Discussion on moment tensor solution and seismogenic structure of Ruichang-Yangxin earthquake on 10 September 2011

Abstract We present regional earthquake magnitude conversion relations among different magnitude scales (Mw, Ms, mb, ML, and MD) for the Himalayan seismic belt developed from data of local, regional, and international seismological agencies (International Seismological Centre [ISC], National Earthquake Information Centre [NEIC], Global Centroid Moment Tensor Solution [CMT], International Data Centre [IDC], China Earthquake Administration [BJI], and National Centre for Seismology [NDI]). The intra- (within the same magnitude scale) and inter- (with different magnitude scales) magnitude regression relations have been established using the general orthogonal regression and orthogonal distance regression techniques. Results show that the intra-magnitude relations for Mw, Ms, and mb reported by the Global CMT, ISC, and NEIC exhibit 1:1 relationships, whereas ML reported by the IDC, BJI, and NDI deviates from this relationship. The IDC underestimates Ms and mb compared with the ISC, NEIC, and Global CMT; this may be due to different measurement procedures adopted by the IDC agency. The inter-magnitude relations are established between Mw,Global CMT and Ms, mb, and ML reported by the ISC, NEIC, IDC, and NDI, and compared with the previously developed regional and global regression relations. The duration (MD) and local (ML) magnitudes reported by NDI exhibit a 1:1 relationship. The derived magnitude regression relations are expected to support the homogenization of the earthquake catalogs and to improve seismic hazard assessment in this region.

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Neogene and active brittle deformation on Amorgos Island (Greece)

10.5194/egusphere-egu2020-10755 ◽

2020 ◽

Author(s):

Jan Behrmann ◽

Jakob Schneider ◽

Benjamin Zitzow

Keyword(s):

Moment Tensor ◽

Spatial Relationship ◽

Shear Zones ◽

Fault System ◽

Normal Faults ◽

Small Scale ◽

Past Century ◽

Fault Plane Solutions ◽

Moment Tensor Solution ◽

Late Neogene

<p>Amorgos is the south-eastern outpost of the Cyclades Islands in the Aegean Sea, which forms part of the Neogene-Quaternary zone of crustal and lithospheric N-S upper plate extension northward of the Hellenic subduction zone and deep sea trench. Apart from subduction-related earthquakes further south, the southern Aegean is affected by frequent earthquakes sourced in the upper plate. The twin earthquakes of 9 July 1956, followed by a strong tsunami, were the strongest events of this kind in the past Century. Hypocenters are related to a NE-SW oriented normal fault bounding the Amorgos-Santorini Graben System. There are questions in the literature regarding the seismic source and fault plane solutions, especially the contribution of a transcurrent faulting component.</p><p>We have analyzed the kinematics of brittle faults exposed on Amorgos Island itself that could be related to Neogene and active extensional and/or transcurrent deformation. Seismic slip often occurs on previously existing faults. Thus, their orientations and kinematics may help shed light on the structure of seismic sources at depth. We present evidence for a complex history of faulting. Early normal detachment faults and shear zones overprint older (rare) reverse faults, and are themselves overprinted by several sets of dominantly dextral NE and SE trending strike slip faults. Youngest is a conjugate set of NE trending high-angle normal faults. These are especially frequent along the SE coast of the island, suggesting a clear spatial relationship with the 1956 rupture. They can be fitted to a moment tensor solution similar to the published solutions for the 1956 Amorgos earthquake. The kinematic solution for the population of early normal faults suggests that the whole of Amorgos Island may have experienced a 15&#176; NNW tilt during later extension, which lets us suspect that the island could be a tilted block of a much larger fault system. Regarding long-term late Neogene to Quaternary kinematics, dextrally transtensive fault slip is required to fit the regional pattern of extensional deformation in the Aegean, and this is reflected by small-scale brittle faulting on Amorgos.</p>

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Characterisation of fault plane and coseismic slip for the May 2, 2020, Mw 6.6 Cretan Passage earthquake from tide-gauge tsunami data and moment tensor solutions

10.5194/nhess-2021-183 ◽

2021 ◽

Author(s):

Enrico Baglione ◽

Stefano Lorito ◽

Alessio Piatanesi ◽

Fabrizio Romano ◽

Roberto Basili ◽

...

