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.

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 2017, MD = 4.0, Casamicciola Earthquake: ESI-07 Scale Evaluation and Implications for the Source Model

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 44
Author(s):  
Rosa Nappi ◽  
Sabina Porfido ◽  
Elisa Paganini ◽  
Luigina Vezzoli ◽  
Maria Francesca Ferrario ◽  
...  
Keyword(s):  
Time Window ◽  
Near Field ◽  
Tectonic Setting ◽  
Seismic Source ◽  
Historical Earthquakes ◽  
Source Model ◽  
Seismic Intensity ◽  
Historical Seismicity ◽  
Macroseismic Observations ◽  
Macroseismic Scale

On 21 August 2017 at 20:57 (local time) a very shallow (H = 1.2 km), moderate (Md = 4.0), earthquake hit the volcanic island of Ischia (Southern Italy), causing the death of two people. The study of the damage to the buildings with the European Macroseismic Scale 98 (EMS-98), carried out immediately after the earthquake, highlighted that hilly area of Casamicciola Terme, on the northern side of the Mt. Epomeo, was the most damaged part of the island with locally quite relevant damage (I = VIII EMS). This seismic event is the first damaging earthquake in Ischia during the instrumental era. In fact, this provides, for the first time, the opportunity to integrate historical seismicity, macroseismic observations, instrumental information, and detailed mapping of the geological coseismic effects. In this work we evaluate the effects induced by the 2017 Casamicciola earthquake on the environment using the Environmental Seismic Intensity 2007 (ESI-07) macroseismic scale. This macroseismic analysis, together with the superficial coseismic faulting characteristics and the available geophysical information, allows us to reconsider the source model for the 2017 earthquake and the previous damaging historical earthquakes in the Casamicciola Terme area. The application of the ESI scale to the Casamicciola Terme earthquake of 21 August 2017 and the assignment of seismic intensity offers better spatial resolution, as well as an increase of the time window for the assessment of the seismic hazard, allowing to reduce the implicit uncertainty in the intensity attenuation laws in this peculiar volcano-tectonic setting. Since intensity is linked to the direct measure of damage, and it is commonly used in hazard assessment, we argue that building damage at Casamicciola Terme is strongly influenced by earthquake surface faulting and near field effects, and therefore controlled by the geometry of the seismic source.

Earthquake Hazard Estimation in Areas of Low Historical Seismicity: A Focus on the Northern Rio Grande Rift, Colorado and New Mexico

1990 ◽  
Vol 6 (4) ◽  
pp. 657-680 ◽  
Author(s):  
Charles E. Glass
Keyword(s):  
New Mexico ◽  
Gaussian Model ◽  
Rio Grande ◽  
Earthquake Hazard ◽  
Weibull Model ◽  
Historical Seismicity ◽  
Rio Grande Rift ◽  
Earthquake Activity ◽  
Sangre De Cristo ◽  
Northern Rio Grande

Estimates of the probability of future earthquake activity are difficult to make in areas where historical seismicity may be low or absent, but where young fault scarps attest to recent or ongoing tectonism. Three non-Poisson models, a Weibull model, a Gaussian model and a lognormal model, are used to estimate the earthquake hazard for one such area, the northern Rio Grande Rift. This portion of the Rio Grande Rift displays numerous Holocene faults attesting to ongoing tectonism, but displays essentially no historical seismicity. The earthquake hazard for the Sangre de Cristo fault zone from Taos, New Mexico to Salida, Colorado calculated using these models is remarkably consistent (probability of at least one Mo = 7 earthquake in the next 50 years ∼ 2.5 × 10−3), with increased hazard for the Sangre de Cristo fault in north San Luis Valley (∼5.0×10−3) and near Taos (∼1.0×10−2) due to the long holding times along these segments.

scholarly journals A short introduction to historical earthquakes in Libya

2009 ◽  
Vol 47 (2-3) ◽  
Author(s):  
A. S. Suleiman ◽  
P. Albini ◽  
P. Migliavacca
Keyword(s):  
Historical Earthquakes ◽  
Historical Seismicity ◽  
Historical Sources ◽  
Short Introduction ◽  
North Central ◽  
The North ◽  
Lack Of Information ◽  
Macroseismic Effects ◽  
Instrumental Recording ◽  
Earthquake Effects

