Exploring the Evolution of Seismic Hazard and Risk Assessment Research: A Bibliometric Analysis

Abstract

A bibliometric analysis spanning from 2002 to 2022 examines the landscape of seismic hazard and risk assessment research, critical for disaster preparedness in earthquake-prone regions. The study uncovers a substantial increase in related studies, notably surging around 2006. Leading contributors hail from China, the United States, Italy, and the United Kingdom, underlining the global significance of the subject. Common terms in scholarly articles include “seismic hazard”, “seismic risk”, “earthquake”, “vulnerability”, “GIS” (Geographic Information System), and “liquefaction”. While seismic hazards remain the primary focus, a growing interest in risk assessment, particularly for induced phenomena like landslides and liquefaction, is noted. Researchers predominantly assess vulnerability across various structural elements, reflecting a holistic approach to understanding and mitigating the impact of earthquakes on infrastructure and communities. In summary, the bibliometric analysis provides a comprehensive overview of seismic hazard and risk assessment research, highlighting field growth, key research areas, and an increasing focus on risk assessment in response to natural phenomena. The findings offer valuable insights for both academics and practitioners invested in the field’s future development.

1. Introduction

Earthquakes can result in severe consequences for human communities, infrastructure, and the natural surroundings. Data from the Center for Research on the Epidemiology of Disasters (CRED) show that earthquakes caused the most widespread devastation, accounting for 58% of total fatalities in natural disasters from 2000 to 2019. According to EM-DAT (2020), the yearly economic losses caused by earthquakes in 2021 are expected to be about $32.7 billion [1]. Mitigating seismic risks is a diverse process, but it always starts with a precise assessment of seismic hazards [2]. The evaluation of earthquake hazards is a critical component of disaster risk reduction and preparedness efforts worldwide. Understanding the spatial and temporal distribution of seismic hazards and the underlying factors contributing to earthquake occurrence and intensity is essential for making informed decisions regarding land-use planning, building construction, and emergency response strategies. Over the years, significant advancements in the field of earthquake hazard assessment have been made, driven by advancements in geophysics, seismology, and geospatial technologies. These developments have allowed for more accurate and comprehensive evaluations of earthquake risks. The objective of this research is to conduct a bibliometric analysis focusing on earthquake hazard assessment, with particular emphasis on crucial data sources, methodologies, and recent trends in research. By synthesising existing knowledge and discussing emerging challenges, this research contributes to the ongoing efforts to enhance our understanding of earthquake hazards and improve societal resilience in earthquake-prone regions. Bibliometric analysis is a powerful quantitative method for evaluating the scientific literature and is increasingly gaining prominence in various research fields [3].

Bibliometric analysis has gained popularity as a useful tool for assessing the quality of scientific output [4]. In the geotechnical field, bibliometric studies on settlement research [5], landslide susceptibility research [6,7], and soil erosion study [8] have been carried out, but no research on seismic hazard assessment has been conducted. The significance of this approach lies in its ability to provide a comprehensive and systematic overview of the existing body of knowledge. In this context, bibliometric analysis plays a pivotal role in mapping the landscape of earthquake hazard assessment research. It helps identify influential publications, prolific authors, key institutions, emerging research trends, and critical gaps in the literature. By scrutinising citation patterns and co-authorship networks, researchers can gauge the impact and dissemination of findings within the scientific community. There are various benefits to using bibliometric approaches in the analysis. First, a thorough comprehension of the research subject is not required. Secondly, they are regarded as ‘objective’ since their cognitive career is not shaped by the interpretation of a researcher. Finally, they are predicated on decisions the researcher made at the moment while doing the research [9]. Researchers employ bibliometric analysis for several purposes, including identifying new trends in the performance of articles and journals, patterns of collaboration, and the components of research, as well as investigating the intellectual framework of a particular field in the body of the existing literature [3]. Additionally, bibliometric analysis enables the monitoring of how research progresses and changes over time, enabling researchers to discern shifts in emphasis and focus within the field. This method aids in informed decision-making by highlighting areas that require further investigation, facilitating the allocation of resources, and fostering collaboration among researchers. Thus, bibliometric analysis provides valuable insights into the current state of earthquake hazard assessment research and serves as an indispensable tool for shaping its future trajectory and enhancing its effectiveness in addressing the complex challenges posed by seismic hazards.

This study emphasizes earthquake hazard assessment and risk, which are particularly relevant to the geotechnical field. The chosen keywords specifically highlight hazard assessment and risk, rather than focusing solely on the seismicity problem itself. In contrast, Gizzi and Potenza [10] conducted a bibliometric analysis with a tailored methodological approach, focusing on the international and national (Italian) studies initiated and advanced since the Irpinia-Basilicata Earthquake of 23 November 1980. Their analysis delves into the evolution and core issues surrounding earthquake and seismicity, including details on fault features. Similarly, Xingjian et al. [11] conducted a bibliometric study on earthquake research from 1900 to 2010, focusing on the core problems of earthquakes during that period without explicitly acknowledging trends in hazard and risk assessment. Commonly used keywords in their study include evolution, California, deformation, model, inversion, seismicity, tectonics, crustal structure, fault, zone, lithosphere, and attenuation. Incorporating references to these two papers alongside the current study will provide a broader perspective on earthquake research.

