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The 2023 M7.8 Kahramanmara\c{s}/Pazarcik earthquake was larger and more destructive than what had been expected. Here we analyzed near-field seismic records and developed a dynamic rupture model that reconciles different currently conflicting inversion results and reveals spatially non-uniform propagation speeds in this earthquake, with predominantly supershear speeds observed along the Narli fault and at the southwest (SW) end of the East Anatolian Fault (EAF). The model highlights the critical role of geometric complexity and heterogeneous frictional conditions in facilitating continued propagation and influencing rupture speed. We also constrained the conditions that allowed for the rupture to jump from the Narli fault to EAF and to generate the delayed backpropagating rupture towards the SW. Our findings have important implications for understanding earthquake hazard and guiding future response efforts and demonstrates the value of physics-based dynamic modeling fused with near-field data in enhancing our understanding of earthquake mechanisms and improving risk assessment.

The Saricicek howardite meteorite shower consisting of 343 documented stones occurred on September 2, 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Saricicek experienced a complex cosmic-ray exposure history, exposed during 12-14Ma in a regolith near the surface of a parent asteroid, and that an 1m sized meteoroid was launched by an impact 22 +/- 2Ma ago to Earth (as did one-third of all HED meteorites). SIMS dating of zircon and baddeleyite yielded 4550.4 +/- 2.5Ma and 4553 +/- 8.8Ma crystallization ages for the basaltic magma clasts. The apatite U-Pb age of 4525 +/- 17Ma, K-Ar age of 3.9Ga, and the U,Th-He ages of 1.8 +/- 0.7 and 2.6 +/- 0.3Ga are interpreted to represent thermal metamorphic and impact-related resetting ages, respectively. Petrographic; geochemical; and O-, Cr-, and Ti-isotopic studies confirm that Saricicek belongs to the normal clan of HED meteorites. Petrographic observations and analysis of organic material indicate a small portion of carbonaceous chondrite material in the Saricicek regolith and organic contamination of the meteorite after a few days on soil. Video observations of the fall show an atmospheric entry at 17.3 +/- 0.8kms(-1) from NW; fragmentations at 37, 33, 31, and 27km altitude; and provide a pre-atmospheric orbit that is the first dynamical link between the normal HED meteorite clan and the inner Main Belt. Spectral data indicate the similarity of Saricicek with the Vesta asteroid family (V-class) spectra, a group of asteroids stretching to delivery resonances, which includes (4) Vesta. Dynamical modeling of meteoroid delivery to Earth shows that the complete disruption of a 1km sized Vesta family asteroid or a 10km sized impact crater on Vesta is required to provide sufficient meteoroids 4m in size to account for the influx of meteorites from this HED clan. The 16.7km diameter Antionia impact crater on Vesta was formed on terrain of the same age as given by the He-4 retention age of Saricicek. Lunar scaling for crater production to crater counts of its ejecta blanket show it was formed 22Ma ago.

