRACT We model the kinematic rupture process of the 2019 Mw 7.1 Ridgecrest, California, earthquake using numerical simulations to reproduce the elastodynamic wave field observed by inertial seismometers, high-rate Global Navigation Satellite System stations, and borehole strainmeters. This was the largest earthquake in Southern California in 20 yr and was widely felt throughout the region. The Mw 7.1 mainshock was part of a large sequence of ∼30,000 aftershocks and was notably preceded by an Mw 6.4 foreshock by 34 hr on fault structures that were once poorly understood. A large number of seismic and geodetic instruments measured the rupture process for both events, with many stations located in the near field. Hence, this is a rare opportunity to better understand complex earthquake processes that arise in an immature fault zone using advanced computing. Of the kinematic rupture models that we tested, our preferred is the simplest one that reproduces signals recorded by the three different geophysical datasets; it is composed of four distinct ruptures that progressively migrate to the southeast with delayed initiation times, and typical rupture speeds. This type of model does a better job at matching the recorded ground motions and deformations than does one composed of a continuous rupture with very low-rupture velocity, as proposed in other studies of this earthquake.

Download Full-text

Resolving dynamic ground motions with high-rate GNSS and implications for data fusion in broadband seismology and Earthquake Early Warning

10.5194/egusphere-egu2020-13360 ◽

2020 ◽

Author(s):

Roland Hohensinn ◽

Nikolaj Dahmen ◽

John Clinton ◽

Alain Geiger ◽

Markus Rothacher

Keyword(s):

Data Fusion ◽

Real Time ◽

Early Warning ◽

Ground Motions ◽

Real Data ◽

Satellite System ◽

Earthquake Early Warning ◽

High Rate ◽

Velocity Waveform ◽

Global Navigation Satellite

In this paper we highlight the potential of geodetic high-precision and high-rate GNSS (Global Navigation Satellite System) sampling (1 to 100 Hz) for resolving seismic ground motions, of both the near and the far field of an earthquake. The analysis of the budget and characteristics of the error of high-rate GNSS displacement time series yields results, discussion, and conclusions on the sensitivity and waveform resolvability as well as on the derivation of a minimum detectable displacement (in the statistical sense).Based on these analyses, we show how GNSS can contribute to optimal broadband displacement and velocity waveform products by means of data fusion by combining measurements taken from co-located sensors &#8211; e.g. accelerometers or gyroscopes &#8211; in real-time, near real-time and postprocessing mode. Concerning the inclusion of GNSS for such an analysis, we also briefly explore the ability of GNSS to record signals from different earthquake magnitudes and epicentral distances. We show that high-rate GNSS is sensitive to displacements down to the level of a few millimeters, and even below &#8211; an example also comes from the detection of very small vibrations from 100 Hz GNSS data.We analyze measurements of synthetized signals obtained from experiments with a shake table, as well as from real data from strong earthquakes, namely the 6.5 Mw event of 2016 near the city of Norcia (Italy) and the 7.0 Mw Kumamoto earthquake of 2016 (Japan). Based on these data and our main findings, we finally discuss the role of GNSS in Earthquake Early Warning in terms of a fast hypocenter localization and reliable magnitude estimation.

Download Full-text

High-rate altimetry in SNR-based GNSS-R: Proof-of-concept of a synthetic vertical array

10.36227/techrxiv.14186930 ◽

2021 ◽

Author(s):

Mauricio Kenji Yamawaki ◽

Felipe Geremia-Nievinski ◽

João Francisco Monico

Keyword(s):

Sea Level ◽

Signal To Noise Ratio ◽

Satellite System ◽

High Rate ◽

Proof Of Concept ◽

Radio Waves ◽

Vertical Array ◽

Remote Sensing Technique ◽

Single Antenna ◽

Global Navigation Satellite

Global Navigation Satellite System Reflectometry (GNSS-R) has emerged as a promising remote sensing technique for coastal sea level monitoring. The GNSS-R based on signal-to-noise ratio (SNR) observations employs a single antenna and a conventional receiver. It performs best for low elevation satellites, where direct and reflected radio waves are very similar in polarization and direction of arrival. One of the disadvantages of SNR-based GNSS-R for sea level altimetry is its low temporal resolution, which is of the order of one hour for each independent satellite pass. Here we present a proof-of-concept based on a synthetic vertical array. It exploits the mechanical movement of a single antenna at high rate (about 1 Hz). SNR observations can then be fit to a known modulation, of the order of the antenna sweeping rate. We demonstrate that centimetric altimetry precision can be achieved in a 5-minute session. [©2021 IEEE]

Download Full-text

Rupture kinematics of 2020 January 24 Mw 6.7 Doğanyol-Sivrice, Turkey earthquake on the East Anatolian Fault Zone imaged by space geodesy

Geophysical Journal International ◽

10.1093/gji/ggaa345 ◽

2020 ◽

Vol 223 (2) ◽

pp. 862-874 ◽

Cited By ~ 6

Author(s):

Diego Melgar ◽

Athanassios Ganas ◽

Tuncay Taymaz ◽

Sotiris Valkaniotis ◽

Brendan W Crowell ◽

...

