First results from temporary deployment of small seismic network following the Mw=6.4 Petrinja earthquake

The Department of Geophysics, University of Zagreb and the Italian National Institute of Oceanography and Applied Geophysics (OGS) installed on January 4th 2021, five temporary seismic stations near the town of Petrinja, Croatia, in the aftermath of&#160; the 29 Decembre 2020 Mw 6.4 earthquake. The stations equipped with a seismometer and a strong motion sensor, recorded the aftershock sequence beginning six days after the mainshock allowing to augment the permanent seismic network in the area improving the azimuthal coverage and providing additional near&#8208;field observations.In this presentation we summarize the motivation and goals of the deployment; details regarding the station installation, instrumentation, and configurations and observations from the network. The collected data set will be useful for carrying out several seismological studies including the analysis of variability of strong ground motions in near field, the determination of the aftershocks source parameters,&#160; the estimation (if any) of rupture directivity of small events, the clustering of events in space and time, the better imaging of the fault zone, the evolution of crustal properties within and outside of the fault zone.

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A SOURCE PARAMETERS STUDY OF THE AFTERSHOCK SEQUENCE OF THE KOZANI- GREVENA 1995 EARTHQUAKE BASED ON ACCELERATION RECORDS

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.16535 ◽

2004 ◽

Vol 36 (3) ◽

pp. 1457 ◽

Cited By ~ 1

Author(s):

A. A. Panou ◽

C. B. Papazachos ◽

Ch. Papaioannou ◽

P. M. Hatzidimitriou

Keyword(s):

Source Parameters ◽

Strong Motion ◽

Aftershock Sequence ◽

Propagation Path ◽

Data Set ◽

Near Surface ◽

Anelastic Attenuation ◽

Geological Formation ◽

Good Agreement

Strong motion recordings of the May 13, 1995 Mw=6.6, earthquake sequence that occurred in the Kozani-Grevena region (Western Macedonia, Greece) have been analyzed for the determination of their source parameters. The data set for this study comes from a temporarily deployed accelerograph network and the source parameters using the shear-wave displacement spectra have been estimated. For this estimation the spectral records have been corrected for the site effects and for the propagation path (geometrical spreading and anelastic attenuation). The magnitude of each event was also re-calculated by estimating appropriate station corrections. The derived relationships arelogMo =(1.43 ±0.09) M, + (16.92 ± 0.29), 2.0 < ML< 5.0 (1)logfc = (-0.56± 0.08) · ML + (2.52 + 0.29), 2.0 < ML< 5.0 (2)logM0 = (-2.20 + 0.08) · log fc + (23.16 ± 0.84), 0.6 < fc < 10.0 (3)The near-surface attenuation parameter κ0 has also been determined for the strong motion stations sites. These values of κ0 are in good agreement with those of Margaris and Boore (1998) for the geological formation on which each station was positioned. The obtained source parameters are in good agreement with those from previous studies for the Aegean region.

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The U.S. Geological Survey’s Rapid Seismic Array Deployment for the 2019 Ridgecrest Earthquake Sequence

Seismological Research Letters ◽

10.1785/0220190296 ◽

2020 ◽

Vol 91 (4) ◽

pp. 1952-1960 ◽

Cited By ~ 10

Author(s):

Elizabeth S. Cochran ◽

Emily Wolin ◽

Daniel E. McNamara ◽

Alan Yong ◽

David Wilson ◽

...

