Identification of infrasonic and seismic components of tremors in single-station records: application to the 2013 and 2018 events at Ioto Island, Japan

Mapping Intimacies ◽

10.21203/rs.3.rs-34753/v2 ◽

2020 ◽

Author(s):

Aika K Kurokawa ◽

Mie Ichihara

Keyword(s):

Correlation Method ◽

Pressure Oscillation ◽

Spectral Amplitude ◽

Wind Noise ◽

Complementary Method ◽

Single Station ◽

Tectonic Earthquakes ◽

Vertical Ground ◽

Instrument Sensitivity ◽

Station Site

Abstract Infrasonic stations are sparse at many volcanoes, especially those on remote islands and those with less frequent eruptions. When only a single infrasound station is available, the seismic-infrasonic cross-correlation method has been used to extract infrasound from wind noise. However, it does not work with intense seismicity and sometimes mistakes ground-to-atmosphere signals as infrasound. This paper proposes a complementary method to identify the seismic component and the infrasonic component using a single microphone and a seismometer. We applied the method to estimate the surface activity on Ioto Island. We focused on volcanic tremors during the phreatic eruption on April 11, 2013, and during an unconfirmed event on September 12, 2018. We used the spectral amplitude ratios of the vertical ground motion to the pressure oscillation and compared those for the tremors with those for known signals generated by volcano-tectonic earthquakes and airplanes flying over the station. We were able to identify the infrasound component in the part of the seismic tremor with the 2013 eruption. On the other hand, the tremor with the unconfirmed 2018 event was accompanied by no apparent infrasound. We interpreted the results that the infrasound with the 2013 event was excited by the vent opening or the ejection of ballistic rocks, and the 2018 event was not an explosive eruption either on the ground or in the shallow water. If there was any gas (and ash) emission, it might have occurred gently undersea. As the method uses the relative values of on-site records instead of the absolute values, it is available even if the instrument sensitivity and the station site effects are poorly calibrated.

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Identification of infrasonic and seismic components of tremors in single-station records: application to the 2013 and 2018 events at Ioto Island, Japan

Earth Planets and Space ◽

10.1186/s40623-020-01302-2 ◽

2020 ◽

Vol 72 (1) ◽

Author(s):

Aika K. Kurokawa ◽

Mie Ichihara

Keyword(s):

Correlation Method ◽

Pressure Oscillation ◽

Spectral Amplitude ◽

Wind Noise ◽

Complementary Method ◽

Single Station ◽

Tectonic Earthquakes ◽

Vertical Ground ◽

Instrument Sensitivity ◽

Station Site

Abstract Infrasonic stations are sparse at many volcanoes, especially those on remote islands and those with less frequent eruptions. When only a single infrasound station is available, the seismic–infrasonic cross-correlation method has been used to extract infrasound from wind noise. However, it does not work with intense seismicity and sometimes mistakes ground-to-atmosphere signals as infrasound. This paper proposes a complementary method to identify the seismic component and the infrasonic component using a single microphone and a seismometer. We applied the method to estimate the surface activity on Ioto Island. We focused on volcanic tremors during the phreatic eruption on April 11, 2013, and during an unconfirmed event on September 12, 2018. We used the spectral amplitude ratios of the vertical ground motion to the pressure oscillation and compared those for the tremors with those for known signals generated by volcano-tectonic earthquakes and airplanes flying over the station. We were able to identify the infrasound component in the part of the seismic tremor with the 2013 eruption. On the other hand, the tremor with the unconfirmed 2018 event was accompanied by no apparent infrasound. We interpreted the results that the infrasound with the 2013 event was excited by the vent opening or the ejection of ballistic rocks, and the 2018 event was not an explosive eruption either on the ground or in the shallow water. If there was any gas (and ash) emission, it might have occurred gently undersea. As the method uses the relative values of on-site records instead of the absolute values, it is available even if the instrument sensitivity and the station site effects are poorly calibrated.

