Optimal time alignment of tide-gauge tsunami waveforms in nonlinear inversions: Application to the 2015 Illapel (Chile) earthquake

2016 ◽  
Vol 43 (21) ◽  
pp. 11,226-11,235 ◽  
Author(s):  
F. Romano ◽  
A. Piatanesi ◽  
S. Lorito ◽  
C. Tolomei ◽  
S. Atzori ◽  
...  
Keyword(s):  
Tide Gauge ◽  
Optimal Time ◽  
Time Alignment ◽  
Chile Earthquake ◽  
Tsunami Waveforms

scholarly journals Benchmarking the Optimal Time Alignment of Tsunami Waveforms in Nonlinear Joint Inversions for the Mw 8.8 2010 Maule (Chile) Earthquake

2020 ◽  
Vol 8 ◽  
Author(s):  
F. Romano ◽  
S. Lorito ◽  
T. Lay ◽  
A. Piatanesi ◽  
M. Volpe ◽  
...  
Keyword(s):  
Coseismic Deformation ◽  
Optimal Time ◽  
Tide Gauges ◽  
First Order ◽  
Time Alignment ◽  
Finite Fault ◽  
Chile Earthquake ◽  
Tsunami Waveforms ◽  
Maule Earthquake ◽  
Seafloor Deformation

Finite-fault models for the 2010 Mw 8.8 Maule, Chile earthquake indicate bilateral rupture with large-slip patches located north and south of the epicenter. Previous studies also show that this event features significant slip in the shallow part of the megathrust, which is revealed through correction of the forward tsunami modeling scheme used in tsunami inversions. The presence of shallow slip is consistent with the coseismic seafloor deformation measured off the Maule region adjacent to the trench and confirms that tsunami observations are particularly important for constraining far-offshore slip. Here, we benchmark the method of Optimal Time Alignment (OTA) of the tsunami waveforms in the joint inversion of tsunami (DART and tide-gauges) and geodetic (GPS, InSAR, land-leveling) observations for this event. We test the application of OTA to the tsunami Green’s functions used in a previous inversion. Through a suite of synthetic tests we show that if the bias in the forward model is comprised only of delays in the tsunami signals, the OTA can correct them precisely, independently of the sensors (DART or coastal tide-gauges) and, to the first-order, of the bathymetric model used. The same suite of experiments is repeated for the real case of the 2010 Maule earthquake where, despite the results of the synthetic tests, DARTs are shown to outperform tide-gauges. This gives an indication of the relative weights to be assigned when jointly inverting the two types of data. Moreover, we show that using OTA is preferable to subjectively correcting possible time mismatch of the tsunami waveforms. The results for the source model of the Maule earthquake show that using just the first-order modeling correction introduced by OTA confirms the bilateral rupture pattern around the epicenter, and, most importantly, shifts the inferred northern patch of slip to a shallower position consistent with the slip models obtained by applying more complex physics-based corrections to the tsunami waveforms. This is confirmed by a slip model refined by inverting geodetic and tsunami data complemented with a denser distribution of GPS data nearby the source area. The models obtained with the OTA method are finally benchmarked against the observed seafloor deformation off the Maule region. We find that all of the models using the OTA well predict this offshore coseismic deformation, thus overall, this benchmarking of the OTA method can be considered successful.

scholarly journals Fault slip distribution of the 2014 Iquique, Chile, earthquake estimated from ocean-wide tsunami waveforms and GPS data

2015 ◽  
Vol 42 (4) ◽  
pp. 1053-1060 ◽  
Author(s):  
Aditya Riadi Gusman ◽  
Satoko Murotani ◽  
Kenji Satake ◽  
Mohammad Heidarzadeh ◽  
Endra Gunawan ◽  
...  
Keyword(s):  
Fault Slip ◽  
Slip Distribution ◽  
Gps Data ◽  
Chile Earthquake ◽  
Tsunami Waveforms ◽  
Fault Slip Distribution

scholarly journals Multi-scale Modelling of Segmentation

2016 ◽  
Vol 34 (2) ◽  
pp. 192-217 ◽  
Author(s):  
Martín Hartmann ◽  
Olivier Lartillot ◽  
Petri Toiviainen
Keyword(s):  
Real Time ◽  
Time Scales ◽  
Time Lag ◽  
Optimal Time ◽  
Boundary Density ◽  
Multi Scale ◽  
Time Alignment ◽  
Scale Modelling ◽  
Time Segmentation ◽  
Segmentation Models