Keyword(s):

Fault Zone ◽

Near Field ◽

Aftershock Sequence ◽

Rupture Directivity ◽

Field Recordings ◽

Stress Drops ◽

The City ◽

Large Earthquakes ◽

The U.S ◽

Strong Ground

Abstract Rapid seismic deployments following large earthquakes capture ephemeral near-field recordings of aftershocks and ambient noise that can provide valuable data for seismological studies. The U.S. Geological Survey installed 19 temporary seismic stations following the 4 July 2019 Mw 6.4 and 6 July 2019 (UTC) Mw 7.1 earthquakes near the city of Ridgecrest, California. The stations record the aftershock sequence beginning two days after the mainshock and are expected to remain in the field through approximately January 2020. The deployment augments the permanent seismic network in the area to improve azimuthal coverage and provide additional near-field observations. This article summarizes the motivation and goals of the deployment; details of station installation, instrumentation, and configurations; and initial data quality and observations from the network. We expect these data to be useful for a range of studies including detailing near-field variability in strong ground motions, determining stress drops and rupture directivity of small events, imaging the fault zone, documenting the evolution of crustal properties within and outside of the fault zone, and others.

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Detection of repeating earthquakes in the West Bohemia swarm region

10.5194/egusphere-egu2020-16840 ◽

2020 ◽

Author(s):

Ali Salama ◽

Tomas Fischer

Keyword(s):

Fault Zone ◽

Seismic Velocity ◽

Background Activity ◽

Source Parameters ◽

The West ◽

Data Set ◽

Repeating Earthquakes ◽

Waveform Cross Correlation ◽

Cross Correlation Analysis ◽

West Bohemia

&#160;&#160;&#160;Repeating earthquakes, sequences of microseismic events with highly similar seismograms and magnitudes, suggest quasi-periodic rupturing of the same asperity. They are observed on creeping fault segments surrounded by aseismic slip area and also in earthquake swarms. However, so far, they have not been documented in the West Bohemia/Vogtland seismic swarm area. These local swarms consist of thousands of ML < 4 events occurring along a small area of fault zone with repeated activation of some patches during the swarms and weak background activity in the intermediate periods. Detecting and analyzing the repeating earthquakes would help revealing the continuing background activity and identifying fault areas that are active permanently. This could point to the possible sources of fluids or aseismic creep that are supposed to play significant role in swarm generation. Repeating earthquakes are identified by waveform cross-correlation analysis comparing waveforms of repeaters with continuous seismic data set. We developed efficient detection algorithm to identify repeating earthquakes using selected event templates to reveal continuing seismic activity along the main Nov&#253; Kostel fault zone, namely in the areas with only episodic activity. The results provide a robust basis for routine application to the long-term seismic dataset that will allow also for further applications including analysis of the source parameters of the repeaters and/or detecting possible seismic velocity variations in the focal zone. &#160;

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Stochastic Source Model for Strong Motion Prediction

International Journal of Geotechnical Earthquake Engineering ◽

10.4018/ijgee.2018070101 ◽

2018 ◽

Vol 9 (2) ◽

pp. 1-22

Author(s):

S. Sangeetha ◽

S.T.G. Raghukanth

Keyword(s):

Near Field ◽

Source Parameters ◽

Strong Motion ◽

Seismic Source ◽

Source Model ◽

Spectral Density Function ◽

Correlation Lengths ◽

Rupture Area ◽

Power Spectral ◽

Finite Fault

The article aims at developing a stochastic model which simulates spatial distribution of slip on the fault plane. This is achieved by analysing a large dataset of 303 finite-fault rupture models from 152 past earthquakes with varying fault mechanisms and in the magnitude range of 4.11-9.12. New scaling relations to predict the seismic source parameters such as fault length, fault width, rupture area, mean and standard deviation of slip have been derived for distinct fault mechanisms. The developed methodology models the spatial variability of slip as a two-dimensional von Karman power spectral density function (PSD) and correlation lengths are estimated. The proposed stochastic slip model is validated by comparing the simulated near-field ground response with the recorded data available for the 20th September 1999 Chi-Chi earthquake, Taiwan.