The MARsite project (Nov 2012-Avril 2016), one of the three SUPERSITE concept FP7 projects, deals with the definition of new directions in seismic hazard assessment through focused earth observation in the Marmara Supersite. This project gathers different research groups in a comprehensive monitoring activity developed in the Sea of Marmara Region. This region is one of the most densely populated parts of Europe and rated at high seismic risk level since the 1999 Izmit and Duzce devastating earthquakes. The 6th Work Package of MARsite project offered a very valuable frame to undertake simultaneous and complementary scientific investigations and studies to get deeper insight in the seismic and rainfall landslide topic, ranging from methodology to hazard assessment tool. This package focused on two sub-regional areas of high interest. First, the Avcilar-Beylikdüzü peninsula, located westwards of Istanbul, is a highly urbanized concentrated landslide prone area, showing high susceptibility to both rainfalls while affected by very significant seismic site effects. Second, the off-shore entrance of the Izmit Gulf, close to the termination of the surface rupture of the 1999 earthquake, that shows an important slump mass facing the Istanbul coastline. For the on-shore area, after refining the landslide inventory of the peninsula, one of the nine inventoried rototranslational landslides was chosen as pilot site, the Büyükçekmece landslide. This landslide has a continuous activity and a composite mechanism (including several secondary sliding surfaces); it moves at low velocity and involves sandy and clayey deposits of a local Cenozoic Succession damaging several infrastructures, such as buildings and roads. Various geophysical campaigns were carried out and then a field temporary multi-parameter monitoring was set up, composed of GPS-RTK, two seismic probes, thermometer, rain-gauge, moisture, etc.. Hyperspectral and Dinsar imagery technologies were also deployed to complete inventory and observational information. In order to analyze the slope stability conditions under seismic shaking, not-conventional pseudostatic slope stability analyses as well as numerical simulations via a finite difference code were performed. These last studies took advantage from the reconstruction of a detailed engineering-geological model on the basis of extensive geological and geomorphological field campaign and a vast drilling program undertaken by the Istanbul Metropolitan Area. According to these numerical simulation results the landslide mass has a high sensitivity to seismic waveforms enriched in low frequencies (

Seismic risk is the first source of life and economical losses in Turkey. Located on the North Anatolian fault line, Istanbul and its surrounding areas have been hit by an estimated 120 earthquakes over the last 2,000 years, according to the Istanbul municipality's Disaster Coordination Center. Besides the seismic threat, landslides in Turkey constitute an important source of loss. The 1999 Earthquake caused extensive landslides while tsunami effects were observed during the post-event surveys in several places along the coasts of the Izmit bay (Altinok et al., 2001). The seismic landslide hazards have received considerable attention in recent years, but quantitative knowledge on seismic landslide phenomena is still fragmentary, databases with high quality observational data are lacking, and those collateral seismic geohazards are clearly challenging both the scientific community and prevention authorities. These phenomena call for further collaborative researches aiming eventually to enhance preparedness and crisis management. As one of the three Supersite concept FP7 (EU’s Seventh Framework Programme for Research) projects dealing with long term high level monitoring of major natural hazards at the European level, the MARsite project (Nov 2012-Nov 2015) assemble research groups in a comprehensive monitoring activity developed in the Sea of Marmara Region, one of the most densely populated parts of Europe and rated at high seismic risk level since the 1999 Izmit and Duzce devastating earthquakes. Supersites is an initiative of the geohazard scientific community. The Supersites provide access to space borne and in-situ geophysical data of selected sites prone to earthquake, volcano or other hazards. The 6th Work Package of MARsite project gathers 9 research groups to study earthquake-induced landslides focusing on two sub-regional areas of high interest. First, the Cekmece-Avcilar peninsula, located westwards of Istanbul, is a highly urbanized concentrated landslide prone area (Duman et al., 2006), showing high susceptibility to both rainfalls while affected by very significant seismic site effects (Ergin et al., 2004; Picozzi et al., 2009). Second, the off-shore entrance of the Izmit Gulf, close to the termination of the surface rupture of the 1999 earthquake, that shows an important slump mass facing the Istanbul coastline. A multidisciplinary research program based on pre-existing studies has been designed with objectives and tasks linked to constrain and tackle progressively some challenging issues related to data integration, modeling, and monitoring. For the on-shore area, this program included the refined analysis of the seismic site response, the installation of a permanent multi-parameter ground monitoring of a representative unstable slope as well as the in-depth slope stability analysis based on the stress-strain dynamic numerical modelling approach. After refining the landslide inventory of the peninsula, one landslide (Beylikdüzü landslide) was chosen as pilot site as it resulted the most dangerous due to the highest susceptibility to seismically-induced re-activation and to the highest exposition of buildings and infrastructures referred to the last decade (i.e. after the 1999 Izmit earthquake occurrence). In this landslide area were carried out geophysical campaigns and a field permanent multi-parameter observatory was set up, composed of GPS-RTK, borehole- and surface-seismometers thermometer, rain-gauge, moisture, etc.. Hyperspectral and Dinsar imagery technologies are also deployed to complete inventory and observational information. Concerning, the modelling of the seismic response and displacements of the pilot landslide, the first step was to have an adequate engineering-geological model. A first engineering-geological model was reconstructed on the basis of extensive geological and geomorphological field campaign and a vast drilling program undertaken by the Istanbul Metropolitan Area. Based on a detailed engineering-geological model of the landslide slope, a not-conventional pseudostatic slope stability analysis (Figure 1) was performed by considering a pseudostatic force distribution within the landslide mass according to a specific wave form instead of a conventional constant pseudostatic force. Numerical simulations of the seismic response in the landslide slope were also performed aiming at evaluating the role of geological and structural setting of the slope on the landslide displacements in case of expected earthquakes. Multi-parameter monitoring with its long-term time series will be an important tool to validate numerical models and simulations and set up an experimental early warning system for earthquake and rainfall induced landslide.

