scholarly journals The 22 December 2018 tsunami from flank collapse of Anak Krakatau volcano during eruption

2020 ◽  
Vol 6 (3) ◽  
pp. eaaz1377 ◽  
Author(s):  
Lingling Ye ◽  
Hiroo Kanamori ◽  
Luis Rivera ◽  
Thorne Lay ◽  
Yu Zhou ◽  
...  
Keyword(s):  
Seismic Data ◽  
Seismic Waves ◽  
Moment Tensor ◽  
Time Duration ◽  
Ground Shaking ◽  
Long Period ◽  
Short Period ◽  
Single Force ◽  
Krakatau Volcano ◽  
Tsunami Warnings

On 22 December 2018, a devastating tsunami struck Sunda Strait, Indonesia without warning, leaving 437 dead and thousands injured along the western Java and southern Sumatra coastlines. Synthetic aperture radar and broadband seismic observations demonstrate that a small, <~0.2 km3 landslide on the southwestern flank of the actively erupting volcano Anak Krakatau generated the tsunami. The landslide did not produce strong short-period seismic waves; thus, precursory ground shaking did not provide a tsunami warning. The source of long-period ground motions during the landslide can be represented as a 12° upward-dipping single-force directed northeastward, with peak magnitude of ~6.1 × 1011 N and quasi-sinusoidal time duration of ~70 s. Rapid quantification of a landslide source process by long-period seismic wave inversions for moment-tensor and single-force parameterizations using regional seismic data available within ~8 min can provide a basis for future fast tsunami warnings, as is also the case for tsunami earthquakes.

scholarly journals Attenuation of long period multiple using F-k filter and surface-related multiple elimination methods on 2D broadband seismic data from Morowali Waters, Sulawesi

2021 ◽  
Vol 944 (1) ◽  
pp. 012005
Author(s):  
G L Situmeang ◽  
H M Manik ◽  
T B Nainggolan ◽  
Susilohadi
Keyword(s):  
Seismic Data ◽  
Seismic Waves ◽  
Frequency Bandwidth ◽  
Long Period ◽  
Time Migration ◽  
Predictive Deconvolution ◽  
Short Period ◽  
Wide Range ◽  
Marine Seismic ◽  
Multiple Elimination

Abstract Wide range frequency bandwidth on seismic data is a necessity due to its close relation to resolution and depth of target. High-frequency seismic waves provide high-resolution imaging that defines thin bed layers in shallow sediment, while low-frequency seismic waves can penetrate into deeper target depth. As a result of broadband seismic technology, its wide range of frequency bandwidth is a suitable geophysical exploration method in the oil and gas industry. A major obstacle that is frequently found in marine seismic data acquisition is the existence of multiples. Short period multiple and reverberation are commonly attenuated by the predictive deconvolution method on prestack data. Advanced methods are needed to suppress long period multiple in marine seismic data. The 2D broadband marine seismic data from deep Morowali Waters, Sulawesi, contains both short and long period multiples. The predictive deconvolution, which is applied to the processing sequences, successfully eliminates short period multiple on prestack data. The combination of F-k filter and Surface Related Multiple Elimination (SRME) methods are successful in attenuating long period multiple of the 2D broadband marine seismic data. The Prestack Time Migration section shows fine resolution of seismic images.

LONG-PERIOD SURFACE-RELATED MULTIPLE SUPPRESSION IN 2D MARINE SEISMIC DATA USING PREDICTIVE DECONVOLUTION AND COMBINATION OF SURFACE-RELATED MULTIPLE ELIMINATION AND PARABOLIC RADON FILTERING

2021 ◽  
Author(s):  
Pimpawee Sittipan ◽  
Pisanu Wongpornchai
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Petroleum Reservoirs ◽  
The United States ◽  
Multiple Reflections ◽  
Long Period ◽  
Predictive Deconvolution ◽  
Short Period ◽  
Marine Seismic ◽  
Multiple Elimination

