Dimitrios Zekkos

Dimitrios Zekkos
University of California, Berkeley | UCB · Department of Civil and Environmental Engineering

PhD, PE

About

167
Publications
71,886
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2,885
Citations
Citations since 2017
89 Research Items
2168 Citations
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Publications

Publications (167)
Article
Full-text available
On August 14, 2021, a Mw 7.2 earthquake struck the Tiburon Peninsula of western Haiti triggering thousands of landslides. Three days after the earthquake on August 17, 2021, Tropical Storm Grace crossed shallow waters offshore of southern Haiti triggering more landslides worsening the situation. In the aftermath of these events, several organizatio...
Article
Developing empirical correlations between the shear-wave velocity (V s) and the standard penetration test (SPT) blow count has been a long-term practice for sandy, silty, and clayey soils. However, the existing correlations are not suitable for gravelly soils because the SPT is not particularly reliable for gravelly soils due to the interference of...
Preprint
Full-text available
Large, sediment-laden floods in mountainous terrain can have disastrous consequences and play important roles in landscape evolution. These events often unfold as a series of interconnected processes, but understanding of such “hazard cascades” has been hampered by lack of quantitative data on sediment movement. Here, we use a time series of high-r...
Article
Ground improvement (GI) techniques have shown promise in effective liquefaction mitigation, but the physical mechanisms governing their three-dimensional (3D) response during dynamic loading are not yet fully understood. To evaluate the 3D performance of one GI technique, the rammed aggregate pier (RAP), in-situ site characterization, full-scale fi...
Article
Excess pore pressure generation of uniform gravel and gravel-sand mixtures was evaluated in this study. Comparisons were made with existing relationships for pore pressure generation of sands and show that gravel and gravel-sand mixtures can exhibit different pore pressure responses. The influence of liquefaction definition, gravel particle angular...
Article
Full-text available
Medicanes, a type of strong hurricanes/cyclones occurring in the Mediterranean, can be the source of major geohazard events in Mediterranean coastal and inland areas. Medicane Ianos that hit Greece during 17–19 September 2020 caused widespread damage, with numerous landsides and floods being the most prominent. Following the landfall of Medicane Ia...
Article
Full-text available
Small Island Developing States (SIDS) are acknowledged as particularly vulnerable to extreme climate events; however, the realities for transport infrastructure and bridges are still poorly studied. Assessing bridges in this context can be challenging due to data scarcity, a lack of local standards, and uncertainty due to climate change. While brid...
Chapter
Strong earthquakes can trigger thousands of landslides in mountainous areas, and accurate prediction of landslide occurrence can reduce the risk of infrastructure and communities to earthquake-induced regional landslides. However, current methods for regional landslide prediction are still in their infancy and prediction of landslide occurrence rem...
Article
Evaluating the liquefaction potential of gravelly soils using in-situ testing remains a challenge in geotechnical engineering practice. The Chinese Dynamic Cone Penetration (DPT) test provides an alternative for in-situ testing in gravelly soils to Becker Penetration Test (BPT) and the Standard Penetration test (SPT). The Chinese DPT was recently c...
Article
During the Mw 6.5 earthquake (2015) in Lefkada Ιsland, Greece, nearly 700 co-seismic landslides occurred along the western coastline of the island, where carbonate fault rocks, primarily fractured limestones and fault breccias, are encountered on steep slopes. The main objective of the present study is the investigation of a selected number of thes...
Conference Paper
Full-text available
Strong winds and heavy rainfall hit western and central Greece on 17–18 September 2020 as the Mediterranean Hurricane (Medicane) “Ianos” made its catastrophic passage through the country. Widespread flooding caused landslides and debris flows, while the erosive forces of water washed away foundation supports and earthworks along swelling rivers, im...
Article
Liquefaction assessment has primarily been performed using in situ penetration testing, but this practice has become problematic for gravelly soils. For example, standard penetration test (SPT)- or cone penetration test (CPT)-based correlations can become unreliable owing to interference with large gravel particles, while the Becker Penetration Tes...
