Joint inversion study using tsunami waveforms and InSAR data provides a new way to understand the magnitude and spatial extent of subduction zone earthquakes. A great earthquake (Mw 8.5) occurred on ...12 September 2007 off the west coast of Bengkulu, Indonesia. The tsunami generated by the event was recorded by tide gauge stations around the Indian Ocean and by two bottom‐pressure sensors in the deep sea. The ground surface displacements produced by the earthquake on Pagai Islands and on Sumatra Island were observed by Interferometric Synthetic Aperture Radar (InSAR). We estimated the slip distribution of the earthquake by joint inversion incorporating a spatial smoothness constraint, using tsunami waveforms and InSAR data. The total released seismic moment calculated from the slip distribution is 6.7 × 1021 N m (Mw 8.5), consistent with the seismic moment of the Global CMT solution, 6.71 × 1021 N m. The maximum observed tsunami heights along the coast of Bengkulu agree with those computed from the slip distribution. The slip amount of the 2007 earthquake is smaller than the amount of potential slip that has been accumulated since after the 1797 and 1833 events. The premise is that, averaged over long periods of time, the entire fault must slip equal amounts. Therefore the 2007 great earthquake could be followed by several great earthquakes that will rupture the plate interface until the potential slip that has been accumulated is completely released.
The tsunami data assimilation method enables tsunami forecasting directly from observations, without the need of estimating tsunami sources. However, it requires a dense observation network to ...produce desirable results. Here we propose a modified method of tsunami data assimilation for regions with a sparse observation network. The method utilizes interpolated waveforms at virtual stations. The tsunami waveforms at the virtual stations between two existing observation stations are estimated by shifting arrival times with the linear interpolation of observed arrival times and by correcting the amplitudes for their water depths. In our new data assimilation approach, we employ the Optimal Interpolation algorithm to both the real observations and virtual stations, in order to construct a complete wavefront of tsunami propagation. The application to the 2004 Sumatra‐Andaman earthquake and the 2009 Dusky Sound, New Zealand, earthquake reveals that addition of virtual stations greatly helps improve the tsunami forecasting accuracy.
Plain Language Summary
Data assimilation is a method to combine observation and numerical simulation and is widely used in weather forecast. The data assimilation methods have been recently applied for tsunami forecast in North America and Japan where dense observation networks exist. In this study, we proposed a data assimilation method by introducing virtual observation data from neighboring real observations. We applied the method for the Indian Ocean with the 2004 Sumatra‐Andaman earthquake tsunami and offshore New Zealand with the 2009 Dusky Sound earthquake tsunami. We found that the method greatly improved the forecasting accuracy and the method could be used for the regions with sparse observation network.
Key Points
A modified tsunami data assimilation approach is proposed for tsunami warning in regions without a dense observation network
The tsunami waveforms are computed at virtual stations and used for data assimilation between two existing real observation points
The method is applied to the 2004 Sumatra‐Andaman earthquake and the 2009 Dusky Sound earthquake and improves the forecasting accuracy
The toxicity of arsenic (As) and the mechanisms of response to this pollutant were analyzed in two aquatic plant species, one sensitive and one tolerant to the pollutant, Salvinia minima and Lemna ...gibba, respectively. The plants, grown in nutrient solution at pH 6.5, were exposed to As concentrations of 0.0 and 1.0mgL−1 for 3 days. Both species accumulated As in their tissues, which resulted in increases in H2O2 production. L. gibba accumulated eleven times more As than S. minima. However, L. gibba was more tolerant, as shown by the absence of cell membrane damage and, despite greater accumulation, smaller growth reduction than S. minima. Indeed, the index of tolerance to As was twenty percent higher in L. gibba than in S. minima, which most likely results from the presence of a more efficient defense system. This defense system in L. gibba is most likely based on sulfate absorption, assimilation and metabolism. L. gibba showed an increase in sulfate absorption and adenosine-5′-triphosphate (ATP) sulfurylase activity (the first enzyme of the inorganic sulfate assimilation pathway) following exposure to As. Consequently, the plant produced greater concentrations of sulfur-containing compounds that are involved in cellular detoxification, such as glutathione and non-protein thiols, and demonstrated greater enzymatic activity of γ-glutamylcysteine synthetase, glutathione S-transferase and glutathione reductase. Therefore, the plant׳s ability to increase absorption, assimilation and metabolism of sulfur are key steps for tolerance to oxidative stress triggered by metals.
•Lemna gibba is more tolerant to arsenic than Salvinia minima.•The mechanisms responsible for tolerance to As are not yet understood.•Sulfur and glutathione metabolism has a key role in the tolerance mechanisms.