Earthquake-triggered landslides have an increasing disastrous impact in seismic regions due to the fast growing urbanization and infrastructures. Just considering disasters from the last fifteen years, among which the 1999 ChiChi earthquake, the 2008 Wenchuan earthquake, and the 2011 Tohoku earthquake, these events generated tens of thousands of coseismic landslides. Those resulted in amazing death toll and considerable damages, affecting the regional landscape including its hydrological main features. Despite a strong impetus in research during past decades, knowledge on those geohazards is still fragmentary, while databases of high quality observational data are lacking. These phenomena call for further collaborative researches aiming eventually to enhance preparedness and crisis management. The MARSITE project gathers research groups in a comprehensive monitoring activity developed in the Sea of Marmara Region, one of the most densely populated parts of Europe and rated at high seismic risk level since the 1999 Izmit and Duzce devastating earthquakes. Besides the seismic threat, landslides in Turkey and in this region constitute an important source of loss. The 6th Work Package of MARSITE project gathers 9 research groups to study earthquake-induced landslides focusing on two sub-regional areas of high interest among which the Cekmece-Avcilar peninsula, located westwards of Istanbul, as a highly urbanized concentrated landslide prone area, showing high susceptibility to both rainfalls while affected by very significant seismic site effects. A multidisciplinary research program based on pre-existing studies has been designed with objectives and tasks linked to constrain and tackle progressively some challenging issues related to data integration, modeling, monitoring and mapping technologies. Since the start of the project, progress has been marked on several important points as follows. The photogeological interpretation and analysis of ENVISAT-ERS DInSAR temporal series has been undertaken, providing global but accurate Identification and characterization of gravitational phenomena covering the aera. Evaluation of the resolution and identification of landslide hazard-related features using space multispectral/hyperspectral image data has been realized. Profit has been gained from a vast drilling and geological - geotechnical survey program undertaken by the Istanbul Metropolitan Area, to get important data to complete the geological model of the landslide as well as one deep borehole to set up permanent instrumentation on a quite large slow landslide, fully encircled by a dense building environment. The selected landslide was instrumented in 2014 with a real-time observational system including GPS, rainfall, piezometer and seismic monitoring. Objective of this permanent monitoring system is three folds: first to detect and quantify interaction between seismic motion, rainfall and mass movement, building a database opened to the scientific community in the future, second to help to calibrate dynamic numerical geomechanical simulations intending to study the sensitivity to seismic loading, and last but not least. Last but not least important geophysical field work has been conducted to assess seismic site effects already noticed during the 1999 earthquake .Data, metadata and main results are from now progressively compiled and formatted for appropriate integration in the cloud monitoring infrastructure for data sharing.

