Variabilities of floor movement in 2023 Mw 7.8 Pazarcık earthquake in Turkey and 2008 Mw 7.9 Wenchuan earthquake in China

On February 6, 2023, a devastating M_w 7.8 earthquake struck southeastern Turkey, at 01:17 UTC. The epicenter situated in Pazarcık, Kahramanmaraş Province (37.288°N, 37.043°E) with a hypocenter depth of 10 km, in line with the Turkish Disaster and Emergency Management Authority (AFAD; https://tadas.afad.gov.tr/). The US Geological Survey (USGS) positioned the Pazarcık earthquake’s epicenter at 37.226°N, 37.014°E, with its hypocenter depth of 10 km, and second magnitude M_w of seven.8¹. According to the Global GMT determinations, the Pazarcık earthquake’s epicenter at 37.226°N, 37.014°E, with a hypocenter depth of 15 km and M_w of seven.8². Seismic second tensor options from talked about establishments (AFAD, USGS, and Global CMT) constantly point out that the Pazarcık occasion was strike-slip earthquakes. Most of Turkey’s territory is situated on the Anatolian fault zone inside the Eurasian seismic belt, the place this zone is caught in a fancy tectonic interplay between the Eurasian, African, and Arabian plates. The Anatolian fault zone is structurally demarcated by two zones: one is the dextral strike-slip Northern Anatolian Fault Zone (NAFZ) lied on northern of Turkey, extending roughly 1500 km in an east–west orientation, one other is the sinistral strike-slip Eastern Anatolian Fault Zone (EAFZ) lied on southeastern of Turkey, spanning 550 km alongside northeast path (Bozkurt, 2001)³. Historically, Turkey’s important seismic occasions have predominantly occurred alongside the NAFZ and EAFZ (Zare et al., 2014)⁴. The 2023 Pazarcık earthquake ruptured the southwestern section of the EAFZ, a fancy fault system comprising a number of parallel, sub-parallel, and indirect faults, with rupture extending alongside a northeast-southwest orientation. The EAFZ represents one in every of Turkey’s most seismically energetic areas, having generated quite a few harmful historic earthquakes together with: the 8.0-magnitude Erzincan earthquake in 1939, the 7.1-magnitude Elmalıdere-Bingol earthquake in 1949, the 6.8-magnitude Erzincan earthquake in 1992, the M_w 6.7-Doganyol earthquake in 2020, and so forth. According to the Middle East seismic hazard zonation map (Sesetyan et al., 2018)⁵, peak floor acceleration (PGA) on bedrock websites (V_S30 > 800 m/s) attain most ranges of 0.5 g and 1.0 g for 475-y (10% chance of exceedance in 50 years) and 2475-y (2% chance of exceedance in 50 years) return intervals, respectively, representing the area’s highest seismic hazard ranges. The 2023 Pazarcık earthquake, adopted by the Elbistan earthquake 9 hours later, triggered widespread destruction throughout 11 provinces, with 55% of buildings being broken or collapsing in Kahramanmaraş, and 58% of buildings being broken in Hatay (Tao et al., 2023)⁶. A big proportion of constructing collapses in quake-affected areas will be attributed to constructions designed in line with outdated seismic codes (Erdik et al., 2023; Turner, 2023)^7,8. Approximately 97% of the collapsed buildings had been constructed previous to seismic code replace in 1997 (Binici et al., 2023)⁹. Numerous of strong-motion recordings through the Pazarcık earthquake had been obtained by the Engineering Strong Motion (ESM) database.

Sichuan province situated in southwestern China located on the Eurasian seismic belt, skilled a devastating M_w 7.9 earthquake in Wenchuan nation (31.021N, 103.367E) on May 12, 2008, hypocenter depth of 14 km. The 2008 Wenchuan earthquake occurred on the Longmenshan Fault Zone, with a reverse-slip earthquake (USGS). This fault zone extends alongside the sting of the Sichuan Basin from northeast to southwest, exhibiting a NE-SW strike orientation. The Wenchuan occasion resulted in quite a few structural collapses throughout 14 severely broken counties or cities, attributable to giant magnitude, and shallow focal depth. Remote sensing evaluation of post-seismic constructing collapse distribution reveals catastrophic collapse charges exceeding 90% in Yingxiu and Beichuan cities, each situated inside the near-field area of the epicenter. Otherwise, Significant constructing collapses had been additionally documented within the city areas of Mianzhu, Shifang, and Pengzhou cities, the place over 60% of constructions failed in a number of surrounding cities and villages (Lei et al., 2010)¹⁰. The National Strong-Motion Observation Networks System (NSMONS) in China, obtained a bigger numbers of sturdy movement recordings through the Wenchuan earthquake.