Aim
To evaluate the resistance to vertical root fracture of root filled teeth using different root canal preparation concepts: apical stop and continuously tapering preparation, with different ...foraminal enlargement. In addition, the effect of filling associated with these different concepts was assessed.
Methodology
Ninety single‐rooted premolars were used. The crowns were removed to standardize the root length at 11 mm. Ten roots were not instrumented and not filled (control group). The other roots were divided into four groups (n = 20): apical stop to finishing file size 25, 0.08 taper; apical stop to finishing file size 45, 0.02 taper; continuously tapering preparation to finishing file size 25, 0.08 taper; and continuously tapering preparation to finishing file size 45, 0.02 taper. Afterwards, 10 roots of each group were root filled using Gutta‐percha and AH Plus. A continuous wave of condensation was used as the filling technique. The roots were evaluated as regards resistance to vertical fracture using a universal testing machine. The data were evaluated using the Kruskal–Wallis and Mann–Whitney tests.
Results
No significant difference in performance was observed between continuously tapering preparation size 25, 0.08 taper and apical stop size 45, 0.02 taper groups. Lower resistance values were found in continuously tapering preparation size 45, 0.02 taper group and the highest in apical stop size 25, 0.08 taper group. After filling, a significant increase in resistance values was observed in all groups. In addition, the continuously tapering preparation size 45, 0.02 taper group had values comparable with those of the control.
Conclusion
The different canal preparation techniques reduced resistance to fracture when compared with the control group; however, after root filling, there was a significant increase in resistance.
Abstract
The tsunami source of the 2021
M
W
8.1 Raoul Island earthquake in the Kermadec subduction zone was estimated by inverting the tsunami signals recorded by Deep‐ocean Assessment and Reporting ...of Tsunamis (DART) bottom pressure sensors and coastal tide‐gauges. The main asperity of up to 5 m of slip is located northeastward from the hypocenter, with features compatible with the aftershock distribution and rapid back‐projection analysis. Three earthquakes of
M
W
∼8 or larger which also produced moderate tsunamis happened in the 20th century in the same portion of the subduction zone. This is the first great tsunamigenic event captured by the new New Zealand DART network in the South West Pacific, which proved valuable to estimate a robust image of the tsunami source. We also show a first proof of concept of the capability of this network to reduce the uncertainty associated with tsunami forecasting and to increase the lead time available for evacuation for future alerts.
Plain Language Summary
We estimated the tsunami source for the 4 March 2021 Raoul Island earthquake (
M
W
8.1), obtained by inverting tsunami data from tide‐gauges and open ocean Deep‐ocean Assessment and Reporting of Tsunamis (DART) stations. The main asperity of up to 5 m of slip is located northeastward from the hypocenter, with features compatible with the aftershock distribution and rapid back‐projection analysis. This event is important because it was the strongest one of three earthquakes that occurred within hours during the same day. Moreover, it caused the largest of three tsunami that altogether represent a great test for the New Zealand DART new network. The results demonstrate the potential importance of this new DART network for resolving the tsunami source and for early warning purposes as it can reduce the uncertainty of the tsunami forecasts and at the same time increase the lead time available for evacuation.
Key Points
Tsunami source of the 2021
M
W
8.1 Raoul Island earthquake by inverting tsunami waveforms
The main slip peaks at 5 m and is located at a depth of ∼20–30 and ∼100 km north of the epicenter
New Deep‐ocean Assessment and Reporting of Tsunamis network was crucial for characterizing the source and will significantly reduce the uncertainty and speed up future warnings
The tsunami source of the 2021 MW 8.1 Raoul Island earthquake in the Kermadec subduction zone was estimated by inverting the tsunami signals recorded by Deep‐ocean Assessment and Reporting of ...Tsunamis (DART) bottom pressure sensors and coastal tide‐gauges. The main asperity of up to 5 m of slip is located northeastward from the hypocenter, with features compatible with the aftershock distribution and rapid back‐projection analysis. Three earthquakes of MW ∼8 or larger which also produced moderate tsunamis happened in the 20th century in the same portion of the subduction zone. This is the first great tsunamigenic event captured by the new New Zealand DART network in the South West Pacific, which proved valuable to estimate a robust image of the tsunami source. We also show a first proof of concept of the capability of this network to reduce the uncertainty associated with tsunami forecasting and to increase the lead time available for evacuation for future alerts.
