Preprints
Search for earthquake (504 results)
Backprojection to image slip
Published: 2018-08-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Waveform backprojection is a key technique of earthquake-source imaging, which has been widely used for extracting information of earthquake source evolution that cannot be obtained by kinematic source inversion. The technique enjoys considerable popularity, owing to the simplicity of its implementation and the robustness of its processing, but the physical meaning of backprojection images has [...]
Dynamic viability of the 2016 Mw 7.8 Kaikōura earthquake cascade on weak crustal faults
Published: 2018-07-26
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a dynamic rupture model of the 2016 Mw 7.8 Kaikōura earthquake to unravel the event’s riddles in a physics-based manner and provide insight on the mechanical viability of competing hypotheses proposed to explain them. Our model reproduces key characteristics of the event and constraints puzzling features inferred from high-quality observations including a large gap separating surface [...]
SITE RESPONSE ACROSS THE LOS ANGELES BASIN FROM AMBIENT NOISE RECORDED BY A HIGH DENSITY ARRAY
Published: 2018-07-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Sedimentary basins, such as the Los Angeles basin, can substantially amplify ground motion and increase its duration. To account for site response and develop better seismic hazard assessment and mitigation, it is essential to determine site characteristics across the basin at a high spatial resolution. We investigate site response within the Los Angeles Basin through the application of the [...]
Using Dark Fiber and Distributed Acoustic Sensing for Near-Surface Characterization and Broadband Seismic Event Detection
Published: 2018-07-21
Subjects: Earth Sciences, Geophysics and Seismology, Hydrology, Physical Sciences and Mathematics
We present the first case study demonstrating the use of regional unlit fiber-optic telecommunication infrastructure (dark fiber) and distributed acoustic sensing for broadband seismic monitoring of both near-surface soil properties and earthquake seismology. We recorded 7 months of passive seismic data on a 27 km section of dark fiber stretching [...]
The rupture extent of low frequency earthquakes near Parkfield, CA
Published: 2018-07-10
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The low frequency earthquakes (LFEs) that constitute tectonic tremor are often inferred to be slow: to have durations of 0.2 to 0.5 s, a factor of 10 to 100 longer than those of typical Mw 1-2 earthquakes. Here we examine LFEs near Parkfield, CA in order to assess several proposed explanations for LFEs long durations. We determine LFE rupture areas and location distributions using a new approach, [...]
Stress change before and after the 2011 M9 Tohoku-oki earthquake
Published: 2018-07-07
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Megathrust systems hold important clues for our understanding of long- and short-term plate boundary dynamics, and the 2011 M9 Tohoku-oki earthquake provides a data-rich case in point. Here, we show that the F-net moment tensor catalog indicates systematic changes in crustal stress in the years leading up to the M9, due to the co-seismic effect, and for the last few years due to [...]
Coseismic extension recorded within the damage zone of the Vado di Ferruccio Thrust Fault, Central Apennines, Italy
Published: 2018-07-02
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Recent high resolution hypocentral localisation along active fault systems in the Central Apennines illuminates the activation of seismogenic volumes dipping at low angle (<30°) in extensional settings overprinting contractional deformations affecting the continental crust of the Adria microplate. Individuation of the geological structures and of the fault processes associated with these [...]
Coulomb pre-stress and fault bends: ignored yet vital factors for earthquake triggering
Published: 2018-06-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Successive locations of individual large earthquakes (Mw>5.5) over years to centuries can be difficult to explain with simple Coulomb stress transfer (CST), because seismicity can miss out nearest-neighbour along-strike faults where coseismic CST increases are greatest. We show that “Coulomb pre-stress” may explain this, because magnitudes are >±50 bars if interseismic loading and local [...]
The impact of earthquake cycle variability on neotectonic and paleoseismic slip rate estimates
Published: 2018-05-29
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Because of the natural variability (aleatoric uncertainty) in earthquake recurrence intervals and coseismic displacements on a fault, cumulative slip on a fault does not increase linearly or perfectly step-wise with time; instead, some amount of variability in shorter-term slip rates results. Though this variability could greatly affect the accuracy of neotectonic (i.e., late Quaternary) and [...]
Crack models of repeating earthquakes predict observed moment-recurrence scaling
Published: 2018-05-25
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Small repeating earthquakes are thought to represent rupture of isolated asperities loaded by surrounding creep. The observed scaling between recurrence interval and seismic moment, Tr ~ M^(1/6), contrasts with expectation assuming constant stress drop and no aseismic slip (Tr ~ M^(1/3)). Here we demonstrate that simple crack models of velocity-weakening asperities embedded in a [...]
Measuring Higher-Mode SurfaceWave Dispersion Using a Transdismensional Bayesian Approach
Published: 2018-05-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a method for measuring the dispersion of higher mode surface wave phase velocities from a single seismogram using a hierarchical transdimensional Bayesian approach. The 1-D shear velocity profiles down to 800km depth between sources and seismic stations are regarded as the controlling parameters to tune the phase velocities of fundamental and higher modes. The misfits between [...]
Strain budget of the Ecuador-Colombia subduction zone: a stochastic view
Published: 2018-04-24
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The 2016 Pedernales earthquake (Mw=7.8) ruptured a portion of the Colombia-Ecuador subduction interface where several large historical earthquakes have been documented since the great 1906 earthquake (M=8.6). Considering all significant ruptures that occurred in the region, it has been suggested that the cumulative moment generated co-seismically along this part of the subduction over the last [...]
Controls on early‐rift geometry: new perspectives from the Bilila‐Mtakataka fault, Malawi
Published: 2018-04-23
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
This study investigates the controls to fault and rift geometry for a young rift system. Our case study is a large fault in southern Malawi. The geometry of the fault at the surface, the scarp, and structures within the rocks the fault cuts through, are measured. We also calculate the scarp height. The orientation and height of the fault scarp implies that local stresses influence its geometry, [...]
Bimodal or quadrimodal? Statistical tests for the shape of fault patterns
Published: 2018-04-23
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Natural fault patterns, formed in response to a single tectonic event, often display significant variation in their orientation distribution. The cause of this variation is the subject of some debate: it could be ‘noise’ on underlying conjugate (or bimodal) fault patterns or it could be intrinsic ‘signal’ from an underlying polymodal (e.g. quadrimodal) pattern. In this contribution, we present [...]
Present-day stress orientations in the Great Sumatran Fault in North Sumatra
Published: 2018-04-20
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
Trench-parallel strike slip faults develop at lithospheric scale during oblique high-angle subduction. A “sliver” plate forms due to slip partitioning between the subduction plane (margin-normal slip) and the strike slip fault (margin-parallel slip). This process ultimately controls the location of volcanoes and earthquakes. The Great Sumatran Fault (GSF) is a showcase of this tectonic [...]