Alexei Gorbatov

Alexei Gorbatov
Geoscience Australia · Resources Division

Ph.D.

About

58
Publications
10,227
Reads
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1,328
Citations
Additional affiliations
January 2017 - present
Geoscience Australia
Position
  • Passive Seismic Activity Leader

Publications

Publications (58)
Article
Full-text available
A three-dimensional tomographic image of the seismic velocity structure in the crust and upper mantle of northwestern Nicaragua was performed using the back-projection technique. The study is based on ~ 15,000 earthquakes located between 1975 and 1982 by the network installed by the USGS and the Institute of Seismic Research of Nicaragua. This data...
Article
Full-text available
Seismological data are used for a variety of purposes, from earthquake hazard zonation to mapping Earth structure and mineral resource exploration. The immense volumes of seismic data now available challenge the application of routine seismic analysis techniques using existing tools. These tools fail to take advantage of recent advances in computin...
Article
Full-text available
To improve exploration success undercover, the UNCOVER initiative identified high-resolution 3D seismic velocity characterisation of the Australian plate as a high priority. To achieve this goal, the Australian Government and academia have united around the Australian Passive Seismic Array Project (AusArray). The aim is to obtain a national half-de...
Article
Full-text available
Mineral deposits are the products of lithospheric-scale processes. Imaging the structure and composition of the lithosphere is therefore essential to better understand these systems, and to efficiently target mineral exploration. Seismic techniques have unique sensitivity to velocity variations in the lithosphere and mantle, and are therefore the p...
Article
Full-text available
Lithospheric structure and composition have direct relevance for our understanding of mineral prospectivity. Aspects of the lithosphere can be imaged using geophysical inversion or analysed from exhumed samples at the surface of the Earth, but it is a challenge to ensure consistency between competing models and datasets. The LitMod platform provide...
Article
Full-text available
Constraints on the morphology of the Moho are essential to establish reliable models of the subsurface and infer the evolution of the Australian crust. Reliable information on crustal thickness variations is important for thermal modelling and structural mapping, for both energy and mineral system studies. Here, we combine information from both pas...
Article
Full-text available
For more than half a century, seismic tomography has been used to map the volumetric structure of Earth’s interior, but only recent advances in computation have enabled the application of this technique at scale. Estimates of surface waves that travel between two seismic stations can be reconstructed from a stack of cross-correlations of continuous...
Article
Full-text available
In order to improve exploration success under cover the UNCOVER initiative identified high resolution 3D seismic velocity characterization of the Australian plate as a high priority. To achieve this goal government and academia have united around the Australian passive seismic Array project (AusArray) which aims to obtain a national half degree dat...
Article
Full-text available
Geoscience Australia (GA), as a part of the Exploring for the Future (EFTF) Programme, is aiming to create a high-resolution three-dimensional (3D) seismic model of Australia to infer physical properties of the lithosphere from depths of few meters to hundreds of kilometres. This work is based on new data collected from National Seismological Netwo...
Preprint
Four large, dominantly strike-slip, earthquakes have occurred in recent years in the Wharton Basin off the coast of Sumatra. The southernmost was the Mw 7.9 event on 2000 June 18, followed by the largest known intraplate earthquake – the Mw 8.6 event on 2012 April 11, with an Mw 8.2 ‘aftershock’ within a few hours. The most recent Mw 7.8 event on 2...
Article
Full-text available
Under the UNCOVER initiative it is generally accepted that construction of accurate cover-thickness maps is the most tractable and urgent means of facilitating resource exploration under cover. To meet this goal we have been undertaking benchmarking of various geophysical techniques, constructing a national database of Estimates of Geological and G...
Article
We illustrate the relation between the spiral-arm array design and the more conventional multi-ring circular arrays by comparing the geometry and response of the Arcess array in northern Norway with three-arm array configurations with many fewer stations. In Figure S1 we display the Arcess array with 25 stations, and two spiral-arm configurations w...
