Future Earthquake Risk Research Articles

Analysis and Statistical Assessment of Liquefaction Potential Using SPT-N Approach in Bhandara Region Maharashtra: Implications for Infrastructure Development

The Bhandara area in Maharashtra, India, has a lot of earthquakes, so its liquefaction potential needs to be studied in detail to help with building infrastructure. This research uses the Standard Penetration Test (SPT-N) method to check how easily the dirt in the area can become liquefied. When SPT-N numbers are added to soil qualities and seismic factors, they are used to figure out how likely it is that the ground will liquefy when it is loaded with earthquake energy. Different types of dirt and different levels are more or less likely to liquefy, according to the results. The makeup of the soil, the level of the groundwater table, and the history of earthquakes are some of the most important things that affect the liquefaction potential. The study finds places where there is a high risk of liquefaction that are also expected to have big building projects. These results make it clear how important it is to include liquefaction mitigating measures when designing and building roads, houses, and other important infrastructure to make sure it is safe and strong. The study also gives a plan for future earthquake risk ratings in the area, showing how important it is to keep an eye on and update records of soil data and earthquakes. Using the SPT-N method along with current geotechnical and earthquake analysis methods, this study gives a full picture of the area's liquefaction risk. The results have big effects on the growth of infrastructure because they help engineers and managers make smart choices about how to lower risks, improve design, and make infrastructure in the Bhandara region last longer and be safer. In the larger field of geotechnical engineering and crisis preparation, this study adds to it by showing how important specific studies are for building strong infrastructure in areas that are prone to earthquakes.

Interseismic slip distribution and locking characteristics of the mid-southern segment of the Tanlu fault zone

We employ the block negative dislocation model to invert the distribution of fault coupling and slip rate deficit on the different segments of the Tanlu (Tancheng-Lujiang) fault zone, according to the GPS horizontal velocity field from 1991 to 2007 (the first phase) and 2013 to 2018 (the second phase). By comparing the deformation characteristics results, we discuss the relationship between the deformation characteristics with the M earthquake in Japan. The results showed that the fault coupling rate of the northern section of Tancheng in the second phase reduced compared with that in the first phase. However, the results of the two phases showed that the northern section of Juxian still has a high coupling rate, a deep blocking depth, and a dextral compressive deficit, which is the enrapture section of the 1668 Tancheng earthquake. At the same time, the area strain results show that the strain rate of the central and eastern regions of the second phase is obviously enhanced compared with that of the first phase. The occurrence of the great earthquake in Japan has played a specific role in alleviating the strain accumulation in the middle and south sections of the Tanlu fault zone. The results of the maximum shear strain show that the shear strain in the middle section of the Tanlu fault zone in the second phase is weaker than that in the first phase, and the maximum shear strain in the southern section is stronger than that in the first phase. The fault coupling coefficient of the south Sihong to Jiashan section is high, and it is also the unruptured section of historical earthquakes. At the same time, small earthquakes in this area are not active and accumulate stress easily, so the future earthquake risk deserves attention.

Recognition of the causative fault of the 2017 MW 4.9 Malard (Tehran, Iran) earthquake from directivity analysis of the recorded ground motions

On December 20, 2017, a light shallow earthquake (Mw 4.9) with a purely strike-slip mechanism occurred on a hidden unknown fault, 30 km west of the city of Tehran. The purpose of this study is to determine the causative fault plane based on the directivity effect that was observed during this shallow crustal depth earthquake, referred to as the Malard earthquake. This was achieved by using data from 96 seismic and accelerometer stations, and employing a variety of methods.For the analysis of the directivity effect, we employed methods including empirical Green's function deconvolution in the frequency domain, inversion of corrected ground motions based on empirical models, and comparison of relative peak ground acceleration and velocity between the mainshock and the largest aftershock. All approaches indicate that the Malard earthquake occurred on a previously unknown fault with a strike of 71°, a steep southward dip, and a confirmed left-lateral strike-slip mechanism, as evidenced by the analysis of aftershock distribution. The earthquake exhibited a strong directivity effect, with rupture propagating unilaterally from the hypocenter to the southwest at a velocity of 2.5 km/s.In addition to enhancing our understanding of active earthquake sources in the densely populated areas of Iran, the findings of this study will also contribute to future earthquake risk assessments in the Tehran region. However, it's important to note that Tehran was situated in the backward zone of the Malard earthquake rupture, where the least ground motion was recorded. Future earthquakes on this fault may exhibit different propagation patterns, toward the city. The determination of a preferred propagation direction can only be achieved probabilistically through the study of a substantial number of earthquakes in the region. The absence of recorded ground motion data will lead to significant uncertainty in predicting the propagation direction of future earthquakes, which must be taken into consideration during hazard analysis.

