The Himalaya was formed due to collision of Indian Plate and Eurasian Plate at about 40 million years ago. It extends in 2400km east – west direction. Its width varies from 230 to 320 km and bounded between the Indo-Gangetic Plain in the south and Tibetan Plateau in the north. Nepal Himalaya occupies the central 800km part. It can be divided into five distinct morpho-geotectonic zones (Fig.1), from south to the north as (1) Terai Plain (2) Sub Himalaya (Siwalik Range), (3) Lesser Himalaya (Mahabharat Range and mid valleys) (4) Higher Himalaya and (5) Inner Himalaya (Tibetan Tethys). Each of these zones is clearly identified by their morphological, geological and tectonic features. Main Frontal Thrust (MFT), Main Boundary Thrust (MBT), Main Central Thrust (MCT) and South Tibetan Detachment Fault system (STDFS), from south to the north respectively are the major linear geological structures that act as the boundary line between the two consecutive units (Fig.2). From mineral resources point of view, Terai Plain is potential for gravel, sand, ground water and petroleum. The Sub Himalaya is the potential area for construction materials, petroleum and natural gas. Similarly, Lesser Himalaya is promising for metallic minerals, industrial minerals, marble, gemstones, fuel minerals, construction materials etc. Some of the areas in Higher Himalaya are highly promising for precious and semiprecious stones, marble and metallic minerals. Tibetan Tethys zone is prospective for limestone, gypsum, brine water (salt) and natural gas.

Table-2: Summary of the published geological maps

Table-3: Available Engineering and Environmental Geological Maps

Seismological Centers and Seismic Research

The National Seismological Network started first in 1978, November as a single seismic station established at Phulchoki hill top which is situated on the southern border of the Kathmandu valley. Today, it consists of 21 short period telemetric seismic stations covering the entire country. As in other parts of the world, the seismic stations have been installed with the objectives of monitoring and evaluating seismic activity so as to better understand the causes and effects of the earthquakes and ultimately to be able to mitigate the associated destruction. The National Seismological Network was established in collaboration with the Laboratory de Geophysique Applique (LGA) and presently is functioning in collaboration with Department Analyse, Surveillance and Environment (DASE), Paris, France. The network can acquire data of magnitudes as low as 2 on the Richter scale occurring in any part of the country. Seismic signals recorded at different stations are relayed to the National Seismological Centre located at Kathmandu and Regional Seismological Centre in Birendranagar, Surkhet for data processing and interpretation. The National Seismological Centre disseminates earthquake data to different national and international agencies. It also makes available to agencies supporting infrastructure development activities in the country. 

Based on micro-seismicity data, DMG has prepared and published Micro-Seismicity Epicenter maps of Nepal at a scale of 1:1,000,000 and 1:2,000,000. Based on these data, the seismo-tectonic models of central and Far-Western Nepal Himalaya have been prepared as part of seismo-tectonic research in the Himalaya. These instrumentally recorded earthquake data are very important for the assessment of earthquake hazard and in disaster mitigation. Data are equally significant for planners and engineers who need to take remedial measures in designing earthquake resistant infrastructures such as dams, bridges, buildings, power transmission lines etc.

In the last 3 years 22GPS stations are set in different parts of the country with the technical collaboration of Department Analyse, Surveillance and Environment (DASE), France and California Institute of Technology (CALTECH), USA to know the movement of the continental plates and crustal deformation etc.