International audience; Earthquake-triggered landslides have an increasing disastrous impact in seismic regions due to the fast growing urbanization and infrastructures. Just considering disasters from the last fifteen years, among which the 1999 Chi-Chi earthquake, the 2008 Wenchuan earthquake, and the 2011 Tohoku earthquake, these events generated tens of thousands of coseismic landslides. Those resulted in amazing death toll and considerable damages, affecting the regional landscape including its hydrological main features. Despite a strong impetus in research during past decades, knowledge on those geohazards is still fragmentary, while databases of high quality observational data are lacking. These phenomena call for further collaborative researches aiming eventually to enhance preparedness and crisis management. As one of the three SUPERSITE concept FP7 projects dealing with long term high level monitoring of major natural hazards at the European level, the MARSITE project gathers research groups in a comprehensive monitoring activity developed in the Sea of Marmara Region, one of the most densely populated parts of Europe and rated at high seismic risk level since the 1999 Izmit and Duzce devastating earthquakes. Besides the seismic threat, landslides in Turkey and in this region constitute an important source of loss. The 1999 Earthquake caused extensive landslides while tsunami effects were observed during the post-event surveys in several places along the coasts of the Izmit bay. The 6th Work Package of MARSITE project gathers 9 research groups to study earthquake-induced landslides focusing on two sub-regional areas of high interest. First, the Cekmece-Avcilar peninsula, located westwards of Istanbul, is a highly urbanized concentrated landslide prone area, showing high susceptibility to both rainfalls while affected by very significant seismic site effects. Second, the off-shore entrance of the Izmit Gulf, close to the termination of the surface rupture of the 1999 earthquake, that shows an important slump mass facing the Istanbul coastline. A multidisciplinary research program based on pre-existing studies has been designed with objectives and tasks linked to constrain and tackle progressively some challenging issues related to data integration, modeling, monitoring and mapping technologies. Concerning the on-shore area, this program includes the refined analysis of the seismic site response, the permanent multi-parameter ground monitoring of a representative unstable slope as well as the in-depth slope stability analysis based on the stress-strain dynamic numerical modelling approach. Hyperspectral and Dinsar imagery technologies are also deployed to complete inventory and observational information. The development of a dynamic GIS tool featuring capabilities to integrate and process very different types of data, and up-date susceptibility maps based on near to real-time rainfall-seismic shaking input, is currently undertaken. Moreover, the research is gaining high profit of a vast drilling program undertaken by the Istanbul Metropolitan Area, aiming to yield a detailed geological and geotechnical characterization of the slopes. Also included in the objectives is to test a landslide early warning system. As regards the selected off-shore area, high resolution geophysical marine surveys are being conducted to complete its geomorphological description to help in mapping possible incipient mass movements. This is especially expected to provide better-constrained input for both laboratory testing and numerical modeling of tsunami scenarios thank to a unique lab-scale tsunami channel.

In the frame of an EU-FP7 project titled as MARsite, a work package with the number of 6 (WP6) aims the characterization and modeling of landslides founding in the western part of Istanbul metropolitan area. In the first stage, we analyzed site effects at 8 stations located in the area by using weak motion earthquake data. The stations were deployed by TUBITAK in 2009 and two of them are still in the field. The largest distance among the stations is about 20 km. The instruments were equipped with Lennartz 1Hz sensors and RefTek 130 dataloggers. The stations work online and are acquiring 100 Hz data. Between 2009 and 2013, 36 earthquakes ranging from M3.4 to M5.2 were recorded by the instruments. Their epicenter distances range from 40 km to 150 km. The study area takes place between Kucukcekmece and Buyukcekmece lakes. It is bordered by the Marmara Sea in the south. While the topography sharply increases from the sea coast to 50-100 m elevation in the south, it has plateau character elevated gently toward to the north. This plateau is incised and dissected by river channels flowing to the Marmara Sea. Both river slopes and coastal slopes are active landslide areas. The materials attached loosely on steep slopes flow downward. While the youngest geological units take place on the top of the plateau, it is possible to see the older units on the bottom of river channels and the coastal slopes. Site response functions at each site were analyzed by using the Horizontal-to-Vertical Spectral Ratio (HVSR) and Standard Spectral Ratio (SSR) methods. The two methods show a general agreement in the estimation of the fundamental resonance frequencies including in some cases their amplitudes as well. On the other hand, the results of the HVSR method show less scattering than those of the SSR method. Two resonance frequencies on the spectral ratios attract attention especially at the stations close to the Marmara Sea corresponding to the deep and shallow transitions. We also computed kappa value for each site, which is an additional site-dependent parameter representing near surface attenuation of seismic waves. High kappa values can be interpreted to sites which have materials attached loosely. Our results show that the sites on rock are represented with low kappa value, whereas the sites on soil show high kappa value.