Plain Language Summary
We estimated the tsunami source for the 4 March 2021 Raoul Island earthquake (MW 8.1), obtained by inverting tsunami data from tide‐gauges and open ocean Deep‐ocean Assessment and Reporting of Tsunamis (DART) stations. The main asperity of up to 5 m of slip is located northeastward from the hypocenter, with features compatible with the aftershock distribution and rapid back‐projection analysis. This event is important because it was the strongest one of three earthquakes that occurred within hours during the same day. Moreover, it caused the largest of three tsunami that altogether represent a great test for the New Zealand DART new network. The results demonstrate the potential importance of this new DART network for resolving the tsunami source and for early warning purposes as it can reduce the uncertainty of the tsunami forecasts and at the same time increase the lead time available for evacuation.
Key Points
Tsunami source of the 2021 MW 8.1 Raoul Island earthquake by inverting tsunami waveforms
The main slip peaks at 5 m and is located at a depth of ∼20–30 and ∼100 km north of the epicenter
New Deep‐ocean Assessment and Reporting of Tsunamis network was crucial for characterizing the source and will significantly reduce the uncertainty and speed up future warnings
Abstract
The rupture patterns of the Sumbawa doublet earthquake that occurred on November 25
th
, 2007 was estimated using teleseismic body wave inversion. The first event occurred at 16:02:18 UTC ...with epicenter at 8.292°N and 118.37°E, short after this, the second event occurred at 19:53:08 UTC with epicenter at -8.224°N and 118.467°E. For each event, teleseismic body wave data were retrieved from the Incorporated Research Institutions for Seismology – Data Management Center (IRIS-DMC). The waves were windowed for 70 s which started at 20 s before the P-wave arrival, band-pass filtered between 0. 01 and 0.1 Hz and then integrated into a displacement with a sampling time of 0.5 s. The Green’s function is calculated using the Kikuchi and Kanamori method. The fault geometry is based on the earthquake parameters of the Global Centroid Moment Tensor solution. Strike and dip for first event were 88° and 23°, respectively and those for the second event were 87° and 25°, respectively. The seismic moment (Mo) estimated by the inversion for the first event is 0.617×10
19
Nm or equivalent to moment magnitude (Mw) 6.46 with source duration of approximately 55 s. While for the second event, the seismic moment is estimated to be 0.644×10
19
Nm (Mw 6.47), with slightly longer source duration. The inversion for both events provided a similar slip pattern. The rupture propagated along the dip direction, and the maximum slip occurred near the hypocenter region. The maximum slip amount for first event and second event were 1.43 m and 1.48 m, respectively.
The rupture patterns of the Sumbawa doublet earthquake that occurred on November 25th, 2007 was estimated using teleseismic body wave inversion. The first event occurred at 16:02:18 UTC with ...epicenter at 8.292°N and 118.37°E, short after this, the second event occurred at 19:53:08 UTC with epicenter at -8.224°N and 118.467°E. For each event, teleseismic body wave data were retrieved from the Incorporated Research Institutions for Seismology - Data Management Center (IRIS-DMC). The waves were windowed for 70 s which started at 20 s before the P-wave arrival, band-pass filtered between 0. 01 and 0.1 Hz and then integrated into a displacement with a sampling time of 0.5 s. The Green's function is calculated using the Kikuchi and Kanamori method. The fault geometry is based on the earthquake parameters of the Global Centroid Moment Tensor solution. Strike and dip for first event were 88° and 23°, respectively and those for the second event were 87° and 25°, respectively. The seismic moment (Mo) estimated by the inversion for the first event is 0.617×1019 Nm or equivalent to moment magnitude (Mw) 6.46 with source duration of approximately 55 s. While for the second event, the seismic moment is estimated to be 0.644×1019 Nm (Mw 6.47), with slightly longer source duration. The inversion for both events provided a similar slip pattern. The rupture propagated along the dip direction, and the maximum slip occurred near the hypocenter region. The maximum slip amount for first event and second event were 1.43 m and 1.48 m, respectively.
There is limited longitudinal research examining multiple ethnic-racial identity (ERI) components from adolescence into young adulthood. The current study modeled Latino adolescents’ ERI trajectories ...across the college transition (
N
= 206;
M
age
= 18.10 years,
SD
= 0.41; 65.0% female). Longitudinal data from a survey administered on five occasions across 3 years were analyzed using multilevel growth modeling. Prior to college, Latino heritage culture orientation was positively associated with ERI exploration and resolution. ERI exploration increased over time. ERI resolution was high with no average change; Latino heritage culture orientation predicted variability in resolution over time. Before college, male-identifying youth reported higher ERI public regard from teachers/professors compared to female-identifying youth. Public regard increased to a greater extent for female compared to male adolescents. The findings join evidence for lifespan and intersectional models of ERI development.
PDF