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SEISMOLOGICAL AND ENGINEERING PARAMETERS OF 24 and 26 SEPTEMBER, 2019 MARMARA SEA EARTHQUAKES

10.5194/egusphere-egu2020-22107 ◽

2020 ◽

Author(s):

Eser Çakti ◽

Fatma Sevil Malcioğlu ◽

Hakan Süleyman

Keyword(s):

Earthquake Engineering ◽

Prediction Models ◽

Source Parameters ◽

Strong Motion ◽

P Wave ◽

Corner Frequency ◽

Marmara Sea ◽

S Wave ◽

Data Set ◽

The North

On 24th&#160;and 26th&#160; September 2019, two earthquakes of Mw=4.5 and Mw=5.6 respectively took place in the Marmara Sea. They were associated with the Central Marmara segment of the North Anatolian Fault Zone, which is pinpointed by several investigators as the most likely segment to rupture in the near future giving way to an earthquake larger than M7.0. Both events were felt widely in the region. The Mw=5.6 event, in particular, led to a number of building damages in Istanbul, which were larger than expected in number and severity. There are several strong motion networks in operation in and around Istanbul. We have compiled a data set of recordings obtained at the stations of the Istanbul Earthquake Rapid Response and Early Warning operated by the Department of Earthquake Engineering of Bogazici University and of the National Strong Motion Network operated by AFAD. It consists of 148 three component recordings, in total. &#160;444 records in the data set, after correction, were analyzed to estimate the source parameters of these events, such as corner frequency, source duration, radius and rupture area, average source dislocation and stress drop. Duration characteristics of two earthquakes were analyzed first by considering P-wave and S-wave onsets and then, focusing on S-wave and significant durations. PGAs, PGVs and SAs were calculated and compared with three commonly used ground motion prediction models (i.e &#160;Boore et al., 2014; Akkar et al., 2014 and Kale et al., 2015). Finally frequency-dependent Q models were estimated using the data set and their validity was dicussed by comparing with previously developed models.

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Loreto Intermediate Depth Earthquake of 26 May 2019 (Northeast Peru): Source Parameters by Inversion of Local to Regional Waveforms and Strong-Motion Observations

Seismological Research Letters ◽

10.1785/0220200459 ◽

2021 ◽

Author(s):

Hernando Tavera ◽

Bertrand Delouis ◽

Arturo Mercado ◽

David Portugal

Keyword(s):

Near Field ◽

Source Parameters ◽

Waveform Inversion ◽

Strong Motion ◽

Seismic Source ◽

Slab Geometry ◽

Nazca Plate ◽

Strong Motion Data ◽

Ground Shaking ◽

Motion Data

Abstract The Loreto earthquake of 26 May 2019 occurred below the extreme northeast part of Peru at a depth of 140 km within the subducting Nazca plate at a distance of 700 km from the trench Peru–Chile. The orientation of the seismic source was obtained from waveform inversion in the near field using velocity and strong-motion data. The rupture occurred in normal faulting corresponding to a tensional process with T axis oriented in east–west direction similar to the direction of convergence between the Nazca and South America plates. The analysis of the strong-motion data shows that the levels of ground shaking are very heterogeneous with values greater than 50 Gal up to distances of 300 km; the maximum recorded acceleration of 122 Gal at a distance of 100 km from the epicenter. The Loreto earthquake is classified as a large extensional event in the descending Nazca slab in the transition from flat-slab geometry to greater dip.

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Near-Real-Time Estimates on Earthquake Rupture Directivity Using Near-Field Ground Motion Data From a Dense Low-Cost Seismic Network

Geophysical Research Letters ◽

10.1029/2018gl078262 ◽

2018 ◽

Vol 45 (15) ◽

pp. 7496-7503 ◽

Cited By ~ 3

Author(s):

Jyh Cherng Jan ◽

Hsin-Hua Huang ◽

Yih-Min Wu ◽

Chien-Chih Chen ◽

Cheng-Horng Lin

Keyword(s):

Real Time ◽

Ground Motion ◽

Low Cost ◽

Near Field ◽

Seismic Network ◽

Earthquake Rupture ◽

Rupture Directivity ◽

Motion Data ◽

Time Estimates

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Nevada Seismological Laboratory Rapid Seismic Monitoring Deployment and Data Availability for the 2020 Mww 6.5 Monte Cristo Range, Nevada, Earthquake Sequence

Seismological Research Letters ◽

10.1785/0220200344 ◽

2021 ◽

Cited By ~ 1

Author(s):

Jayne M. Bormann ◽

Emily A. Morton ◽

Kenneth D. Smith ◽

Graham M. Kent ◽

William S. Honjas ◽

...

