Estimation of the Parameters of Historical Earthquakes with a New Attenuation Equation in Yunnan Province, China

2020 ◽  
Vol 91 (5) ◽  
pp. 2651-2661 ◽  
Author(s):  
Guoliang Lin ◽  
Jian Wang
Keyword(s):  
Yunnan Province ◽  
Hazard Analysis ◽  
Source Parameters ◽  
Historical Earthquakes ◽  
Intensity Data ◽  
Earthquake Parameters ◽  
Intensity Attenuation ◽  
Earthquake Source Parameters ◽  
Data Points ◽  
Optimal Intensity

Abstract Yunnan Province is in southwest China, where the seismicity has been active since ancient times. Generally, the uncertainty of historical earthquake parameters is larger. To amend the parameters of historical earthquakes, we have developed a new intensity attenuation equation. From 2000 to 2018, there were 25 instrumentally recorded earthquakes with Ms 5.0–6.6 in Yunnan. The parameters of those earthquake events, including their epicentral locations and magnitudes, are determined with high accuracy. Meanwhile, total intensity values of 1345 intensity data points have been carefully assessed by survey. With both accurate earthquake parameters and valuable intensity data, a new intensity attenuation equation has been established. The result shows the optimal intensity magnitude MI can be calculated from the mean of Mi=(I−2.1113+0.0412Δi+1.3717lgΔi)/1.1641, in which Δi is the distance between the epicenter and the surveyed seismic point. By adapting the method proposed by Bakun and Wentworth (1997) for determining earthquake source parameters directly from historical intensity data, we have tested retrospectively the new attenuation on the 25 instrumentally recorded earthquakes. Then this attenuation was applied to deal with the parameters of two historical earthquakes, the 26 February 1713 Xundian earthquake and the 11 May 1909 Huaning earthquakes. Our results reduced the uncertainty of previously estimated parameters, which were large. The amended parameters will be valuable for seismic hazard analysis and earthquake disaster reduction.

scholarly journals The use of parallel computing for the high-resolution determination of earthquake source parameters

2019 ◽  
pp. 68-75
Author(s):  
A. S. Fomochkina ◽  
V. G. Bukchin
Keyword(s):  
Parallel Computing ◽  
Focal Mechanism ◽  
Source Parameters ◽  
Nodal Plane ◽  
Earthquake Parameters ◽  
Earthquake Source Parameters ◽  
Detailed Search ◽  
High Degree ◽  
Special Case

Alongside the determination of the focal mechanism and source depth of an earthquake by direct examination of their probable values on a grid in the parameter space, also the resolution of these determinations can be estimated. However, this approach requires considerable time in the case of a detailed search. A special case of a shallow earthquake whose one nodal plane is subhorizontal is an example of the sources that require the use of a detailed grid. For studying these events based on the records of the long-period surface waves, the grids with high degree of detail in the angles of the focal mechanism are required. We discuss the application of the methods of parallel computing for speeding up the calculations of earthquake parameters and present the results of studying the strongest aftershock of the Tohoku, Japan, earthquake by this approach.

scholarly journals Large submarine earthquakes that occurred worldwide in a 1-year period (June 2013 to June 2014) – a contribution to the understanding of tsunamigenic potential

2015 ◽  
Vol 15 (10) ◽  
pp. 2183-2200 ◽  
Author(s):  
R. Omira ◽  
D. Vales ◽  
C. Marreiros ◽  
F. Carrilho
Keyword(s):  
Numerical Modeling ◽  
Subduction Zones ◽  
Source Parameters ◽  
Tsunami Generation ◽  
Earthquake Parameters ◽  
Shallow Earthquakes ◽  
Earthquake Source Parameters ◽  
Tsunami Numerical Modeling ◽  
Submarine Earthquakes ◽  
Earthquake Model