As a result of the relative motion of the African and European plates, Libya, located at the north central margin of the African continent, has experienced a considerable intraplate tectonism, particularly in its northern coastal regions. If the seismic activity of the last fifty years, at most, is known from instrumental recording, macroseismic effects of those earthquakes which affected Libya in the past centuries are still imperfectly known. To try and partly overcome this lack of information, in this contribution we present a short introduction to historical earthquakes in Libya, focusing on the period up to 1935. According to the studies published in the last twenty years, the earliest records of earthquakes in Libya are documented in the Roman period (3rd and 4th century A.D.). There is a gap in information along the Middle and Modern Ages, while the 19th and early 20th century evidence is concentrated on effects in Tripoli, in the western part of nowadays Libya. The Hun Graben area (western part of the Gulf of Sirt) has been identified as the location of many earthquakes affecting Libya, and it is in this area that the 19 April 1935 earthquake (Mw = 7.1) struck, followed by many aftershocks. Further investigations are needed, and some hints are here given at historical sources potentially reporting on earthquake effects in Libya. Their investigation could result in the needed improvement to lay the foundations of a database and a catalogue of the historical seismicity of Libya.

scholarly journals A new catalogue of earthquakes in the historical Armenian area from antiquity to the 12th century

1995 ◽  
Vol 38 (1) ◽  
Author(s):  
E. Guidoboni ◽  
G. Traina
Keyword(s):  
Historical Earthquakes ◽  
Historical Seismicity ◽  
Seismic Events ◽  
Specific Nature ◽  
Present Contribution ◽  
12Th Century ◽  
Literary Sources ◽  
New Localities ◽  
History Of ◽  
Catalogue Of Earthquakes

The present contribution describes the method of work, the types of source materia] used, and the historio- graphical and historico-eismic tradition of Armenia. The catalogue' s territorial frame of reference is that of socalled historical Armenia (which included part of present Eastern Turkey, and part of present Azerbaijan). The sources belong to different languages and cultures: Armenian, Syriac, Greek, Arab, Persian and Georgian. A comparison of the local sources with those belonging to other cultures enab]es the historical and seismological I"adition of the Mediterl'anean to be "linked" with that of the Iranian p]ateau, traditionally considered as two separate areas. We analyzed historical events listed in the most recent catalogues of earthquakes in the Armenian area compiled by Kondorskaya and Shebalin (1982) and Karapetian (1991). Important and valuable though these catalogues are, they are in need of revision. We found evidence for six hitherto unrecorded seismic events. Numerous errors of dating and location have been corrected, and several new localities and seismic effects have been evidenced. Each modification of the previous catalogues has been documented on the hasis of the historiographical and literary sources and the data from the written sources have been linked with those concerning the history of Armenian cities and architecture (monasteries, churches, episcopal complexes). On the whole. the revised earthquakes seem underestimated in the previous catalogues. The aim of this catalogue is to make a contribution to the knowledge of historical seismicity in Armenia, and at the same time to underline the specific nature of the Armenian case, thus avoiding a procedure which has generally tended to place this area in a marginal position, within the wider field of other research on historical earthquakes.

scholarly journals Seismic hazard assessment of Iran

1999 ◽  
Vol 42 (6) ◽  
Author(s):  
B. Tavakoli ◽  
M. Ghafory-Ashtiany
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Grid Point ◽  
Seismic Hazard Assessment ◽  
Earthquake Hazard ◽  
Seismic Source ◽  
Historical Earthquakes ◽  
Earthquake Insurance ◽  
Ground Acceleration ◽  
Seismic Source Models

The development of the new seismic hazard map of Iran is based on probabilistic seismic hazard computation using the historical earthquakes data, geology, tectonics, fault activity and seismic source models in Iran. These maps have been prepared to indicate the earthquake hazard of Iran in the form of iso-acceleration contour lines, and seismic hazard zoning, by using current probabilistic procedures. They display the probabilistic estimates of Peak Ground Acceleration (PGA) for the return periods of 75 and 475 years. The maps have been divided into intervals of 0.25 degrees in both latitudinal and longitudinal directions to calculate the peak ground acceleration values at each grid point and draw the seismic hazard curves. The results presented in this study will provide the basis for the preparation of seismic risk maps, the estimation of earthquake insurance premiums, and the preliminary site evaluation of critical facilities.

