Structure of the oceanic lithosphere and upper mantle north of the Gloria Fault in the eastern mid‐Atlantic by receiver function analysis

Hannemann, Katrin; Dahm, Torsten; Lange, Dietrich

doi:10.1002/2016jb013582

Cited by 27 publications

(49 citation statements)

References 125 publications

(210 reference statements)

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“…The parameters used in the processing and comparison of results with other methods are detailed in Supplementary Discussion 4. The final group calculated RFs by using a time-domain Wiener filter that transforms the complex P wavetrain on the Z component into a band-limited spike 58,59 . This Wiener filter was applied to all three components of the seismogram to produce the RFs.…”

Section: Methodsmentioning

confidence: 99%

Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data

et al. 2020

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T he Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission landed on Mars on 26 November 2018 in Elysium Planitia 1,2 , 38 years after the end of Viking 2 lander operations. At the time, Viking's seismometer 3 did not succeed in making any convincing Marsquake detections, due to its on-deck installation and high wind sensitivity. InSight therefore provides the first direct geophysical in situ investigations of Mars's interior structure by seismology 1,4. The Seismic Experiment for Interior Structure (SEIS) 5 monitors the ground acceleration with six axes: three Very Broad Band (VBB) oblique axes, sensitive to frequencies from tidal up to 10 Hz, and one vertical and two horizontal Short Period (SP) axes, covering frequencies from ~0.1 Hz to 50 Hz. SEIS is complemented by the APSS experiment 6 (InSight Auxiliary Payload Sensor Suite), which includes pressure and TWINS (Temperature and Winds for InSight) sensors and a magnetometer. These sensors monitor the atmospheric sources of seismic noise and signals 7. After seven sols (Martian days) of SP on-deck operation, with seismic noise comparable to that of Viking 3 , InSight's robotic arm 8 placed SEIS on the ground 22 sols after landing, at a location selected through analysis of InSight's imaging data 9. After levelling and noise assessment, the Wind and Thermal Shield was deployed on sol 66 (2 February 2019). A few days later, all six axes started continuous seismic recording, at 20 samples per second (sps) for VBBs and 100 sps for SPs. After onboard decimation, continuous records at rates from 2 to 20 sps and event records 5 at 100 sps are transmitted. Several layers of thermal protection and very low self-noise enable the SEIS VBB sensors to record the daily variation of the

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Section: Methodsmentioning

confidence: 99%

Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data

et al. 2020

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“…The influence of uncertainties in the measured azimuth on Mars on the results is discussed below. For both data sets, the vertical component is deconvolved from the vertical and radial components in the time domain using a Wiener filter to obtain the receiver functions, as discussed in detail by Hannemann et al (2017).…”

Section: Receiver Function Calculationmentioning

confidence: 99%

“…After adjusting the method to the boundary conditions at the ocean bottom, Hannemann et al (2016) successfully applied it to an OBS data set with one to five receiver functions per station, thus demonstrating its usefulness when only a small number of event recordings is available. It has also been shown that a priori S-velocity information deduced from P-wave polarization measurements can be useful when attempting to model or invert the actual receiver function waveforms (Peng et al 2012;Hannemann et al 2017), even when polarization information at long periods is missing (Kieling et al 2011). Schiffer et al (2015Schiffer et al ( , 2016 used the frequency-dependent apparent S-wave velocities as stabilizing information in a joint inversion with receiver function waveforms, whereas Chong et al (2018) directly inverted the measured receiver function amplitude ratios instead.…”

Section: Introductionmentioning

confidence: 99%

Crustal S-Wave Velocity from Apparent Incidence Angles: A Case Study in Preparation for InSight