While listening to music, people often unwittingly break down musical pieces into constituent chunks such as verses and choruses. Music segmentation studies have suggested that some consensus regarding boundary perception exists, despite individual differences. However, neither the effects of experimental task (i.e., real-time vs. annotated segmentation), nor of musicianship on boundary perception are clear. Our study assesses musicianship effects and differences between segmentation tasks. We conducted a real-time experiment to collect segmentations by musicians and nonmusicians from nine musical pieces. In a second experiment on non-real-time segmentation, musicians indicated boundaries and their strength for six examples. Kernel density estimation was used to develop multi-scale segmentation models. Contrary to previous research, no relationship was found between boundary strength and boundary indication density, although this might be contingent on stimuli and other factors. In line with other studies, no musicianship effects were found: our results showed high agreement between groups and similar inter-subject correlations. Also consistent with previous work, time scales between one and two seconds were optimal for combining boundary indications. In addition, we found effects of task on number of indications, and a time lag between tasks dependent on beat length. Also, the optimal time scale for combining responses increased when the pulse clarity or event density decreased. Implications for future segmentation studies are raised concerning the selection of time scales for modelling boundary density, and time alignment between models.

In situ Measurements of Tide Gauge Response and Corrections of Tsunami Waveforms from the Niigataken Chuetsu-oki Earthquake in 2007

2009 ◽  
pp. 97-116
Author(s):  
Yuichi Namegaya ◽  
Yuichiro Tanioka ◽  
Kuniaki Abe ◽  
Kenji Satake ◽  
Kenji Hirata ◽  
...  
Keyword(s):  
Tide Gauge ◽  
In Situ Measurements ◽  
Tsunami Waveforms

scholarly journals Time Difference Between the 1854 CE Ansei–Tokai and Ansei–Nankai Earthquakes Estimated from Distant Tsunami Waveforms on the West Coast of North America

2021 ◽  
Author(s):  
Satoshi Kusumoto ◽  
Kentaro Imai ◽  
Takane Hori
Keyword(s):  
North America ◽  
San Francisco ◽  
West Coast ◽  
Tide Gauge ◽  
Historical Earthquakes ◽  
Time Difference ◽  
The West ◽  
Origin Time ◽  
Significant Difference ◽  
Tsunami Waveforms

Abstract We estimated the time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai earthquakes from tidal records of two tide gauge stations (San Francisco and San Diego) on the west coast of North America. The first signals of the Ansei–Tokai tsunami were apparent, whereas those of the Ansei–Nankai tsunami were obscured by the later waves of the Ansei–Tokai tsunami. Waveforms of the Ansei–Nankai tsunami simulated with non-linear dispersive wave theory by assuming an origin time of 07:00 GMT on 24 December arrived earlier than in the observations. The normalized root mean square and the misfit between the simulated and observed waveforms of the Ansei–Nankai tsunami showed a time difference between them of approximately 0.4 h. This finding suggests that the actual origin time of the Ansei–Nankai tsunami was approximately 07:24 GMT on 24 December. A previous study estimated the origin time of the Ansei–Tokai tsunami to be about 00:30 GMT on 23 December. Thus, we concluded that the time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai tsunamis was 30.9 h. Despite the significant difference in the time resolution between the seasonal timekeeping system used in Japan in 1854 and waveform digitization, our result is roughly in agreement with historical descriptions of the tsunamis, suggesting that such information can be effectively used to determine the origin times of historical earthquakes.

scholarly journals In situ Measurements of Tide Gauge Response and Corrections of Tsunami Waveforms from the Niigataken Chuetsu-oki Earthquake in 2007

2009 ◽  
Vol 166 (1-2) ◽  
pp. 97-116 ◽  
Author(s):  
Yuichi Namegaya ◽  
Yuichiro Tanioka ◽  
Kuniaki Abe ◽  
Kenji Satake ◽  
Kenji Hirata ◽  
...  
Keyword(s):  
Tide Gauge ◽  
In Situ Measurements ◽  
Tsunami Waveforms

scholarly journals Time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai earthquakes estimated from distant tsunami waveforms on the west coast of North America

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Satoshi Kusumoto ◽  
Kentaro Imai ◽  
Takane Hori
Keyword(s):  
North America ◽  
San Francisco ◽  
West Coast ◽  
Tide Gauge ◽  
Historical Earthquakes ◽  
Time Difference ◽  
The West ◽  
Origin Time ◽  
Significant Difference ◽  
Tsunami Waveforms

AbstractWe estimated the time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai earthquakes from tidal records of two tide gauge stations (San Francisco and San Diego) on the west coast of North America. The first signals of the Ansei–Tokai tsunami were apparent, whereas those of the Ansei–Nankai tsunami were obscured by the later waves of the Ansei–Tokai tsunami. Waveforms of the Ansei–Nankai tsunami simulated with nonlinear dispersive wave theory by assuming an origin time of 07:00 GMT on 24 December arrived earlier than in the observations. The normalized root mean square and the misfit between the simulated and observed waveforms of the Ansei–Nankai tsunami showed a time difference between them of approximately 0.4 h. This finding suggests that the actual origin time of the Ansei–Nankai tsunami was approximately 07:24 GMT on 24 December. A previous study estimated the origin time of the Ansei–Tokai tsunami to be about 00:30 GMT on 23 December. Thus, we concluded that the time difference between the 1854 CE Ansei–Tokai and Ansei–Nankai tsunamis was 30.9 h. Despite the significant difference in the time resolution between the seasonal timekeeping system used in Japan in 1854 and waveform digitization, our result is roughly in agreement with historical descriptions of the tsunamis, suggesting that such information can be effectively used to determine the origin times of historical earthquakes.