Ground movement prediction equations (GMPEs) incorporate key parameters as predictor variables, together with magnitude, distance, style-of-faulting, web site class. However, the GMPEs adopted for China’s seismic zoning map, had been developed by the NGA-West2 and NSMONS databases, however their predictor variables don’t embrace fault kind. China is situated on the intersection of the circum-Pacific and Eurasian seismic belts, energetic crustal motion ends in frequent earthquakes. Since the 20th century, China has skilled a number of devastating earthquakes, e.g., the 7.9-magnitude Wenchuan in 2008, the 8.1-magnitude Kunlunshan in 2001, the 7.8-magnitude Tangshan in 1976, the 8.0-magnitude Gulang in 1927, the 8.5-magnitude Haiyuan in 1920, and so forth. Operational because the finish of 2007, the NSMONS has captured strong-motion information for under a single M ≥ 7.5 occasion: the 12 May 2008 Wenchuan earthquake. Both Turkey and China are located alongside the Eurasian seismic belt. The 2023 Pazarcık earthquake (strike-slip, M_w7.8) and 2008 Wenchuan earthquake (reverse-fault, M_w 7.9) exhibited comparable magnitudes however completely different fault varieties. Comparative evaluation of their ground-motion depth measures (IMs) distinction gives useful insights into large-magnitude ground-motion traits throughout completely different fault varieties, whereas offering important references for future revisions of floor movement prediction equations (GMPEs) in China’s seismic zonation map. Therefore, on this research, the IMs of floor movement had been calculated for each earthquakes, corresponding to PGA, PGV, PSAs, important period (5–95%), Arias depth and Newmark displacement, to research floor movement traits based mostly on the anticipated values from GMPEs.

Recordings and web site circumstances

In this research, a complete of 227 processed strong-motion recordings from the Pazarcık earthquake within the ESM database had been used, with Joyner–Boore distance (R_JB) starting from near-fault to 400 km (final accessed March 2023). The R_JB values had been calculated by the USGS-inverted rupture aircraft. Figure 1a,b present two dominant fault planes. The fault aircraft #1 prolonged roughly 180 km alongside a 60.0° strike path, and the fault aircraft #2 propagated roughly 170 km alongside a 25.0° strike orientation. Figure 1b shows the positions of 227 used stations with R_JB < 400 km.

(a) The epicenter and rupture faults (black strains) of the geographical location for the Pazarcık earthquake; The map was generated utilizing Generic Mapping Tools (model 6.0, https://www.generic-mapping-tools.org/download/)¹¹; (b) Shows the strong-motion stations used within the Pazarcık earthquake for R_JB < 400 km; (c) Shows the strong-motion stations used within the Wenchuan earthquake for R_JB < 400 km.

For comparability with the 2023 Pazarcık earthquake, 149 strong-motion recordings (R_JB < 400) from the 2008 Wenchuan earthquake (Fig. 1c) had been used to research floor movement variations between the 2 occasions. All recordings had been filtered utilizing a Butterworth Bandpass filter (0.01–35 Hz). Figure 2a reveals the R_JB distributions of strong-motion recordings thought of for each earthquakes. The majority of strong-motion recordings had been acquired at stations with R_JB > 80 km for each occasions. Only 54 of 227 recordings from Pazarcık earthquake, and 30 of 149 recordings from Wenchuan earthquake obtained at stations R_JB < 80 km. There are 12 stations at R_JB = 0 km from the Pazarcık earthquake, and reveals the sq. at R_JB = 1.0 km on the vertical axis in determine. Figure 2b shows histograms of the V_S30 distributions for strong-motion stations used on this research throughout Pazarcık and Wenchuan earthquakes. The V_S30 distributions at stations are comparable for each earthquakes, with the vast majority of their V_S30 values ranging inside 600 m/s. For the Pazarcık earthquake, V_S30 values for 99 strong-motion stations had been obtained immediately from the ESM database, whereas the remaining 128 stations of V_S30 values estimated based mostly on topographic slope. For the Wenchuan earthquake, V_S30 values for 97 strong-motion stations had been obtained from the Western China web site Flatfile (Xie et al., 2022)¹², whereas the remaining 52 stations V_S30 values had been estimated utilizing the Chinese web site classification by Ji et al. (2017)¹³ HVSR methodology and topographic slope. The Wenchuan earthquake recordings had been processed utilizing a Butterworth bandpass filter with a variety of 0.01–35 Hz.

(a) Joyner–Boore distance (R_JB) distributions for the 227 recordings within the Pazarcık earthquake, and 149 recordings within the Wenchuan earthquake. The sq. image at R_JB = 1.0 km on the vertical axis signifies the 12 recordings from stations with R_JB = 0 km within the Pazarcık earthquake. (b) Histograms of V_S30 distributions for strong-motion stations in Pazarcık and Wenchuan earthquakes. The black dash-dotted strains signify the medians V_S30 values for strong-motion stations thought of in every earthquake.

Analysis of recorded knowledge

Figure 3 illustrates the noticed IMs, whole residuals (R_es) and their stacked column, for PGA and PSAs with intervals at T = 0.5 s, 2.0 s, and 5.0 s in Pazarcık and Wenchuan earthquakes. Additionally, the determine consists of the anticipated medians from one in every of world NGA-West2 GMPE developed by Boore et al. (2014; hereafter, BSSA14)¹⁴. The BSSA14 mannequin was developed by world strong-motion recordings, together with from Turkey, China and different areas. To distinguish regional variations in crustal medium, the BSSA14 included anelastic attenuation adjustment coefficientΔc₃, calculated by linear regression between within-event residuals and Joyer-Boore distance. Both Turkey and China had been assigned the identical regional adjustment coefficientΔc₃ on this mannequin. Therefore, the BSSA14 mannequin is adopted on this research, and its constraints are as follows: the magnitude vary of M_w = 3 to eight.5 for each strike-slip and reverse-slip earthquakes, the R_JB ranges from 0 to 400 km, the V_S30 from 150 to 1500 m/s, and the basin depth Z_1.0 ranges from 0 to three.0 km. In the calculations of predicted medians, web site circumstances had been characterised utilizing V_S30 = 484 m/s for the Pazarcık earthquake (the median of all used stations on this occasion) and V_S30 = 379 m/s for the Wenchuan earthquake. The parameter Z_TOR within the BSSA14 mannequin represents depth to high of rupture, we adopted Z_TOR = 0 km on this research. The regional adjustment of anelastic attenuation for each Turkey and China had been thought of. Moreover, basin results had been excluded from the anticipated medians. It is price noting that the anticipated medians can not mirror precise predictions at every web site location, because the web site results represented by fixedV_S30 values. The utilization of predicted medians was used as a reference to focus on the disparities in PGA and PSAs noticed between the 2 occasions.