Article
Full-text available
Seismic arrays havemany uses for signal enhancement, from surface-wave characterization of the near surface to teleseismic detection in the context of monitoring nuclear tests. Many variants of the geometrical configuration of stations have been used with the objective of maximizing potential resolution of the incoming wavefronts direction of arriv...
Article
Full-text available
Starting from the hypocentre, the point of initiation of seismic energy, we seek to estimate the subsequent trajectory of the points of emission of high-frequency energy in 3-D, which we term the ‘evocentres’. We track these evocentres as a function of time by energy stacking for putative points on a 3-D grid around the hypocentre that is expanded...
Article
The 2004 Mw 8.1 event on 23 December 2004 near the Macquarie Ridge is a very large intraplate event that has been overshadowed by the Mw 9.3 Sumatra-Andaman event only 3 days later. We are able to track the progress of source evolution by estimating the progression of the points of energy emission, exploiting the good azimuthal distribution of avai...
Article
Full-text available
Stations on the Australian continent receive a rich mixture of continuous ground motion with ambient seismic noise from the surrounding oceans, and numerous small earthquakes in the earthquake belts to the north in Indonesia, and east in Tonga-Kermadec, as well as more distant source zones. The ground motion at a seismic station contains informatio...
Conference Paper
Full-text available
Stations on the Australian continent receive a rich mixture of ambient seismic noise from the surrounding oceans and the numerous small earthquakes in the earthquakes belts to the north in Indonesia and east in Tonga-Kermadec as well as more distant source zones. The noise field at a station contains information about the structure in the vicinity...
Article
Joint seismic tomography exploiting P and S wave arrivals conducted before the 2011 Offshore Tohoku earthquake reveals an area comparable to the faulting surface for the 2011 March 11 event with different properties from other areas along the shallow part of the subduction zone. The differences are revealed by using a measure R of the relative vari...
Article
Tomographic images of Southeast Asia and Australia were created by inverting the traveltimes of the Rayleigh wave Green's functions retrieved from cross-correlations of the ambient seismic noise. The traveltimes of the Green's functions are inverted with a nonlinear two dimensional inversion scheme to map the seismic velocity perturbations of the E...
Conference Paper
There is significant seismic activity in the region around Australia, largely due to the plate boundaries to the north and to the east of the mainland. This seismicity poses serious seismic and tsunamigenic hazard in a wider region, and risk to coastal areas of Australia, and is monitored by Geoscience Australia (GA) using a network of permanent br...
Article
The Northern Sumatra subduction zone is distinguished by the occurrence of the 2004 Sumatra-Andaman megathrust earthquake and has a peculiar subduction of two major bathymetric structures; the Investigator fracture zone and the Wharton fossil ridge. Four stations in Northern Sumatra (BSI, PSI, PPI, GSI) and two stations in Malaysia (KUM and KOM) ha...
Article
Within the development of the Australian Tsunami Warning System at Geoscience Australia attempts are being made to automatically detect the later phases pP, sP and S and to use them for more accurate locations. Therefore, the autoregressive method described in GSE/JAPAN/40 (1992) is included in the automatic earthquake location algorithm provided w...
Article
The intersection of the Japan and Kurile arcs is expressed as a cuspate feature at the trench, a bend in the Japanese islands, and a complex lithospheric structure and is known as the Hokkaido corner. The Pacific plate is subducting beneath the two arcs in the northwest Pacific at different velocities, which has resulted in an arc–arc collision and...
Article
Full-text available
A shear-wave splitting analysis was performed in the Mariana trench on data recorded by an array of semi broad-band Ocean Bottom Seismometers (OBS), with the aim of studying the Mariana back-arc spreading system and clarifying the nature of the back-arc process. We look for possible mechanisms relating anisotropy and mantle flow. Direct sampling of...
Article
Distinct zones of seismic heterogeneity along the Izu–Bonin–Mariana arc have been investigated using complimenting regional bulk sound, shear wave speed, and P-wave tomographic images. The distribution of seismic anomalies and the inferred geometry of the subducting Pacific plate have been modelled in unprecedented detail using joint tomography and...