scholarly journals Tsunami Source Inversion Using Tide Gauge and DART Tsunami Waveforms of the 2017 Mw8.2 Mexico Earthquake

2017 ◽  
Vol 175 (1) ◽  
pp. 35-48 ◽  
Author(s):  
Bruno Adriano ◽  
Yushiro Fujii ◽  
Shunichi Koshimura ◽  
Erick Mas ◽  
Angel Ruiz-Angulo ◽  
...  
Keyword(s):  
Tide Gauge ◽  
Tsunami Source ◽  
Source Inversion ◽  
Tsunami Source Inversion ◽  
Tsunami Waveforms ◽  
Mexico Earthquake

scholarly journals High resolution tsunami inversion for 2010 Chile earthquake

2011 ◽  
Vol 11 (12) ◽  
pp. 3251-3261 ◽  
Author(s):  
T.-R. Wu ◽  
T.-C. Ho
Keyword(s):  
High Resolution ◽  
Least Square ◽  
Inversion Method ◽  
Small Unit ◽  
Inversion Result ◽  
Chile Earthquake ◽  
Tsunami Waveforms ◽  
And Performance ◽  
Dart Buoy ◽  
Good Agreement

Abstract. We investigate the feasibility of inverting high-resolution vertical seafloor displacement from tsunami waveforms. An inversion method named "SUTIM" (small unit tsunami inversion method) is developed to meet this goal. In addition to utilizing the conventional least-square inversion, this paper also enhances the inversion resolution by Grid-Shifting method. A smooth constraint is adopted to gain stability. After a series of validation and performance tests, SUTIM is used to study the 2010 Chile earthquake. Based upon data quality and azimuthal distribution, we select tsunami waveforms from 6 GLOSS stations and 1 DART buoy record. In total, 157 sub-faults are utilized for the high-resolution inversion. The resolution reaches 10 sub-faults per wavelength. The result is compared with the distribution of the aftershocks and waveforms at each gauge location with very good agreement. The inversion result shows that the source profile features a non-uniform distribution of the seafloor displacement. The highly elevated vertical seafloor is mainly concentrated in two areas: one is located in the northern part of the epicentre, between 34° S and 36° S; the other is in the southern part, between 37° S and 38° S.

Investigations on skeletal growth zones via bone scans as base of determination of optimal time for surgery in mandibular asymmetry

2000 ◽  
Vol 39 (05) ◽  
pp. 121-126 ◽  
Author(s):  
R. Werz ◽  
P. Reuland
Keyword(s):  
Bone Growth ◽  
Region Of Interest ◽  
Tracer Uptake ◽  
Optimal Time ◽  
Mandibular Bone ◽  
The Third ◽  
Mandibular Asymmetry ◽  
Bone Scans ◽  
Epiphyseal Plates

Summary Aim of the study was to find out wether there is a common stop of growth of mandibular bone, so that no individual determination of the optimal time for surgery in patients with asymmetric mandibular bone growth is needed. As there are no epiphyseal plates in the mandibular bone, stop of growth cannot be determined on X-ray films. Methods: Bone scans of 731 patients [687 patients (324 male, 363 female) under 39 y for exact determination of end of growth and 44 (21 male, 23 female) patients over 40 y for evaluation of nongrowth dependant differences in tracer uptake] were reviewed for the study. All the patients were examined 3 hours after injection of 99mTc-DPD. Tracer uptake was measured by region of interest technique in different points of the mandibular bone and in several epiphyseal plates of extremities. Results: Tracer uptake in different epiphyseal plates of the extremities shows strong variation with age and good correlation with reported data of bone growth and closure of the epiphyseal plates. The relative maximum of bone activity is smaller in mandibular bone than in epiphyseal plates, which show well defined peaks, ending at 15-18 years in females and at 18-21 years in males. In contrast, mandibular bone shows no well defined end of growing but a gradually reduction of bone activity which remains higher than bone activity in epiphyseal plates over several years. Conclusion: No well defined end of growth of mandibular bone exists. The optimal age for surgery of asymmetric mandibular bone growth is not before the middle of the third decade of life, bone scans performed earlier for determination of bone growth can be omitted. Bone scans performed at the middle of the third decade of life help to optimize the time of surgical intervention.

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