Rapid Estimation of Source Parameters Using Finite Fault Modeling--Case Studies from the Sikkim and Garhwal Himalayas

2009 ◽  
Vol 80 (1) ◽  
pp. 89-96 ◽  
Author(s):  
A. Raj ◽  
S. K. Nath ◽  
B. K. Bansal ◽  
K. K. S. Thingbaijam ◽  
A. Kumar ◽  
...  
Keyword(s):  
Case Studies ◽  
Source Parameters ◽  
Fault Modeling ◽  
Rapid Estimation ◽  
Garhwal Himalayas ◽  
Finite Fault

Present-day orogenic processes in the western Kalpin nappe explored by interseismic GNSS measurements and coseismic InSAR observations of the 2020 Mw 6.1 Kalpin event

2021 ◽  
Author(s):  
Ping He ◽  
Yangmao Wen ◽  
Shuiping Li ◽  
Kaihua Ding ◽  
Zhicai Li ◽  
...  
Keyword(s):  
Source Parameters ◽  
Satellite System ◽  
Tien Shan ◽  
Dislocation Model ◽  
Maximum Displacement ◽  
Finite Fault ◽  
Instantaneous Deformation ◽  
Gnss Measurements ◽  
Global Navigation Satellite ◽  
Finite Fault Model

Summary As the largest and most active intracontinental orogenic belt on Earth, the Tien Shan (TS) is a natural laboratory for understanding the Cenozoic orogenic processes driven by the India-Asia collision. On 19 January 2020, a Mw 6.1 event stuck the Kalpin region, where the southern frontal TS interacts with the Tarim basin. To probe the local ongoing orogenic processes and potential seismic hazard in the Kalpin region, both interseismic and instantaneous deformation derived from geodetic observations are employed in this study. With the constraint of interseismic global navigation satellite system (GNSS) velocities, we estimate the décollement plane parameters of the western Kalpin nappe based on a two-dimensional dislocation model, and the results suggest that the décollement plane is nearly subhorizontal with a dip of ∼3° at a depth of 24 km. Then, we collect both Sentinel-1 and ALOS-2 satellite images to capture the coseismic displacements caused by the 2020 Kalpin event, and the interferometric synthetic aperture radar (InSAR) images show a maximum displacement of 7 cm in the line of sight near the epicentral region. With these coseismic displacement measurements, we invert the source parameters of this event using a finite-fault model. We determine the optimal source mechanism in which the fault geometry is dominated by thrust faulting with an E–W strike of 275° and a northward dip of 11.2°, and the main rupture slip is concentrated within an area 28.0 km in length and${\rm{\,\,}}$10.3 km in width, with a maximum slip of 0.3 m at a depth of 6–8 km. The total released moment of our preferred distributed slip model yields a geodetic moment of 1.59 × 1018 N$\cdot $m, equivalent to Mw 6.1. The contrast of the décollement plane depth from interseismic GNSS and the rupture depth from coseismic InSAR suggests that a compression still exists in the Kalpin nappe forefront, which is prone to frequent moderate events and may be at risk of a much more dangerous earthquake.

Slip Distribution of the 2020 Mw6.9 Samos Earthquake Using a Bayesian Approach

2021 ◽  
Author(s):  
Figen Eskikoy ◽  
Semih Ergintav ◽  
Uğur Dogan ◽  
Seda Özarpacı ◽  
Alpay Özdemir ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Fault Plane ◽  
Source Parameters ◽  
Geodetic Data ◽  
Slip Distribution ◽  
Double Difference ◽  
Gps Data ◽  
Analysis Tool ◽  
Finite Fault ◽  
Continuous Gps

