Estimating plume heights of explosive eruptions using high-frequency seismic amplitudes

2019 ◽  
Vol 219 (2) ◽  
pp. 1365-1376 ◽  
Author(s):  
Azusa Mori ◽  
Hiroyuki Kumagai
Keyword(s):  
High Frequency ◽  
Seismic Source ◽  
Source Model ◽  
Explosive Eruptions ◽  
Seismic Signals ◽  
Volume Flux ◽  
Plinian Eruptions ◽  
Seismic Waveform ◽  
Eruption Volume ◽  
Seismic Amplitudes

SUMMARY Seismic signals during explosive eruptions have been correlated to eruption size or eruption volume flux for individual eruptive episodes. However, the universality of these correlations has yet to be confirmed. We quantified the sources of high-frequency seismic signals associated with sub-Plinian and Vulcanian eruptions at Kirishima (Japan), Tungurahua (Ecuador) and other volcanoes in Japan using a simple approach based on highly scattered seismic waveform characteristics. We found that eruption plume heights scale to seismic source amplitudes and are described by two relations depending on the value of source amplitudes: power-law and exponential relations for plume height >6 km and <6 km, respectively. Though conceptually similar, our scaling relations differ from the previously proposed relation based on reduced displacement. By comparing seismic and geodetic data during sub-Plinian eruptions at Kirishima, we found that the source amplitude is proportional to eruption volume flux. Combining these relations, we show that our scaling relation for Plinian eruptions is consistent with predictions from plume dynamics models. We present a source model to explain the proportionality between the source amplitude and eruption volume flux assuming a vertical crack or a cylindrical conduit as the source. The source amplitude can be estimated in seconds without any complicated data processing, whereas eruption plumes take minutes to reach their maximum heights. Our results suggest that high-frequency seismic source amplitudes are useful for estimating plume heights in real time.

High-frequency spectral scaling of a main shock/ aftershock sequence near the Norwegian coast

1988 ◽  
Vol 78 (2) ◽  
pp. 561-570
Author(s):  
Eric P. Chael ◽  
Richard P. Kromer
Keyword(s):  
Stress Drop ◽  
High Frequency ◽  
Background Noise ◽  
Main Shock ◽  
Source Model ◽  
Aftershock Sequence ◽  
Constant Stress ◽  
P Wave ◽  
Western Coast ◽  
Seismic Signals

Abstract A high-frequency seismic element was recently added to the NORESS regional array in Norway. This system can monitor seismic signals at frequencies up to 50 Hz. In February 1986, the high-frequency seismic element recorded an mbLg 4.7 main shock and several aftershocks which occurred 420 km northwest of NORESS, off Norway's western coast. These events produced high-frequency signals which were well above the background noise at the station. P-wave spectra of these events scale in a manner consistent with the ω-square, constant-stress-drop source model. The data do not require any change in this scaling to magnitudes (mbLg) below 2, in contrast to previous reports that constant-stress-drop scaling breaks down at smaller magnitudes.

Seismic source model for moving vehicles

2005 ◽  
Vol 43 (2) ◽  
pp. 248-256 ◽  
Author(s):  
S.A. Ketcham ◽  
M.L. Moran ◽  
J. Lacombe ◽  
R.J. Greenfield ◽  
T.S. Anderson
Keyword(s):  
Seismic Source ◽  
Source Model ◽  
Moving Vehicles ◽  
Seismic Source Model

On the Nature of Logic Trees in Probabilistic Seismic Hazard Assessment

2012 ◽  
Vol 28 (3) ◽  
pp. 1291-1296 ◽  
Author(s):  
Roger Musson
Keyword(s):  
Seismic Hazard Assessment ◽  
Seismic Source ◽  
Source Model ◽  
Probabilistic Seismic Hazard Assessment ◽  
Motion Model ◽  
Logic Tree ◽  
Ground Motion Model ◽  
Seismic Source Model ◽  
Kolmogorov Axioms ◽  
Better Than

An objection sometimes made against treating the weights of logic tree branches as probabilities relates to the Kolmogorov axioms, but these are only an obstacle if one believes that logic tree branches represent a seismic source model or ground motion model as being “true.” Models are never true, but some models are better than others. It is argued here that a logic tree weight represents the probability that the model in question is better than the others considered. Only one branch can be the best one, and one branch must be the best one. It is also argued that there are situations in PSHA where uncertainty exists but the analyst lacks the means to express it. Therefore it is not necessarily the case that more information increases uncertainty; it may be that more information increases the possibility of expressing uncertainty that was previously unmanageable.

Source parameter analysis from strong motion records of the Friuli, Italy, earthquake sequence (1976-1977)

1987 ◽  
Vol 77 (4) ◽  
pp. 1127-1146
Author(s):  
Giuseppe De Natale ◽  
Raul Madariaga ◽  
Roberto Scarpa ◽  
Aldo Zollo
Keyword(s):  
Frequency Domain ◽  
Stress Drop ◽  
High Frequency ◽  
Epicentral Distance ◽  
Strong Motion ◽  
Source Model ◽  
Parameter Analysis ◽  
Corner Frequency ◽  
Spectral Parameters ◽  
Single Station