It is important to highlight that despite the increasing interest in earthquake research, there has been a lack of comprehensive global attention to systematically measure and assess scholarly papers. This study utilized VOS viewer software for map visualization and data mining in conjunction with the Scopus database. The following major goals are the focus of this paper: (1) demonstrate how seismic hazard assessment evolved and spread throughout the world between 2002 and 2022; (2) determine prominent journals, significant writers, leading nations, and the extent of international collaboration; and (3) ascertain the most often used keywords in publications and investigate their relationships with one another. The overarching aim is to pinpoint gaps in the existing literature and offer future scholars’ insights into new directions for exploration in this field of study.

2. Methodology

The data-gathering approach utilised in this research was based on the methodology outlined by refs. [12,13], with certain adjustments made to align with the research goals.

Sources and Gathering of Data

The data for the analysis were obtained electronically from the Scopus database, using the most recent version accessible as of October 2023. Scopus was chosen because of its recent advances as one of the most comprehensive online databases for academic articles, beating competitors such as Web of Science and Google Scholar in terms of frequent updates and growth [14,15,16,17]. The primary focus of this study was to explore the evolution of seismic hazard and risk assessment. To identify pertinent publications, the following search terms were employed: (earthquake AND hazard AND assessment) AND (vulnerability OR risk) AND (seismic AND hazard) OR (ground AND motion AND prediction) AND (analysis OR assessment OR method).

A comprehensive initial search using a broad query yielded 4765 documents without restrictions on language, document type, publication year, or data sources. Abbate et al. (2022) established specific exclusion criteria to refine the search results, ensuring precision and relevance in their study [18]. The data collection spanned from 2002 to 2022, with the exclusion of review papers and materials not aligned with the study’s objectives. Review papers were not included because the bibliometric analysis intends to present original new research discoveries rather than recapitulate the existing literature. The focus was on final-stage publications and English-language articles published in journals. Figure 1 illustrates the research framework and the procedure for selecting studies. For additional analysis, the complete dataset—which included publication years, keywords, and citation details—was saved to a CSV file. The search outcomes were examined through Scopus’s “result analysis” feature, focusing particularly on factors like publication year, authorship, country of origin, institutional affiliations, subject categories, and total citations.

Version 1.6.15 of the VOS viewer programme was used to analyse variables such publication years, document types, authors, co-cited authors, institutions, nationalities, journal sources, and keywords to create social network maps. All the data collecting and analysis for this procedure was performed in Microsoft Excel 365, and Excel was also used to create any related graphics. Cluster analysis and the creation of social network maps to look at co-occurrence and co-authorship patterns were made possible by VOS viewer. On these maps, node size and line thickness indicate their importance. Nodes stand for amount or frequency of occurrence, while lines that connect them indicate relationships. The strength or depth of the link is indicated by the line thickness. The approach described by van Eck and Waltman (2022) makes it easier to see patterns in research on seismic risk and hazard [19].

3. Bibliometric Analysis

A total of 4062 entries on seismic hazard and risk assessment were found in this investigation. Before drawing an initial conclusion, statistical data obtained during the investigation need to be organised and carefully reviewed. The documents were classified into six groups (see Figure 2). Most of the publications were articles (65%) followed by conference papers (25%). The study on seismic hazard assessment may show development trends and changes based on the volume of published publications and conference papers.

3.1. Annual Publication and Growth Interests

A total of 1842 journal articles about earthquake and seismic hazard assessment have been successfully published in the past ten years. To identify trends and yearly growth rates of publications from 2002 to 2022, the gathered data were arranged and displayed chronologically (Figure 3). The percentage of international publications has been rising over time. In 10 years, the year with the fewest articles (21) was 2005, and the year with the most (185) was 2020. As seen by the graph, less than 30 articles per year were published between 2002 and 2006. However, scientific interest grew after 2006. The 2004 Indian Ocean earthquake, one of the deadliest earthquake disasters, was probably the reason for the increase in studies 2006. According to Stein and Okal (2007), the Sumatra-Andaman earthquake on December 26, 2004, was the first “giant” or “extreme” earthquake (with moment magnitude Mw > 9) since the earthquake that struck Alaska in 1964, due to its tremendous size and the deadly tsunami that occurred, earth scientists all around the world conducted a variety of investigations [20,21]. From 2006 to 2011, the number of papers published each year ranged between 23 and 139. From 2018 to 2022, research outputs in this area have received significant attention, with publication numbers remaining in the triple digits each year.

Figure 4 displays the overall number of citations and the citations normalised per article in the context of seismic hazard assessment research spanning 2002 to 2022. These publications collectively garnered a total of 48,923 citations. The chart reveals a fluctuating growth pattern characterised by several fluctuations in annual citation counts over the years. The year 2011 saw the highest total citations, amounting to 6620, whereas 2022 had the lowest, with just 649 citations. Notably, articles published in earlier years tended to receive more citations than more recent publications, which is understandable, as it takes time to accumulate references. On the other hand, the years 2003 and 2006 had the highest normalised citations per article, averaging 71 citations, while 2022 had the lowest, with only three normalised citations per paper. Figure 4 and Figure 5 demonstrate that more publications are created throughout time, but the average number of citations per article declines from 2012 to 2022. This is because as a field develops and matures, more scholars participate, resulting in a greater number of published papers. However, this increase in publications does not necessarily imply that the overall effect of the research rises accordingly.