Keyword(s):

Fault Zone ◽

Satellite System ◽

High Rate ◽

Slip Model ◽

Slip Region ◽

Global Navigation Satellite ◽

Rupture Kinematics ◽

Source Duration ◽

East Anatolian Fault Zone ◽

East Anatolian Fault

SUMMARY Here, we present the results of a kinematic slip model of the 2020 Mw 6.7 Doğanyol-Sivrice, Turkey Earthquake, the most important event in the last 50 yr on the East Anatolian Fault Zone. Our slip model is constrained by two Sentinel-1 interferograms and by 5 three-component high-rate GNSS (Global Navigation Satellite System) recordings close to the earthquake source. We find that most of the slip occurs predominantly in three regions, two of them at between 2 and 10 km depth and a deeper slip region extending down to 20 km depth. We also relocate the first two weeks of aftershocks and find a distribution of events that agrees with these slip features. The HR-GNSS recordings suggest a predominantly unilateral rupture with the effects of a directivity pulse clearly seen in the waveforms and in the measure peak ground velocities. The slip model supports rupture propagation from northeast to southwest at a relatively slow speed of 2.2 km s−1 and a total source duration of ∼20 s. In the absence of near-source seismic stations, space geodetic data provide the best constraint on the spatial distribution of slip and on its time evolution.

Download Full-text

Source Characteristics of the 2020 Mw 7.4 Oaxaca, Mexico, Earthquake Estimated from GPS, InSAR, and Teleseismic Waveforms

Seismological Research Letters ◽

10.1785/0220200313 ◽

2021 ◽

Author(s):

Yangmao Wen ◽

Zhuohui Xiao ◽

Ping He ◽

Jianfei Zang ◽

Yang Liu ◽

...

Keyword(s):

Near Field ◽

Rupture Process ◽

High Rate ◽

Coseismic Deformation ◽

Interferometric Synthetic Aperture Radar ◽

Key Factors ◽

Factors Affecting ◽

Initial Rupture ◽

Mexico Earthquake ◽

Nonlinear Joint

Abstract On 23 June 2020, an Mw 7.4 earthquake struck offshore Oaxaca, Mexico, providing a unique opportunity to understand the seismogenic tectonics of the Mexican subduction zone. In this study, near-field coseismic deformation caused by the event was retrieved from Global Positioning System (GPS) observations and Interferometric Synthetic Aperture Radar (InSAR) measurements. Given static geodetic measurements, high-rate GPS waveforms, and teleseismic waveforms, the fault geometry and rupture process for the 2020 Oaxaca earthquake were robustly determined by nonlinear joint inversions. The main slip was located at a depth of 20–30 km with a peak slip of 3.4 m near the epicenter. The total released moment was 1.70×1020 N·m, corresponding to Mw 7.4. The whole rupture process lasted 14 s, with the dominant rupture slip occurring 5–8 s after initial rupture. The mainshock rupture mostly occurred along the fault strike, covering a size of ∼55 km(along strike)×∼35 km(along dip) and totally overlapping with the 1965 Mw 7.5 rupture zone. We speculate that this 2020 earthquake is a repeat event following that in 1965. Fluid percolation under the slab may be one of the key factors affecting the seismogenic depth in the Oaxaca region.

Download Full-text

Comparison of high rate GNSS and GNSS-R measurements for detecting tidal bores in the Garonne River

10.5194/egusphere-egu2020-20898 ◽

2020 ◽

Author(s):

Pierre Zeiger ◽

José Darrozes ◽

Frédéric Frappart ◽

Guillaume Ramillien ◽

Laurent Lestarquit ◽

...

Keyword(s):