Article
Unmanned aerial vehicles (UAVs) equipped with onboard sensors empower end‐users to collect data within a wide range of civil engineering applications such as structural condition assessment. While UAVs have been used primarily as mobile sensing platforms to obtain imagery or other data, their mobility can also be used to deploy sensor networks. In...
Article
Full-text available
Shallow bedrock strength controls both landslide hazard and the rate and form of erosion, yet regional patterns in near‐surface mechanical properties are rarely known quantitatively due to the challenge in collecting in situ measurements. Here we present seismic and geomechanical characterizations of the shallow subsurface across the central Himala...
Article
Full-text available
Flash floods are common manifestations of extreme weather events and one of the most severe natural hazards. In Europe, they have been responsible for 359 fatalities and an economic loss totalling 67 million USD in the past decade (EM-DAT), while their increasing severity is linked to climate change. Nevertheless, flash floods remain a poorly docum...
Conference Paper
On May 19, 2020, after several days of heavy precipitation, two earth dams failed (Edenville and Sanford) and two other dams were damaged (Secord and Smallwood), north of the town of Midland, MI. The failures resulted in about $100M in damages and the evacuation of about 11,000 people during the COVID-19 pandemic. In response to this destructive ev...
Article
Full-text available
Modern regulated landfills are designed to protect the environment by containing and isolating municipal solid waste (MSW) from the environment. Instead of treating MSW as a hazard to be contained, next generation landfills, here termed Sustainable Energy Reactor Facilities (SERFs) are envisioned to be designed and operated with a main focus on ene...
Article
Full-text available
Following the Cephalonia, Greece, 2014 earthquake sequence (Mw=6.1 and Mw=6.0), liquefaction of gravelly earthfill materials at the ports of Lixouri and Argostoli resulted in the manifestation of ground cracking and coarse-grained soil ejecta, while the quay walls in these ports exhibited lateral ground displacements ranging from 0.1 m to 1.5 m. To...
Article
Full-text available
To evaluate ground deformation resulting from large (~10 m) coseismic strike-slip displacements, we focus on deformation of the Kekerengu fault during the November 2016 Mw 7.8 Kaikōura earthquake in New Zealand. Combining post-earthquake field observations with analysis of high-resolution aerial photography and topographic models, we describe the s...
Conference Paper
Regional three-dimensional (3D) forward modeling stability analyses are presented for the Egkremnoi coastline of Lefkada Island in Greece. The pre-earthquake 5-m resolution DEM of the region was used as input for the regional 3D model and the modeling results were evaluated for five large landslides that occurred in the area during a Mw 6.5 earthqu...
Article
Full-text available
Rock mass strength is recognized as an important control on landscape morphology and evolution. However, the controls on rock strength in mountainous topography remain poorly characterized, in part because strength remains challenging to quantify at spatial scales relevant to geomorphology. Here we quantify the mechanical properties of rock masses...
Article
Full-text available
Three landfill gas generation models following two established kinetic pathways – first-order decay (Landfill Gas Emissions Model and Intergovernmental Panel on Climate Change) and sigmoidal growth (modified Gompertz) – are considered and fitted against a range of methane generation data generated from large-scale degradation experiments of seven w...
Technical Report
Full-text available
On September 17-20 2020 Medicane Ianos impacted Greece. The Medicane was associated with significant wind speeds, and precipitation. The amount of precipitation during a duration of about ~48 hrs was among the highest recorded in certain areas and exceeded in certain areas the mean annual precipitation. The extent of the affected area was very larg...
Article
Full-text available
Estimation of landslide erosion rates and hazard prediction require a firm understanding of the physical controls on landslide size. In this study we seek to understand how the characteristics of different landscapes and forcing events influence the distribution of landslide size at a regional scale. We explore the parameter space of a mechanically...
Article
Full-text available
In 2017, hurricane Maria caused unprecedented damage and fatalities on the Caribbean island of Dominica. In order to ‘build back better’ and to learn from the processes causing the damage, it is important to quickly document, evaluate and map changes, both in Dominica and in other high-risk countries. This paper presents an innovative and relativel...