Abstract. This paper is a contribution to a better understanding of the tsunamigenic potential of large submarine earthquakes. Here, we analyze the tsunamigenic potential of large earthquakes which have occurred worldwide with magnitudes around Mw = 7.0 and greater during a period of 1 year, from June 2013 to June 2014. The analysis involves earthquake model evaluation, tsunami numerical modeling, and sensors' records analysis in order to confirm the generation of a tsunami (or lack thereof) following the occurrence of an earthquake. We also investigate and discuss the sensitivity of tsunami generation to the earthquake parameters recognized to control tsunami occurrence, including the earthquake location, magnitude, focal mechanism and fault rupture depth. Through this analysis, we attempt to understand why some earthquakes trigger tsunamis and others do not, and how the earthquake source parameters are related to the potential of tsunami generation. We further discuss the performance of tsunami warning systems in detecting tsunamis and disseminating the alerts. A total of 23 events, with magnitudes ranging from Mw = 6.7 to Mw = 8.1, have been analyzed. This study shows that about 39 % of the analyzed earthquakes caused tsunamis that were recorded by different sensors with wave amplitudes varying from a few centimeters to about 2 m. Tsunami numerical modeling shows good agreement between simulated waveforms and recorded waveforms, for some events. On the other hand, simulations of tsunami generation predict that some of the events, considered as non-tsunamigenic, caused small tsunamis. We find that most generated tsunamis were caused by shallow earthquakes (depth < 30 km) and thrust faults that took place on/near the subduction zones. The results of this study can help the development of modified and improved versions of tsunami decision matrixes for various oceanic domains.

The analysis of historical seismograms: an important tool for seismic hazard assessment. Case histories from French and Italian earthquakes

2011 ◽  
Vol 182 (4) ◽  
pp. 367-379 ◽  
Author(s):  
Nicola Alessandro Pino
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Southern Italy ◽  
Source Parameters ◽  
Seismic Hazard Assessment ◽  
Historical Earthquakes ◽  
Waveform Analysis ◽  
Source Characteristics ◽  
Seismic Waveform ◽  
Earthquake Source Parameters

AbstractSeismic hazard assessment relies on the knowledge of the source characteristics of past earthquakes. Unfortunately, seismic waveform analysis, representing the most powerful tool for the investigation of earthquake source parameters, is only possible for events occurred in the last 100–120 years, i.e., since seismographs with known response function were developed. Nevertheless, during this time significant earthquakes have been recorded by such instruments and today, also thanks to technological progress, these data can be recovered and analysed by means of modern techniques.In this paper, aiming at giving a general sketch of possible analyses and attainable results in historical seismogram studies, I briefly describe the major difficulties in processing the original waveforms and present a review of the results that I obtained from previous seismogram analysis of selected significant historical earthquakes occurred during the first decades of the XXth century, including (A) the December 28, 1908, Messina straits (southern Italy), (B) the June 11, 1909, Lambesc (southern France) – both of which are the strongest ever recorded instrumentally in their respective countries –and (C) the July 13, 1930, Irpinia (southern Italy) events. For these earthquakes, the major achievements are represented by the assessment of the seismic moment (A, B, C), the geometry and kinematics of faulting (B, C), the fault length and an approximate slip distribution (A, C). The source characteristics of the studied events have also been interpreted in the frame of the tectonic environment active in the respective region of interest. In spite of the difficulties inherent to the investigation of old seismic data, these results demonstrate the invaluable and irreplaceable role of historical seismogram analysis in defining the local seismogenic potential and, ultimately, for assessing the seismic hazard. The retrieved information is crucial in areas where important civil engineering works are planned, as in the case of the single-span bridge to be built across the Messina straits and the ITER nuclear fusion power plant to be built in Cadarache, close to the location of the Lambesc event, and in regions characterized by high seismic risk, such as southern Apennines.

National Seismological Network in India for Real-Time Earthquake Monitoring

2021 ◽  
Author(s):  
Brijesh K. Bansal ◽  
Ajeet P. Pandey ◽  
Ajay P. Singh ◽  
Gaddale Suresh ◽  
Ravi K. Singh ◽  
...  
Keyword(s):  
Real Time ◽  
Source Parameters ◽  
Focal Depth ◽  
Streaming Data ◽  
Small Aperture ◽  
Earthquake Parameters ◽  
Seismic Stations ◽  
National Network ◽  
Earthquake Source Parameters ◽  
Seismological Network

Abstract The National Seismological Network (NSN) of India has a history of more than 120 yr. During the last two decades, the NSN has gone through a significant modernization process, involving installation of seismic stations equipped with a broadband seismograph (BBS) and a strong-motion accelerograph (SMA). Each station has a very-small-aperture terminal connectivity for streaming data in real time to the central receiving station (CRS) in New Delhi. Seismic data recorded by the network are analyzed continuously on 24×7 basis to monitor the earthquakes in India and its adjoining regions. In this article, we present details of BBS and SMA network configurations; data streaming from the field seismic stations to the CRS for analysis; and the automatic and manual publication of the earthquake parameters including location coordinates, focal depth, time of occurrence, and magnitude, etc. Details of historically significant analog seismic charts and the seismic catalog, which includes more than 34,000 events with magnitude Mw 1.7–9.3 since 1505, are provided. The national network of India has been strengthened over the years and is now capable of estimating the main earthquake source parameters within ∼5–10min with an average of about 8.0 min. The spatial analysis of minimum magnitude of completeness further indicates a significant enhancement in minimum threshold magnitude detection capability of the network in recent decades.

