Transtensional Rupture within a Diffuse Plate Boundary Zone during the 2020 Mw 6.4 Puerto Rico Earthquake

2021 ◽  
Author(s):  
Renier Viltres ◽  
Adriano Nobile ◽  
Hannes Vasyura-Bathke ◽  
Daniele Trippanera ◽  
Wenbin Xu ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Plate Boundary ◽  
Large Earthquake ◽  
Satellite System ◽  
Coseismic Deformation ◽  
Fault Parameters ◽  
Earthquake Potential ◽  
Global Navigation Satellite ◽  
Plate Boundary Zone ◽  
East West

Abstract On 7 January 2020, an Mw 6.4 earthquake occurred in the northeastern Caribbean, a few kilometers offshore of the island of Puerto Rico. It was the mainshock of a complex seismic sequence, characterized by a large number of energetic earthquakes illuminating an east–west elongated area along the southwestern coast of Puerto Rico. Deformation fields constrained by Interferometric Synthetic Aperture Radar and Global Navigation Satellite System data indicate that the coseismic movements affected only the western part of the island. To assess the mainshock’s source fault parameters, we combined the geodetically derived coseismic deformation with teleseismic waveforms using Bayesian inference. The results indicate a roughly east–west oriented fault, dipping northward and accommodating ∼1.4 m of transtensional motion. Besides, the determined location and orientation parameters suggest an offshore continuation of the recently mapped North Boquerón Bay–Punta Montalva fault in southwest Puerto Rico. This highlights the existence of unmapped faults with moderate-to-large earthquake potential within the Puerto Rico region.

Fault parameters of the Mw 6.4 January 7, 2020, Puerto Rico earthquake estimated from teleseismic, GNSS and InSAR data

2021 ◽  
Author(s):  
Adriano Nobile ◽  
Renier Viltres ◽  
Hannes Vasyura-Bathke ◽  
Daniele Trippanera ◽  
Wenbin Wenbin Xu ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Fault Zone ◽  
Ground Deformation ◽  
Source Parameters ◽  
Active Faults ◽  
Geodetic Network ◽  
Seismic Sequence ◽  
Seismicity Rates ◽  
Fault Parameters ◽  
East West

<p>We used teleseismic waveforms and ground deformation data from GNSS and InSAR to estimate source fault parameters of the M<sub>w</sub>6.4 earthquake that occurred just offshore southwestern Puerto Rico on 7 January 2020. The mainshock was a part of an energetic seismic sequence that started on 28 December 2019 and led to a M<sub>w</sub>5.8 earthquake on 6 January 2020, a day before the M<sub>w</sub>6.4 mainshock. The ground-shaking due to the largest earthquakes of the sequence caused significant damage to buildings and infrastructures in Puerto Rico and one casualty was reported by the local media. The mainshock was followed by a strong aftershock sequence that included four M<sub>w </sub>≥ 5 events within the first 3 hours. In the first 40 days of the seismic sequence, data from the Puerto Rico Seismic Network were used to locate ~3800 earthquakes of magnitude > 2, illuminating an east-west elongated 30x50 km<sup>2</sup> area, just offshore the southwestern coast of Puerto Rico. The region affected by this activity was before characterized by relatively low seismicity rates, even if a system of active faults, both onshore and offshore, had been mapped. The sequence is peculiar due to its complex development and many large aftershocks (magnitude > 4.5), with the mainshock releasing only  ~60% of the total seismic moment.</p><p>We estimated the key source parameters of the mainshock using teleseismic data, GNSS data from the Puerto Rico Geodetic Network, and InSAR data from the Sentinel-1 and ALOS-2 satellites. The modeled source is consistent with a ~15 km long and ~11 km wide blind fault, oriented roughly east-west and dipping 46<sup>o</sup> towards north, and with up to 1.1 m of oblique normal and left-lateral strike-slip.</p><p>The optimal fault plane source indicates that it is an offshore continuation of the mapped North Boquerón Bay - Punta Montalva fault zone, supported by the large number of the aftershocks that trend along the same direction. However, most of the aftershocks, even those of magnitude > 5, occurred on other nearby faults, highlighting the complexity of this fault zone area.</p>

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

2019 ◽  
Vol 11 (19) ◽  
pp. 2232 ◽  
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.

scholarly journals An Improved Method of Soil Moisture Retrieval Using Multi-Frequency SNR Data

2021 ◽  
Vol 13 (18) ◽  
pp. 3725
Author(s):  
Kun Chen ◽  
Xinyun Cao ◽  
Fei Shen ◽  
Yulong Ge
Keyword(s):  
Soil Moisture ◽  
Plate Boundary ◽  
Principal Component ◽  
Ground Truth ◽  
Satellite System ◽  
Entropy Method ◽  
Single Frequency ◽  
Retrieval Accuracy ◽  
Using Data ◽  
Global Navigation Satellite