Keyword(s):

Tide Gauge ◽

Moment Tensor ◽

Early Warning Systems ◽

Thrust Fault ◽

Coseismic Slip ◽

Moment Tensor Solution ◽

Crete Island ◽

Tsunami Forecasting ◽

Oblique Convergence ◽

Splay Fault

Abstract. We present a source solution for the tsunami generated by the Mw 6.6 earthquake that occurred on May 2, 2020, about 807thinsp;km offshore south of Crete, in the Cretan Passage, on the shallow portion of the Hellenic Arc Subduction Zone (HASZ). The tide-gauges recorded this local tsunami on the southern coast of Crete island and Kasos island. We used these tsunami observations to constrain the geometry and orientation of the causative fault, the rupture mechanism and the slip amount. We first modelled an ensemble of synthetic tsunami waveforms at the tide-gauge locations, produced for a range of earthquake parameter values as constrained by some of the available moment tensor solutions. We allow for both a splay and a back-thrust fault, corresponding to the two nodal planes of the moment tensor solution. We then measured the misfit between the synthetic and the observed marigrams for each source parameter set. Our results identify the shallow steeply-dipping back-thrust fault as the one producing the lowest misfit to the tsunami data. However, a rupture on a lower angle fault, possibly a splay fault, with a sinistral component due to the oblique convergence on this segment of the HASZ, cannot be completely ruled out. This earthquake reminds us that the uncertainty regarding potential earthquake mechanisms at a specific location remains quite significant. In this case, for example, it is not possible to anticipate if the next event will be one occurring on the subduction interface, on a splay fault, or on a back-thrust which seems the most likely for the event under investigation. This circumstance bears important consequences because back-thrust and splay faults might enhance the tsunamigenic potential with respect to the subduction interface due to their steeper dip. Then, these results are relevant for tsunami forecasting both in the framework of the long-term hazard assessment and of the early warning systems.

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Local seismotectonic analysis of the July 2019 Molucca Sea earthquake sequence based on moment tensor solutions

Geoscience Letters ◽

10.1186/s40562-021-00200-z ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Aditya Dwi Prasetio ◽

Mohammad Hasib ◽

Andi Amran ◽

Syuhada ◽

Febty Febriani ◽

...

Keyword(s):

Moment Tensor ◽

Normal Fault ◽

Earthquake Sequence ◽

Tectonic Activity ◽

Waveform Data ◽

Moment Tensor Solution ◽

Compressional Stress ◽

Fault Mechanism ◽

Sea Area ◽

Full Moment Tensor

AbstractWe investigate the local seismotectonic of the Molucca Sea area using moment tensor calculations for the earthquakes that occurred in July 2019 at a depth of 10–55 km. The mainshock of Mw 6.8 occurred on July 7, followed by aftershocks until July 18, with magnitudes ranging from Mw 4.6 to Mw 5.8. Moment tensor solutions are calculated by applying Isolated Asperities (ISOLA) software using the full waveform data recorded at regional seismic stations. The analyzed frequency bands used in this study are 0.01–0.03 Hz and 0.04–0.05 Hz for the event with Mw ≥ 5 and Mw < 5, respectively. We provide validations of new moment tensor solutions for Mw < 5 events in the Molucca Sea region for the period during the earthquake sequence. The results show that thrust and oblique faults are dominant during this event, which indicate a compressional stress of divergent double subduction (DDS) of the Sangihe and Halmahera arcs. Only one full moment tensor solution reveals the normal fault mechanism, which may indicate the manifestation of strain release of compressional stress in the surrounding area. Furthermore, these results also support the previous studies suggesting that the Talaud-Mayu Ridge located in the middle of the Molucca Sea has developed as a consequence of the transpressional tectonic activity.

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Mathematical theory of acoustic emission and moment tensor solution.