Some of the important petroleum reservoirs accumulate beneath the seas and oceans. Marine seismic reflection method is the most efficient method and is widely used in the petroleum industry to map and interpret the potential of petroleum reservoirs. Multiple reflections are a particular problem in marine seismic reflection investigation, as they often obscure the target reflectors in seismic profiles. Multiple reflections can be categorized by considering the shallowest interface on which the bounces take place into two types: internal multiples and surface-related multiples. Besides, the multiples can be categorized on the interfaces where the bounces take place, a difference between long-period and short-period multiples can be considered. The long-period surface-related multiples on 2D marine seismic data of the East Coast of the United States-Southern Atlantic Margin were focused on this research. The seismic profile demonstrates the effectiveness of the results from predictive deconvolution and the combination of surface-related multiple eliminations (SRME) and parabolic Radon filtering. First, predictive deconvolution applied on conventional processing is the method of multiple suppression. The other, SRME is a model-based and data-driven surface-related multiple elimination method which does not need any assumptions. And the last, parabolic Radon filtering is a moveout-based method for residual multiple reflections based on velocity discrimination between primary and multiple reflections, thus velocity model and normal-moveout correction are required for this method. The predictive deconvolution is ineffective for long-period surface-related multiple removals. However, the combination of SRME and parabolic Radon filtering can attenuate almost long-period surface-related multiple reflections and provide a high-quality seismic images of marine seismic data.

scholarly journals A simple method to evaluate the air-to-ground coupling efficiency: a tool helping the assessment of seismic/infrasonic energy partitioning during an eruption

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Mie Ichihara ◽  
Kazuya Yamakawa ◽  
Dan Muramatsu
Keyword(s):  
Response Function ◽  
Seismic Data ◽  
Seismic Waves ◽  
Seismic Station ◽  
Coupling Efficiency ◽  
Data Set ◽  
Simple Method ◽  
Ground Shaking ◽  
Acoustic Data ◽  
Single Station

AbstractA volcanic eruption transmits both seismic and infrasound signals. The seismo-acoustic power ratio is widely used to investigate the eruption behaviors and the source dynamics. It is often the case that seismic data during an eruption are significantly contaminated or even dominated by ground shaking due to infrasound (air-to-ground signals). To evaluate the contribution of infrasound-originated power in the seismic data, we need a response function of the seismic station to infrasound. It is rare to obtain a seismo-acoustic data set containing only infrasound signals, though it is ideal for calculating the response function. This study proposes a simple way to calculate the response function using seismo-acoustic data containing infrasound and independent seismic waves. The method requires data recorded at a single station and mainly uses the cross-correlation function between the infrasound data and the Hilbert transform of the seismic data. It is tested with data recorded by a station at Kirishima volcano, Japan, of which response function has been constrained. It is shown that the method calculates a proper response function even when the seismic data contain more significant seismic power (or noise) than the air-to-ground signals. The proposed method will be useful in monitoring and understanding eruption behaviors using seismo-acoustic observations.

Slow earthquake signatures in the ratio between acoustic and internal gravity wave amplitudes in coseismic ionospheric disturbances

2021 ◽  
Author(s):  
Kosuke Heki ◽  
Yuki Takasaka
Keyword(s):  
Gravity Wave ◽  
Seismic Waves ◽  
Internal Gravity Wave ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Atmospheric Waves ◽  
Crustal Movements ◽  
Long Period ◽  
Short Period ◽  
Vertical Crustal Movements

&lt;p&gt;Frequency spectra of seismic waves from a fault rupture reflects the size of the faults, i.e. relatively large amplitudes of long period waves are excited by larger earthquakes. Anomalies in rise times of the fault movements would also influence the spectra. For example, earthquakes characterized by slow faulting, known as tsunami earthquakes, excite large tsunamis for the amplitudes of short-period seismic waves. In this study, we compare amplitudes of long- and short-period atmospheric waves excited by vertical crustal movements associated with earthquake faulting. Such atmospheric waves often reach the ionospheric F region and cause coseismic ionospheric disturbances (CID) observed as oscillations in ionospheric total electron content (TEC), with ground Global Navigation Satellite System (GNSS) receivers. CID often includes long-period internal gravity wave (IGW) components in addition to short period acoustic wave (AW) components. The latter has a period of ~4 minutes and propagate by 0.8-1.0 km/s, while the former has a period of ~12 minutes and propagate as fast as 0.2-0.3 km/s. Here we compare amplitudes of these two different waves for five earthquakes, 2011 Tohoku-oki (Mw9.0), 2010 Maule (Mw8.8), 1994 Hokkaido-Toho-Oki (Mw8.3), 2003 Tokachi-oki (Mw8.0), and the 2010 Mentawai (Mw7.9) earthquakes, using data from regional dense GNSS networks. We found two important features, i.e. (1) larger earthquakes show larger IGW/AW amplitude ratios, and (2) Mentawai earthquake, a typical tsunami earthquake, exhibits abnormally large IGW amplitudes relative to AW amplitudes. These findings demonstrate that earthquakes with longer durations for faulting, or with longer times for vertical crustal movements, excite longer period atmospheric waves such as IGW more efficiently.&lt;/p&gt;