Soil moisture monitoring using Global Navigation Satellite System (GNSS) multipath signals has gained continuous interests in recent years. However, traditional GNSS-interferometric reflectometry (GNSS-IR) soil moisture retrieval methods generally utilize a single frequency or single satellite, which fail to take full advantage of different and complementary of satellite signals with different frequencies. An improved algorithm for soil moisture retrieval based on principal component analysis (PCA) and entropy method using multi-frequency amplitude and phase offset fusion data was proposed in this research. The performance of the proposed soil moisture retrieval method was evaluated using data recorded by Plate Boundary Observatory (PBO) H2O networks and a self-built site in Henan, China. The results from GPS and BeiDou both showed that the retrieved soil moisture has a stronger correlation with in situ soil moisture, which can better reflect the fluctuation of ground truth measurements. Compared with the traditional method, the retrieval accuracy of the proposed method in terms of root-mean-square error (RMSE) was improved by 50.93%, and the average correlation coefficient were increased by 11.71%. This research proved that the proposed method could effectively improve retrieval accuracy due to the increasing number of frequencies and tracks clustering. Moreover, this study has illustrated the feasibility of BeiDou signals to precisely estimate surface soil moisture.

scholarly journals Excess strain in the Echigo Plain sedimentary basin, NE Japan: evidence from coseismic deformation of the 2011 Tohoku-oki earthquake

2016 ◽  
Vol 205 (3) ◽  
pp. 1613-1617 ◽  
Author(s):  
T. Nishimura ◽  
H. Suito ◽  
T. Kobayashi ◽  
Q. Dong ◽  
T. Shibayama
Keyword(s):  
High Strain ◽  
Satellite System ◽  
Coseismic Deformation ◽  
Tectonic Zone ◽  
Displacement Profile ◽  
Extensional Strain ◽  
Global Navigation Satellite ◽  
Crustal Inhomogeneity ◽  
Fault Source ◽  
Ne Japan

Abstract Coseismic deformation depends on both the source fault and on the elastic properties of the crust. Large coseismic deformation associated with the 2011 Mw 9.0 Tohoku-oki earthquake enabled us to investigate strain anomalies from crustal inhomogeneity. Concentrated contractional strain was observed in the Echigo Plain (Niigata-Kobe Tectonic Zone) before the Tohoku-oki earthquake, whereas continuous and campaign global navigation satellite system measurements show a widespread distribution of coseismic extensional strain in and around the plain. A 1-D displacement profile shows high strain (7.2 ± 0.7 microstrain) in a 17 km long section across the Echigo Plain and low strain (3.3 ± 0.4 microstrain) along a 15 km long section east of the plain, despite the latter being closer to the megathrust fault source. We performed numerical modelling of coseismic deformation using a heterogeneous subsurface structure and successfully reproduced excess extension in the plain, which is filled by low-rigidity sediments. This study demonstrates the importance of considering heterogeneous crust in deformation modelling.

scholarly journals Source Parameter Estimation of the 2009 Ms6.0 Yao’an Earthquake, Southern China, Using InSAR Observations

2019 ◽  
Vol 11 (4) ◽  
pp. 462 ◽  
Author(s):  
Wei Qu ◽  
Bing Zhang ◽  
Zhong Lu ◽  
Jin Kim ◽  
Qin Zhang ◽  
...  
Keyword(s):  
Southern China ◽  
Source Parameters ◽  
Focal Depth ◽  
Satellite System ◽  
Local Economy ◽  
Coseismic Deformation ◽  
Mountainous Area ◽  
Radar Images ◽  
L Band ◽  
Global Navigation Satellite

On 9 July 2009, an Ms6.0 earthquake occurred in mountainous area of Yao’an in Yunnan province of Southern China. Although the magnitude of the earthquake was moderate, it attracted the attention of many Earth scientists because of its threat to the safety of the population and its harm to the local economy. However, the source parameters remain poorly understood due to the sparse distribution of seismic and GNSS (Global Navigation Satellite System) stations in this mountainous region. Therefore, in this study, the two L-band ALOS (Advanced Land Observing Satellite-1) PALSAR (Phased Array type L-band Synthetic Aperture Radar) images from an ascending track is used to investigate the coseismic deformation field, and further determine the location, fault geometry and slip distribution of the earthquake. The results show that the Yao’an earthquake was a strike-slip event with a down-dip slip component. The slip mainly occurred at depths of 3–8 km, with a maximum slip of approximately 70 cm at a depth of 6 km, which is shallower than the reported focal depth of ~10 km. An analysis of the seismic activity and tectonics of the Yao’an area reveals that the 9 July 2009 Yao’an earthquake was the result of regional stress accumulation, which eventually led to the rupture of the northwestern most part of the Maweijing fault.