Sea Level ◽

Sampling Rate ◽

Acoustic Doppler Current Profiler ◽

Satellite System ◽

High Rate ◽

Tidal Bore ◽

Garonne River ◽

Current Profiler ◽

Oceanic Tides ◽

Global Navigation Satellite

The Reflected Global Navigation Satellite System (GNSS-R) is a bi-static radar system in which the receiver collect GNSS signals reflected from the Earth surface and compares them with corresponding direct signals. Measurements can be performed on the waveforms to determine the elevation of the free surface, leading to applications such as ocean altimetry, inland water level variations, soil moisture, snow depth and atmospheric water changes. This study presents the potential of in-situ GNSS-R for tidal bore detection and characterization, and compares it to high rate GNSS observations and other reference datasets.The data we used were acquired on 17th and 18th October 2016 in the Garonne River, at 126 km upstream the mouth of the Gironde estuary. We processed GNSS-based elevations from data acquired on a buoy at a 20 Hz sampling rate using differential GNSS (DGNSS) technique. Acoustic Doppler Current Profiler (ADCP) measurements as well as pressure data were used for validation purposes. These techniques show good results in estimating the amplitude of the first wave, the period of the tidal bore and the oceanic tides. All of these datasets were compared to the retrieval of GNSS-R signals above the river. We have processed the changes in water height throughout the acquisition using Larson et al. (2013) and Roussel et al. (2015) techniques. We finally separate the atmospheric component from the tidal bore and the oceanic tides ones.&#160;Larson, K. M., L&#246;fgren, J. S., and Haas, R. (2013). Coastal sea level measurements using a single geodetic gps receiver. Advances in Space Research, 51(8):1301&#8211;1310.Roussel, N., Ramillien, G., Frappart, F. et al. (2015). Sea level monitoring and sea state estimate using a single geodetic receiver. Remote Sensing of Environment, 171:261 &#8211; 277.

Download Full-text

High-Rate Monitoring of Satellite Clocks Using Two Methods of Averaging Time

Remote Sensing ◽

10.3390/rs11232754 ◽

2019 ◽

Vol 11 (23) ◽

pp. 2754 ◽

Cited By ~ 6

Author(s):

Maciuk ◽

Lewińska

Keyword(s):

Satellite System ◽

High Rate ◽

Allan Deviation ◽

International Gnss Service ◽

Orbit Type ◽

Averaging Time ◽

Orbit Types ◽

Global Navigation Satellite ◽

Satellite Clock Error ◽

Reference Clock

Knowledge of the global navigation satellite system (GNSS) satellite clock error is crucial in real-time precise point positioning (PPP), seismology, and many other high-rate GNSS applications. In this work, the authors show the characterisation of the atomic GNSS clock’s stability and its dependency on the adopted orbit type using Allan deviation with two methods of averaging time. Four International GNSS Service (IGS) orbit types were used: broadcast, ultra-rapid, rapid and final orbit. The calculations were made using high-rate 1 Hz observations from the IGS stations equipped with external clocks (oscillators). The most stable receiver oscillator was chosen as a reference clock. The results show the advantage of the newest GPS satellite block with respect to the other satellites. Significant differences in the results based on the orbit type used have not been recorded. Many averaging time methods used in Allan deviation (ADEV) show the clock’s fluctuations, usually smoothed in 2n s averaging times.

Download Full-text

Mitigation of Unmodeled Error to Improve the Accuracy of Multi-GNSS PPP for Crustal Deformation Monitoring

Remote Sensing ◽

10.3390/rs11192232 ◽

2019 ◽

Vol 11 (19) ◽

pp. 2232 ◽

Cited By ~ 3

Author(s):

Kai Zheng ◽

Xiaohong Zhang ◽

Xingxing Li ◽

Pan Li ◽

Xiao Chang ◽

...

Keyword(s):

Large Earthquake ◽

Seismic Signal ◽

Satellite System ◽

Deformation Monitoring ◽

High Rate ◽

Navigation Satellite ◽

Jiuzhaigou Earthquake ◽

Reliable Technique ◽

New Findings ◽

Global Navigation Satellite

High-rate multi-constellation global navigation satellite system (GNSS) precise point positioning (PPP) has been recognized as an efficient and reliable technique for large earthquake monitoring. However, the displacements derived from PPP are often overwhelmed by the centimeter-level noise, therefore they are usually unable to detect slight deformations which could provide new findings for geophysics. In this paper, Global Positioning System (GPS), GLObalnaya NAvigatsionnaya Sputnikovaya Sistema (GLONASS), and BeiDou navigation satellite system (BDS) data collected during the 2017 Mw 6.5 Jiuzhaigou earthquake were used to further exploit the capability of BDS-only and multi-GNSS PPP in deformation monitoring by applying sidereal filtering (SF) in the observation domain. The equation that unifies the residuals for the uncombined and undifferenced (UCUD) PPP solution on different frequencies was derived, which could greatly reduce the complexity of data processing. An unanticipated long-term periodic error term of up to ± 3 cm was found in the phase residuals associated with BDS satellites in geostationary Earth orbit (GEO), which is not due to multipath originated from the ground but is in fact satellite dependent. The period of this error is mainly longer than 2000 s and cannot be alleviated by using multi-GNSS. Compared with solutions without sidereal filtering, the application of the SF approach dramatically improves the positioning precision with respect to the weekly averaged positioning solution, by 75.2%, 42.8%, and 56.7% to 2.00, 2.23, and 5.58 cm in the case of BDS-only PPP in the east, north, and up components, respectively, and 71.2%, 27.7%, and 37.9% to 1.25, 0.81, and 3.79 cm in the case of GPS/GLONASS/BDS combined PPP, respectively. The GPS/GLONASS/BDS combined solutions augmented by the SF successfully suppress the GNSS noise, which contributes to the detection of the true seismic signal and is beneficial to the pre- and post-seismic signal analysis.