Source Model of the 2023 Turkey Earthquake Sequence Imaged by Sentinel-1 and GPS Measurements: Implications for Heterogeneous Fault Behavior along the East Anatolian Fault Zone

On 6 February 2023, a devastating doublet of earthquakes with magnitudes of Mw 7.8 and Mw 7.6 successively struck southeastern Turkey near the border of Syria. The earthquake sequence represents the strongest earthquakes in Turkey during the past 80 years and caused an extensive loss of life and property. In this study, we processed Sentinel-1 and GPS data to derive the complete surface displacement caused by the earthquake sequence. The surface displacements were adopted to invert for the fault geometry and coseismic slip distribution on the seismogenic faults of the earthquake sequence. The results indicate that the coseismic rupture of the Turkey earthquake sequence was dominated by left-lateral strike slips with a maximum slip of ~10 m on the East Anatolian Fault Zone (EAFZ) and the Sürgü fault (SF). Significant surface ruptures are recognized based on the geodetic inversion, which is consistent with the analysis of post-earthquake satellite images. The cumulative released moment of the two earthquakes reached 9.62 × 1020 Nm, which corresponds to an event of Mw 7.95. Additionally, the interseismic fault slip rates and locking depths along the central and western segments of the EAFZ were estimated using the high-resolution long-term velocity field. The results reveal significant lateral variations of fault slip rates and locking depths along the central and western segments of the EAFZ. Generally, the estimated fault locking zone showed good spatial consistency with the coseismic fault rupture of the Mw 7.8 shock on the EAFZ. The static coulomb failure stress (CFS) change due to the Mw 7.8 earthquakes suggests that the subsequent Mw 7.6 event was certainly promoted by the Mw 7.8 shock. The stress transfers from the fault EAFZ to the fault SF were realized by unclamping the interface of the fault SF, which significantly reduces the effective normal stress on the fault plane. Large CFS increases in the western Puturge segment of the EAFZ, which was not ruptured in the 2020 Mw 6.8 and the 2023 Mw 7.8 earthquakes, highlight the future earthquake risk in this fault segment.

Liquefaction potential analysis for Palu City based on CPT method

During the 28 September 2018 Palu-Donggala earthquake, liquefaction was also a prominent hazard causing significant damage to buildings and infrastructures in Palu City. To mitigate such a hazard in Palu City, knowledge of the depth of the liquified soil layer is necessary. This paper presents the results of CPT-based liquefaction potential analysis in some locations around the city where sand boiling and ground settlement occurred. The analysis shows that liquefaction occurs at various depths less than 15 m and may induce ground settlement up a few centimeters. In the Palu-Koro Fault zone, the liquified sand layer is likely thicker than in other locations. Consequently, the total ground settlement is higher than in other locations The results of this study suggest that the liquefaction potential should be accounted for in the development of Palu City to reduce future earthquake risk.

Modeling Household Earthquake Hazard Adjustment Intentions: An Extension of the Protection Motivation Theory

While existing literature has explored how hazard experience, salience, and demographics characteristics shape threat appraisal and hazard adjustment intentions, this study expands on past studies by exploring how additional factors such as qualitative characteristics of the hazard, political ideology, and oil entanglements shape threat appraisals, coping appraisals, and adjustment intentions in response to a techna hazard. This study builds on protection motivation theory (PMT) to explore factors that shape Oklahomans’ intentions to adjust to induced seismicity using data collected from households (n=866) across 27 counties in Oklahoma that have experienced varying levels of seismic activity resulting from oil and gas exploration. Correlational analyses and structural equation modeling show that several variables not included in the original PMT, such as feelings of dread or negative emotions associated with earthquakes, are important predictors of intentions to adopt hazard adjustments. This study concludes with examining the effect of additional factors on adjustment intentions and risk perceptions that can help guide future earthquake risk management in identifying and taking appropriate actions that will stimulate precautionary behavior of private actors.

