For disaster resilience, assessment of hazard and risk and mitigation planning is the most important initiatives. The first step in disaster risk mitigation is to recognize the existence and level of risk. For seismic hazard assessment, risk reduction, and resilience, we should better understand level of hazard. For the evaluation of the rate of occurrence of any hazard, long term previous event data are required (Alam 2019). Earthquake recurrence relation obtained from previous earthquake histories is appropriate for the prediction of future earthquake. For seismic hazard assessment (SHA) studies earthquake catalog is essential which should be unified especially in terms of magnitude (Di Giacomo et al. 2015). Earthquake catalogs provide some basic parameters about earthquakes e.g., their occurrence, time, epicenter, magnitudes, and often some other information. They are useful for seismotectonic and seismicity studies, earthquake physics analysis, seismic hazard assessment, micro-zonation, ground response studies, etc. (Woessner and Wiemer 2005; Das et al. 2012; Ullah et al. 2015). A severe earthquake hazard may lead to cause several human casualties, infrastructure damages and economic & other losses (Steckler et al. 2016). Seismic hazard assessment studies will be helpful in decision making and risk mitigation planning to make the country seismically resilient with safe recovery in case of future earthquake within minimum time and with less economic and social loss.
For seismic hazard assessment of a country or region, world practice is to use long term, updated and unified earthquake data. For example, Ullah et al. (2015) compiled an earthquake catalog for the purpose of probabilistic seismic hazard assessment (PSHA) of central Asia, Markušić et al. (2016) developed an earthquake catalog for western Balkan region to implement it in PSHA for updated seismic hazard map, Khan et al. (2018) compiled catalog for previously occurred earthquakes in Pakistan, Rahman and Bai (2018) compiled catalog from different sources for Nepal and performed PSHA, Sawires et al. (2019) developed an updated and unified catalog for Mexico, Şeşetyan et al. (2019) assessed the seismic hazard in Marmara, Turkey with updated database of earthquakes, Stevens et al. (2020) performed seismic hazard as well as seismic risk assessment for Bhutan, İnce and Yılmazoğlu (2021) performed PSHA for Muğla, Turkey using collected seismic data. For India, the neighboring and surrounding country of Bangladesh, several attempts have been made for the development of homogenized earthquake catalog for seismic hazard assessment both in local and regional level, e.g., Bhatia et al. (1999); Yadav et al. (2009); Martin and Szeliga (2010); Das et al. (2012); Kolathayar et al. (2012a); Pandey et al. (2017); Ananda et al. (2022). Seismic hazard assessment was performed by many studies along with the development of earthquake catalog for India for selected region as well as for the whole country, e.g., Nath and Thingbaijam 2012; Kolathayar et al. (2012a, b); Sitharam and Kolathayar (2013); Mandal et al. (2013); Ashish et al. (2015); Das et al. (2016); Bahuguna and Sil (2018); Anbazhagan (2019); Surve et al. (2021); Ansari et al. (2022). The National Disaster Management Authority (NDMA), India compiled an earthquake catalog and performed comprehensive PSHA for the India using those earthquake event data (NDMA 2011). Rao et al. (2020) performed PSHA and risk assessment of India using the catalog developed by Nath and Thingbaijam (2012). Scaria et al. (2021) developed earthquake catalog collecting data from various sources to prepare PSHA map of peninsular shield of India. Ramkrishnan et al. (2021) assessed PSHA for North and Central Himalayas using the catalog of Kolathayar et al. (2012a) previously developed for India and surrounding region for seismic hazard assessment of India. Thus, an earthquake catalog is an inevitable part of seismic hazard studies which is justified from these studies performed by several researchers.