scholarly journals Appraising the Early-est earthquake monitoring system for tsunami alerting at the Italian Candidate Tsunami Service Provider

2015 ◽  
Vol 15 (9) ◽  
pp. 2019-2036 ◽  
Author(s):  
F. Bernardi ◽  
A. Lomax ◽  
A. Michelini ◽  
V. Lauciani ◽  
A. Piatanesi ◽  
...  
Keyword(s):  
Service Provider ◽  
Epicentral Distance ◽  
Source Parameters ◽  
Earthquake Source ◽  
Tsunami Warning ◽  
Earthquake Parameters ◽  
Warning Messages ◽  
Earthquake Source Parameters ◽  
Hypocenter Depth ◽  
Epicenter Location

Abstract. In this paper we present and discuss the performance of the procedure for earthquake location and characterization implemented in the Italian Candidate Tsunami Service Provider at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome. Following the ICG/NEAMTWS guidelines, the first tsunami warning messages are based only on seismic information, i.e., epicenter location, hypocenter depth, and magnitude, which are automatically computed by the software Early-est. Early-est is a package for rapid location and seismic/tsunamigenic characterization of earthquakes. The Early-est software package operates using offline-event or continuous-real-time seismic waveform data to perform trace processing and picking, and, at a regular report interval, phase association, event detection, hypocenter location, and event characterization. Early-est also provides mb, Mwp, and Mwpd magnitude estimations. mb magnitudes are preferred for events with Mwp &amp;lesssim; 5.8, while Mwpd estimations are valid for events with Mwp &amp;gtrsim; 7.2. In this paper we present the earthquake parameters computed by Early-est between the beginning of March 2012 and the end of December 2014 on a global scale for events with magnitude M &amp;geq; 5.5, and we also present the detection timeline. We compare the earthquake parameters automatically computed by Early-est with the same parameters listed in reference catalogs. Such reference catalogs are manually revised/verified by scientists. The goal of this work is to test the accuracy and reliability of the fully automatic locations provided by Early-est. In our analysis, the epicenter location, hypocenter depth and magnitude parameters do not differ significantly from the values in the reference catalogs. Both mb and Mwp magnitudes show differences to the reference catalogs. We thus derived correction functions in order to minimize the differences and correct biases between our values and the ones from the reference catalogs. Correction of the Mwp distance dependency is particularly relevant, since this magnitude refers to the larger and probably tsunamigenic earthquakes. Mwp values at stations with epicentral distance Δ &amp;lesssim; 30° are significantly overestimated with respect to the CMT-global solutions, whereas Mwp values at stations with epicentral distance Δ &amp;gtrsim; 90° are slightly underestimated. After applying such distance correction the Mwp provided by Early-est differs from CMT-global catalog values of about δ Mwp &amp;approx; 0.0 &amp;mp; 0.2. Early-est continuously acquires time-series data and updates the earthquake source parameters. Our analysis shows that the epicenter coordinates and the magnitude values converge within less than 10 min (5 min in the Mediterranean region) toward the stable values. Our analysis shows that we can compute Mwp magnitudes that do not display short epicentral distance dependency overestimation, and we can provide robust and reliable earthquake source parameters to compile tsunami warning messages within less than 15 min after the event origin time.

A New Concept of Intensity Data Area and Its Effect on the Parameter Determination of Historical Earthquakes

2020 ◽  
Vol 91 (5) ◽  
pp. 2685-2694 ◽  
Author(s):  
Jian Wang ◽  
Guoliang Lin
Keyword(s):  
Ming Dynasty ◽  
Population Distribution ◽  
Historical Earthquakes ◽  
Parameter Determination ◽  
Intensity Data ◽  
Historical Earthquake ◽  
Earthquake Parameters ◽  
Case Examples ◽  
The Government ◽  
High Tier