Challenging Intraplate Orogens: from geomorphology to lithospheric dynamic. The French Massif Central Case study

2020 ◽  
Author(s):  
Oswald Malcles ◽  
Philippe Vernant ◽  
Jean-François Ritz ◽  
David Fink ◽  
Gaël Cazes ◽  
...  
Keyword(s):  
Landscape Evolution ◽  
Plate Boundary ◽  
Satellite System ◽  
Plate Tectonic ◽  
Ural Mountains ◽  
Massif Central ◽  
First Order ◽  
Denudation Rates ◽  
The Earth ◽  
Global Navigation Satellite

<p><span><span>In the 60’s, the formulation of the plate tectonic theory changed our understanding of the Earth dynamics. Aiming at explaining the earth first order kinematics, this primary theory of plate tectonic assumed rigid plates, a necessity to efficiently transfer stress from one boundary to another. </span></span></p><p><span><span>If successful to explain, at first order, the plate-boundary evolutions, this theory fails when compared to the unpredicted but identified deformation located inside the plate-domains: the intraplate orogens. Indeed, the intraplate regions are thought to be slowly, if at all, deforming. Therefore, it is expected that intraplate regions do not show important finite deformation, that is to say, no mountains. Some intraplate regions, however, have important relief: the Snowy Mountains (Australia), the Ural Mountains (Russia) or the Massif Central (France) for examples. Traditionally, such regions are interpreted as old structures that are slowly eroded, interpretations that are most of the time weakly constrained. </span></span></p><p> </p><p><span><span>Our study is aiming at providing stronger constraints and then a better understanding of such challenging area that are the intraplate orogen domains. Because direct measurements of deformations (e.g. GNSS: Global Navigation Satellite System or InSAR: Interferometric Synthetic Aperture Radar) are most of the time below the precision level, it is necessary to derive this information from the landscape evolution. To do so, terrestrial cosmogenic nuclide (TCN) technics are a key method, allowing to constraint the temporal landscape evolution. Classically, two TCN-based approaches are used to quantify the landscape evolution rate: burial ages and watershed-wide denudation rates, based on measurement in quartz sediment of 10Be and 26Al concentrations, two radioactive cosmogenic isotopes.</span></span></p><p> </p><p><span><span>Using the Massif Central (France) as study area, we show that this region is currently deforming.</span></span></p><p><span><span>From new geochronological constraints and a geomorphometric study, we propose that the region undergoes an active uplift encompassing the last c.a. 4 Ma. It can be explained by the combination of at least two phenomena: the first one is the uplift triggering event, that has yet to be clearly identified, and the second one: the erosional isostatic adjustment enhancing the first one and possibly continuing after the end of the first one. </span></span></p>

Wide-area seismicity anomalies before the 2011 Tohoku–Oki earthquake

2020 ◽  
Vol 223 (2) ◽  
pp. 1304-1312
Author(s):  
Takao Kumazawa ◽  
Yosihiko Ogata ◽  
Shinji Toda
Keyword(s):  
Plate Boundary ◽  
Extended Period ◽  
Satellite System ◽  
Aftershock Sequence ◽  
Wide Area ◽  
Epidemic Type Aftershock Sequence ◽  
The Pacific ◽  
Stress Changes ◽  
Inland Earthquake ◽  
Global Navigation Satellite

Summary This study investigates various types of seismicity changes that occurred in several regions in and around the Tohoku District, prior to the 2011 M9.0 Tohoku–Oki earthquake. In particular, we focus on the seismicity anomalies that were revealed not only in inland local areas but also in a wide area for several years before the 2008 M7.2 earthquake in the inland Tohoku District. We reconsider these seismicity anomalies in nearly identical regions, which persisted in the extended period up until the M9 mega event. This suggests that the stress changes due to transient slow slips on the Pacific Plate boundary are more likely to be the cause of the wider seismicity changes than the slips beneath the inland earthquake. To confirm the significance, we use the two-stage stationary epidemic-type aftershock sequence model and explore the relationship between seismicity changes and stress rate changes due to slow slip by means of global navigation satellite system geodetic observations.

The characteristics of transforming coordinates from the geocentric system WGS-84 for the Mercator projection under low latitudes conditions

2018 ◽  
Vol 940 (10) ◽  
pp. 2-6
Author(s):  
J.A. Younes ◽  
M.G. Mustafin
Keyword(s):  
Coordinate System ◽  
Satellite System ◽  
Programming Algorithm ◽  
Low Latitude ◽  
Model Calculations ◽  
Mercator Projection ◽  
Low Latitudes ◽  
Rectangular Coordinates ◽  
Global Navigation Satellite ◽  
Coordination Methods

The issue of calculating the plane rectangular coordinates using the data obtained by the satellite observations during the creation of the geodetic networks is discussed in the article. The peculiarity of these works is in conversion of the coordinates into the Mercator projection, while the plane coordinate system on the base of Gauss-Kruger projection is used in Russia. When using the technology of global navigation satellite system, this task is relevant for any point (area) of the Earth due to a fundamentally different approach in determining the coordinates. The fact is that satellite determinations are much more precise than the ground coordination methods (triangulation and others). In addition, the conversion to the zonal coordinate system is associated with errors; the value at present can prove to be completely critical. The expediency of using the Mercator projection in the topographic and geodetic works production at low latitudes is shown numerically on the basis of model calculations. To convert the coordinates from the geocentric system with the Mercator projection, a programming algorithm which is widely used in Russia was chosen. For its application under low-latitude conditions, the modification of known formulas to be used in Saudi Arabia is implemented.

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