Play to Learn: A Game to Improve Seismic-Risk Perception

A board game designed by psychologists and geologists to improve seismic-risk perception is presented. In a within-subjects repeated-measure study, 64 Italian high-school students rated their perception of seismic risk in relation to the hazard, vulnerability and exposure of the area in which they lived, before and after the game. A repeated-measures analysis of variance (ANOVA), which considered perception of seismic risk as the dependent variable and time as the independent variable, revealed that the board game affected the dependent variable, particularly the perception of hazard and vulnerability. The results confirm the effectiveness of the game in changing participants’ seismic risk perception, properly because the game was built with consideration of the variables that make up seismic risk. The board game proved to be an effective and fun educational tool to be used in future earthquake risk prevention programs.

Strong ground motion data of the 2015 Gorkha Nepal earthquake sequence in the Kathmandu Valley

Strong-motion records of earthquakes are used not only to evaluate the source rupture process, seismic wave propagation and strong ground motion characteristics, but also to provide valuable data for earthquake disaster mitigation. The Kathmandu Valley, Nepal, which is characterised by having soft sediments that have been deposited in an earthquake-prone zone, has experienced numerous earthquakes. We have operated four strong-motion stations in the Kathmandu Valley since 2011. These stations recorded the 2015 magnitude 7.8 Gorkha Nepal earthquake that occurred in the Himalayan continental collision zone. For several months after the mainshock, we deployed four additional temporary stations. Here, we describe the seismic data for 18 earthquakes over magnitude 5.0 collected by this array, including the 2015 magnitude 7.3 Dolakha earthquake of maximum aftershock and three large aftershocks of magnitude 6-class. These data are essential for validating the sedimentary structure of the basin and for evaluating the hazard and risk of future earthquakes in the Kathmandu Valley.

Assessment for Seismic Activities in Pesisir Selatan West Sumatra in 2018

The tendency of the recurring earthquake phenomenon in the same place in an area with a high seismic level has triggered an increase in earthquake activity in the region. Kabupaten Pesisir Selatan, which is located in West Sumatra Province, is a coastal area that is very close to the waters of the Sumatran sea as well as a source of destructive earthquakes that hit Sumatra. To anticipate the risk of future earthquakes and as an effort to increase public awareness and preparedness in the South Coast, in particular, it is necessary to provide understanding and knowledge of the seismic activities that have occurred there. The research method was carried out by collecting earthquake event data in the South Coast region for the period of January - December 2018 from the United States Geological Survey (USGS) data. The results of the analysis concluded, that in the Pesisir Selatan District there were frequent tectonic earthquakes, and also followed by landslides due to the contours of many hilly areas.

Coseismic deformation and source model of the 12 November 2017 MW 7.3 Kermanshah Earthquake (Iran–Iraq border) investigated through DInSAR measurements

ABSTRACTA large earthquake with a magnitude of MW 7.3 struck the border of Iran and Iraq at the province of Kermanshah, Iran. In our study, coseismic deformation and source model of the 12 November 2017 Kermanshah Earthquake are investigated using ALOS-2 ScanSAR and Sentinel-1A/B TOPSAR Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques. Geodetic inversion has been performed to constrain source parameters and invert slip distribution on the fault plane. The optimised source model from joint inversion shows a blind reverse fault with a relatively large right-lateral component, striking 353.5° NNW-SSE and dipping 16.3° NE. The maximum slip is up to 3.8 m at 12–14 km depth and the inferred seismic moment is 1.01 × 1020 Nm, corresponding to MW 7.3, consistent with seismological solutions. The high-resolution optical images from SuperView-1 satellite suggest that most of the linear surface features mapped by DInSAR measurements are landslides or surface cracks triggered by the earthquake. Coulomb stress changes on the source fault indicating consistency between aftershock distribution and high loaded stress zones. Based on the stress change on neighbouring active faults around this area, the Kermanshah Earthquake has brought two segments of the Zagros Mountain Front Fault (MFF), MFF-1 and MFF-2, 0.5–3.1 MPa and 0.5–1.96 MPa closer to failure, respectively, suggesting the risk of future earthquakes. Recent major aftershocks (MW≥ 5.0) could probably ease the seismic hazard on MFF-2, but the risk of earthquakes on MFF-2 is still increasing.