Table 1. Total publications and citations on seismic hazard assessment research from the Scopus database.

Year of Citation	Annual Publication	Number of Citations	H-Index	Articles Cited (%)
2002	28	757	15	75
2003	25	1790	13	72
2004	25	649	14	90
2005	21	1152	16	90
2006	23	1635	16	91
2007	39	1584	21	89
2008	54	2635	26	96
2009	92	5448	36	97
2010	117	3905	39	96
2011	139	6620	43	98
2012	70	2530	28	92
2013	70	1851	26	95
2014	102	3039	30	94
2015	80	2364	24	93
2016	85	1634	23	96
2017	112	2501	30	99
2018	129	2386	28	96
2019	113	1796	24	96
2020	185	2473	24	97
2021	167	1526	20	90
2022	166	609	11	86

shows the total publications and citations on seismic hazard assessment studies from the Scopus database annually. The column labelled in Table 1; ‘Year of Citation’ indicates the specific year in which a citation to the referenced publication appears in the citing document. ‘Annual Publication’ is the number of journals published in a year. ‘Number of citations’ in Table 1 refers to the number of times other works in the academic literature have cited each publication. ‘H index’ is a metric used to measure the productivity and impact of a researcher’s scholarly output. The percentage of the article cited is the proportion of articles published by a journal. This metric is calculated by dividing the number of articles cited at least once by the total number of articles published, then multiplying by 100. As indicated in Table 1, the total number of citations, amounting to 48,923, was distributed among 1842 articles. The analysis of the data revealed that there was no correlation between the overall number of published papers and the corresponding total number of citations received each year. For instance, in 2020, despite having the highest number of published articles at 185, they only accumulated a total of 2473 citations. Conversely, in 2011, there were the highest total citations, amounting to 6620, while the number of publications for that year was 139. This suggests that the methodologies and approaches employed in 2011, such as operational earthquake forecasting [22], techniques for evaluating earthquake-triggered landslides [23], and the introduction of CyberShake, a physics-based hazard model [24], played a crucial role in shaping the emerging research interests. In addition, 2011 had the highest H-index value (43). Among the 1842 documents, the journal article titled ‘Landslip hazards triggered by the 2008 Wenchuan earthquake, Sichuan, China’ by Yin et al. (2009) holds the highest number of citations, totalling 652 [25]. Following closely is the article by Lagomarsino and Giovinazzi (2006) titled ‘Macroseismic and mechanical models for the vulnerability and damage assessment of current buildings’, which has garnered 567 citations [26].

3.2. Top Contributing Country

In terms of the quantity of publications on seismic hazard assessments,

Table 2. Top 10 countries with productive publications on seismic hazard and risk assessment.

List	Country	Total Publication	Total Citations	H-Index	Normalised Citation per Article
1	United States	369	5611	58	15
2	Italy	350	4999	52	14
3	China	169	1853	27	11
4	United Kingdom	138	1980	33	14
5	India	120	673	21	6
6	France	115	322	29	3
7	Iran	108	674	17	6
8	Canada	98	956	24	10
9	Germany	93	1143	28	12
10	Turkey	83	846	24	10

lists the top 10 producing nations. Table 2 shows the total publication, total citations, H-index and normalised citation per article. Normalised citation per article is the average amount of citations that an article receives. With 369 papers, the United States is the biggest contributor among the 112 countries covered in this study, which represents 13% of total publications across all 112 countries. Italy comes in second with 350 publications. The United States and Italy have a high H-index of 58 and 52, with total citations of 5611 and 4999, respectively. Traditionally, the United States (US) has been leading the world in publication output [27]. In the year 2020, the total number of published articles amounted to 2.9 million, with the United States, the United Kingdom, and Canada collectively contributing to over 90% of this total. The United States’ high interest in earthquakes may also be attributed to the country’s experience with ground shaking earthquake prone areas such as Hawaii, Alaska, and California. Nonetheless, Italy may be a second research hotspot because of the devastating earthquakes that frequently occur there. Italy suffered substantial damage following the seismic events of the 2009 L’Aquila earthquake, which registered a magnitude of 6.3 on the Richter scale, and the subsequent earthquakes in Central Italy during 2016–2017. The lessons learned encourage scientists and other experts to work hard in the field to establish reliable approaches for predicting seismic risk at various sizes and to apply them in various ways based on the desired level of precision [28]. The United Kingdom and China secured the fourth and third positions, respectively, with a total of 169 and 138 publications. There is a huge gap of total publications between China and Italy.

A co-authorship map created by a VOS viewer is shown in Figure 5. Co-authorship analysis in VOS viewer is the process of analysing the collaboration patterns among authors of academic or scientific papers. Researchers commonly input datasets containing information on co-authored publications, encompassing paper titles, author names, and occasionally supplementary metadata like keywords, publication years, or citation counts, into VOS viewer for co-authorship analysis. VOS viewer examines the data to find author collaboration patterns. It then displays these patterns as networks or clusters of writers who have worked together on several publications.

Table 3. Parameters used for building the VOS viewer map for countries.