A possible triggering mechanism for large Hawaiian earthquakes derived from analysis of the 26 June 1989 Kilauea south flank sequence

1992 ◽  
Vol 82 (6) ◽  
pp. 2368-2390
Author(s):  
Carol J. Bryan
Keyword(s):  
Energy Release ◽  
Focal Mechanism ◽  
Seismic Data ◽  
Focal Mechanisms ◽  
Rupture Process ◽  
Body Waves ◽  
Local Network ◽  
High Angle ◽  
Long Period ◽  
Short Period

Abstract Examination of short-period seismic data from the ML = 6.1 Kilauea south flank earthquake and aftershock sequence indicates that the rupture process in large Hawaiian earthquakes is more complex than previously modeled. In contrast to the low-angle thrust solution determined for the mainshock from long-period teleseismic body waves by other workers, I find an intermediate- to high-angle reverse solution; I find, however, that focal mechanisms for coastal aftershocks of ML &gt; 3.0 are similar to the teleseismic mechanism for the mainshock. A difference in focal mechanisms determined from short-period local-network seismic data and from long-period teleseismic data has been noted for other recent large Hawaiian earthquakes. Both the mapping of surface cracks and the focal mechanism derived from short-period seismic data for the ML = 6.6 1983 Kaoiki earthquake show strike-slip motion, whereas the centroid moment tensor solution shows low-angle thrusting. The focal mechanism calculated from short-period seismic data for the ML = 7.2 1975 Kalapana mainshock shows low-angle thrusting according to some workers, but intermediate- to high-angle reverse faulting according to others, whereas focal mechanisms calculated from long-period seismic data show low-angle thrusting. This result suggests that rupture initiation in large Hawaiian earthquakes, as represented by the short-period focal mechanisms, differs significantly from the overall rupture process, as represented by the teleseismic mechanisms. I propose that small earthquakes trigger the large-scale energy release at the bases of the volcanic edifices, the type of energy release often observed in large Hawaiian earthquakes. These triggering events may occur along rupture surfaces that differ from those along which the long-period moment release occurs and thus may represent release of a local stress concentration superposed upon the regional stress field.

scholarly journals A simple method to evaluate the seismic/infrasonic energy partitioning during an eruption using data contaminated by air-to-ground signals

2021 ◽  
Author(s):  
Mie Ichihara ◽  
Kazuya Yamakawa ◽  
Dan Muramatsu
Keyword(s):  
Response Function ◽  
Seismic Data ◽  
Seismic Waves ◽  
Seismic Station ◽  
Acoustic Power ◽  
Data Set ◽  
Simple Method ◽  
Ground Shaking ◽  
Acoustic Data ◽  
Single Station

Abstract A volcanic eruption transmits both seismic waves and infrasound signals. The seismo-acoustic power ratio is widely used to investigate the eruption behaviors and the source dynamics. It is often the case that seismic data during an eruption are significantly contaminated or even dominated by ground shaking due to infrasound (air-to-ground signals). To evaluate the contribution of infrasound-originated power in the seismic data, we need a response function of the seismic station to infrasound. It is rare to obtain a seismo-acoustic data-set containing only infrasound signals, though it is ideal for calculating the response function. This study proposes a simple way to calculate the response function using seismo-acoustic data containing infrasound and independent seismic waves. The method requires data recorded at a single station and mainly uses the cross-correlation function between the infrasound data and the Hilbert transform of the seismic data. It is tested with data recorded by a station at Kirishima volcano, Japan, of which response function has been constrained. It is shown that the method calculates a proper response function even when the seismic data contain more significant seismic power (or noise) than the air-to-ground signals. The proposed method will be useful in monitoring and understanding eruption behaviors using seismo-acoustic observations.

scholarly journals Long-period seismographs

1960 ◽  
Vol 50 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Hugo Benioff
Keyword(s):  
Seismic Waves ◽  
Transfer Characteristic ◽  
Displacement Transducer ◽  
Photographic Recording ◽  
Long Period ◽  
Short Period

ABSTRACT Descriptions and theories of a number of different seismographs developed particularly for recording of very long-period seismic waves are presented. These include (1) electromagnetic strain seismograph with galvanometer of 8 minutes period and photographic recording; (2) displacement transducer strain seismometer with resistance-capacitance network and short-period galvanometer photographic recorder or with ink-writing recorder; (3) electromagnetic pendulum seismometer with RC network having transfer characteristic of a long-period galvanometer recorder or a heated stylus visible writer; (4) electromagnetic pendulum with period increased tenfold or more using shunt capacitance; and (5) electromagnetic pendulum with condenser-lengthened period and triple RC integrating network recording with either heated stylus visible writer, ink writer, or short-period galvanometer photographic recorder.