Abstract In ancient China, the government annals provided abundant historical earthquake records, which lasted more than 2000 yr. In some cases, the earthquake damage descriptions from the high-tier government annals are so concise that the specific place names were omitted, even the names of towns where the damage might have actually occurred. The intensity data point (IDP) was assigned to the capital town of the high-tier government, which might lead to large uncertainties in the historical earthquake parameters. A new concept of intensity data area (IDA) is proposed specifically to deal with this issue. An approach on how to convert the IDA to an IDP, based on nonseismological information, is described. In this process, we emphasize the effectiveness of field trips to investigate local features, such as natural environment, population distribution, historical administration zoning, and so forth. As case examples, two historical earthquakes in the Ming Dynasty are analyzed. The documentations of both earthquakes have a common problem, in that some damage was described with the name of the highest-tier local government (Fu); this led to the dispute about the parameter of historical earthquakes. With the proposed method, the IDA for Fu is successfully converted to an IDP at the suitable site. This is the key step to solve the dispute and reduce the parameter uncertainty. Our results have revealed that the parameters of both case earthquakes in the latest edition of the catalog (“The Catalog of Chinese Historical Strong Earthquakes (2300 B.C.–A.D. 1911)”) were wrong (Min et al., 1995). It is noteworthy that the latest edition of the catalog is currently in common use. To avoid the misuse of the catalog, it is better that the parameters in the catalog be restudied, especially for those labeled with large uncertainties.

scholarly journals Appraising the Early-est earthquake monitoring system for tsunami alerting at the Italian candidate Tsunami Service Provider

2015 ◽  
Vol 3 (4) ◽  
pp. 2913-2952 ◽  
Author(s):  
F. Bernardi ◽  
A. Lomax ◽  
A. Michelini ◽  
V. Lauciani ◽  
A. Piatanesi ◽  
...  
Keyword(s):  
Service Provider ◽  
Epicentral Distance ◽  
Source Parameters ◽  
Earthquake Source ◽  
Tsunami Warning ◽  
Earthquake Parameters ◽  
Earthquake Source Parameters ◽  
Hypocenter Depth ◽  
Epicenter Location ◽  
Distance Correction

Abstract. In this paper we present the procedure for earthquake location and characterization implemented in the Italian candidate Tsunami Service Provider at INGV in Roma. Following the ICG/NEAMTWS guidelines, the first tsunami warning messages are based only on seismic information, i.e. epicenter location, hypocenter depth and magnitude, which are automatically computed by the software Early-est. Early-est is a package for rapid location and seismic/tsunamigenic characterization of earthquakes. The Early-est software package operates on offline-event or continuous-realtime seismic waveform data to perform trace processing and picking, and, at a regular report interval, phase association, event detection, hypocenter location, and event characterization. In this paper we present the earthquake parameters computed by Early-est from the beginning of 2012 till the end of December 2014 at global scale for events with magnitude M &amp;geq; 5.5, and the detection timeline. The earthquake parameters computed automatically by Early-est are compared with reference manually revised/verified catalogs. From our analysis the epicenter location and hypocenter depth parameters do not differ significantly from the values in the reference catalogs. The epicenter coordinates generally differ less than 20 &amp;mp; 20 km from the reference epicenter coordinates; focal depths are less well constrained and differ generally less than 0 &amp;mp; 30 km. Early-est also provides mb, Mwp and Mwpd magnitude estimations. mb magnitudes are preferred for events with Mwp &amp;lesssim; 5.8, while Mwpd are valid for events with Mwp &amp;gtrsim; 7.2. The magnitude mb show wide differences with respect to the reference catalogs, we thus apply a linear correction mbcorr = mb · 0.52 + 2.46, such correction results into δmb ≈ 0.0 &amp;mp; 0.2 uncertainty with respect the reference catalogs. As expected the Mwp show distance dependency. Mwp values at stations with epicentral distance Δ &amp;lesssim; 30° are significantly overestimated with respect the CMT-global solutions, whereas Mwp values at stations with epicentral distance Δ &amp;gtrsim; 90° are slightly underestimated. We thus apply a 3rd degree polynomial distance correction. After applying the distance correction, the Mwp provided by Early-est differs from CMT-global catalog values of about δ Mwp ≈ 0.0 &amp;mp; 0.2. Early-est continuously acquires time series data and updates the earthquake source parameters. Our analysis shows that the epicenter coordinates and the magnitude values converge rather quickly toward the final values. Generally we can provide robust and reliable earthquake source parameters to compile tsunami warning message within less than about 15 min after event origin time.