Parameter	Value Used
Method Normalization	Association strength
Clustering Resolution	1.0
Minimum Cluster Size	1
Minimum number documents per country	1

shows the parameter used for building the VOS viewer map for countries. The weight of an item influences the size of the label on it. The higher the country’s publications, the larger the country’s label. In the visualisation, the distance between the two countries resembles the relatedness of the country publication in terms of co-authorship links [19]. In general, the closer two countries are to one another, the stronger their bond. Lines represent the strongest co-authorship links between countries. The United States holds the highest level of affiliation, establishing connections with 40 countries and territories and a cumulative link strength of 223. The connection between the United States and Italy, as indicated by a link strength of 28, suggests a robust collaboration in the field of seismic hazard and risk assessment between these two countries.

Contributions from all nations were significantly less between 2002 and 2022 than those from the US, Italy, China, the UK, India, Canada, and Iran. A total of 42 of the 106 nations released one to twenty articles, which is a moderate amount. The research is of the same calibre even when co-authors come from various countries. Rather, it offers perspectives on how nations and research facilities might work together productively to produce scholarly articles. A number of factors, such as the desire to diversify research areas, changes in funding patterns, an increase in human resources, and the difficulties presented by some experiments requiring specialised equipment, can be attributed to the rising participation in international collaborative research [29,30]. Based on an investigation using VOS viewer to look into co-authorship trends amongst countries, it was found that these countries have strong international ties. The need for research financing, information sharing, resource access, and the joint publication of research findings are the main drivers of this strong partnership.

3.3. Top-Performing Journals

A search was conducted on the Scopus database to identify journals most pertinent to the seismic hazard and risk assessment topic.

Table 4. Top 10 productive journals of seismic hazard and risk assessment from 2002 to 2022.

List	Journals	TP	TC	NCPA	PCA (%)	CS (2022)	SJR (2022)	SNIP (2022)	Q	HCA	Publisher
1	Natural Hazards	161	1544	10	95	5.5	0.747	1.151	Q1	The Wenchuan Earthquake (12 May 2008), Sichuan Province, China, and resulting geohazards [31]	Springer Nature
2	Bulletin Of Earthquake Engineering	130	2304	18	92	8.3	1.233	1.998	Q1	Macro seismic and mechanical models for the vulnerability and damage assessment of current buildings [26]	Springer Nature
3	Bulletin Of the Seismological Society of America	127	2031	16	93	5.4	1.286	1.218	Q1	Seismic hazard assessment (2003–2009) for the Italian building code [32]	Seismological Society of America
4	Soil Dynamics and Earthquake Engineering	66	648	10	89	7.5	1.251	1.924	Q1	Processing Italian damage data to derive typological fragility curves [33]	Elsevier
5	Earthquake Spectra	60	673	11	85	7.1	1.55	2.062	Q1	Definition of Collapse Mechanisms and Seismic Vulnerability of Historic Masonry Buildings [34]	Earthquake Engineering Research Institute
6	Earthquake Engineering and Structural Dynamics	54	997	18	93	6.9	1.714	2.322	Q1	Correlation model for spatially distributed ground-motion Intensities [35]	Wiley-Blackwell
7	International Journal of Disaster Risk Reduction	50	398	8	88	7.4	1.132	1.546	Q1	Developing a holistic model for earthquake risk assessment and disaster management interventions in urban fabrics [36]	Elsevier
8	Tectonophysics	42	299	7	88	5.8	1.309	1.166	Q1	Static Coulomb stress changes on faults caused by the 2008 Mw 7.9 Wenchuan, China earthquake [37]	Elsevier
9	Journal Of Seismology	39	183	5	82	3	0.431	0.713	Q2	Development of an earthquake loss model for Turkish catastrophe insurance [38]	Springer Nature
10	Engineering Structures	38	848	22	82	9.2	1.607	2.177	Q1	Derivation of vulnerability functions for European-type RC structures based on observational data [39]	Elsevier

provides a summary of these journals, encompassing total article count, citations, and additional details like the most-cited articles, publisher names, Cite Score, and quartile ranking. Among the top ten most productive journals in this field, several academic publishers distinguished themselves, including Elsevier Ltd., Springer Nature, the Seismological Society of America, the Earthquake Engineering Research Institute, and Wiley-Blackwell Publishing Ltd. Notably, Elsevier Ltd. took the lead with the highest number of journals, totalling four. The top ten most productive journals collectively published 767 papers and received a total of 9925 citations. These publications originate from well-developed countries.

Among the journals analysed, Natural Hazards has the greatest volume of publications, with 161 articles, constituting 20% of the total published works. One of the documents in this journal entitled ‘The Wenchuan Earthquake (2008), Sichuan Province, China’, and resulting geohazards has received the highest citations [31]. The second and third top following productive journals are Bulletin of Earthquake Engineering and Bulletin of the Seismological Society of America, with 123 and 127 total articles published. While the journal Natural Hazards has the highest number of publications, it does not hold the top spot in terms of citations. In contrast, the Bulletin of Earthquake Engineering and Bulletin of the Seismological Society of America have higher citation counts, with 2304 and 2031 citations, respectively, surpassing Natural Hazard, which has 1544 citations. This suggests that academics may prefer to publish their papers in Natural Hazards, but papers in the Bulletin of Earthquake Engineering are more likely to be cited by others.

Based on analysis from Scopus, there were 6 journals with a cite score (2022) greater than 6. Engineering Structures earned the highest cite score (9.2). Earthquake Engineering and Structural Dynamics has achieved outstanding journal rankings, with the highest SJR score of 1.714 and the top SNIP score of 2.32. Nine out of the top ten productive journals in this area are in the Q1 ranking, indicating their excellent standing. The Journal of Seismology, while still respectable, falls within the Q2 ranked. This highlights that the primary journals in this field are indeed considered high-quality publications with a strong scientific reputation.