For Bangladesh, some researchers contributed in the development of earthquake catalog as well as seismic hazard assessment studies of the country (e.g., Kundu 1992; Bhatia et al. 1999; Ansary and Sharfudin 2002; Noor et al. 2005; Al-Hussaini and Hasan 2006; Chowdhury 2016; Haque et al. 2020; Rahman et al. 2020) or of a selected region, site, or city (e.g., Dhar & Ansary 2011; Trianni et al. 2014; Carlton et al. 2018; Ray et al. 2019; Kamal et al. 2021). Bhatia et al. (1999) performed SHA of India including Bangladesh under the Global Seismic Hazard Assessment Program (GSHAP) launched in 1992. Kundu (1992) developed the first catalog of earthquakes occurred from 1897 to 1991. That catalogue consists of a few numbers of earthquake data for 200-280 N latitude and 870-940 E longitude. This catalog shows earthquake magnitude M (unknown type) for period up to 1962 and from 1962 onwards earthquakes are represented by body-wave magnitude. Sharfuddin (2001) developed an earthquake catalog for 200-280 N and 860-950 E for the period of 1869–1995. The major problem of this catalog is that the catalog represents many earthquakes with unknown magnitude and magnitude of the earthquakes is not unified. Al-Hussaini (2006) presented about seismicity and seismic vulnerability in Bangladesh and assessment of seismic hazard. The study was done based on a catalog of 2,122 earthquakes occurred between 1845–2005. Two models were used, one with five and another with eight sources, for recurrence relation and seismic hazard assessment. Al-Hussaini and Al-Noman (2010) utilized the previously developed catalog compiled by Al-Hussaini and Hasan (2006) and added the 1762 Chittagong earthquake for seismic hazard assessment. The study considered seven earthquake sources, proposed earthquake recurrence relations for those and performed probabilistic seismic hazard assessment. Dhar & Ansary (2011) performed seismic hazard assessment for Cox’s Bazar using 31 earthquakes for the period 1995–2006. They developed micro zonation maps for liquefaction potentials, amplification, and fundamental frequencies and concluded that the northern part where loose sand exists in thick layer has high liquefaction potential. Trianni et al. (2014) performed probabilistic seismic hazard assessment (PSHA) for oil pipeline route along the offshore of Bay of Bengal. They considered 905 earthquakes with Mw ≥ 4 for the period 1663–2012. Siddique (2015) proposed Gutenberg-Richter recurrence relation (magnitude-frequency relation) for the country using 782 earthquake events collected from USGS for the period 1973–2013. The work of Das et al. (2016) conducted for the India also covered Bangladesh in which PSHA was performed. Carlton et al. (2018) performed probabilistic seismic hazard assessment (PSHA) considering fault sources for a site in Maheskhali Island and found peak ground acceleration 0.63 for Maximum Credible Earthquake (MCE). Imtiaz et al. (2018) proposed a methodology for multi-hazard seismic risk assessment for Cox’s Bazar and developed seismic micro zonation maps based on earthquake occurrence potential and ground susceptibility. They considered site amplification and soil liquefaction potential. Landslide potential was also assessed using slope stability analysis. Ray et al. (2019) proposed earthquake magnitude- frequency relationship for Sylhet using Gutenberg- Richter recurrence relation. They used least square regression method and Gumble’s extreme method to estimate b- value for Sylhet considering 184 earthquakes with magnitude 4 to 7.2. They calculated earthquake recurrence probability and return period for different damaging earthquake occurred in this region. Rahman et al. (2020) performed PSHA of Bangladesh using a compiled catalog, seismic source modeling for the country and prepared hazard maps for the country. Haque et al. (2020) performed PSHA by modifying source, path and site characteristics using catalogue of 3472 earthquakes for 1505–2018. The study represented b values, Vs30 values, hazard maps. Kamal et al. (2021) carried out deterministic seismic hazard analysis (DSHA) considering worst-case scenario for the south-central coastal region of Bangladesh. The study provides peak ground acceleration (PGA) and spectral acceleration (SA) values at bedrock and ground surface using possible seismogenic sources, and controlling earthquakes. In recent years, a comparatively new approach, neo-deterministic seismic hazard analysis (NDSHA) has been performed for the country. Al-hussaini et al. (2015) conducted a review of previous seismic hazard studies and represented preliminary outcome of Chowdhury (2016) from neo-deterministic seismic hazard analysis (NDSHA) approach for the country and compared it with previous SHA. Chowdhury (2016) performed NDSHA for the country using catalog compiled for a period 1762–2015 and prepared hazard map choosing some scenario earthquakes, and the outcome of the study has been also represented in Al-Hussaini et al. (2017, 2022).
Seismic hazard assessment studies of a country or region should be performed with complete, updated and unified earthquake event data. Thus, for effective and reliable seismic hazard assessment, development of a comprehensive, updated and unified earthquake catalog is essential (Sawires 2019). From the available previous studies, it has been noticed that some of the existing catalogs are site specific, developed for regional purpose and those which are for the whole country are grossly deficient, not complete in period of occurrences, magnitudes, depths, etc. Again, homogenization of magnitudes of the seismic events to moment magnitude is a pre-requisite for seismic hazard assessment. Because of these and the point of view of long-term prediction and seismic hazard assessment, it is very important that the earthquake catalogue of Bangladesh and adjoining region be updated and homogenized with long-term data. In this study a new Mw based earthquake catalog has been compiled from various sources. Five earthquake sources which were identified by CDMP (CDMP 2009a) are considered and earthquake recurrence relations have been proposed for all the sources as well as for the whole study region based on Guttenberg- Richter recurrence relation for earthquake (Gutenberg & Richter 1944). The goal of the present is to produce unified earthquake event data that reflect the seismicity of the region as homogeneously and completely as possible which will help in future seismic hazard assessment and ground response studies.