<p>On 2020 October 30, an M<sub>w</sub>6.9 earthquake struck offshore Samos Island. Severe structural damages were observed in Greek Islands and city of Izmir (Turkey). 114 people lost their lives and more than a thousand people were injured in Turkey. The earthquake triggered local tsunami. Significant seismic activity occurred in this region following the earthquake and ~1800 aftershocks (M>1) were recorded by KOERI within the first three days. In this study, we analyze the slip distribution and aftershocks of the 2020 earthquake.</p><p>For the aftershock relocations, the continuous waveforms were collected from NOA, Disaster and Emergency Management Authority of Turkey (AFAD) and KOERI networks. The database   was created based on merged catalogs from AFAD and KOERI. For estimating optimized aftershock location distribution, the P and S phases of the aftershocks are picked manually and relocated with double difference algorithm. In addition, source mechanisms of aftershocks M>4 are obtained from regional body and surface waveforms.</p><p>The surface deformation of the earthquake was obtained from both descending and ascending orbits of the Sentinel-1 A/B and ALOS2 satellites. Since the rupture zone is beneath the Gulf of Kusadası, earthquake related deformation in the interferograms can only be observed on the northern part of the Samos Island. We processed all possible pairs chose the image pairs with the lowest noise level.</p><p>In this study, we used 25 continuous GPS stations which are compiled from TUSAGA-Aktif in Turkey and NOANET in Greece. In addition to continuous GPS data, on 2020 November 1, GPS survey was initiated and the earthquake deformation was measured on 10 GNSS campaign sites (TUTGA), along onshore of Turkey.</p><p>The aim of this study is to estimate the spatial and temporal rupture evolution of the earthquake from geodetic data jointly with near field displacement waveforms. To do so, we use the Bayesian Earthquake Analysis Tool (BEAT).</p><p>As a first step of the study, rectangular source parameters were estimated by using GPS data. In order to estimate the slip distribution, we used both ascending and descending tracks of Sentinel-1 data, ALOS2 and GPS displacements. In our preliminary geodetic data based finite fault model, we used the results of focal mechanism and GPS data inversion solutions for the initial fault plane parameters. The slip distribution results indicate that earthquake rupture is ~35 km long and the maximum slip is ~2 m normal slip along a north dipping fault plane. This EW trending, ~45° north dipping normal faulting system consistent with this tectonic regime in the region. This seismically active area is part of a N-S extensional regime and controlled primarily by normal fault systems.</p><p><strong>Acknowledgements</strong></p><p>This work is supported by the Turkish Directorate of Strategy and Budget under the TAM Project number 2007K12-873.</p>

10 July 1894 Istanbul Earthquake: Comparing Damages and Ground Motion Simulations

2021 ◽  
Author(s):  
Nesrin Yenihayat ◽  
Eser Çaktı ◽  
Karin Şeşetyan
Keyword(s):  
Ground Motion ◽  
Fault Simulation ◽  
Source Parameters ◽  
Historical Earthquakes ◽  
Corner Frequency ◽  
Simulation Approach ◽  
Ground Motion Simulations ◽  
Finite Fault ◽  
Intensity Map ◽  
Observed Damage

<p>One of the major earthquakes that resulted in intense damages in Istanbul and its neighborhoods took place on 10 July 1894. The 1894 earthquake resulted in 474 losses of life and 482 injuries. Around 21,000 dwellings were damaged, which is a number that corresponds to 1/7 of the total dwellings of the city at that time. Without any doubt, the exact loss of life was higher. Because of the censorship, the exact loss numbers remained unknown. There is still no consensus about its magnitude, epicentral location, and rupture of length. Even though the hardness of studying with historical records due to their uncertainties and discrepancies, researchers should enlighten the source parameters of the historical earthquakes to minimize the effect of future disasters especially for the cities located close to the most active fault lines as Istanbul. The main target of this study is to enlighten possible source properties of the 1894 earthquake with the help of observed damage distribution and stochastic ground motion simulations. In this paper, stochastic based ground motion scenarios will be performed for the 10 July 1894 Istanbul earthquake, using a finite fault simulation approach with a dynamic corner frequency and the results will be compared with our intensity map obtained from observed damage distributions. To do this, in the first step, obtained damage information from various sources has been presented, evaluated, and interpreted. Secondly, we prepared an intensity map associated with the 1894 earthquake based on macro-seismic information, and damage analysis and classification. For generating ground motions with a stochastic finite fault simulation approach, the EXSIM 2012 software has been used. Using EXSIM, several scenarios are modeled with different source, path, and site parameters. Initial source properties have been obtained from findings of our previous study on the simulation of the 26 September 2019 Silivri (Istanbul) earthquake with Mw 5.8. With the comparison of spatial distributions of the ground motion intensity parameters to the obtained damage and intensity maps, we estimate the optimum location and source parameters of the 1894 Earthquake.</p>

scholarly journals Real-time inversion of GPS data for finite fault modeling and rapid hazard assessment