3.4. Leading Authors

Table 5. Top 10 leading authors in research of seismic hazard and risk assessment from 2002 to 2022.

List	Authors	TP	TC	H-Index	Country	Scopus ID	HCA	HCAC	Journal
1	Goda, K.	20	419	11	United Kingdom	12759820500	Spatial correlation of peak ground motions and response spectra [40]	105	Bulletin of the Seismological Society of America
2	Bommer, J.J.	18	272	12	United Kingdom	7102893762	A prioritisation scheme for seismic intervention in school buildings in Italy [41]	38	Earthquake Spectra
3	Silva, V.	17	518	12	Italy	55617133000	Development of the Open Quake engine, the Global Earthquake Model’s open-source software for seismic risk assessment [42]	212	Seismological Research Letter
4	Crowley, H.	16	905	12	Italy	16244751500	A comparison of seismic risk maps for Italy [43]	63	Bulletin of Earthquake Engineering
5	Iervolino, I.	16	321	12	Italy	6506755474	Probability of occurrence of velocity pulses in near-source ground motions [44]	39	Bulletin of the Seismological Society of America
6	Atkinson, G.M.	13	204	10	Canada	7102995271	Modifications to existing ground-motion prediction equations in light of new data [45]	39	Bulletin of the Seismological Society of America
7	Erdik, M.	13	155	10	Turkey	7003962489	Earthquake risk assessment for Istanbul metropolitan area [46]	28	Earthquake Engineering and Engineering Vibration
8	Douglas, J.	11	204	7	United Kingdom	15047879100	Risk-targeted seismic design maps for mainland France [47]	53	Natural Hazards
9	Hong, H.P.	11	130	7	Canada	7401521473	A comparison of seismic-hazard and risk deaggregation [48]	15	Bulletin of the Seismological Society of America
10	Panza, G.F.	11	39	5	Italy	7005935881	Neo-Deterministic and Probabilistic Seismic Hazard Assessments: A Comparison over the Italian Territory [49]	17	Pure and Applied Geophysics

TP: total publication; TC: total citations; HCA: Highest Cited Article; HCAC: Highest citation of article cited.

presents the leading authors in this field gauged by their publication output. According to the analysis, the ten most notable authors wrote 146 articles between them, which accounts for 8% of the total amount of work (1842) in the field of seismic hazard and risk assessment. These top 10 authors hail from four different countries, namely Italy (with 4 authors), the United Kingdom (with 3 authors), Turkey (with 2 authors), and Canada (with 2 authors). Katsuichiro Goda stands out as the leading author with 20 publications, followed closely by Julian Bommer with 18. Notably, Helen Crowley has the highest number of citations, reaching 905, and possesses an H-index of 12. Following her is Silva, who has 518 citations and an H-index of 12.

Katsuichiro Goda holds the position of Associate Professor and Canada Research Chair in Multi-Hazard Risk Assessment at Western University. His research primarily revolves around managing multi-hazard risks associated with catastrophic earthquakes, considering both economic and societal aspects [40]. His work spans across various academic disciplines. Notably, Katsuichiro Goda has collaborated on several earthquake-related papers with Hanping Hong (ranked 9th among the top ten authors) and Gail Marie Atkinson (ranked 6th among the top ten authors). It is worth mentioning that all these experts are affiliated with the University of Western Ontario in London. Julian Bommer, the next productive author, is a seismic hazard and risk specialist and Senior Research Investigator at the Department of Civil and Environmental Engineering, Imperial College London. He is currently working on projects related to seismic hazard assessments for nuclear facilities and for induced earthquakes [41].

Helen Crowley, the author who boasts the highest number of citations and the most impressive H-index, is associated with the European Centre for Training and Research in Earthquake Engineering (EUCENTRE) located in Pavia, Italy. One of her most widely cited publications, titled “A Comparison of Seismic Map of Italy”, was published in the Bulletin of Earthquake Engineering in 2009 [42]. The second-highest cited author, Vitor Gorni Silva, is also based in Italy but is affiliated with the Global Earthquake Model Foundation in Pavia. According to the Scopus database, this author has contributed to 17 journals focused on Seismic Hazard and Risk Assessment research. Among these journals, the paper “Development of the Open Quake engine”, published in 2014, has garnered the highest number of citations [43]. This paper is renowned for its content regarding the Open Quake (v0.8) software developed for seismic risk assessment. Remarkably, this software remains relevant and in use for seismic hazard risk assessment up to the present day. The paper comprehensively describes each calculator used in the assessment process.

3.5. Keyword Analysis

The effectiveness of research identification and accessibility is significantly influenced by the keywords chosen by authors. These keywords play a crucial role by providing essential information that establishes connections with scientific papers in databases. Acting as a crucial link, these keywords enable the differentiation of information sources from the extensive pool of available articles [50]. To establish the study emphasis and pinpoint any knowledge gaps in the field of seismic hazard and risk assessment, it is crucial to perform a keyword analysis. Keyword co-occurrence analysis, a potent feature within the VOS viewer software, serves as a valuable tool for knowledge extraction [51]. From 2002 to 2022, a cumulative of 1821 papers were published, yielding a collection of 4225 extracted keywords.