Technical Report
Full-text available
Available also at: https://www.michigan.gov/mdot/0,4616,7-151-9622_11045_24249-533554--,00.html
Conference Paper
In situ assessment of waste settlements is a critical consideration for the operation, closure, and post-closure development of municipal solid waste (MSW) landfills. Settlement evolution is influenced by the biodegradation processes underway in the waste mass. Presently, the measurement of such settlements involves instrumentation at specific loca...
Article
A case history is presented of lateral spreading in two reclaimed port areas of the Cephalonia island, Greece, in the 2014 earthquake doublet (M w 6.1 & 6). Lateral ground displacements along 24 transects perpendicular to the quay walls in the two port areas were directly measured by ground surveys. Liquefaction of gravel-size fills was observed th...
Conference Paper
Full-text available
A fully autonomous flux chamber was designed, built, validated in the laboratory, and deployed at an MSW landfill in the state of Michigan. The self-powered chamber is capable of continuous methane emission data collection, analysis, and transmission. The chamber is controlled by the Urbano low-power microcontroller sensing platform and is equipped...
Conference Paper
Full-text available
The Corinth Canal crosses the Isthmus of Corinth and is of great importance for Mediterranean navigation as well as for railroad and highway connectivity between southern and central Greece. Since its operation, in 1893, the slopes have shown stability problems due to their steepness, the mechanical behavior of the Corinth Canal marl and the strong...
Conference Paper
Full-text available
Social media activity following the occurrence of an earthquake has the potential to provide valuable data on infrastructure condition and for disaster response and reconnaissance purposes. The challenge however is that the data with valuable content (i.e., the signal) is small compared to the earthquake-related social media activity overall (i.e.,...
Conference Paper
Full-text available
On November 17 th 2015, a Mw 6.5 earthquake struck the island of Lefkada in Greece. The shaking caused landslides and rockfalls particularly in the western part of the island. The stability of a major landslide that occurred in Egremnoi beach, was investigated with the objective to back-calculate the shear strength of the failed ground, which is ge...
Conference Paper
Constant volume direct simple shear testing is one of the most common tests used to characterize the cyclic response of earth materials. It is especially used to assess liquefaction susceptibility of a soil. Constant volume conditions are typically considered equivalent to undrained conditions, but are dependent on minimal volumetric strain during...
Conference Paper
The sequence of two major earthquakes with moment magnitudes of 6.0 and 6.1 that hit the island of Cephalonia in Greece in 2014, resulted in significant liquefaction of gravelly soils. Two of the island's main ports, Lixouri and Argostoli, were impacted by lique-faction of gravel-size fills and experienced significant lateral displacements (up to 1...
Conference Paper
Full-text available
Highways consist of many large structures requiring vigilant inspection and maintenance. While significant research attention has been focused on the health management of bridges, comparatively less attention has been paid to other highway structures, including retaining walls. In the United States, there has been a recent emphasis on extending the...
Conference Paper
Due to their mobility and autonomy, unmanned aerial vehicles (UAVs) provide an unprecedented opportunity to perform data gathering in a wide array of civil engineering applications such as visual inspection of infrastructure. Given their versatility, the role of UAVs can be expanded by leveraging their autonomous operations to deploy wireless sensi...
Article
Full-text available
Unmanned aerial vehicles (UAV), or drones, have become popular tools for practitioners and researchers alike. Recent years have seen a significant increase in UAV uses for many applications in the fields of science and engineering. A broad array of research development in UAVs has been reported in the literature. This paper provides a summary revie...
Chapter
Full-text available
Landfill gas (LFG) is a product of the biodegradation of municipal solid waste (MSW) under anaerobic conditions. LFG primarily consists of methane (CH4) (40–60%) and carbon dioxide (CO2) (40–60%), both greenhouse gases. Methane has high energy potential that remains largely untapped as a national energy source. In order to recover LFG for energy ge...
Chapter
For municipal solid waste (MSW) landfills that are situated in seismically active regions, the response of MSW under dynamic loading is critical to landfill design. In this study, a large-size simple shear device is utilized to perform cyclic testing on MSW under constant load (CL) and constant volume (CV) conditions which are considered equivalent...
Article
Understanding the factors that affect the monotonic and cyclic response of gravelly soils during earthquake events is critical to infrastructure design. In this study a large-size Cyclic Simple Shear (CSS) device was utilized to perform monotonic and cyclic shear tests on mixtures of either subrounded 9 mm Pea Gravel or angular 8 mm Crushed Limesto...
