A seismic microzonation study of Bhubaneswar has identified a significant difference in earthquake exposure between the city’s eastern and western zones, placing the performance of buildings, bridges and other infrastructure at the centre of the city’s disaster-preparedness challenge. The National Centre for Seismology (NCS) found that softer soil, deeper bedrock and stronger potential for seismic-wave amplification make parts of the eastern belt, especially areas along the Kuakhai and Daya rivers, more vulnerable to earthquake-induced ground shaking.
The study does not describe Bhubaneswar as uniformly hazardous. The NCS said the overall hazard index was low across most of the city, while parts of the eastern belt showed moderate to high hazard. That distinction is important because it shifts the question from whether Bhubaneswar is in an earthquake-risk region to how different parts of the same urban area may respond differently to the same seismic event.
Presented by NCS Director Dr G. Suresh at a national workshop on Environmental Hazards and Disaster Management at SOA Deemed to be University, the findings point to the limits of treating a city’s seismic risk through a single broad classification. Odisha falls under Seismic Zones II and III, and the Mahanadi valley—from Jharsuguda and Sambalpur through Angul, Cuttack and Bhubaneswar to Paradip and Puri—is classified as a moderate-risk Zone III region. Within that regional category, however, local soil and geological conditions can change the intensity of shaking experienced at the ground surface.
That is the purpose of seismic microzonation: to examine variations within a city that a state- or region-level hazard map may not capture. For Bhubaneswar, the NCS studied 420 square kilometres of the Bhubaneswar Development Plan Area in July 2025. Researchers measured ground vibrations at 1,650 locations, drilled boreholes to depths of up to 30 metres and analysed more than 1,200 soil samples. The scale of this fieldwork gives the resulting map a direct connection to the physical conditions beneath the city rather than relying only on a general seismic-zone designation.
The clearest variation concerns shear-wave velocity in the upper 30 metres of the ground. Across much of Bhubaneswar, the velocity ranged from 360 to 760 metres per second, which the NCS characterised as relatively firm ground. In the eastern areas, it fell to between 184 and 360 metres per second, indicating softer soil. Shear-wave velocity is an important measure in seismic assessment because it helps describe how ground material transmits earthquake energy. The lower values recorded in the east indicate that the same earthquake may produce a different surface response there than in areas with firmer ground.
The depth of engineering bedrock shows an equally sharp contrast. In the western and central parts of the city, engineering bedrock was found at depths ranging from 2 to 20 metres. In the east, it was found at depths of up to 86 metres. This deeper bedrock means that structures in the eastern belt may be founded above a thicker layer of soil and sediment. The NCS findings indicate that this local geological profile contributes to a greater potential for amplification of seismic waves.
The study estimated that soil conditions could amplify earthquake shaking by up to three times. In Jagamara, peak ground amplification ranged from two to five times, while the microzonation map indicated ground acceleration of 0.14 to 0.17 g. The NCS said this was nearly twice the 0.08 g design value prescribed for Zone III under the national building code. Similar concerns were identified in Chakeisiani, Pahala, Old Town and Uttara.
These figures do not mean that every building in these localities will fail during an earthquake, nor does the study state that a major earthquake is imminent. They do show that the broad Zone III design value may not represent the full range of ground response within Bhubaneswar. The difference between a regional design assumption and a location-specific ground condition is therefore central to how the findings should be understood.
For urban construction, the practical implication identified by the NCS is a stronger focus on local ground conditions before construction. Dr Suresh said tall buildings, bridges and other structures in the eastern part of the city need more attention than those in the centre and west. His statement places the emphasis on engineering assessment and construction quality, rather than on public alarm.
That distinction also clarifies the role of a microzonation map in city governance. The map is not, by itself, a building permit, a demolition order or a prediction of when an earthquake will occur. Its significance lies in supplying more detailed evidence for decisions that are otherwise made using broad classifications. Building design, foundation decisions and structural assessment can be informed by the local conditions identified through the study, provided the findings are incorporated into the relevant planning and construction processes.
The institutional challenge is that seismic safety is distributed across several stages of urban development. The NCS has generated the ground data and identified areas of differing hazard. Building designers and structural engineers are responsible for translating site conditions into design decisions. Planning and construction authorities determine how technical requirements are reflected in approvals, inspections and enforcement. Developers, contractors and building owners influence whether approved designs are executed properly and whether existing structures are assessed when risk information changes.
The supplied findings do not establish whether Bhubaneswar’s current approval or enforcement systems have already incorporated the new microzonation map. They also do not specify which categories of existing buildings require reassessment, whether revised local regulations have been issued, or how the map will be used in future permissions. Those are not minor administrative details. They determine whether a scientific study remains a technical document or becomes part of the city’s everyday development control system.
The numbers in the study reveal why this implementation question matters. The survey covered 420 square kilometres and used measurements from 1,650 locations, but the risk is not evenly distributed across that area. Ground conditions change from relatively firm soil in much of the city to softer soil in the eastern belt. Bedrock depth ranges from 2 metres in some western and central locations to as much as 86 metres in the east. Ground acceleration in the mapped areas reaches 0.14 to 0.17 g, compared with the 0.08 g design value cited for Zone III.
The result is a layered risk picture. The regional classification provides the broad baseline. The city-level study adds local geological detail. The hazard index identifies areas where the combined conditions produce greater concern. The construction response must then account for the specific site and structure. A single citywide label cannot perform all of those functions.
Bhubaneswar’s development pattern makes this distinction relevant beyond earthquake science. The NCS specifically highlighted tall buildings, bridges and other structures in the eastern part of the city. These assets connect housing, employment, mobility and public services, meaning that seismic performance is not limited to the safety of individual buildings. Damage to transport links or critical structures could also affect access and urban functioning, although the supplied study does not quantify such consequences.
The findings also raise a question about how cities manage risk when most days provide no visible warning of it. Softer soil, deep bedrock and amplification are not necessarily apparent to residents or observable in routine urban activity. They are subsurface conditions that become consequential during a high-intensity event. That makes them easy to overlook in fast-growing areas where attention is often directed towards visible construction, road capacity and new development.
The NCS presentation therefore offers Bhubaneswar more than a general warning about earthquakes. It provides a spatial explanation of why risk varies within the city and identifies the eastern belt as an area requiring closer engineering attention. It also shows that the city’s moderate-risk regional classification does not eliminate the need for local assessment.
What remains uncertain is how the findings will move from the study to implementation. The supplied report does not state whether the microzonation map has been formally adopted by the Bhubaneswar Development Authority or municipal authorities, whether construction rules will be revised, or whether public guidance will be issued for the identified localities. It also does not provide a building-by-building assessment of existing structures.
The next stage, as indicated by Dr Suresh’s comments, is better engineering attention to local ground conditions, especially for tall buildings, bridges and other structures in eastern Bhubaneswar. The significance of the study will ultimately be measured by whether its detailed evidence informs design, approvals and structural assessment before the city is forced to learn the value of that information during an earthquake.