Seismic inversions of large, rapid landslides: what they can and cannot tell us about event dynamics

2021 ◽  
Author(s):  
Kate Allstadt ◽  
Andrew Mitchell ◽  
Liam Toney ◽  
David George ◽  
Scott McDougall
Keyword(s):  
Seismic Data ◽  
Seismic Waves ◽  
Numerical Models ◽  
Seismic Inversion ◽  
Two Phase ◽  
Flow Equations ◽  
Long Period ◽  
Wide Range ◽  
Regularization Techniques ◽  
Event Dynamics

&lt;p&gt;Researchers are increasingly incorporating force histories derived from long-period seismic waves into multidisciplinary studies of large, rapid landslides. The force history can provide important information about what happened during failure &amp;#8212; information that complements data available from field investigations and remote sensing analyses. It can also provide additional constraints on the dynamics of landslide motion than can be used to validate and/or calibrate numerical landslide models. However, the inversions need to be of high quality and must be interpreted properly. Because this technique is relatively new, we are still discovering how to best conduct inversions to obtain robust results and how to appropriately interpret these results. In this study, we run numerical models of landslides with idealized source and path geometries using two different modeling packages, DAN3D and D-Claw, and we use the model outputs to generate synthetic long-period seismic data. Both models use depth-averaged flow equations over 3D topography, with DAN3D using semi-empirical material rheologies and D-Claw using a two-phase granular and fluid flow approach. To examine the influence of station azimuthal coverage and distance, we synthesize seismic data for a wide range of possible station configurations. We then use these synthetic seismic data to conduct seismic inversions using the recently released open-source Python-based software package, lsforce (https://code.usgs.gov/ghsc/lhp/lsforce). In doing these inversions, we add differing levels and types of noise, vary the inversion options (e.g., frequency range, regularization techniques) and then compare the results to the &amp;#8220;known&amp;#8221; dynamics of the modeled idealized landslides. We aim to understand common artefacts, limitations, and other potential pitfalls in interpretation, to guide the inversion process in future studies. We repeat this process for idealized landslides of increasing complexity, including multi-part failures, sinuous paths, and gradual versus sudden initiations, to simulate how these characteristics are reflected in the force history and to better understand what level of detail can be constrained from the seismic inversion. This work will help guide researchers to obtain more reliable information about landslide dynamics from seismic inversions in future landslide studies.&lt;/p&gt;

Contribution of seismic tomography in moment-tensor inversions using teleseismic surface-wave spectra

1997 ◽  
Vol 87 (1) ◽  
pp. 114-122
Author(s):  
Hugues Dufumier ◽  
Jeannot Trampert
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Moment Tensor ◽  
Frequency Filtering ◽  
Multiple Frequency ◽  
Moment Tensors ◽  
Long Period ◽  
Short Period ◽  
Earth Models ◽  
Filtering Techniques

Abstract The knowledge of lateral heterogeneities is crucial for path corrections in moment tensor inversions using surface waves. After some attempts to use regionalized Earth models for very long-period surface-wave moment-tensor inversions, recent tomographic Earth models offer the possibility to make short-period path corrections and therefore retrieve more reliable moment tensors for teleseismic earthquakes. First we try to evaluate the precision required for path corrections in comparison with source effects. Some selected Earth models are tested to evaluate how their results compare to those using multiple-frequency filtering techniques. Some real cases illustrate the sensitivity of moment-tensor solutions to the different path corrections, and it appears clearly that regionalized Earth models and tomographic models deduced from long-period data alone (greater than 150 sec) cannot lead to trustworthy broadband moment-tensor inversions. Recent tomographic models using phase velocities at much shorter periods (40 to 200 sec) offer a precision comparable to that of the multiple-frequency filtering technique. Both methods lead to acceptable source mechanisms, using a small number of stations, in more than two cases out of three. The use of recent global tomographic models based upon shorter-period surface waves might thus be a useful alternative to heavy multiple-frequency filtering techniques to automate source studies, especially for rapid determinations using a small number of stations.

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