Effects of Framing on Earthquake Risk Perception in Chiang Rai, Thailand

The effects of framing are important to the perception of earthquake risk. This research investigated the effects of framing on the people’s perception of earthquake risk in Chiang Rai, Thailand. There were three frames conveying the same earthquake risk but presented in different terms. These statements were in frequency terms of building damage: 475 severely damaged private buildings in 500 years, 10% chance of occurrence in 50 years, and one severely damaged private building per year. The objective of this research was to determine whether framing the same earthquake risk in different terms led to different perceptions of the risk by different people, leading to 1. what would be the most effective framing type regarding severely damaged private buildings, 2. which affected people’s earthquake risk perception most, and 3. whether experiencing an earthquake disaster would change the risk perception of the residents. The result showed that presenting the risk as “one severely damaged private building per year” was the most commonly selected among the three frames and was statistically significant. This finding clarifies that short time frames influence people’s earthquake risk decisions, and agencies can effectively use framing to communicate the earthquake risk to people in seismic regions to stimulate their earthquake preparedness and to reduce future earthquake risk. However, earthquake experience does not change the risk perception of the residents.

Numerical simulation of the segmentation of the stress state of the Anninghe-Zemuhe-Xiaojiang faults

We established a three-dimensional finite element model of the Anninghe-Zemuhe-Xiaojiang faults region using contact surfaces of different sizes to describe the spatial segmentation characteristics of the faults. Our model is based on constraints from GPS observations, models of the crust and upper mantle, precise earthquake locations, the tectonic stress field, the slip rate of the faults, and the rheology of the lithosphere in the Sichuan-Yunnan area. Considering the influence of strong earthquakes since A.D. 1327, we analyzed the main controlling factors of the characteristics of the strong earthquakes and also studied by numerical simulation the possible areas of future earthquake risk and their relationship with tectonic stress. The numerical results showed that the gravitational potential energy of the Qinghai-Tibet Plateau and the interaction of adjacent blocks are the main kinetic factors affecting the characteristics of the tectonic stress distribution. There appears to be some correspondence between the distribution of tectonic stress and the b value; however, we also found that some low b value locations correspond to regions of lower stress. This contradiction may be the result of some comprehensive factors, such as the release of strain energy caused by strong earthquakes.

Structural geometry of the source region for the 2013 Mw 6.6 Lushan earthquake: Implication for earthquake hazard assessment along the Longmen Shan

The 2013 Mw 6.6 Lushan earthquake occurred in the Longmen Shan fold-and-thrust belt, Sichuan Province, China, near the five-year anniversary of the devastating 2008 Mw 7.8 Wenchuan earthquake. To define the fault that generated the 2013 earthquake and its relationship with the Beichuan fault, which ruptured in the Wenchuan earthquake, we construct several cross sections and a 3D structural model. The sections and models reveal that the main-shock of the Lushan earthquake occurred on a portion of the Range Front blind thrust (RFBT) and that the structural geometry of this fault varies along strike. The Lushan main-shock occurred at a location along the strike of the fault where the geologic shortening and total fault slip are greatest. A lateral ramp of the RFBT appears to coincide with the northern limit of aftershocks from the Lushan earthquake, leading to a 75 km seismic gap between the Wenchuan earthquake and the 2013 earthquake sequence. Although both the Wenchuan and Lushan earthquakes occurred within the Longmen Shan fold-and-thrust belt, different faults generated the two events. Based on this structural characterization and analysis of the aftershocks of the Wenchuan and Lushan earthquakes, we suggest that the Lushan earthquake may have been triggered by the 2008 rupture but is best considered as an independent event rather than an aftershock of the Wenchuan earthquake. The RFBT that generated the Lushan earthquake is linked to a detachment that extends into the Sichuan basin along the Triassic evaporite layer. The coulomb stress change simulation suggests that other faults linked to this detachment may have been loaded by the 2008 and 2013 earthquake, posing the risk of future earthquakes along the Longmen Shan and in the densely populated Sichuan basin.

