Your contribution is valuable to earthquake science, seismic hazard analysis and mitigation efforts. You can use your device location or the map to indicate where you were during the earthquake. Thank you! Data for the same earthquake reported by different agencies Info: The more agencies report about the same quake and post similar data, the more confidence you can have in the data. It takes normally up to a few hours until earthquake parameters are calculated with near-optimum precision.
Most recent quakes Top 20 past 24 hrs Quakes in Japan. User reports for this quake User reports estimate the perceived ground shaking intensity according to the MMI Modified Mercalli Intensity scale. Contribute: Leave a comment if you find a particular report interesting or want to add to it. Crescent-shaped coasts and harbors, such as those near Sendai, can play a role in focusing the waves as they approach the shore.
Also, since land elevation is low and flat along much of the Japanese coast, many areas are particularly vulnerable to tsunamis.
The Japan Meteorological Agency reported maximum tsunami heights of 4. The U. Other PTWC reports:. Caption by Michael Carlowicz. On March 11, , a magnitude 8. Mark as helpful or interesting. Send your own user report! Try our free app! Android iOS version. More info. Based on its magnitude, the fault that was active during the quake ruptured along a surface of approx. The length of the rupture zone thus was probably around 31 km 19 mi.
Aftershocks typically occur during the weeks and months following the quake at or near the same fault, at distances of up to approx. The synthetic waveforms of the horizontal component for the other Events appear to explain the observation. The synthetic waveform for the mechanism of the optimal solution determined by evaluating the variance reduction is shown in the bottom right of Fig. The magnitude estimated from the comparison of the synthetic waveform amplitude with that of the observed one is M w 5.
Displacement waveforms at station OIT modeled by the discrete wavenumber method. Black and red traces show the observed and synthetic waveforms of the triggered event, respectively. Shadow areas indicate the time window to calculate the variance reduction.
The synthetic waveform for the mechanism obtained by the grid search for the variance reduction is shown at the bottom right. We plot the estimated variance reduction for the source location estimated by the back-projection analysis for various mechanisms on the triangle diagram of the focal mechanism Frohlich in Fig. The distribution of the source mechanism indicates that the normal-fault are probable mechanisms to explain the observations, although we cannot constrain the strike direction, which is presented as nearly invariant for the strike angle in Additional file 1 : Figure S3, which shows the comparison of the distribution of variance reductions as a function of the fault parameters.
We also plot the estimated variance reduction from the hypocenter of the second optimal solution Fig. In contrast, the opposite of the normal-fault and the normal-fault with strike-slip component, i. These investigations suggest that the triggered event might occur near station OIT via a normal-fault mechanism or a normal-fault with strike-slip components. Variance reduction plotted on a triangle diagram of the focal mechanism.
A red circle indicates the optimal solution for the mechanism. A dashed red circle indicates the optimal solution for the mechanism. We investigated the source location and mechanism of an event triggered during the Kumamoto earthquake M w 7.
We applied the back-projection method for velocity waveforms within the frequency range 3—8 Hz. The timing of large energy release of the triggered event is estimated to be We reproduced observed waveforms of high-pass filtered displacements in a corner frequency of 0.
The convolved waveforms for the smaller events show agreement with the waveform of the triggered event. Synthetic waveforms for a normal-fault mechanism and a normal-fault with strike-slip components at the estimated source locations also explain the observed waveforms. Although our approach does not constrain the strike direction well, the results of our waveform analysis indicate that the triggered earthquake occurred near the station that observed the strong motions, primarily by a normal-fault mechanism or a normal-fault with strike-slip components.
Frohlich C Triangle diagrams: ternary graphs to display similarity and diversity of earthquake focal mechanisms. Phys Earth Planet Int 75 1—3 — Article Google Scholar. Geophys Res Lett —4. Nature — Google Scholar. Bull Volcanol 51 5 — Kao H, Shan SJ The source-scanning algorithm: mapping the distribution of seismic sources in time and space.
Geophys J Int 2 — Bull Seismol Soc Am 81 6 — Earth Planets Space Zisin 2 59 — Nakamura T, Takenaka H A numerical analysis of seismic waves for an anisotropic fault zone. Earth Planets Space — Spudich P, Cranswick E Direct observation of rupture propagation during the Imperial Valley earthquake using a short baseline accelerometer array.
Bull Seismol Soc Am 74 6 — Spudich P, Frazer LN Use of ray theory to calculate high-frequency radiation from earthquake sources having spatially variable rupture velocity and stress drop. Geophys Prospect 64 6 — Download references. TN conducted the data analysis and the calculation of seismic waveforms and wrote the paper. SA coordinated the strong-motion network data and contributed to the data analysis and the calculation. Both authors read and approved the final manuscript.
Constructive comments and suggestions from two anonymous reviewers were very helpful. You can also search for this author in PubMed Google Scholar. Correspondence to Takeshi Nakamura. This file includes additional figures Figures S1— 3 and a table Table S1.
Reprints and Permissions. Nakamura, T. Source location and mechanism analysis of an earthquake triggered by the Kumamoto, southwestern Japan, earthquake. Earth Planets Space 69, 6 Download citation. Received : 01 August Accepted : 09 December
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