(a) Observed peak floor acceleration (PGA) and 5%-damped pseudo-spectral accelerations (PSAs) at intervals T = 0.5, 2.0, and 5.0 s for Pazarcık earthquake and Wenchuan earthquake. The thick gray strains signify the medians predicted by BSSA14 fashions for Pazarcık earthquake triggered on a strike-slip fault, the place the V_S30 worth is 484 m/s. The black strong strains signify the medians predicted by BSSA14 fashions developed for Wenchuan earthquake triggered on a reverse-slip fault, the place the V_S30 worth is 379 m/s. (b) Total residuals had been computed utilizing the precise V_S30 values for every occasion and web site. (c) The chosen knowledge as a (horizonal) 100% Stacked Column Graph of the overall residuals (i.e. Values of whole residual under zero and above zero) had been listed.

For the PGA from the Pazarcık earthquake, they do not want at a quicker than the anticipated medians, whereas these for the Wenchuan earthquake is per predicted medians. Similarly, for PSA at T = 0.5 s, the Pazarcık earthquake decays quicker than predicted, whereas the Wenchuan earthquake follows the anticipated pattern. Additionally, the noticed PSA at intervals T = 2.0 s and T = 5.0 s for each earthquakes decays extra quickly than predicted medians (Fig. 3a). The whole residuals for 2 occasions had been obtained by the precise V_S30 at every station, and calculated by the noticed values minus the anticipated medians from the GMPEs on the pure logarithmic scale, as illustrated in Fig. 3b. The most of R_es values for PGAs in Pazarcık earthquake had been unfavorable at R_JB > 80 km, whereas constructive result’s noticed for Wenchuan earthquake. For PSA at T = 0.5 s, R_es values at R_JB > 80 km had been unfavorable for the Pazarcık earthquake, whereas the Wenchuan occasion confirmed no important deviation. For PSAs at intervals T = 2.0 s and T = 5.0 s, probably the most of R_es values had been constructive for each earthquakes with R_JB exceeding 80 km. Figure 3c shows the share distribution of constructive and unfavorable R_es values at R_JB > 80 km, per the outcome noticed in Fig. 3b. In the Pazarcık earthquake, constructive R_es values accounted for 16% (PGA), 18% (T = 0.5 s), 28% (T = 2.0 s), and 18% (T = 5.0 s), with corresponding unfavorable values of 84%, 82%, 72%, and 82%. In distinction, the Wenchuan earthquake exhibited greater constructive R_es values percentages: 66% (PGA), 43% (T = 0.5 s), 31% (T = 2.0 s), and 31% (T = 5.0 s), with unfavorable percentages of 34%, 57%, 69%, and 69%, respectively. Therefore, these outcomes reveal period-dependent variations in floor movement traits between the 2 earthquakes.

The between-events residuals (δB_e) mirror the supply traits, and are calculated by averaging the overall residuals for particular person earthquakes. The whole residuals for each earthquakes present important deviations at R_JB > 80 km. To get rid of the deviations of the δB_e, and extra actuality reveal the supply discrepancy between the Pazarcık earthquake and Wenchuan earthquake, a linear mannequin f(R) (Eq. 1) was regressed on the connection between R_es and R_JB:

the place c is a trend-adjusted coefficient, and σ is the overall commonplace deviation. Then, the corrected δB_e values had been obtained by subtracting the trend-adjusted residuals from the unique residuals. Earthquake magnitude serves as a basic parameter for floor movement interpretation. The M or M_w scale was derived from seismic second utilizing Southern California earthquake knowledge, however it has not been adequately validated for magnitudes lower than 7.5 outdoors that area. Recent research additionally spotlight that the M or M_w scale tends to overestimate radiated vitality for smaller to moderate-magnitude earthquakes under 7.5. The detailed limitations are mentioned in Das and Das (2025)¹⁵. To handle these shortcomings, the Das magnitude scale M_wg was proposed¹⁶. To higher evaluate the supply results of the Pazarcık and Wenchuan earthquakes, we calculated one other magnitude scale M_wg for each occasions utilizing seismic second (M₀) from the Global Centroid Moment Tensor database². The outcomes yield an M_wg of seven.8 for the 2008 Wenchuan earthquake and seven.7 for the 2023 Pazarcık earthquake. These corrected δB_e values for each M_w and M_wg had been used to comparative evaluation between two earthquakes, as proven in Fig. 4.