2018

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Retrieval of crustal structure and thickness of Mars is among the main goals of InSight. Here we investigate which constraints on the crust at the landing site can be provided by apparent P-wave incidence angles derived from P-receiver functions. We consider receiver functions for six different Mars models, calculated from synthetic seismograms generated via Instaseis from the Green's function databases of the Marsquake Service, in detail. To allow for a larger range of crustal thicknesses and structures, we additionally analyze data from five broad-band stations across Central Europe. We find that the likely usable epicentral distance range for P-wave receiver functions on Mars lies between 35• and the core shadow, and can be extended to more than 150• by also using the PP-phase. Comparison to models for the spatial distribution of Martian seismicity indicates that sufficient seismicity should occur within the P-wave distance range around InSight within the nominal mission duration to allow for the application of our method. Apparent P-wave incidence angles are derived from the amplitudes of vertical and radial receiver functions at the P-wave onset within a range of period bands, up to 120 s. The apparent incidence angles are directly related to apparent S-wave velocities, which are inverted for the subsurface S-wave velocity structure via a grid search. The veracity of the forward calculated receiver functions and apparent S-wave velocities is ensured by benchmarking various algorithms against the Instaseis synthetics. Results indicate that apparent S-wave velocity curves provide valuable constraints on crustal thickness and structure, even without any additional constraints, and considering the location uncertainty and limited data quantity of InSight. S-wave velocities in the upper half of the crust are constrained best, but if reliable measurements at long periods are available, the curves also provide constraints down to the uppermost mantle. Besides, it is demonstrated that the apparent velocity curves can differentiate between crustal velocity models that are indistinguishable by other methods.The InSight Mission to Mars II Edited

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“…We acknowledge all institutions providing seismic data used in this research: Deep Ocean Test Array (DOCTAR) project (Hannemann et al, , , ), FCT project WILAS‐West Iberia Lithosphere and Asthenosphere Structure (doi:10.14470/3n7565750319), Instituto Português do Mar e da Atmosfera (IPMA) Seismic Network, University of Lisbon Seismic Network and Western Mediterranean Seismic Network (doi:10.14470/JZ581150). DOCTAR and WILAS waveform data were accessed through the ORFEUS data center.…”

Section: Acknowledgmentsmentioning

confidence: 99%

An Active Seismic Zone in Intraplate West Iberia Inferred From High‐Resolution Geophysical Data

et al. 2018

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Intraplate Iberia is a region of slow lithopsheric deformation (<1 mm/yr) with significant historical earthquake activity. Recent high‐quality instrumental data have shown that small‐magnitude earthquakes collapse along clusters and lineaments, which however do not bear a clear relationship to geologically mapped active structures. In this article, we investigate the controls of these earthquake clusters. In particular, we study two of the identified clusters—the Arraiolos and the Évora seismic zones (ASZ and ESZ), located in the Western Ossa Morena Zone, southwest Iberia. The ASZ marks a sharp boundary between a seismically active region to its south and a more quiet region to its north. We revise historical earthquakes in order to clarify whether earthquake activity in the region is persistent. We use data from a local network to compute accurate epicenters, focal depth, focal mechanisms, and spatiotemporal clustering, thus characterizing ongoing small‐scale fracturing. Finally, we analyze complementary data sets, including tomographic models, Global Navigation Satellite Systems data, magnetic anomalies, and gravity anomalies, in order to discuss the factors that control seismogenesis in the two seismic zones. Consistency between earthquake locations, focal mechanisms and Global Navigation Satellite Systems data suggests that the ASZ is an active right‐lateral shear zone, which divides two blocks within the Western Ossa Morena Zone. The ESZ seems to localize microseismicity due to its granitic lithology. These results suggest that high‐resolution geophysical data have the potential to reveal blocks with different seismogenic and rheological behaviors, which may be used to improve our understanding of fault systems and the assessment of earthquake hazard in slowly deforming regions.

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Structure of the oceanic lithosphere and upper mantle north of the Gloria Fault in the eastern mid‐Atlantic by receiver function analysis

Cited by 27 publications

References 125 publications

Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data

Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data

Crustal S-Wave Velocity from Apparent Incidence Angles: A Case Study in Preparation for InSight

An Active Seismic Zone in Intraplate West Iberia Inferred From High‐Resolution Geophysical Data

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