Download Full-text

High-rate altimetry in SNR-based GNSS-R: Proof-of-concept of a synthetic vertical array

10.36227/techrxiv.14186930.v1 ◽

2021 ◽

Author(s):

Mauricio Kenji Yamawaki ◽

Felipe Geremia-Nievinski ◽

João Francisco Monico

Keyword(s):

Sea Level ◽

Signal To Noise Ratio ◽

Satellite System ◽

High Rate ◽

Proof Of Concept ◽

Radio Waves ◽

Vertical Array ◽

Remote Sensing Technique ◽

Single Antenna ◽

Global Navigation Satellite

Download Full-text

The GAGE Data and Field Response to the 2019 Ridgecrest Earthquake Sequence

Seismological Research Letters ◽

10.1785/0220190283 ◽

2020 ◽

Vol 91 (4) ◽

pp. 2075-2086 ◽

Cited By ~ 4

Author(s):

Glen S. Mattioli ◽

David A. Phillips ◽

Kathleen M. Hodgkinson ◽

Chris Walls ◽

David J. Mencin ◽

...

Keyword(s):

Data Center ◽

Satellite System ◽

Earthquake Sequence ◽

High Rate ◽

Surface Model ◽

High Temporal Resolution ◽

Epicentral Area ◽

Time Period ◽

National Science ◽

Global Navigation Satellite

Abstract The July 2019 Ridgecrest sequence was observed in exquisite detail by the National Science Foundation’s (NSF) Geodetic Facility for the Advancement of Geoscience (GAGE) Network of the Americas (NOTA), which has a dense array of continuously observing Global Navigation Satellite System (GNSS) stations and subarrays of strain and seismic borehole networks in southern California. Two hundred and eighteen GNSS and 10 borehole NOTA stations within 250 km of the epicentral area recorded the sequence. Special downloads of high-rate data from sites within a specified radius of each earthquake were initiated by the GAGE Facility for the time period of 1.5 days before and 1.5 days after each event to ensure transient deformation was captured at a high-temporal resolution. Rapid field deployments of temporary GNSS stations were carried out by UNAVCO in support of NSF-funded investigators and U.S. Geological Survey activities. The data recorded by the permanent network are available from the GAGE Facility’s Data Center at UNAVCO, data recorded at the temporary campaign sites will also be made available on completion of data collection. The OpenTopography project, of which UNAVCO is a partner, released a preliminary pre-event digital surface model of the area covering the Ridgecrest earthquake sequence to support the ongoing imaging efforts to measure the deformation from these events. In this article, we document the significant amount of detailed, open-access geodetic data available from GAGE to study this sequence and advance our understanding of earthquake processes, the geodynamics of the California eastern shear zone, and our capacity to respond to damaging earthquakes for research.

Download Full-text

HDDM Hardware Evaluation for Robust Interference Mitigation

Sensors ◽

10.3390/s20226492 ◽

2020 ◽

Vol 20 (22) ◽

pp. 6492

Author(s):

Fabio Garzia ◽

Johannes Rossouw van der Merwe ◽

Alexander Rügamer ◽

Santiago Urquijo ◽

Wolfgang Felber

Keyword(s):

Hardware Implementation ◽

Interference Mitigation ◽

Dynamic Range ◽

State Of The Art ◽

Satellite System ◽

High Rate ◽

Gnss Receivers ◽

Improved Performance ◽

Global Navigation Satellite ◽

Mitigation Methods

Interference can significantly degrade the performance of global navigation satellite system (GNSS) receivers. Therefore, mitigation methods are required to ensure reliable operations. However, as there are different types of interference, robust, multi-purpose mitigation algorithms are needed. This paper describes the most popular state-of-the-art interference mitigation techniques. The high-rate DFT-based data manipulator (HDDM) is proposed as a possible solution to overcome their limitations. This paper presents a hardware implementation of the HDDM algorithm. The hardware HDDM module is integrated in three different receivers equipped with analog radio-frequency (RF) front-ends supporting signals with different dynamic range. The resource utilization and power consumption is evaluated for the three cases. The algorithm is compared to a low-end mass-market receiver and a high-end professional receiver with basic and sophisticated interference mitigation capabilities, respectively. Different type of interference are used to compare the mitigation capabilities of the receivers under test. Results of the HDDM hardware implementation achieve the similar or improved performance to the state of the art. With more complex interferences, like frequency hopping or pulsed, the HDDM shows even better performance.

Download Full-text