The corrected between-events residuals δB_e for PGAs and PSAs at T = 0.2 s–5.0 s between the Pazarcık earthquake and the Wenchuan earthquake utilizing each M_w and M_wg, based mostly on the GMPEs developed by Boore et al. (2014)¹⁴, respectively.

Figure 4 reveals important distinction for the corrected δB_e values between these two earthquakes. For the Pazarcık earthquake, the corrected δB_e values for each M_w and M_wg are unfavorable values at intervals of < 0.2 s, whereas constructive values at intervals of > 0.2 s, indicating overprediction of the supply results in short-period floor movement for BSSA14 mannequin, however underprediction on intermediate- and long-period floor motions. The δB_e values for M_w are barely greater than these of M_wg at intervals of < 0.2 s, whereas the alternative pattern happens at longer intervals. The outcome signifies that the M_wg scale matches the typical supply impact from BSSA14 extra intently at quick intervals, demonstrating its higher consistency with high-frequency floor movement. This conduct aligns with the anticipated efficiency of the proposed M_wg scale¹⁵. For the Wenchuan earthquake, all of the corrected δB_e values for each M_w and M_wg are constructive, indicating underpredictions of the supply results in floor movement throughout all intervals for BSSA14 mannequin. The δB_e values for M_w present barely variations from these for M_wg at intervals of < 1.0 s, whereas the bigger discrepancies emerge at intervals of > 1.0 s. The corrected δB_e values for Pazarcık earthquake was bigger than these of the Wenchuan earthquake at T > 0.2 s, however smaller for each PGA and PSAs at T < 0.2 s. The outcome could also be attributed to the completely different rupture kinds between two earthquakes: strike slip for the Pazarcık earthquake and reverse slip for the Wenchuan earthquake. Furthermore, the fault slip distribution of the Pazarcık earthquake was concentrated close to the bottom floor, whereas the Wenchuan occasion occurred deeper location (at a depth of ~ 10 km) (USGS). The shallower depth of the Pazarcık earthquake might generate larger floor waves in longer intervals. Similar outcome was discovered for 2013 M7.0 Lushan strike-slip earthquake and 2017 M 7.0 Jiuzhaigou reverse-slip earthquake (Ren et al. 2018)^17,18.

Seismic amplitude traits

PGA and PGV

In this part, the seismic amplitude parameters had been calculated to research floor movement variations between Pazarcık earthquake and Wenchuan earthquake. First, we established empirical relationships between PGA and PGV for each the Pazarcık and Wenchuan earthquakes individually, with regression outcomes offered in Table 1. The Pearson correlation coefficients are 0.917 (Pazarcık occasion) and 0.782 (Wenchuan occasion), indicating sturdy correlation for each earthquakes. Figure 5a reveals the distribution of PGA and PGV through the two earthquakes. To guarantee constant comparability, solely recordings with PGA exceeding 5 cm/s² had been thought of for each earthquakes. The two strong strains in determine signify the PGA and PGV thresholds akin to depth IX in line with the China Earthquake Intensity Scale (GB/T 17742, 2008)¹⁹; equal to modified Mercalli depth [MMI] IX), with values of 354 cm/s² and 36 cm/s, respectively. Above the PGA threshold akin to Chinese Intensity IX, the Wenchuan earthquake present typically comparable amplitudes to the Pazarcık earthquake, although with fewer accessible recordings. However, PGV distributions for Chinese Intensity IX reveals that the Wenchuan earthquake exhibited each decrease amplitudes and fewer recordings in comparison with the Pazarcık occasion.

(a) The noticed PGAs versus PGVs had been in contrast for Pazarcık earthquake and Wenchuan earthquake. The horizontal strong line represents the PGV threshold akin to Chinese earthquake depth scale IX. The vertical strong line represents the PGA threshold akin to Chinese earthquake depth scale IX; (b) The PGAs and the equal predominant frequency f_eq had been in contrast for Pazarcık earthquake and Wenchuan earthquake. The horizontal strong line represents the PGA threshold akin to Chinese earthquake depth scale IX. The indirect strong line represents the PGV threshold akin to Chinese earthquake depth scale IX.

The equal dominant frequency (f_eq), denoted as PGA/(2·π·PGV), is a crucial indicator for measuring the connection between floor movement and structural harm. The f_eq is obtained by discrete Fourier remodel with assumption of floor movement’s sine or cosine traits, which was employed to moderately elucidate the structural harm through the M_w 9.0 earthquake in Japan (Kawase, 2011)²⁰. Therefore, with the intention to investiage the affect variations of floor movement on structural harm between Pazarcık and Wenchuan earthquakes, the f_eq had been calculated for each occasions.

Figure 5b presents the distribution of PGV and f_eq for each earthquakes. The city residential buildings within the Pazarcık earthquake-affected space are primarily multi-storey body construction and small high-rise strengthened concrete body construction and body supported shear wall construction. In Wenchuan earthquake-affected areas, the predominant constructing varieties consisted of strengthened concrete body constructions, brick-concrete constructions, and bottom-frame constructions, with most constructions starting from 3 to 10 flooring. The shaded space within the determine represents the structural pure frequency vary (0.5 ~ 1.5 Hz) of the first buildings in each earthquakes affected space. The floor motions between the 2 earthquakes exhibit important variations in seismic amplitude traits. Within frequency vary of 0.5 ~ 1.5 Hz, many PGA and PGV for Pazarcık earthquake exceeded the thresholds, akin to Chinese earthquake depth scale IX, whereas just one recording from Wenchuan earthquake surpassed these thresholds. Such many recordings for Pazarcık earthquake exceeded the Chinese Intensity IX thresholds inside the construction pure frequency vary of in affected space, indicating that its floor motions have larger influence on constructions harm in comparison with Wenchuan occasion.