scholarly journals Historical Earthquake Scenarios for the Middle Strand of the North Anatolian Fault Deduced from Archeo-Damage Inventory and Building Deformation Modeling

2020 ◽  
Vol 92 (1) ◽  
pp. 583-598
Author(s):  
Yacine Benjelloun ◽  
Julia de Sigoyer ◽  
Hélène Dessales ◽  
Laurent Baillet ◽  
Philippe Guéguen ◽  
...  
Keyword(s):  
Historical Earthquakes ◽  
Historical Seismicity ◽  
North Anatolian Fault ◽  
First Century ◽  
Building Vulnerability ◽  
Earthquake Scenarios ◽  
The North ◽  
Seismicity Catalog ◽  
Quality Ranking ◽  
The City

Abstract The city of İznik (ancient Nicaea), located on the middle strand of the North Anatolian fault zone (MNAF), presents outstanding archeological monuments preserved from the Roman and Ottoman periods (first to fifteenth centuries A.D.), bearing deformations that can be linked to past seismic shaking. To constrain the date and intensity of these historical earthquakes, a systematic survey of earthquake archeological effects (EAEs) is carried out on the city’s damaged buildings. Each of the 235 EAEs found is given a quality ranking, and the corresponding damage is classified according to the European Macroseismic Scale 1998 (EMS-98). We show that the walls oriented north–south were preferentially damaged, and that most deformations are perpendicular to the walls’ axes. The date of postseismic repairs is constrained with available archeological data and new C14 dating of mortar charcoals. Three damage episodes are evidenced: (1) between the sixth and late eighth centuries, (2) between the nineth and late eleventh centuries A.D., and (3) after the late fourteenth century A.D. The repartition of damage as a function of building vulnerability points toward a global intensity VIII on the EMS-98. The 3D modeling of a deformed Roman obelisk shows that only earthquakes rupturing the MNAF can account for this deformation. Their magnitude can be bracketed between Mw 6 and 7. Our archeoseismological study complements the historical seismicity catalog and confirms paleoseismological data, suggesting several destructive earthquakes along the MNAF, since the first century A.D. We suggest the fault might still have accumulated enough stress to generate an Mw 7+ rupture.

Contemporary deformation and earthquake hazard of the Capital Circle of China inferred from GPS Measurements

2021 ◽  
Author(s):  
Shaogang Wei ◽  
Xiwei Xu ◽  
Tuo Shen ◽  
Xiaoqiong Lei
Keyword(s):  
High Risk ◽  
Earthquake Hazard ◽  
Historical Earthquakes ◽  
Tectonic Stress ◽  
Middle Part ◽  
Earthquake Hazards ◽  
Seismic Belt ◽  
Fault Plane Solutions ◽  
The North ◽  
Recent Earthquakes

<p>The Capital Circle (CC) is a region with high risk of great damaging earthquake hazards. In our present study, by using a subset of rigorously GPS data around the North China Plain (NCP), med-small recent earthquakes data and focal mechanism of high earthquakes data covering its surrounding regions, the following major conclusions have been reached: (a) Driven by the deformation force associated with both eastward and westward motion, with respect to the NCP, of the rigid South China and the rigid Amurian block, widespread sinistral shear appear over the NCP, which results in clusters of parallel NNE-trending faults with predominant right-lateral strike-slips via bookshelf faulting within the interior of the NCP. (b) Fault plane solutions of recent earthquakes show that tectonic stress field in the NCP demonstrate overwhelming NE-ENE direction of the maximum horizontal principal stress, and that almost all great historical earthquakes in the NCP occurred along the NWW-trending Zhangjiakou-Bohai seismic belt and the NNE-trending Tangshan-Hejian-Cixian seismic belt. Additionally, We propose a simple conceptual model for inter-seismic deformation associated with the Capital Circle, which might suggest that two seismic gaps are located on the middle part of Tangshan-Hejian-Cixian fault seismic belt (Tianjin-Hejian segment) and the northeast part of Tanlu seismic belt (Anqiu segment), and constitute as, in our opinion, high risk areas prone to great earthquakes.</p>

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