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.36.1025 ◽

1987 ◽

Vol 36 (408) ◽

pp. 1025-1031 ◽

Cited By ~ 10

Author(s):

Masayasu OHTSU

Keyword(s):

Acoustic Emission ◽

Mathematical Theory ◽

Moment Tensor ◽

Moment Tensor Solution

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Scisola: Automatic Moment Tensor Solution for SeisComP3

Seismological Research Letters ◽

10.1785/0220150065 ◽

2015 ◽

Vol 87 (1) ◽

pp. 157-163 ◽

Cited By ~ 6

Author(s):

Nikolaos Triantafyllis ◽

Efthimios Sokos ◽

Aristidis Ilias ◽

Jiří Zahradník

Keyword(s):

Moment Tensor ◽

Moment Tensor Solution

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The Mw 6.6 Gisborne earthquake of 2007

Bulletin of the New Zealand Society for Earthquake Engineering ◽

10.5459/bnzsee.41.4.266-277 ◽

2008 ◽

Vol 41 (4) ◽

pp. 266-277 ◽

Cited By ~ 9

Author(s):

Caroline François-Holden ◽

Stephen Bannister ◽

John Beavan ◽

Jim Cousins ◽

Bryan Field ◽

...

Keyword(s):

Structural Damage ◽

Main Shock ◽

Fault Plane ◽

Moment Tensor ◽

High Stress ◽

Strong Motion ◽

Slow Slip ◽

Plate Interface ◽

Direction Parallel ◽

Moment Tensor Solution

Gisborne city experienced recorded peak ground accelerations exceeding 0.25g for the third time since 1966 in the magnitude Mw 6.6 earthquake at 075516 UT (8:55 pm local time) on 20 December 2007. The earthquake was at a hypocentral distance of 64 km from Gisborne at a depth of 40 km, well within the mantle of the subducted slab of the Pacific plate as it dips beneath the North Island of New Zealand. At this location the plate interface is about 10-15 km deep. The main event was followed by sparse aftershocks consistent with a rupture of the subducted plate, with the largest aftershock of magnitude 4.6 occurring on December 22nd. The GeoNet website received 3,257 felt reports, with a strongest intensity of MM8 (heavily damaging) assigned to the main shock. The 122 strong motion records of this event show a clear regional directional variation in the wave propagation, as well as a distinct 2 Hz peak widely observed throughout the country. At a local scale, three sites in the Gisborne region recorded accelerations around 0.2g. Recordings in Gisborne city also revealed a predominant displacement direction, parallel to the main street where most of the damage occurred. Source studies from moment tensor solution, aftershock relocations, GPS and strong motion data showed that the earthquake occurred within the subducted plate on a 45 degree eastward dipping fault plane. The mainshock rupture area is about 10 km2 reaching a maximum slip of 2.6 m. The computed high stress drop value of 17 MPa is as expected for an intraslab event and consistent with observations of very energetic seismic waves as well as heavy structural damage. GPS data recorded by continuous GPS instruments have also shown that slow slip occurred for about three weeks after the main shock. The slow slip was triggered on the subduction interface, rather than on the same fault plane as the aftershocks. This is the first clear-cut case worldwide of triggered slow slip, although three non-triggered slow-slip events have occurred in the same region since 2002.

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Strong ground motion simulation of the 27 May 2006 Yogyakarta earthquake using Empirical Green’s Function

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/873/1/012080 ◽

2021 ◽

Vol 873 (1) ◽

pp. 012080

Author(s):

Yeremia Hanniel ◽

Ade Anggraini ◽

Agus Riyanto ◽

Drajat Ngadmanto ◽

Wiwit Suryanto

Keyword(s):

Green’S Function ◽

Green's Function ◽

Moment Tensor ◽

Source Parameters ◽

Maximum Amplitude ◽

Earthquake Source ◽

Ground Acceleration ◽

Moment Tensor Solution ◽

Earthquake Source Parameters ◽

Strong Ground Motion Simulation

Abstract On May 27, 2006, 05:54 am local time, a moderate crustal earthquake of magnitude Mw 6,3 struck the Yogyakarta province, especially in the Bantul regency in the south part of the province. The earthquake damaged or destroyed more than 400,000 houses and buildings and caused more than 5,700 people killed. Several earthquake stations recorded the ground vibration caused by the mainshock very well, except at the stations closest to the earthquake source, namely YOGI in Gamping, West of Yogyakarta, which experienced saturation due to significant vibration. Therefore, information about the maximum ground acceleration near the source is yet not known. We model the ground vibrations near the earthquake source using a stochastic Green’s Function approach to obtain information about the ground motions’ maximum amplitude. The earthquake source parameters we referred to is the moment tensor solution from the Harvard Moment Tensor. The calculations show that the amplitude is consistent with observations recorded at the BJI Banjarnegara (0.04g) and YOGI Yogyakarta (0.3g).

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