Normal- and oblique-slip of the 2008 Yutian earthquake: Evidence for eastward block motion, northern Tibetan Plateau

The 2008 Yutian Mw 7.1 earthquake occurred in a junction area of the Altyn Tagh, Karakax and Kunlun fault systems and becomes a most northerly normal faulting event in the northern Tibetan Plateau. High resolution satellite image interpretation and field investigation indicate that the surface rupture zone produced by the Yutian earthquake is ~31km long along the Yulong Kashgar fault, a NS-trending fault at the western piedmont of a snow-covered mountain at the headwater of the Yulong Kashgar River, about 20km south of the Ashikule volcanoes. The surface rupture zone along the Yulong Kashgar fault consists of four different types of surface ruptures with both normal- and oblique-slip components. The maximum left-lateral slip and vertical offset, we measured in the field, are ~3.6m and ~3.3m, respectively. This NS-trending seismogenic fault belongs to one of the boundary faults between the Qaidam–Qilian and the western Kunlun blocks. Thus, the Yutian earthquake is as a result of abrupt normal- and oblique-slip faulting, which fits the eastward escape of the Qaidam–Qilian block, relative to the western Kunlun block. This surface rupture pattern supports the eastward block-like motion model whose deformation takes place mainly along the block boundaries delineated by mega-strike-slip faults in the northern Tibetan Plateau. More important may be that the Yutian earthquake has implication on future earthquake risk along the boundary faults of the Qaidam–Qilian block.

PROBABILISTIC SEISMIC HAZARD ASSESSMENT OF BABOL, IRAN

This paper presents a probabilistic seismic hazard assessment of Babol, one of big cities in north of Iran. Many destructive earthquakes happened in Iran in the last centuries. It comes from historical references that at least many times; Babol has been destroyed by catastrophic earthquakes. In this paper, the peak horizontal ground acceleration over the bedrock (PGA) is calculated by a probabilistic seismic hazard assessment (PSHA). For this reason, at first, a collected catalogue, containing both historical and instrumental events that occurred in a radius of 200 km of Babol city and covering the period from 874 to 2004 have been gathered. Then, seismic sources are modeled and recurrence relationship is established. After elimination of the aftershocks and foreshocks, the main earthquakes were taken into consideration to calculate the seismic parameters (SP) by Kijko method. The calculations were performed using the logic tree method and four weighted attenuation relationships Ghodrati, 0.35, Khademi, 0.25, Ambraseys and Simpson, 0.2 and Sarma and Srbulov, 0.2. Seismic hazard assessment is then carried out for 8 horizontal by 7 vertical lines grid points using SEISRISK III. Finally, two seismic hazard maps of the studied area based on Peak Horizontal Ground Acceleration (PGA) over bedrock for 2 and 10% probability of exceedance in one life cycles of 50 year are presented. These calculations have been performed by the Poisson distribution of two hazard levels. The results showed that the PGA ranges from 0.32 to 0.33 g for a return period of 475 years and from 0.507 to 0.527 g for a return period of 2475 years. Since population is very dense in Babol and vulnerability of buildings is high, the risk of future earthquakes will be very significant.

A Review of Earthquake Statistics: Fault and Seismicity-Based Models, ETAS and BASS

There are two fundamentally different approaches to assessing the probabilistic risk of earthquake occurrence. The first is fault based. The statistical occurrence of earthquakes is determined for mapped faults. The applicable models are renewal models in that a tectonic loading of faults is included. The second approach is seismicity based. The risk of future earthquakes is based on the past seismicity in the region. These are also known as cluster models. An example of a cluster model is the epidemic type aftershock sequence (ETAS) model. In this paper we discuss an alternative branching aftershock sequence (BASS) model. In the BASS model an initial, or seed, earthquake is specified. The subsequent earthquakes are obtained from statistical distributions of magnitude, time, and location. The magnitude scaling is based on a combination of the Gutenberg-Richter scaling relation and the modified Bath’s law for the scaling relation of aftershock magnitudes relative to the magnitude of the main earthquake. Omori’s law specifies the distribution of earthquake times, and a modified form of Omori’s law specifies the distribution of earthquake locations. Unlike the ETAS model, the BASS model is fully self-similar, and is not sensitive to the low magnitude cutoff.