Arais depth

The Arias depth (I_a), derived by integrating squared accelerations time historical past, displays the vitality content material of the recorded sign (Arias, 1970)²¹. Given its essential function in evaluating seismic potential destructiveness (landslide, soil liquefaction, and structural harm), many researchers have established on the GMPEs of Arias depth (Travasarou et al., 2003; Stafford et al., 2009; Lee et al., 2012; Li et al., 2017)^22,23,24,25. This research analyzes the variations in Arias depth between the Pazarcık and Wenchuan earthquakes, by way of evaluating with a predictive mannequin estimated by Li et al. (2017, hereafter, LYX17)²⁵. The LYX17 mannequin was adopted as a result of it was developed utilizing strong-motion recordings from earthquakes in Western America, and Central Asia from the NGA database, its continental tectonic surroundings is much like that of China. The predictor variables in LYX17 mannequin embrace second magnitude M_w, rupture distance R_JB, web site kind and fault kind, as follows the Eq. 2:

the place I_a represents Arias depth, with software limits of R_JB not exceeding 200 km and the M_w vary from 5.5 to eight.0. The two dummy indicators SA and SC classify web site classes as follows: S_A = 1 and S_C = 0 for bedrock web site; S_A = 0 and S_C = 0 for laborious web site; S_A = 0 and S_C = 1 for tender web site. The web site classification follows these V_S30 standards: bedrock web site with V_S30 > 500 m/s, laborious web site V_S30 starting from 250 to 500 m/s, and tender web site V_S30 < 250 m/s. A dummy variable V is used to signify the fault kind: V = 1 represents reverse faults, and V = 0 represents all different fault varieties. Figure 6 reveals a comparability between noticed I_a values from the Pazarcık and the Wenchuan earthquakes, and their corresponding predicted medians utilizing Eq. 2. According to the above-described, the median V_S30 values are decided to be 484 m/s for the Pazarcık earthquake and 379 m/s for the Wenchuan earthquake. Consequently, the laborious web site situation (S_A = 0, S_C = 0) was employed to estimate the anticipated medians on this evaluation.

(a) The noticed Arais depth had been in contrast within the Pazarcık earthquake and Wenchuan earthquake, in contrast with prediction imply by the Li et al. (2017)²⁵, respectively; (b) The reprocessed strong-motion recordings of Arais depth, utilizing a low-pass filter with a 5 Hz cut-off frequency, had been in contrast within the Pazarcık earthquake and Wenchuan earthquake, in contrast with prediction imply by the Li et al. (2017)²⁵, respectively.

In Fig. 6a, for the Pazarcık earthquake, the noticed I_a values present good settlement with the anticipated medians by the LYX17 mannequin at R_JB < 80 km. However, most noticed I_a values are decrease than the anticipated ones when R_JB exceeds 80 km. For the Wenchuan earthquake, almost all noticed I_a values exceed the anticipated medians. Wenchuan earthquake reveals considerably larger deviations from the anticipated imply in comparison with the Pazarcık earthquake. We reprocessed the strong-motion recordings for each earthquakes utilizing a low-pass filter with a 5 Hz cut-off frequency to take away high-frequency elements. Figure 6b presents a comparability between the reprocessed I_a values for each occasions, and their corresponding predicted medians. The reprocessed I_a values for the Wenchuan earthquake reveal considerably lowered deviations from the anticipated medians, indicating its floor motions comprise comparatively ample high-frequency elements. This outcome could also be attributed to the completely different kinds of fault rupture, that’s, strike slip for the Pazarcık earthquake and reverse slip for the Wenchuan earthquake. The Δσ, a basic supply parameter performs a essential function in characterizing earthquake physics and seismic hazard evaluation, and intently linked to the amplitude of high-frequency (short-period) floor movement. The earlier research (Mohammadioun, 2002; McGarr, 2002)^26,27 displaying that the Δσ for reverse-slip earthquakes is larger than that of strike-slip earthquakes, as a result of reverse-slip occasion in focal mechanism having bigger in friction energy and shear stress. Hence stress drop (Δσ) might be one other attribution.

As effectively often known as, the PGA serves as a essential indicator for assessing earthquake-induced constructing harm, demonstrating sturdy correlation with structural harm traits. Consequently, the PGA is at the moment probably the most broadly used floor movement parameter in code for seismic design of buildings. However, the PGA has important limitations when employed to evaluate seismically-induced secondary disasters corresponding to landslides or liquefaction. The Arias depth, calculated by integrating the sq. of acceleration time histories, captures the frequency content material, period, and amplitude traits of floor movement. This parameter serves as a dependable indicator for assessing earthquake-induced landslides and liquefaction potential. Therefore, investigating the correlation between Arias depth and PGA is essential for using the conversion strategies between floor movement parameters in predicting seismic secondary disasters. Previous research have investigated the correlation between Arias depth and PGA, establishing empirical relationships between these parameters (Arias, 1970; Jibson, 1993; Romeo, 2000: Liu et al., 2015.2016)^{21,28,29,30,31}. The two prediction fashions had been chosen to research the bottom movement variations for PGA and I_a between the 2 occasions. One of the prediction fashions derived by Romeo (2000)²⁹ was used on this research (Eq. 3), which is simply the correlation relationship between PGA and I_a.