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Identification of infrasonic and seismic components of tremors in single-station records: application to the 2013 and 2018 events at an isolated volcanic island, Ioto, Japan

10.21203/rs.3.rs-34753/v1 ◽

2020 ◽

Author(s):

Aika K. Kurokawa ◽

Mie Ichihara

Keyword(s):

Correlation Method ◽

Pressure Oscillation ◽

Spectral Amplitude ◽

Volcanic Island ◽

Wind Noise ◽

Complementary Method ◽

Single Station ◽

Tectonic Earthquakes ◽

Vertical Ground ◽

Station Site

Abstract Infrasonic stations are sparse at many volcanoes, especially those on remote islands and those with less frequent eruptions. When only a single infrasound station is available, the seismic-infrasonic cross-correlation method has been used to extract infrasound from wind noise. However, it does not work with intense seismicity and sometimes mistakes ground-to-atmosphere signals as infrasound. This paper proposes a complementary method to identify the seismic component and the infrasonic component using a single microphone and a seismometer. We applied the method to estimate the surface activity on the isolated volcanic island, Ioto. We focused on volcanic tremors during the phreatic eruption on April 11, 2013, and during an unconfirmed event on September 12, 2018. We used the spectral amplitude ratios of the vertical ground motion to the pressure oscillation and compared those for the tremors with those for known signals generated by volcano-tectonic earthquakes and airplanes flying over the station. We were able to identify the infrasound component in the part of the seismic tremor with the 2013 eruption. On the other hand, the tremor with the unconfirmed 2018 event was accompanied by no apparent infrasound. We interpreted the results that the infrasound with the 2013 event was excited by the vent opening or the ejection of ballistic rocks, and the 2018 event was not an explosive eruption either on the ground or in the shallow water. If there was any gas (and ash) emission, it might have occurred gently undersea. As the method uses the relative values of on-site records instead of the absolute values, it is available even if the instrument sensitivity and the station site effects are poorly calibrated.

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How Can the International Monitoring System Infrasound Network Contribute to Gravity Wave Measurements?

Atmosphere ◽

10.3390/atmos10070399 ◽

2019 ◽

Vol 10 (7) ◽

pp. 399 ◽

Cited By ~ 1

Author(s):

Patrick Hupe ◽

Lars Ceranna ◽

Alexis Le Pichon

Keyword(s):

Monitoring System ◽

Deep Convection ◽

Weather Prediction ◽

Correlation Method ◽

International Monitoring System ◽

Wind Noise ◽

Wave Measurements ◽

International Monitoring ◽

Energy And Momentum ◽

The Tropics

Gravity waves (GWs) propagate horizontally and vertically in the atmosphere. They transport energy and momentum, and therefore GWs can affect the atmospheric circulation at different altitude layers when dissipating. Thus knowledge about the occurrence of GWs is essential for Numerical Weather Prediction (NWP). However, uniform networks for covering GW measurements globally are rare, especially in the troposphere. It has been shown that an infrasound station of the International Monitoring System (IMS) infrasound network is capable of measuring GWs at the Earth’s surface. The IMS was deployed for monitoring the atmosphere to verify compliance with the Comprehensive Nuclear-Test-Ban-Treaty. In this study, the Progressive Multi-Channel Correlation Method (PMCC) is used for re-processing up to 20 years of IMS infrasound recordings in order to derive GW detections. For this purpose, two alternative PMCC configurations are discussed, covering GW frequencies equivalent to periods of between 5 min and 150 min. These detections mainly reflect sources of deep convection, particularly in the tropics. At mid-latitudes, coherent wind noise more often produces spurious detections. Combining the results of both configurations provides a global dataset of ground-based GW measurements, which enables the calculation of GW parameters. These can be used for improving NWP models.