Keyword(s):

Real Time ◽

Near Field ◽

Data Access ◽

Aftershock Sequence ◽

Seismic Network ◽

Data Availability ◽

Earthquake Catalog ◽

Waveform Data ◽

Walker Lane ◽

Mina Deflection

Abstract The Nevada Seismological Laboratory (NSL) at the University of Nevada, Reno, installed eight temporary seismic stations following the 15 May 2020 Mww 6.5 Monte Cristo Range earthquake. The mainshock and resulting aftershock sequence occurred in an unpopulated and sparsely instrumented region of the Mina deflection in the central Walker Lane, approximately 55 km west of Tonopah, Nevada. The temporary stations supplement NSL’s permanent seismic network, providing azimuthal coverage and near-field recording of the aftershock sequence beginning 1–3 days after the mainshock. We expect the deployment to remain in the field until May 2021. NSL initially attempted to acquire the Monte Cristo Range deployment data in real time via cellular telemetry; however, unreliable cellular coverage forced NSL to convert to microwave telemetry within the first week of the sequence to achieve continuous real-time acquisition. Through 31 August 2020, the temporary deployment has captured near-field records of three aftershocks ML≥5 and 25 ML 4–4.9 events. Here, we present details regarding the Monte Cristo Range deployment, instrumentation, and waveform availability. We combine this information with waveform availability and data access details from NSL’s permanent seismic network and partner regional seismic networks to create a comprehensive summary of Monte Cristo Range sequence data. NSL’s Monte Cristo Range temporary and permanent station waveform data are available in near-real time via the Incorporated Research Institutions for Seismology Data Management Center. Derived earthquake products, including NSL’s earthquake catalog and phase picks, are available via the Advanced National Seismic System Comprehensive Earthquake Catalog. The temporary deployment improved catalog completeness and location quality for the Monte Cristo Range sequence. We expect these data to be useful for continued study of the Monte Cristo Range sequence and constraining crustal and seismogenic properties of the Mina deflection and central Walker Lane.

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Rapid Detection of Earthquake Rupture Directivity Using Strong Ground Motion Data in Taiwan

10.5194/egusphere-egu2020-22441 ◽

2020 ◽

Author(s):

Cheng-Feng Wu ◽

Ting-Li Lin ◽

Ying-Chi Chen

Keyword(s):

Real Time ◽

Detection System ◽

Near Field ◽

Strong Motion ◽

Peak Ground Velocity ◽

Earthquake Rupture ◽

Rupture Directivity ◽

Motion Data ◽

Directivity Effect ◽

Source Studies

In the past decade, there have been several disaster earthquakes occurred in Taiwan. From the observed data of the disaster earthquakes, the stations located in the source rupture direction have obvious directivity pulses, and the distribution of the earthquake disaster is related to the peak ground velocity. Therefore, how to use a large and high- dense seismic database to develop a near-real-time detection system on the earthquake rupture directivity, which is a very important task in Taiwan. In this study, we determine the earthquake rupture directivity using near-field velocity data from 1991 to 2018, which were collected under the Taiwan Strong Motion Instrument Program (TSMIP). The used method is mainly constructed in the interpolation of the peak-ground-velocity map and the directional attenuation regression analysis. Through the analysis of moderate-to-large magnitude (M L > 5.5) seismic events, the source rupture directivity can be detected effectively and quickly by the applied method. The detection results are also comparable with those from the previous source studies. We also find out a linear relationship between the directivity effect and earthquake magnitude. Since the TSMIP station may provide real-time services in the future, the detection system proposed by this research can quickly provide disaster prediction information, which is of great importance for earthquake emergency response and hazard mitigation.

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