Previous research (Chousianitis et al., 2014and Sokolov and Wenzel, 2013)^32,33 have demonstrated that the I_a are considerably influenced by supply and web site results. Another prediction mannequin derived by Liu et al. (2016)³¹ was adopted on this research, which includes second magnitude M_w, and web site situation V_S30, as predictor variables (Eq. 4).

during which I_a is independently for every horizontal part, a, b, c and d is regression coefficients. Figure 7a presents the noticed PGA and I_a values for each Pazarcık and Wenchuan earthquakes, demonstrating a robust correlation between these two parameters. The values noticed for 2 earthquakes principally surpass the anticipated medians from two fashions, a bigger discrepancy noticed for Eq. 3 that doesn’t incorporate magnitude and web site circumstances. Subsequently, the overall residuals had been computed for Pazarcık and Wenchuan earthquakes, based mostly on the Eqs. 3, 4. Most whole residuals and their Error bars for each earthquakes exceeded zero (Fig. 7b–e), indicating underprediction by each equations. Additionally, noticed that the Wenchuan earthquake displayed greater error bars in comparison with the Pazarcık occasion. Error bars for each earthquakes from Eq. 3 (with out accounting for magnitude and web site circumstances) reveals the reducing pattern with rising V_S30 (Fig. 7d), indicating the site-dependence of PGA and I_a. In distinction, Error bars for each earthquakes from Eq. 4 (incorporates magnitude and web site circumstances) reveals a flat pattern (Fig. 7e).

(a) The noticed I_a and PGA values for the Pazarcık and Wenchuan earthquakes had been in contrast with the median predictions estimated by Remo (2000)²⁹ and Liu et al. (2016)³¹; (b) The whole residuals plotted in opposition to PGA for the Pazarcık and Wenchuan earthquakes, based mostly on Eq. 3 from Romeo (2000)²⁹; (c) The whole residuals versus R_JB for the Pazarcık and Wenchuan earthquakes based mostly on Eq. 4 from Liu et al. (2016)³¹; (d) The whole residuals versus V_S30 for the Pazarcık and Wenchuan earthquakes based mostly on Eq. 3 from Romeo (2000)²⁹. V_S30-binned means with one commonplace deviation error bars are plotted for every earthquake; (e) The whole residuals versus V_S30 for the Pazarcık and Wenchuan earthquakes based mostly on Eq. 4 from Liu et al. (2016)³¹, V_S30-binned mens with one commonplace deviation error bars for every earthquake.

The sturdy movement period

Significant period—outlined because the time interval between particular share thresholds of Arias depth (Trifunac and Brady, 1975)³⁴– is broadly adopted as one in every of period measures in engineering purposes. The D_5-95 (the time interval between 5 and 95% of cumulative Arias depth) was computed for each the Pazarcık and Wenchuan earthquakes on this research. The noticed D_5-95 values for the Pazarcık and Wenchuan earthquakes had been in contrast, as illustrated in Fig. 8a. Most D_5-95 values for the Wenchuan earthquake (reverse-slip fault) had been considerably greater than these for the Pazarcık earthquake (strike-slip fault) at comparable rupture distances. Figure 8b shows the noticed D_5-95 ploted in opposition to V_S30 for each the Pazarcık and Wenchuan earthquakes, revealing comparable D_5-95 values inside comparable V_S30 ranges for many D_5-95 noticed. In addition, the overall residuals of D_5-95 had been analyzed utilizing the GMPE mannequin developed by Afshari and Stewart (2016, hereafter, AS2016)³⁵. This mannequin was derived utilizing the NGA-West2 database (Ancheta et al., 2014)³⁶, using the geometric imply of two horizontal elements. The AS2016 mannequin has the next limitations for predictor variables: second magnitudes M_w 3.0 to eight.0, focal mechanisms (regular, strike-slip, reverse-slip and Unkown), R_rup ≤ 300 km, and V_S30 = 150 to 1500 m/s. Figure 8c,d current the overall residuals and error bars for each earthquakes. The predominantly constructive residuals point out that the noticed D_5-95 exceed the regional averages predicted by the AS2016 mannequin. The Wenchuan earthquake reveals greater error bars than the Pazarcık occasion for each R_rup and V_S30, suggesting that bigger D_5-95 for Wenchuan occasion. Such distinction in Significant period could also be attributed to the completely different fault kinds between the 2 earthquakes. The reverse-slip fault sometimes generates longer floor movement durations than the strike-slip fault with comparable magnitude. Another issue could also be rupture directivity. The Wenchuan earthquake featured unilateral rupture with a rupture size of roughly 300 km, whereas the Pazarcık earthquake exhibited bilateral rupture with a most size not more than 180 km (USGS). Significant period displays the vitality accumulation technique of floor movement, subsequently, the remark might relate to rupture mechanisms. The Pazarcık earthquake exhibited each supershear and subshear rupture propagation (Ren CM, 2024; Jia Z et al., 2023; He L et al., 2023)^37,38,39, with the extraordinarily quick rupture velocity. Propagation effectivity of seismic waves is greater, and might launch a considerable amount of vitality inside shorter intervals.

