We propose passive image interferometry as a technique for seismology that allows to continuously monitor small temporal changes of seismic velocities in the subsurface. The is independent sources classical sense and requires just one or two permanent stations. retrieve Green's functions we use from ambient noise. Applying data Merapi volcano show velocity variations can be measured with an accuracy 0.1% resolution single day. At Mt. strong seasonal influence present depth dependent...

The technique of passive image interferometry applies interferometric methods to correlation functions seismic noise monitor small temporal variations the Earth interior. We computed autocorrelation function recorded at a single seismometer located in vicinity source region Mw= 6.6 Mid‐Niigata earthquake. Analysing evolution function, which is interpreted as source–receiver collocated elastic wave Green's we detect sudden decrease relative velocity crust −0.6 per cent that coincides with...

Passive Image Interferometry (PII) is a seismological method employing ambient seismic noise to monitor the temporal evolution of mean shear wave velocity within Earth. First, elastic Green's tensor between two seismometers computed from cross correlation recorded during certain period. Second, constructed seismograms different time periods are treated as earthquake multiplets, and small shifts in their coda used invert relative change velocity. When applied source region 2004 M w = 6.6...

We analyze coseismic and postseismic velocity variations caused by the June 13, 2008 Iwate‐Miyagi Nairiku earthquake ( M W = 6.9) using Passive Image Interferometry (PII). Seismic noise is correlated in order to reconstruct Green's function between two sensors. Shear wave changes are determined relating coda parts of daily functions a long‐term reference function. Our study extends from January August 2010 includes correlations for 190 station pairs three different frequency ranges 0.125 1.0...

It has been shown theoretically and observationally that the Green's function for acoustic elastic waves can be retrieved by cross-correlating fluctuations recorded at two locations. We extend concept of extraction to a wide class scalar linear systems. For systems are not invariant under time reversal, must excited volume sources in order satisfy energy balance (equipartitioning) is needed extract function. The general theory retrieving illustrated with examples include diffusion equation,...

The seismic structure of the stratovolcano Merapi (Java, Indonesia) was studied using an active experiment. Three 3km long profiles each consisting up to 30 three component seismometers with interstation distance 100m were built in altitude range between 1000 and 2000m above sea level. detailed study properties propagation media volcanic regions is important understand natural signals used for eruption forecasting. experiment at therefore concentrates on heterogeneous within a radius 5km...

We introduce the single-station cross-correlation (SC) technique of processing ambient seismic noise and compare its results with established (CC) autocorrelation (AC) techniques. While CC is correlation signals two stations each other AC a signal itself, SC different components single three-component sensor. The comparison three techniques shows that CCs give best at frequencies below 0.5 Hz SCs higher frequencies. In all techniques, correlated in order to reconstruct Green's function...

We present a systematic study of seismic velocity changes associated with megathrust and five strong crustal earthquakes in Japan. perform both cross-correlation single-station analysis for station pairs stations, respectively. The correlation ambient noise allows us to reconstruct the Green's functions wave propagation. By relating coda parts daily long-term reference functions, shear are determined. analyse data from four areas Japan where large occurred: Iwate-Miyagi (2008 MW 6.9 Nairiku...

We developed an improved method for the separation of intrinsic and scattering attenuation seismic shear waves by envelope inversion called Qopen. The optimizes fit between Green's functions acoustic, isotropic radiative transfer theory observed energy densities earthquakes. allows determination attenuation, site corrections spectral source energies investigated frequency bands. Source displacement spectrum moment analysed events can be estimated from obtained energies. report coefficients...

In this study, frequency-dependent seismic scattering and intrinsic attenuation parameters for the crustal structure beneath W-Bohemia/Vogtland swarm earthquake region close to border of Czech Republic Germany are estimated. Synthetic seismogram envelopes modelled using elastic acoustic radiative transfer theory. Scattering absorption determined by fitting these synthetic observed from 14 shallow local events October 2008 swarm. The two different simulation approaches yield similar results...