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A discrimination analysis of short-period regional seismic data recorded at Tonto Forest Observatory

Bulletin of the Seismological Society of America ◽

10.1785/bssa0720041351 ◽

1982 ◽

Vol 72 (4) ◽

pp. 1351-1366

Author(s):

J. R. Murphy ◽

T. J. Bennett

Keyword(s):

Epicentral Distance ◽

Test Site ◽

P Wave ◽

Set Cover ◽

Spectral Amplitude ◽

Nevada Test Site ◽

Data Set ◽

Short Period ◽

Single Station ◽

Regional Phases

abstract A new seismic discriminant based on spectral differences of regional phases from earthquakes and explosions recorded at a single station has been tested and found to work remarkably well. The test data consisted of a well-constrained set of 30 Nevada Test Site (NTS) explosions and 21 earthquakes located within about 100 km of NTS which were recorded on short-period seismographs at the Tonto Forest Observatory in central Arizona at an epicentral distance averaging 530 km. The events in the data set cover a magnitude range from 3.3 to 4.8 (mb) for which Pn, Pg, and Lg phases have been analyzed. We found that, although Lg phases from earthquakes are typically more prominent than for explosions with comparable P-wave amplitude levels, simple time-domain Lg/P amplitude ratios do not result in a separation of the earthquake and explosion samples consistent enough to provide reliable discrimination. However, spectral analyses of the data over the frequency band from 0.5 to 5.0 Hz revealed significant differences in the spectra of certain regional phases which proved to be a quite reliable discriminant. In particular, both the Pg and Lg spectra from earthquakes have been found to be richer in high-frequency content than corresponding explosion spectra. A discriminant measure, defined as the ratio of average Lg spectral amplitude level in the 0.5- to 1.0-Hz passband to that in the 2.0- to 4.0-Hz passband, provides good separation of earthquake and explosion populations.

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A waveform correlation method for identifying quarry explosions

Bulletin of the Seismological Society of America ◽

10.1785/bssa0810062395 ◽

1991 ◽

Vol 81 (6) ◽

pp. 2395-2418

Author(s):

D. B. Harris

Keyword(s):

Linear Combination ◽

Correlation Method ◽

P Wave ◽

Large Signal ◽

Source Regions ◽

Single Station ◽

Using Data ◽

Element Array ◽

Test Ban ◽

Master Event

Abstract A waveform correlation method is presented for identifying quarry explosions by attributing them to known mines characterized by multiple master events. The objective is to provide a reliable automatic procedure for screening the large number of quarry explosions likely to be detected by networks of in-country stations monitoring compliance with test-ban treaties. The method generalizes existing correlation techniques to compare waveforms from an unlocated event recorded at an array of sensors with a linear combination of master event waveforms recorded at the same array. The use of a linear combination reduces the chance of a missed location caused by some variation in mechanism or spectral excitation between the events being compared. The weights in the linear combination are filters, offering some compensation for variations in source time functions and errors of waveform alignment. The use of array data reduces the likelihood of false attribution by reducing bias and variance in the correlation measurement. In a test conducted with P-wave data segments recorded at a 13-element array, the method successfully resolves two source regions separated by 4 km at a range of 150 km. Resolution with single-station waveform correlations is marginal due to the limited amount of data. The statistics of the sample waveform correlation coefficient are developed and demonstrate that single-station waveform correlations are unreliable unless estimated with large signal durations T or bandwidths B. A time-bandwidth TB product exceeding 100 (or smaller TB with more stations) is necessary for reliable event attribution. The related problem of separating superimposed waveforms from two events in different source regions may be solved by cancellation. The waveforms of one event are again approximated by a linear combination of waveforms from master events in the same mine. The residual signals, obtained by subtracting the approximation from the superimposed waveforms, estimate the waveforms from the second event. This method achieves significant separation of waveforms from events 6 km apart at a range of 150 km, using data from the 13-element array. Its resolution exceeds that of conventional beam-forming methods.