(a) The important durations (5%-95%) calculated for the Pazarcık earthquake and Wenchuan earthquake in opposition to R_rup; (b) The whole residual calculated for important durations (5%-95%), based mostly on the GMPE of Afshari and Stewart (2016)³⁵ for the Pazarcık earthquake and Wenchuan earthquake in opposition to R_rup, respectively.

Newmark displacement

Earthquake-triggered landslides are one in every of most devastating secondary hazards. Prediction of their spatial distribution and triggering circumstances is essential for regional seismic landslide hazard evaluation. Newmark (1965)⁴⁰ proposed a inflexible sliding block mannequin to estimate coseismal slope displacement. This mannequin treats the slope as a inflexible block with a recognized essential acceleration, the acceleration required to beat frictional resistance and start sliding on the inclined aircraft. Since the slope is subjected to seismic acceleration time historical past, it’s essential to calculate cumulative displacement of block. The Newmark displacement is calculated by way of double integration of acceleration time historical past exceeding the essential acceleration. At current, many Newmark displacement prediction fashions have been developed (Jibson, 2007; Lee, 2008etc.)^41,42. Most present fashions formulate Newmark displacement as a perform of essential acceleration and floor movement parameters, notably PGA or Arias depth I_a. In this part, Newmark displacements had been calculated for sturdy movement recordings from each Pazarcık and Wenchuan earthquakes, utilizing 4 essential accelerations (0.02 g, 0.05 g, 0.10 g, and 0.2 g). All strong-motion recordings from each the Pazarcık earthquake (0.01–40 Hz bandpass filtered) and Wenchuan earthquake (0.01–35 Hz bandpass filtered), processed utilizing Butterworth filters. Figure 9 presents the connection between Newmark displacement and PGA for each Pazarcık and Wenchuan earthquakes. Both earthquakes exhibit a nonlinear relationship in logarithmic coordinates between Newmark displacement and PGA at every essential acceleration. However, the Pazarcık earthquake reveals bigger scatter.

Observed Newmark displacement and PGAs at essential acceleration of 0.02, 0.05, 0.1 and 0.2 g for Pazarcık earthquake and Wenchuan earthquake, respectively. The black strong strains signify the Newmark displacement predicted medians developed by Jibson 2007⁴¹.

The Newmark displacement prediction fashions developed by Jibson 2007⁴¹ had been used on this research, which expresses displacement as a perform of essential acceleration and PGA, as following the Eq. 5:

the place D_n is Newmark displacement in centimeters, A_c is essential acceleration (starting from 0.02 to 0.4 g), and the anticipated medians had been proven in Fig. 9. As proven within the determine, because the essential acceleration will increase, the discrepancy between the Newmark displacement and the anticipated medians turn out to be extra pronounced for each two earthquakes. At a essential acceleration of 0.02 g, the Newmark displacement values for the Pazarcık earthquake are in good settlement with the predictive medians, whereas probably the most values for Wenchuan earthquake are larger. At essential accelerations of 0.05 g and 0.1 g, virtually all Newmark displacement values for each earthquakes are bigger than the anticipated medians. Newmark displacements are apparently larger than the anticipated medians for each occasions, because the essential acceleration of 0.2 g. This phenomenon advised that the Newmark displacement of each earthquakes exceed the averages predicted by Jibson’s (2007) mannequin⁴¹ at essential acceleration values of 0.05, 0.1, and 0.2 g, and reveals a dependence on essential acceleration dependence.

The Arias depth has been confirmed to be a dependable indicator of earthquake-induced slope instability (Harp and Wilson, 1995)⁴² Therefore, many researchers have adopted Arias depth for estimating seismic Newmark displacement. Unlike PGA, which solely displays the depth at a single level inside an acceleration time historical past, Arias depth integrates all the acceleration time historical past, thereby offering a extra complete characterization of floor movement (Rathje and Saygili, 2008; Hesieh and Lee, 2011)^43,44. Research on earthquake-induced landslide susceptibility (Lee et al., 2008)⁴⁵ reveals a robust correlation between landslide and Arias depth. Consequently, Arias depth is deemed superior to different floor movement parameters for landslide hazard evaluation. Figure 10 compares the noticed Newmark displacements underneath 4 essential accelerations for each earthquakes, with the anticipated displacement medians by the worldwide empirical mannequin of Hsieh and Lee 2011⁴⁴. The mannequin describes the connection between Newmark displacement and Arias depth on the fixed essential acceleration, as expressed by the next equation.