Table 6. Parameters used for building the VOS viewer map for keyword co-occurrence analysis.

Parameter	Value Used
Minimum number of occurrences	3
Normalization Method	Association Strength
Clustering Resolution	1
Minimum Cluster Size	2

shows the parameter used for building the VOS viewer map for the keywords. Through the application of VOS viewer, a subset of 423 keywords, each occurring at least 3 times, was selected for the conclusive mapping. The term “seismic hazard” emerged as the most frequently encountered term in the papers, occurring 212 times, and exhibited robust associations (with a total link strength of 439) to other keywords chosen by the authors. Following closely were terms like “earthquake”, “seismic risk”, “vulnerability”, “liquefaction”, and “GIS”. Additionally, several countries, such as “Spain”, “Iran”, “Italy”, “Tehran”, “Egypt”, “Mexico”, “Turkey”, “Europe”, “France”, and “Pakistan”, were prominently featured as keywords related to seismic hazard. This highlights that researchers in these countries tend to focus their studies on their specific regions, likely to aid their respective governments in formulating effective strategies for earthquake assessment.

Researchers can learn more about their research interests and find pertinent connections by visualising and connecting the retrieved keywords. Figure 6 displays the density visualisation using keywords and the density of hotspots using the colour spectrum. Hot areas are indicated by warm red and cool areas by cool blue, respectively. Warm red denotes keywords with the highest frequency of usage, green represents keywords with moderate usage, and blue signifies keywords with the lowest frequency. “Seismic hazard”, “seismic risk”, “vulnerability”, “earthquakes”, “vulnerability assessment”, “seismicity”, “peak ground acceleration”, “seismic risk assessment”, “liquefaction”, “risk assessment”, and “fragility analysis” are keywords with the highest density.

An overlay visualisation map of keywords from 2002 to 2022 is shown in Figure 7. In this map, newer keywords are represented in reddish tones, and those closer to the blue areas were introduced before 2013. The VOS overlay visualisation, incorporating co-occurring terms across publications, highlights a shift in research priorities. Specifically, the emphasis in research topics evolved from areas such as “seismic hazard assessment”, “seismicity”, and “ground motion” in 2014 to a new focus on subjects like “seismic vulnerability”, “seismic design”, “strategy” and “landslides” by 2017. This shift underscores a more recent concentration on the vulnerability of structures to seismic events and the impact of earthquakes on landslide occurrences.

Four sub-periods were selected from the time span to enhance the comprehension of this trend: 2002–2007, 2008–2012, 2012–2017 and 2018–2022, as shown in

Table 7. Top 20 most used keywords for four sub periods (2002–2007), (2008–2012), (2013–2018) and (2019–2022).

2002–2007	Frequency	2008–2012	Frequency	2013–2018	Frequency	2019–2022	Frequency
seismic hazard	22	seismic hazard	61	seismic hazard	50	seismic hazard	79
seismic risk	16	earthquakes	23	seismic risk	46	seismic risk	71
earthquakes	16	seismic risk	18	earthquake	41	vulnerability	36
earthquakes	12	vulnerability	12	vulnerability	20	seismic vulnerability	30
vulnerability	11	Wenchuan earthquake	11	seismic vulnerability	17	earthquakes	25
seismicity	7	ground motion	9	gis	15	risk assessment	23
probability	6	liquefaction	9	seismicity	15	risk	21
peak ground acceleration	4	seismic vulnerability	9	fragility curves	15	induced seismicity	20
probabilistic seismic hazard assessment	4	fragility	7	risk	15	seismic risk assessment	19
risk assessment	4	gis	7	liquefaction	15	resilience	16
seismic vulnerability	4	Italy	7	risk assessment	15	fragility	15
earthquake engineering	3	landslides	7	active fault	15	liquefaction	14
fragility curves	3	seismicity	7	fragility functions	7	fragility curves	13
hazard	3	earthquake hazard	6	micro zonation	7	gis	13
industrial risk	3	Iran	6	seismic hazard assessment	7	fragility curve	12
landslides	3	mitigation	6	vulnerability assessment	7	probabilistic seismic hazard analysis	12
reliability	3	probabilistic	6	fragility analysis	6	rapid visual screening	12
seismic hazard assessment	3	seismic effects	6	peak ground acceleration	6	seismicity	12
seismic risk analysis	3	seismic hazard assessment	6	performance-based earthquake engineering	6	site effects	12

. “Seismic Hazard” remained the primary keyword for all the periods. However, it was observed that “vulnerability” and “seismic vulnerability” started to surpass “earthquakes” recently. Notably, during the last decade, a set of new keywords emerged, which were not present in the first and second periods, and some of these have risen to the top 10 in terms of usage. Examples of these newly prominent terms include “seismic risk assessment”, “seismic vulnerability”, “resilience”, “rapid visual screening” and “induced seismicity”. The focus on determining seismic risk has grown significantly within the scientific community in recent decades because it enables the identification of the most susceptible parts of urban areas, thus facilitating the development of effective strategies to reduce seismic risks. To accurately assess the seismic risk in urban areas, it is imperative to thoroughly evaluate the seismic vulnerability of all existing buildings within the designated area.

3.6. Top Prolific Institutions and Funding Sponsors

The top ten institutes involved in earthquake seismic hazard assessment research from 2002 to 2022 are given in

Table 8. Top 10 institutions active in research of seismic hazard and risk assessment from 2002 to 2022.