Historical Earthquakes: New Intensity Data Points Using Complementary Data from Churches and Monasteries

2018 ◽  
pp. 103-116
Author(s):  
Gheorghe Marmureanu ◽  
Radu Vacareanu ◽  
Carmen Ortanza Cioflan ◽  
Constantin Ionescu ◽  
Dragos Toma-Danila
Keyword(s):  
Historical Earthquakes ◽  
Intensity Data ◽  
Data Points ◽  
Intensity Data Points

Seismic Intensity Attenuation for Intraplate Earthquakes in Brazil with the Re‐Evaluation of Historical Seismicity

2019 ◽  
Vol 90 (6) ◽  
pp. 2217-2226 ◽  
Author(s):  
Lúcio Quadros ◽  
Marcelo Assumpção ◽  
Ana Paula Trindade de Souza
Keyword(s):  
Earthquake Hazard ◽  
Historical Earthquakes ◽  
Seismic Intensity ◽  
Historical Seismicity ◽  
Qualitative Description ◽  
Intensity Data ◽  
Intraplate Earthquakes ◽  
Intensity Attenuation ◽  
Hypocentral Distance ◽  
Root Mean Square Residual

ABSTRACT Intensity evaluation attempts to quantify a qualitative description of the effects observed in an earthquake ranked in terms of how strong it was felt and the amount of damage. Despite its qualitative nature, intensity data are essential to study both historical and recent earthquakes such as in earthquake hazard studies and in which dense accelerometric data are missing. The magnitude of historical earthquakes in Brazil has been determined with relations involving magnitude and felt area. Intensity attenuation equations (decay of intensity as a function of magnitude, depth, and distance) determined in other regions of the world are intrinsically dependent on the crustal tectonic characteristics and cannot be applied to Brazil without proper evaluation. We determined an intensity attenuation equation using 20 earthquakes in Brazil and neighboring intraplate areas, in the magnitude range mb 3.5–6.2 and hypocentral distances up to 720 km. The best attenuation model was I=0.995M−1.505logR−0.00116R+2.08 (standard deviation = 0.778), in which M is the magnitude (mb) and R is the hypocentral distance (in kilometers). The uncertainties of the estimated magnitudes using this equation are around mb±0.72 for events with 30 or more intensity points. We tested the new equation with intensity data from two important events: the 1939 offshore earthquake (mb 6) in southern Brazil and the 2018 Venezuela earthquake (mb 6.9). The fit was reasonable for both earthquakes, with a root mean square residual of 1.0 and 1.1 intensity units, respectively. We also re‐evaluated the 1861 earthquake in southeast Brazil. The new epicenter was 23.1° S 44.7° W with a magnitude of mb 5. The epicenter was located onshore, but the estimated uncertainties include a large offshore region. Given that, the location of the 1861 event remains uncertain.

scholarly journals Fully probabilistic seismic source inversion – Part 1: Efficient parameterisation

2013 ◽  
Vol 5 (2) ◽  
pp. 1125-1162 ◽  
Author(s):  
S. C. Stähler ◽  
K. Sigloch
Keyword(s):  
Moment Tensor ◽  
Source Parameters ◽  
Practical Importance ◽  
Principal Component ◽  
Seismic Source ◽  
Empirical Orthogonal Functions ◽  
Time Function ◽  
Source Inversion ◽  
Source Time Function ◽  
Earthquake Parameters

Abstract. Seismic source inversion is a non-linear problem in seismology where not just the earthquake parameters themselves, but also estimates of their uncertainties are of great practical importance. Probabilistic source inversion (Bayesian inference) is very adapted to this challenge, provided that the parameter space can be chosen small enough to make Bayesian sampling computationally feasible. We propose a framework for PRobabilistic Inference of Source Mechanisms (PRISM) that parameterises and samples earthquake depth, moment tensor, and source time function efficiently by using information from previous non-Bayesian inversions. The source time function is expressed as a weighted sum of a small number of empirical orthogonal functions, which were derived from a catalogue of >1000 STFs by a principal component analysis. We use a likelihood model based on the cross-correlation misfit between observed and predicted waveforms. The resulting ensemble of solutions provides full uncertainty and covariance information for the source parameters, and permits to propagate these source uncertainties into travel time estimates used for seismic tomography. The computational effort is such that routine, global estimation of earthquake mechanisms and source time functions from teleseismic broadband waveforms is feasible.

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