In local earthquake seismology depth-dependent elastic models of P- and S-wave velocities are indispensable, e. g. to locate earthquakes. If not only travel times but also amplitudes seismic waves important, Earth insufficient visco-elastic required include intrinsic absorption waves. This applies the estimation moment magnitudes physics-based ground motion modeling in hazard analysis. The attenuation parameters is significantly more difficult than for two reasons: (1) Scattering as well...

The Federal Seismic Survey at BGR routinely evaluates seismic events in Germany and neighbouringcountries on a daily basis. results are supplemented by the outcomes of seismological agencies ofthe federal states German universities stored an event database Germanearthquake catalogue, which is complete for earthquakes with magnitudes ML ≥ 2.Furthermore, classified as natural earthquakes, induced or explosions (mostlyquarry blasts). A considerable number earthquakes. They originate...

High‐frequency seismograms mainly consist of incoherently scattered waves. Although their phases are more or less random, envelopes show smooth and stable variations depending on frequency distance. Envelope modeling can thus be used to infer stochastic parameters the heterogeneous Earth medium. Radiative transfer theory (RTT) describes energy transport through a random medium neglecting phase information has been frequently simulate observed mean square (MS) high‐frequency The radiative...

We infer temporal changes in the elastic properties of edifice Merapi volcano (Java, Indonesia) before its eruption 1998 by analyzing multiply scattered waves excited a repeatable controlled seismic source. A pre‐eruptive increase shear wave velocity, which correlates well with seismicity and dome‐growth is revealed. The method can be used as “pressure‐gauge” for pressure inside volcanoes, because increasing pressures rocks are known to cause proportionally velocities.

We propose a new technique to obtain source spectra and seismic moments of regional earthquakes from envelopes coda. As compared existing methods, our approach is based on physical model the scattering process that produces This allows direct estimation parameters, without necessity fix proportionality coefficients with reference events. see an appreciable advantage because method independent output other techniques, such as events provided by moment inversions. The main component joint...

Abstract We use 10 years of data the USArray project to estimate areal distribution crustal intrinsic and scattering attenuation shear waves for frequencies between 1 Hz 20 in contiguous United States. Additionally, we report energy site amplification factors moment magnitudes small earthquakes ( M 1.5 3.5). The Qopen method is used invert each event nearby stations. Observations are collected around 25,000 events, averaged at station interpolated locations. In a second inversion,...

We present results of Monte Carlo simulations elastic radiative transfer theory, especially in the range strong forward scattering. Simulations were done for several types continuous random media a full space model. show that fluctuation strength and correlation length are not resolvable scattering regime, but combinations these parameters related to transport mean free path (TMFP) can be obtained. From frequency dependence TMFP we also obtain type medium. As an example, invert local data...

We analyze envelopes of 233 and 22 $M_{\text L}$0.0 to L}$1.8 earthquakes induced by two geothermal stimulations in the Helsinki, Finland, metropolitan area. separate source spectra site terms determine intrinsic attenuation scattering strength shear waves 3 Hz 200 frequency range using radiative transfer based synthetic envelopes. Displacement yield scaling relations with a general deviation from self-similarity, stronger albeit more controversial signal weaker 2020 stimulation. The also...

SUMMARY The Mw 7.8 earthquake in Turkey on 6 February 2023 was extraordinary for various reasons. It originated depth of only 10 km, ruptured along a fault plane around 300 km long and the surface covered by an extensive network high-quality seismic instruments. strong motions resulted vast number tragic casualties huge material losses Syria. However, abundant proximate observations this event numerous aftershocks give opportunity to deepen understanding processes. In study, we carried out...

Multiple scattering of seismic waves in an inhomogeneous layer over a homogeneous half‐space is studied. A new model using analytical solution the diffusion equation with absorbing boundary condition presented and compared to existing models radiation numerical solutions radiative transfer equation. thick for validity approach derived showing that thickness must be much larger than transport mean free path times averaged reflection coefficient. The theory simpler ones especially useful at...