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Here we update a catalogue of 2001–2011 New Zealand earthquakes relocated with a 3-D seismic velocity model, which has recent improvements. We use P- and S-wave arrival times from earthquakes during 2001–2011 as these were manually picked with assigned quality. We demonstrate the usefulness of the catalogue by considering results from the southern South Island where GeoNet seismograph spacing is large. Later phase data used automatic picking and processing of arrival times. We relocate the 2019–2020 data from National Geohazards Monitoring Centre (NGMC) and compare seismicity patterns to consider its usefulness. We find that the auto-detected crustal earthquakes are more sparse in most of the southern South Island compared to the earlier analyst-picked data period, including Fiordland, which is one of the most seismically active areas in New Zealand. The auto-detected seismicity pattern is also problematic at greater depth and does not show a seismicity band in the lower crust across Southland evident in 2001–2011 data. The detection capability could be improved with a much denser permanent network. We recommend that the 2001–2011 relocated catalogues be used in studies of tectonics and seismic hazard across the South Island, and in studies that consider New Zealand wide seismicity patterns. [ABSTRACT FROM AUTHOR]

Hypocenter relocation is a method used to get precise earthquake parameters. They will be useful for an advanced tectonic study like seismic hazard assessment in an area. The hypocenter relocation using a 3-D velocity model will theoretically obtain better results than a 1-D velocity model because the earth subsurface model is closed with a 3-D model. Some 767 earthquakes recorded by DOMERAPI, MERAMEX, BMKG, and BPPTKG networks used in this research. They were relocated by using a 3-D velocity model and analyzed for seismotectonic study in Central Java area and its surroundings. The result of hypocenter relocation using a 3-D velocity model is successfully detecting some tectonic features more clearly like columnar structure related to the backthrust structure at the south of Kebumen. The west-east vertical cross-section crossing the Opak fault indicates the dip of the fault plane is directing to the east. This study could not identify the double seismic zone, which was detected by the previous research. Some volcano-tectonic (VT) earthquakes related to the shallow magma activity of Mount Merapi also are detected clearly in this study.

Multi-frequency P- and S- wave attenuation tomography models of Lake Van area (East Anatolia) have been obtained by estimating coda-normalized wave spectra of 3027 local earthquakes (2.0 < Mw < 7.1). The 6998 waveforms sampled from surface to a depth of 25 km, and were recorded from 2004 to 2020 at seven broadband, three-component digital seismic stations operated by Kandilli Observatory and Earthquake Research Institute (KOERI). We adopted a two-point ray-bending method to trace rays in a 3-D velocity model. We applied the coda normalization (CN) method to P - and S -wave data sets. We inverted the spectral data with a multiple resolution seismic attenuation (MuRAT) approach to obtain final tomographic models. On average, high (low) attenuation corresponds to low (high) velocity anomalies. The P- and S- wave attenuation contrasts delimit four well-known geological zones. High frequency-short wavelength attenuation contrasts constrain the 5-km-deep zone of interaction between magma and sediments within the Lake Van basin. Low frequency-long wavelength attenuation anomalies mark the central section of Lake Van between depths of 10 km and 20 km. This zone coincides with a rigid stable shear zone overlying a possible weak-ductile lower crust, interpreted as a detachment. Both low (5–15 km depth) and high attenuation (>20 km) anomalies mark the area of maximum seismic energy release during the Van event. Their contrast highlights the maximum seismogenetic depth above weak-warm, unstable materials. High attenuation in the SE-part of the Lake Van area coincides with a large hydrothermal and/or magmatic folding-overthrusting, interpreted as a suture-metamorphic complex between depths of 10–15 km. Other minor high-attenuation zones deeper than 5 km focus on complex shear zones in the area damaged by the Van event. The paired attenuation structure of the Lake Van area appears linked to multiple tectonic processes of crust-magma interaction better constrains subsurface segmentation structures and differential deformation types at upper-middle crustal depths. [Display omitted] • The attenuation contrasts at Lake Van delimit distinct geological units. • Shallower short wavelength attenuation revealed weak unstable shear zones. • Deeper long wavelength attenuation marked rigid stable shear zones. • This study better constrained crustal segmentation and differential deformation types. [ABSTRACT FROM AUTHOR]

Using over 3 500 first P arrival times recorded by nine digital seismic stations from Hainan Digital Seismic Network during 1999∼2005, a 3-D P-wave velocity model of the crust under Hainan Island and adjacent regions has been determined. The results show that the pattern of velocity anomalies in the shallower upper crust is somewhat associated with the surface geological tectonics in the region. A relative low-velocity anomaly appears north of the Wangwu-Wenjiao fault zone and a relative high-velocity anomaly appears south of the Wangwu-Wenjiao fault zone, corresponding to the depressed areas in north Hainan Island, where many volcanoes are frequently active and geothermal values are relatively higher, and the uplifted and stable regions in central and south of the Hainan Island. In the middle and lower crust velocities are relatively lower in east Hainan than those in west Hainan, possibly suggesting the existence of the upwelling of hot materials from the mantle in east Hainan. The pattern of velocity anomalies also indicates that NW faults, i.e., the Puqian-Qinglan fault, may be shallower, while the E-W Wangwu-Wenjiao fault may be deeper, which perhaps extends down to Moho depth or deeper. [ABSTRACT FROM AUTHOR]