Earthquakes: Recurrence and Interoccurrence Times

The purpose of this paper is to discuss the statistical distributions of recurrence times of earthquakes. Recurrence times are the time intervals between successive earthquakes at a specified location on a specified fault. Although a number of statistical distributions have been proposed for recurrence times, we argue in favor of the Weibull distribution. The Weibull distribution is the only distribution that has a scale-invariant hazard function. We consider three sets of characteristic earthquakes on the San Andreas fault: (1) The Parkfield earthquakes, (2) the sequence of earthquakes identified by paleoseismic studies at the Wrightwood site, and (3) an example of a sequence of micro-repeating earthquakes at a site near San Juan Bautista. In each case we make a comparison with the applicable Weibull distribution. The number of earthquakes in each of these sequences is too small to make definitive conclusions. To overcome this difficulty we consider a sequence of earthquakes obtained from a one million year "Virtual California" simulation of San Andreas earthquakes. Very good agreement with a Weibull distribution is found. We also obtain recurrence statistics for two other model studies. The first is a modified forest-fire model and the second is a slider-block model. In both cases good agreements with Weibull distributions are obtained. Our conclusion is that the Weibull distribution is the preferred distribution for estimating the risk of future earthquakes on the San Andreas fault and elsewhere.

A Retrospective on the 1906 Earthquake's Impact on Bay Area and California Public Policy

The 1906 earthquake's influence has been both a blessing and curse on the Bay Area's and California's progress to effectively manage earthquake risk. This earthquake, and its impacts noted in the historical record, have both motivated and discouraged policymakers to act through mitigation and improved emergency response. This paper scrutinizes the 1906 earthquake using a public policy perspective. Building from that experience improves the region's future earthquake risk management efforts.

SEISMIC HAZARD ASSESSMENT OF METROPOLITAN TEHRAN, IRAN

This paper presents a probabilistic seismic hazard assessment of Tehran, the capital of Iran. Two maps have been prepared to indicate the earthquake hazard of Tehran and its vicinity in the form of iso-acceleration contour lines. They display the probabilistic estimate of Peak Ground Acceleration (PGA) over bedrock for the return periods of 475 and 950 years. Tehran is a densely populated metropolitan in which more than 10 million people live. Many destructive earthquakes happened in Iran in the last centuries. It comes from historical references that at least 6 times, Tehran has been destroyed by catastrophic earthquakes. The oldest one happened in the 4th century BC. A collected catalogue, containing both historical and instrumental events and covering the period from the 4th century BC to 1999 is then used. Seismic sources are modelled and recurrence relationship is established. For this purpose the method proposed by Kijko [2000] was employed considering uncertainty in magnitude and incomplete earthquake catalogue. The calculations were performed using the logic tree method and three weighted attenuation relationships; Ramazi [1999], 0.4, Ambraseys and Bommer [1991], 0.35, and Sarma and Srbulov [1996], 0.25. Seismic hazard assessment is then carried out for 12×11 grid points using SEISRISK III. Finally, two seismic hazard maps of the studied area based on Peak Ground Acceleration (PGA) over bedrock for 10% probability of exceedance in two life cycles of 50 and 100 years are presented. The results showed that the PGA ranges from 0.27(g) to 0.46(g) for a return period of 475 years and from 0.33(g) to 0.55(g) for a return period of 950 years. Since population is very dense in Tehran and vulnerability of buildings is high, the risk of future earthquakes will be very significant.

Earthquakes and geological discovery

Earthquakes and Geological Discover describes how and whv scientists trace seismic activirv and measure the extent and patterns of seismic waves. Through analvsis of numerous earthquakes, both historical a'nd present, eminent seismologist Bruce Bolt illustrates that basic geological lessons are learned in almost even, occurrence of these highly varied events. In addition, Bolt shows how seismographic data are used to mitigate the risk of future earthquakes by incorporating the latest theoretical models, technologies, and techniques (including manmade earthquakes). Bolt describes the three-pronged effort to predict the occurrence of earthquakes-the search for warning signs, the review of patterns of past occurrences, and the measurement of the strain on faults. fle concludes bv focusing on the crucial challenge of predicting the intensity of ground shaking, demonstrating how an understanding of seismic intensity leads to the construction of safer buildings and to other measures that reduce an earthquake's potential for destruction.