Abstract Time and frequency domain analyses are applied to strong motion data recorded in Friuli, Italy, during 1976 to 1977. An inversion procedure to estimate spectral parameters (low frequency level, corner frequency, and high frequency decay) has been applied to displacement spectra using a simple earthquake source model with a single corner frequency. The data were digitized accelerograms from ENEA-ENEL portable and permanent networks. Instrument-corrected SH waves were selected from a set of 138 three-component, hand-digitized records and 28 automatically digitized records. Thirty-eight events with stations having 8 to 32 km epicentral distance were studied. Different stress drop estimates were performed showing high values (200 to 300 bars, on the average) with seismic moments ranging from 2.8 × 1022 to 8.0 × 1024 dyne-cm. The observation of systematic higher values of Brune stress drop (obtained from corner frequencies) with respect to other time and frequency domain estimates of stress release, and the evidence on time series of multiple rupture episodes suggest that the observed corner frequencies are most probably related to subevent ruptures rather than the overall fault size. Seven events recorded at more than one station show a good correlation between rms, Brune, and dynamic stress drops, and a constant scaling of this parameter as a function of the seismic moment. When single station events are also considered, a slight moment dependence of these three stress drop estimates is observed differently. This may be explained by an inadequacy of the ω−2 high-frequency decay of the source model or by high-frequency attenuation due to propagation effects. The high-frequency cutoff of acceleration spectra indicates the presence of an Fmax in the range of 5 to 14 Hz, except for the stations where local site effects produce spectral peaks.

scholarly journals Variation patterns of landslide basal friction revealed from long-period seismic waveform inversion

2019 ◽  
Vol 100 (1) ◽  
pp. 313-327
Author(s):  
Dan Yu ◽  
Xinghui Huang ◽  
Zhengyuan Li
Keyword(s):  
Steady State ◽  
Friction Coefficient ◽  
Water Waves ◽  
Waveform Inversion ◽  
Time History ◽  
Seismic Signals ◽  
Long Period ◽  
Basal Friction ◽  
Seismic Waveform ◽  
Variation Patterns

Abstract A catastrophic landslide struck the Xiaoba village in Fuquan, Guizhou, southwestern China at about 8:30 p.m. (Beijing Time, UTC + 8) on August 27, 2014. The landslide and induced impulse water waves destroyed two villages and killed 23 persons. By reprocessing seismic signals from a seismic network deployed in the surrounding area of the landslide, we recognized the event from low-frequency seismic signals and subsequently performed a long-period seismic waveform inversion to obtain its force–time history. The inversion results reveal that the maximum force for the landslide is 5 × 109 N, and the duration of the landslide is 38.4 s. The landslide reached its maximum velocity of 12.4 m/s at 13.2 s after its initiation, and the mass center plugged into the quarry at 24.2 s. Based on the inversion results, we estimated basal friction of the landslide. We found the friction coefficient rapidly reduces to a relatively steady-state value of ~ 0.4 at a steady-state distance of 35 m and subsequently reduces in a near-linear manner that satisfies the empirical formula $$ \mu = - 1.4d + 0.44 $$μ=-1.4d+0.44, where $$ d $$d is sliding distance in km. The reduction in friction revealed by the formula is compatible with the finding of previous studies for landslides of similar volume in landslide acceleration stage. However, our result does not make it possible for the friction coefficient to increase again in landslide deceleration stage that a velocity-dependent friction law would allow. The friction variation patterns can be used to constrain input parameters in numerical landslide simulation, which can predicate runout distance and deposit areas for massive landslides to carry out landslide hazard assessment.

Developing a seismic source model for the Arabian Plate

2018 ◽  
Vol 11 (15) ◽  
Author(s):  
I. El-Hussain ◽  
Y. Al-Shijbi ◽  
A. Deif ◽  
A. M. E. Mohamed ◽  
M. Ezzelarab
Keyword(s):  
Seismic Source ◽  
Source Model ◽  
Arabian Plate ◽  
Seismic Source Model

High-Frequency Spectral Decay Characteristics of Seismic Records of Inland Crustal Earthquakes in Japan: Evaluation of the fmax and κ Models

2020 ◽  
Vol 110 (2) ◽  
pp. 452-470
Author(s):  
Masato Tsurugi ◽  
Reiji Tanaka ◽  
Takao Kagawa ◽  
Kojiro Irikura
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Strong Ground Motion ◽  
Cutoff Frequency ◽  
Source Model ◽  
Power Coefficient ◽  
Crustal Earthquakes ◽  
Log Linear ◽  
Large Earthquakes ◽  
Strong Ground

ABSTRACT We examined high-frequency spectral decay characteristics of ground motions for inland crustal earthquakes in Japan, which are important in strong ground motion predictions. We examined 105 earthquakes (Mw 3.3–7.1), including seven large earthquakes (Mw 5.9–7.1). Spectral decay characteristics were accurately evaluated assuming the ω-squared source model and using two approaches: the fmax model (commonly used in Japan), described by the cutoff frequency fmax and the power coefficient of spectral decay s, and the κ model (commonly used in worldwide), the exponential spectral decay model, described by the parameter κ and the specific frequency fE at which a spectrum starts to decrease linearly with increasing frequency in log–linear space. For large earthquakes, we estimated fmax to range from 6.5 to 9.9 Hz and s from 0.78 to 1.60 in the fmax model, and κ to range from 0.014 to 0.051 s and fE from 2 to 4.5 Hz in the κ model. In both approaches, we found that the spectral decay characteristics are regionally dependent. fmax in the fmax model and fE in the κ model tended to be smaller for large earthquakes than for moderate and small earthquakes, clearly demonstrating a seismic moment dependency. We confirmed positive correlations between equivalent parameters of the two approaches, that is, between s and κ and between fmax and fE. Moreover, we found that both approaches are appropriate for evaluating spectral decay characteristics, as long as the spectral decay parameters are appropriately evaluated by comparison with observed spectra. We examined the effects of the spectral decay characteristics on strong ground motion predictions, and demonstrated that simulated motions corrected using the fmax model and those corrected using the κ model are almost the same. The results presented in this article contribute to improving predictions of high-frequency strong ground motion.

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