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Global gravity wave detections at infrasound stations of the International Monitoring System

10.5194/egusphere-egu2020-1610 ◽

2020 ◽

Author(s):

Patrick Hupe ◽

Lars Ceranna ◽

Alexis Le Pichon

Keyword(s):

Monitoring System ◽

Deep Convection ◽

Weather Prediction ◽

Low Frequency ◽

Correlation Method ◽

International Monitoring System ◽

Wind Noise ◽

Global Gravity ◽

International Monitoring ◽

Energy And Momentum

<p>Atmospheric gravity waves (GWs) transport energy and momentum horizontally and vertically. The dissipation of GWs can modify the atmospheric circulation at different altitude layers. Knowledge about the occurrence of GWs is thus essential for Numerical Weather Prediction (NWP). However, uniform networks for global GW measurements are rare, and satellite observations generally allow to derive GW parameters in the middle and upper atmosphere only. The barometric sensors of the International Monitoring System (IMS) infrasound network can potentially fill this gap of global GW observations at the Earth&#8217;s surface. This infrasound network has been established for monitoring the atmosphere to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty.<br>Two alternative configurations of the Progressive Multi-Channel Correlation Method (PMCC) are discussed for deriving GW detections from the differential pressure data. These configurations focus on GW frequencies equivalent to periods of between 5 min and 150 min. This range covers sources of deep convection, particularly in the tropics, whereas at mid-latitudes, GWs are hard to distinguish from other low-frequency signals, e.g. coherent wind noise. Challenges and perspectives of using the IMS infrasound data for deriving ground-based GW parameters useful for NWP will be discussed.</p>

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Monitoring Local Earthquakes in Central Italy Using 4C Single Station Data

Sensors ◽

10.3390/s21134297 ◽

2021 ◽

Vol 21 (13) ◽

pp. 4297

Author(s):

Andreino Simonelli ◽

Matteo Desiderio ◽

Aladino Govoni ◽

Gaetano De Luca ◽

Angela Di Virgilio

Keyword(s):

Rotation Rate ◽

Ring Laser ◽

Central Italy ◽

Broadband Seismometer ◽

National Monitoring ◽

Single Station ◽

Ring Laser Gyroscope ◽

Vertical Ground ◽

Laser Gyroscope ◽

Monitoring Service

In this study, performed on a set of twenty-two earthquakes that occurred in central Italy between 2019 and 2020, we will explore the possibility to locate the hypocenter of local events by using a ring laser gyroscope observing the vertical ground rotation and a standard broadband seismometer. A picking algorithm exploiting the four components (4C) polarization properties of the wavefield is used to identify the first shear onset transversely polarized (SH). The wavefield direction is estimated by correlation between the vertical rotation rate and the transverse acceleration. The picked times for Pg and Sg onsets are compared to the ones obtained after manual revision on the GIGS station seismometer. The results are compared with the location provided by the national monitoring service of the INGV.

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Application of cross correlation to HREM images of surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100128080 ◽

1987 ◽

Vol 45 ◽

pp. 754-755

Author(s):

D. E. Luzzi ◽

L. D. Marks ◽

M. I. Buckett

Keyword(s):

Cross Correlation ◽

A Priori ◽

Matrix Material ◽

Correlation Method ◽

Accurate Knowledge ◽

Complex Image ◽

Fourier Filtering ◽

The Matrix ◽

Low Pass ◽

Data Reduction Technique

As the HREM becomes increasingly used for the study of dynamic localized phenomena, the development of techniques to recover the desired information from a real image is important. Often, the important features are not strongly scattering in comparison to the matrix material in addition to being masked by statistical and amorphous noise. The desired information will usually involve the accurate knowledge of the position and intensity of the contrast. In order to decipher the desired information from a complex image, cross-correlation (xcf) techniques can be utilized. Unlike other image processing methods which rely on data massaging (e.g. high/low pass filtering or Fourier filtering), the cross-correlation method is a rigorous data reduction technique with no a priori assumptions.We have examined basic cross-correlation procedures using images of discrete gaussian peaks and have developed an iterative procedure to greatly enhance the capabilities of these techniques when the contrast from the peaks overlap.

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