2012 ◽  
Vol 39 (9) ◽  
pp. n/a-n/a ◽  
Author(s):  
Brendan W. Crowell ◽  
Yehuda Bock ◽  
Diego Melgar
Keyword(s):  
Real Time ◽  
Hazard Assessment ◽  
Fault Modeling ◽  
Gps Data ◽  
Time Inversion ◽  
Finite Fault

scholarly journals Using Satellite Data to Determine Empirical Relationships between Volcanic Ash Source Parameters

Atmosphere ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 342 ◽  
Author(s):  
Meelis J. Zidikheri ◽  
Chris Lucas
Keyword(s):  
Case Studies ◽  
Volcanic Ash ◽  
Dispersion Model ◽  
Source Parameters ◽  
Difficult Problem ◽  
Emission Rates ◽  
Empirical Relationships ◽  
Mass Load ◽  
Satellite Retrievals ◽  
Mass Loads

Poor knowledge of dispersion model source parameters related to quantities such as the total fine ash mass emission rate, its effective spatial distribution, and particle size distribution makes the provision of quantitative forecasts of volcanic ash a difficult problem. To ameliorate this problem, we make use of satellite-retrieved mass load data from 14 eruption case studies to estimate fine ash mass emission rates and other source parameters by an inverse modelling procedure, which requires multidimensional sampling of several thousand trial simulations with different values of source parameters. We then estimate the dependence of these optimal source parameters on eruption height. We show that using these empirical relationships in a data assimilation procedure leads to substantial improvements to the forecasts of ash mass loads, with the use of empirical relationships between parameters and eruption height having the added advantage of computational efficiency because of dimensional reduction. In addition, the use of empirical relationships, which encode information in satellite retrievals from past case studies, implies that quantitative forecasts can still be issued even when satellite retrievals of mass load are not available in real time due to cloud cover or other reasons, making it especially useful for operations in the tropics where ice and water clouds are ubiquitous.

Operational Capabilities during Crisis: The Chilean Seismographic Network

2020 ◽  
Vol 92 (1) ◽  
pp. 119-126 ◽  
Author(s):  
Sergio Eduardo Barrientos ◽  
Sebastian Riquelme ◽  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Emergency Services ◽  
Negative Impact ◽  
Fault Modeling ◽  
Capital City ◽  
Timely Manner ◽  
Operational Capabilities ◽  
Finite Fault ◽  
Maintenance Work ◽  
Seismographic Network

Abstract The severe mobility restrictions imposed countrywide by authorities of Chile in response to the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have impacted all areas of activities. Major difficulties began in March 2020, with partial quarantines in the capital city, which later extended to other cities in the country, and it soon transformed in total confinement. We examine the evolution of the pandemic and its consequences on the field and headquarters operations of the National Seismological Centre (CSN), as remote stations could not be visited to carry out maintenance work. Several indicators, as a function of time, such as station operability percentage, timely reports, and ability to deliver requested information, reveal some negative impact on the uptime of stations but not in the capability of the CSN to fulfill its mission, which is to deliver timely seismic information to emergency services. The largest event in the country within this period took place on 3 June 2020, activating in a timely manner, the new tools on finite-fault modeling being developed within the center.

Finite Fault Modelling for the Wenchuan Earthquake Using Hybrid Slip Model with Truncated Normal Distributed Source Parameters

2012 ◽  
Vol 256-259 ◽  
pp. 2161-2167 ◽  
Author(s):  
Xiao Dan Sun ◽  
Xia Xin Tao ◽  
Cheng Qing Liu
Keyword(s):  
Wenchuan Earthquake ◽  
Ground Motion ◽  
Source Parameters ◽  
Field Investigation ◽  
Local Source ◽  
Slip Model ◽  
Fault Models ◽  
Average Spectrum ◽  
Finite Fault ◽  
Truncated Normal

An hybrid slip model combining asperity model and k square model was outlined. In the model, both the global and local source parameters follow a trancated normal distribution. The hybrid slip model was then applied to generate finite fault models for the great Wenchuan earthquake, where the fault plane was assumed to have two segments, a reverse segment on the southwestern of the fault and a right-lateral strike-slip segment on the northeastern of the fault. The location of the asperities on each segment was determined considering the results from inversion and field investigation. 30 different finite fault models were obtained, and the one which generates the ground motion best fitting the average spectrum was picked out using spectral deviation evaluation. Finally, ground motion at six near field stations were simualted based on the best-fit fault model and compared to the records.

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