No.	Institutions	Country	TP	TC	H-Index	PCA	HCA	HCAC	Journal
1	National Institute of Geophysics and Volcanology	Italy	73	1084	22	99	Operational earthquake forecasting: State of knowledge and guidelines for utilisation	110	Annals of Geophysics
2	University of Naples Federico II	Italy	53	852	23	91	Near-source seismic demand and pulse-like records: A discussion for L’Aquila earthquake	115	Earthquake Engineering and Structural Dynamics
3	ETH Zürich	Switzerland	43	872	20	95	Openquake engine: An open hazard (and risk) software for the global earthquake mode	211	Seismological Research Letters
4	Deutsches GeoForschungsZentrum GFZ	Germany	35	449	18	91	Towards global volcano monitoring using multisensor sentinel missions and artificial intelligence: The MOUNTS monitoring system	58	Remote Sensing
5	Western University	Canada	34	365	14	88	Spatial correlation of peak ground motions and response spectra	84	Bulletin of the Seismological Society of America
6	International Institute of Earthquake Engineering and Seismology, Tehran	Iran	31	200	11	90	The vertical separation of mainshock rupture and microseismicity at Qeshm island in the Zagros fold-and-thrust belt, Iran	47	Earth and Planetary Science Letters
7	Universidad Nacional Autónoma de México	Mexico	31	197	11	90	Site-city seismic interaction in Mexico City—Like environments: An analytical study	41	Bulletin of the Seismological Society of America
8	Scuola Universitaria Superiore IUSS di Pavia	Italy	29	350	14	86	Probabilistic seismic hazard macrozonation of Tamil Nadu in Southern India	71	Bulletin of the Seismological Society of America
9	Chinese Academy of Sciences	China	27	453	11	85	The Wenchuan Earthquake (12 May 2008), Sichuan Province, China, and resulting geohazards	103	Natural Hazards
10	University of Bristol	United Kingdom	27	265	14	93	Intraevent spatial correlation of ground-motion parameters using SK-net data	41	Bulletin of the Seismological Society of America

. Six of the top ten institutions were in European countries: Italy, Switzerland, Germany, and the United Kingdom. The four remaining institutions were in Canada, Iran, Mexico, and China. In terms of overall publications, the National Institute of Geophysics and Volcanology led the field with 73 publications and the highest number of citations (1084). The University of Naples Federico II followed suit (57 publications). The University of Naples Federico II holds the top H-index score (23), pursued by the National Institute of Geophysics and Volcanology (22) and ETH Zürich (18). The most highly cited paper within these was published by Pagani et al. (2014) and came from the ETH Zürich in Switzerland (211 citations) [52]. This was followed by publications Chioccarelli, and Iervolino (2010), with 115 citations originating from the University of Naples Federico II [53].

The foremost 10 funding supporters in research on seismic hazards and risk assessment are the National Natural Science Foundation of China, the National Science Foundation (USA), the European Commission, the Horizon 2020 Framework Programme, the National Key Research and Development Program of China, Seventh Framework Programme, Natural Sciences and Engineering Research Council of Canada, Natural Environment Research Council, and U.S. Geological Survey [54,55,56,57,58,59,60,61,62]. The order presented in

Table 9. Top 10 funding sponsor on the research of seismic hazard and risk assessment worldwide.

List	Sponsor	TP	TC	H-Index	HCA	HCAC
1	National Natural Science Foundation of China	103	874	21	Co-seismic ruptures of the 12 May 2008, Ms 8.0 Wenchuan earthquake, Sichuan: East–west crustal shortening on oblique, parallel thrusts along the eastern edge of Tibet	88
2	National Science Foundation	65	992	22	CyberShake: A Physics-Based Seismic Hazard Model for Southern California	144
3	European Commission	51	648	19	Derivation of vulnerability functions for European-type RC structures based on observational data	146
4	Horizon 2020 Framework Programme	39	390	14	Towards global volcano monitoring using multisensor sentinel missions and artificial intelligence: The MOUNTS monitoring system	58
5	National Key Research and Development Program of China	30	158	8	Experimental study of a novel multi-hazard resistant prefabricated concrete frame structure	32
6	Seventh Framework Programme	27	446	17	PERPETUATE guidelines for seismic performance-based assessment of cultural heritage masonry structures	84
7	Natural Sciences and Engineering Research Council of Canada	24	148	8	Probabilistic seismic risk assessment of concrete bridge piers reinforced with different types of shape memory alloys	40
8	Natural Environment Research Council	21	248	12	The 2009 L’Aquila earthquake (central Italy): A source mechanism and implications for seismic hazard	57
9	U.S. Geological Survey	21	328	14	The 2010 explosive eruption of Java’s Merapi volcano-A ‘100-year’ event	117
10	Italian Civil Protection Department	20	434	14	The Italian guidelines for seismic risk classification of constructions: technical principles and validation	97

is determined by the overall number of publications. Italian Civil Protection Department is also one of the top 10 funding supporters in this research. The substantial increase in publications following the L’Aquila earthquake compared to mega-earthquakes in Indonesia and Japan with magnitudes of 9 is influenced by various factors. For instance, Italy being a developed country means that research efforts are highly focused on local issues. Moreover, the availability of funding, such as from the Italian Civil Protection Department contributes significantly to the rise in publications related to the L’Aquila earthquake compared to mega-earthquakes.