Observed Newmark displacement and arias depth at essential acceleration with 0.02, 0.05, 0.1 and 0.2 g for Pazarcık earthquake and Wenchuan earthquake, respectively. The black strong strains signify the anticipated Newmark displacement medians developed by Hsieh and Lee in 2011⁴⁴.

during which D_n is Newmark displacement in centimeters, I_a represents Arias depth, and A_c denotes essential acceleration (starting from 0.02 to 0.3 g). Observed that Newmark displacement values for Pazarcık earthquake reveals rising dispersion with reducing Arias depth, at A_c of 0.02 g, 0.05 g and 0.1 g. At A_c = 0.02 g, the noticed D_n values for Pazarcık and Wenchuan earthquakes present good settlement with the empirical mannequin at a variety of I_a from 0.2 to 1.3 m/s, whereas the remaining noticed D_n values fall under the anticipated medians. Almost noticed D_n values fall under the anticipated median on the A_c is 0.05 and 0.1 g. At A_c = 0.2 g, the noticed D_n values for Pazarcık earthquake present match with the anticipated medians, whereas all noticed D_n values for Wenchuan earthquake are under the anticipated medians. The outcome signifies that the D_n values of each earthquakes had been constantly decrease than the averages predicted by Hsieh and Lee in 2011⁴⁴ mannequin at 4 essential accelerations, apart from Pazarcık earthquake at A_c = 0.2 g.

Generally, seismic slope displacement is often estimated by way of a two-step process: (1) analysis of ground-motion depth measures utilizing applicable GMPEs; adopted by (2) software of Newmark displacement prediction fashions that make the most of depth measures and significant acceleration to foretell slope displacement. However, the analysis outcomes point out that the two-step strategy might enhance computational complexity, notably in a large-scale space software (Du and Wang, 2014)⁴⁶. Hence, Du and Wang (2016; hereafter, DW2016)⁴⁷ proposed a one-step empirical mannequin for predicting Newmark displacement. The mannequin immediately incorporates seismic info and web site circumstances as a substitute of depth measures. The predictive variables embrace M_w, R_rup, V_S30, and fault kind, expressed as follows,

the place D_n is Newmark displacement in centimeters, C₁–C₈ is regression coefficients; each R₁ and R₂ signify rupture distance (km): if R₁ ≤ 20 km, R₁ equals to R_rup, in any other case, R₁ is about to twenty km; if R₂ ≥ 20 km, R₂ equals to R_rup, in any other case, R₂ is about to twenty km; F_r is an indicator variable (1 for reverse slip sorts of faulting and 0 for in any other case); h is a fictitious depth in km estimated through the regression, and V_S30 denotes the averaged shear wave velocity of the higher 30 m (m/s). Figure 11 compares the noticed Newmark displacements underneath 4 essential accelerations for each earthquakes, with the anticipated medians from the Du and Wang (2016)⁴⁷ fashions. The Newmark displacement decreases with rising rupture distance. At A_c of 0.02, 0.05 and 0.1 g, Wenchuan earthquake reveals considerably bigger D_n values than Pazarcık earthquake with R_rup < 80 km, indicating its floor movement had extra pronounced impacts on slope stability within the affected space. At A_c of 0.02 g, the noticed D_n values for the Pazarcık earthquake had been considerably decrease than the anticipated medians at R_rup < 30 km, whereas most Wenchuan earthquake observations exceeded predicted medians at R_rup > 30 km. At A_c of 0.05 g, the noticed D_n values for the Pazarcık earthquake had been considerably decrease than the anticipated medians at R_rup ≤ 10 km, whereas the alternative outcome was noticed at R_rup > 10 km. Nearly all noticed D_n values for the Wenchuan earthquake exceeded the anticipated medians. At A_c of 0.1 g, most noticed D_n values for the Pazarcık earthquake exceeded the anticipated medians, and virtually Wenchuan earthquake observations confirmed considerably greater D_n values than predicted medians at R_rup ≤ 50 km. At A_c of 0.2 g, most noticed D_n values for each earthquakes had been bigger than the anticipated medians. The outcome point out that the D_n values of each earthquakes had been greater than the averages predicted by Du and Wang in 2016⁴⁷ mannequin at A_c = 0.05 and 0.1 and 0.2 g, apart from Pazarcık earthquake at A_c = 0.02 g.

Observed Newmark displacement versus rupture distance (R_rup) at essential acceleration with 0.02, 0.05, 0.1 and 0.2 g for Pazarcık earthquake and Wenchuan earthquake, respectively. The black strong strains signify the anticipated Newmark displacement medians for strike slip earthquake developed by Du and Wang (2016)⁴⁷. The black sprint dot strains signify the anticipated Newmark displacement medians for reverse slip earthquake developed by Du and Wang (2016)⁴⁷.

Research by Wilson and Keefer (1983, 1985)^48,49 advised that slopes produced the everlasting harm to slopes happens when the Newmark displacement worth exceeds 2 cm. Typically, the extra intense floor movement, the extra extreme and in depth the floor harm. Conversely, the larger floor harm signifies a extra intense floor movement, rising the chance of large-scale space landslides⁴⁹. As seen in Fig. 11, probably the most noticed D_n values exceeded 2 cm throughout two earthquakes throughout all essential accelerations (A_c = 0.02 g, 0.05 g, 0.1 g, and 0.2 g). The Pazarcık earthquake occurred within the japanese components of Anatolian plateau, the Wenchuan earthquake occurred in Longmenshan Fault Zone, situated between the seismically energetic Tibetan Plateau and Sichuan basin (Zhang 2013)⁵⁰. Both areas exhibit excessive terrain ruggedness index and elevated landslide susceptibility. The observations present most of Newmark displacements for each earthquakes exceeding 2 cm, indicating a sever landslide threat of their respective affected areas.