Article
Full-text available
The application of the Structure-from-Motion (SfM) methodology, as enabled by the growth of Unmanned Aerial Vehicle (UAV) technology, is expected to have significant impact in geotechnical engineering research and practice. SfM outputs are presented using selected geotechnical projects as examples, and include orthophotos, 3D point clouds, and thre...
Article
Full-text available
Municipal solid waste (MSW) is biodegradable in landfills under anaerobic conditions. The evolution of the hydrobiochemical-mechanical (HBM) processes during degradation is investigated first through experiments and subsequently through modelling. Three well-characterised MSW specimens from US landfill sites with significantly different waste compo...
Conference Paper
The ability to quickly, efficiently and reliably characterize changes in the landscape following an earthquake has remained a challenge for the earthquake engineering profession. The 2016 Mw7.8 Kaikoura earthquake provided a unique opportunity to document changes in topography following an earthquake on a regional scale using satellite derived high...
Conference Paper
Following the November 14 2016 Mw7.8 Kaikoura earthquake, field expeditions were undertaken using Unmanned Aerial Vehicles (UAVs) to map 25 sites of scientific interest with a plan area of 7.2 km2. A total of 23,172 images collected by the UAVs were used as input in Structure-from-Motion (SfM) to create 3D models of the target areas with a focus on...
Conference Paper
Multichannel analysis of surface waves (MASW) is an established method for measuring the in situ shear wave velocity (Vs) of geomaterials. Depending on the site conditions, a sledgehammer may be incapable of generating a signal within the desired frequency band or the site may be difficult to access. In this study, the sledgehammer was replaced by...
Conference Paper
The effects of ground motion modification on the characteristics and time histories of the original seed motion have been the topic of recent studies. However, the effects of ground motion modification on the results of subsequent seismic analyses for which the ground motions are used has not been studied. This paper examines the impact that ground...
Conference Paper
This paper presents preliminary results of a field experimental program that was conducted to investigate the dynamic properties of municipal solid waste (MSW) disposed of and comingled with hazardous waste at a hazardous waste landfill in Southern California. The investigation was performed in the linear and nonlinear strain range. The linear port...
Article
Direct simple shear (DSS) testing, despite its limitations, is one of the most common laboratory element tests in geotechnical engineering practice. The development and validation of a 300-mm diameter DSS device as well as test data generated for two materials with oversized particles, specifically pea gravel and municipal solid waste, are presente...
Article
Full-text available
We present field evidence and a kinematic study of a rock block mobilized in the Ponti area by a Mw = 6.5 earthquake near the island of Lefkada on 17 November 2015. A detailed survey was conducted using an unmanned aerial vehicle (UAV) with an ultrahigh definition (UHD) camera, which produced a high-resolution orthophoto and a digital terrain model...
Article
Full-text available
Seven municipal solid waste (MSW) specimens with variable initial waste compositions were biodegraded in large (d = 300 mm, h = 600 mm) laboratory landfill simulators under leachate-recirculation-enhanced anaerobic biodegradation conditions to investigate changes in the biochemical and physical characteristics of solid waste, leachate and biogas du...
Conference Paper
Full-text available
Unlike dynamic properties of municipal solid waste (MSW), the dynamic properties of engineered fill landfill covers at MSW and other landfill sites have not been extensively investigated. The two main reasons for the dearth of research on this topic are: (i) design engineers realize that modern landfill covers are relatively thin (on the order of 1...
Article
The evolution of volcanic landscapes and their landslide potential are both dependent upon the weathering of layered volcanic rock sequences. We characterize critical zone structure using shallow seismic Vp and Vs profiles and vertical exposures of rock across a basaltic climosequence on Kohala peninsula, Hawai'i, and exploit the dramatic gradient...
Article
Research on the cities of the Classical Greek world has traditionally focused on mapping the organisation of urban space and studying major civic or religious buildings. More recently, newer techniques such as field survey and geophysical survey have facilitated exploration of the extent and character of larger areas within urban settlements, raisi...