4. Future Direction and Prospects of Seismic Hazard and Risk Assessment

The current body of literature pertaining to seismic hazard and risk assessment caused by earthquakes has offered valuable insights into a wide array of topics. This includes methods of assessment, in-depth geological research, environmental factors, techniques for vulnerability analysis, integration of machine learning, the generation of seismic risk assessments, and the enhancement of structural designs to mitigate the impacts of earthquakes. However, to enhance understanding, certain areas of knowledge gaps and constraints still necessitate further investigation. The results of the bibliometric analysis indicate that seismic hazards continue to be a significant subject within earthquake research, with a growing emphasis on investigating vulnerability and resilience, shifting attention toward risk-related aspects.

Historical data have underscored the prevalence of high-frequency earthquakes throughout Asia, resulting in a substantial collective death toll. Several countries in this region, including China (1), Indonesia (2), and Japan (4), rank among the top ten globally in terms of the highest number of earthquakes in the past century. As such, ASEAN nations should take a leading role in seismic research and assessment due to the significant seismic activity in the region. Nonetheless, there are geographical disparities in the advancement of methods, approaches, and techniques for seismic assessment. Research in this field has rapidly expanded in countries like Italy, the UK, Germany, and Switzerland. However, a significant research development gap exists in certain earthquake-prone regions, such as Indonesia, Japan, and other ASEAN countries.

The comprehensive dataset, which includes 1842 articles and a selected portion of the 1100 most cited ones, indicates that nations such as China and Turkey are becoming more interested in studying seismic hazard assessment. Nonetheless, their presence in the most cited articles is comparatively low, which could be attributed to things like the limited availability of top-notch research or fewer links with academics from developed nations like the US. Despite these challenges, research institutions in these nations have significant potential because of this circumstance. Advances in databases, online access, academic exchange programs, and participation in international conferences are making it easier to obtain high-quality research. If these steps are taken, research in nations whose interest in this area is growing could become more visible and of higher quality. It is recommended that research with case studies be conducted in every country, particularly those that are susceptible to earthquakes.

Regarding the research focus, there is a predominant emphasis on vulnerability assessment across various structural elements, including historical buildings, structural buildings, RC walls, bridges, and more. This emphasis is substantiated by examining recent highly cited articles, such as the one authored by Lagomarsino and Giovinazzi in 2006. Furthermore, there has been a growing attention to risk assessment related to induced phenomena like landslides and liquefaction. As an example, Liao and Xie (2022) published an article titled “Landslide Hazard Assessments of a Potential Earthquake-triggered in Central Taiwan Using Newmark’s Model with the Stochastic Semi-Empirical Technique” [63]. This research seeks to assess the likelihood of landslides being triggered by a potential earthquake by evaluating their probability distribution.

5. Conclusions

The annual publications and citation output on seismic hazard and risk from 2002 to 2022 were found in the Scopus database by this bibliometric review. Both scholars and the public have shown a growing interest in studies concerning seismic hazard and risk assessment. With a rising number of articles focusing on methods for assessing seismic hazards, bibliometrics is a significant tool for academics looking to obtain insights about scholarly partnerships, research patterns, and novel problems. The annual publications and citation output on seismic hazard and risk from 2002 to 2022 were found in the Scopus database by this bibliometric review. The limitation of this bibliometric study is that it relies only on Scopus for data. While Scopus is comprehensive, including additional sources such as Web of Science (WOS) and Google Scholar would enhance the research and allow for future comparisons. In the analysis, all the information gathered from articles from numerous countries, journals, institutions, authors, and co-cited data were thoroughly summarised. According to the findings, researchers from the United Kingdom, Italy, and the United States have demonstrated remarkable productivity and influence through their numerous research contributions. Furthermore, there are geographical variations in the development of seismic assessment methods and procedures. Notably, research in nations such as Italy, the United Kingdom, Germany, and Switzerland has grown. However, considerable research gaps exist in earthquake-prone areas such as Indonesia, Japan, and other ASEAN countries. To acquire insights into this divide, it is critical to examine the relationship between researchers and their respective countries. Katsuhiro Goda emerged as the author with the highest total publications, while Helen Crowley received the most citations and held an impressive H-index. The academic journal “Natural Hazards” was the preferred choice among researchers in terms of publications. Nevertheless, when considering citation counts, the “Bulletin of Earthquake Engineering” and the “Bulletin of the Seismological Society” were the most frequently cited publications. “Seismic Hazard” remained the predominant keyword for over two decades. However, in recent years, scientists have shown an increased interest in keywords such as “vulnerability” and “seismic risk assessment”. Italian research institutions have also played a significant role in advancing this field. Promoting international research collaboration is vital in tackling the worldwide issue of earthquake disasters and reducing their impact. This involves supporting collaboration among scientists from various backgrounds to share knowledge and drive innovation. Additionally, advocating for increased research efforts in specific areas of seismic assessment is essential for addressing existing gaps and challenges effectively. Research on seismic hazard and risk assessment has garnered increasing attention from the public and academic researchers in recent times. As the number of publications devoted to the study of seismic hazard assessment techniques rises, bibliometrics becomes an increasingly important tool for researchers to understand research trends, patterns of scholarly cooperation, and new concerns.