Article
SUMMARYA striking feature of the tomographic images of the Earth's mid-mantle is the long, high-velocity belt extending in a north–south direction under the North and South American continents, which is believed to be the remnant subduction of the Farallon Plate. In the Oligocene epoch the North Farallon Plate subduction terminated off Baja Califor...
Conference Paper
Joint body-wave tomography exploiting the arrival times of both P and S waves can provide high-resolution images of the bulk-sound and shear wavespeed for more than half of the mantle. The use of source-and station pairs for which both P and S arrivals have been picked provides strong quality control on the data and ensures comparable coverage of P...
Conference Paper
Seismic tomography has developed into one of the most effective and significant sources of information in modern geophysical research, specifically in understanding subduction zone dynamics. The Western Pacific convergent margin is a well studied area, but as more data is collected and technology improves further detailed observations and theories...
Article
The primary source of information on heterogeneity within the Earth comes from seismic tomography. A powerful tool for examining the character of heterogeneity comes from the comparison of images of bulk-sound and shear wavespeed extracted in a single inversion, since this isolates the dependencies on the elastic moduli. However, particularly in su...
Article
Full-text available
Recent seismic tomography imaging shows clear evidence for southwestward subduction along the entire length of the New Guinea Trench (NGT) in Indonesia and Papua New Guinea. Viewed in conjunction with the occurrence of large (Mw > 7) thrust earthquakes that are known to have occurred on the trench, this confirms conclusions of earlier studies that...
Article
Full-text available
1] The use of seismic imaging techniques is widespread. Numerous three-dimensional (3-D) tomographic models have been presented over the last 30 years and subsequently analyzed by a wider community of seismologists, geodynamicists, mineral physicists, and geochemists. However, platform-independent, open source, user-friendly software for interactiv...
Article
Detailed regional body wave tomographic inversion of the Western Pacific region has been performed using P and S travel times from common sources and receivers, with a joint inversion in terms of bulk-sound and shear wave-speed variations in the mantle. This technique allows the separation of the influence of bulk and shear moduli, and hence a more...
Article
Direct observations of the regional crustal structure, seismicity, magnetic, and heat flow anomalies of the northern Sea of Okhotsk indicate the presence of anomalous zone in this area. Tomographic images suggest the presence of remnant subduction zone (RSZ) in the northern Sea of Okhotsk, which extends northeastward from the Schmidt Peninsula (nor...
Article
Detailed P-wave tomographic inversion was performed in the area of Mexican subduction zone. All available regional and teleseismic travel-time data was recompiled and carefully reprocessed to reduce as much as possible the uneven ray path coverage. The mantle was parameterized by cells varying from 0.5 to 2 degrees in horizontal size under the stud...
Conference Paper
Analysis of bulk-sound and shear wave speed variations in the Earth's interior provides valuable information about the tectonic fabric of the subduction zones because the results can be directly compared with the elastic properties of the subducting material determined in the laboratory experiments. A detailed regional tomographic inversion for the...
Article
Full-text available
Hardware installation and performance tests were carried out to prepare the infrastructure for a database of seismic wave- forms. Digital seismic traces are transmitted in real-time through a satellite connection from a network of short-period stations, HiNet, operated by the National Research Institute for Earth Science and Disaster Prevention. Re...
Article
A total of 5270 shallow and intermediate-depth earthquakes recorded by the 32 stations of the regional seismic network of the Geophysical Service of Russia are used to assess the P-wave velocity structure beneath the Kamchatka peninsula in the Western Pacific. The tomographic inversion is carried out in three steps. First, a 1-D tomographic problem...
Conference Paper
Detailed shear wave tomography based on the arrival times of shear phases reveals a strong signature for many subducted slabs in the upper mantle and particularly in the deep slabs associated with Farallon and Tethyan subduction. Most of the P image of such subduction zones arises from shear variations as demonstrated by both independent inversion...
Article
A 3-D ray-path tracing algorithm was successfully applied to global P-wave traveltime tomography. The inversion was conducted iteratively using the resultant P-wave velocity model as the initial model for the subsequent iteration. The LSQR method was adopted to solve a large and sparse system of equations. This iteratively linearized inversion with...
Article
A non-linear iterative P-wave traveltime tomography has revealed a mantle plume originating at a depth of nearly 1000km, rising across the 600 km discontinuity, and deflecting subhorizontally in the uppermost mantle presumably by shear flow due to the overlying moving plate. Data from the Geophysical Survey of Russia (1955-1997) were inverted joint...
Article
Full-text available
 The Pacific coast of Guerrero state in Mexico is recognized as the `Guerrero seismic gap', with a high probability of producing a large subduction earthquake (M > 8). A study of the vertical surface deformation was undertaken to understand the interseismic process of elastic strain accumulation. Four leveling lines were installed in the states of...
Article
Full-text available
An average shear-wave velocity structure has been estimated for the path between the Kamchatka Isthmus and Petropavlovsk-Kamchatski. It is obtained from the Monte Carlo inversion of the Rayleigh and Love wave group velocity dispersion curves measured using broad-band seismograms of events in Northern Kamchatka recorded by the IRIS station PET in Pe...
Article
A 3-D ray-tracing technique was used in a global tomographic inversion in order to obtain tomographic images of the North Pacific. The data reported by the Geophysical Survey of Russia (1955–1997) were used together with the catalogues of the International Seismological Center (1964–1991) and the US Geological Survey National Earthquake Information...
Article
With the aid of the non-linear inversion, a number of global S models have been constructed using different assumptions about the character of the model; for example, solutions can be produced that are designed to introduce minimum differences from a 1-D reference model. A variance reduction of 48 per cent was achieved in the inversions, with consi...
Article
A total of 5270 shallow and intermediate-depth earthquakes recorded by the 32 stations of the regional seismic network of the Geophysical Service of Russia are used to assess the P-wave velocity structure beneath the Kamchatka peninsula in the Western Pacific. The tomographic inversion is carried out in three steps. First, a 1-D tomographic problem...
Article
Full-text available
The configuration of the Pacific plate subducted beneath the Kamchatka peninsula and the stress distribution in the Kamchatka subduction zone (KSZ) were studied using the catalog of the Kamchatka regional seismic network, focal mechanism solutions estimated from P wave first motions, the formal inversion of long-period waveforms, and centroid momen...
Article
The maximum depth of seismicity (Dm) in subduction zones is limited by some physical mechanisms related to the rheological strength of slab material, metastability conditions, failure strength etc. The main factors controlling these properties are temperature and pressure within the lithosphere sinking into the mantle. These P-T conditions may be c...
Article
The maximum seismic depth (Dm) depends on the thermal parameter of the descending slab (φ), which is a product of the age of the subducted lithosphere (A) and the vertical component of convergence rate (V⊥). We analyze seismicity profiles across the subduction zones of Mexico, Chile, Kamchatka, Kuriles, Japan, Sumatra, New Hebrides and Alevtians. T...
Article
Full-text available
The fine structure of a double-planed deep seismic zone is studied over a wide area of the Kamchatka peninsula. This prominent feature of deep seismic zone configuration is ascertained through the analysis of microearthquake hypocenters from the local seismic network of the Institute of Volcanology of Kamchatka (IVK) and 22 focal mechanism solution...
Article
A detailed regional tomographic inversion of the Western Pacific region has been performed using P and S travel times from common sources and receivers, with a joint inversion in terms of bulk-sound and shear wave speed variations in the mantle. This parameterization allows the separation of the influence of bulk and shear moduli, and hence a more...

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Project (1)
Project
The goal is to infer lithospheric structure from few meters to hundred kilometres depth range.