How will man tackle quakes when he colonises moon in the not-so-distant future? India will be joining some nations in the quest for a better understanding of moonquakes as plans are afoot to send a seismometer on board the landing instrument of Chandrayaan-2 scheduled to be launched in 2014/15.
Sensors of the seismometer built by Indian Space Research Organisation (ISRO) are now undergoing calibration at the CSIR-National Geophysical Research Institute (NGRI) here. The first phase of calibration is over and the second phase will start soon, according to seismologist D. Srinagesh, who will be studying the seismic aspects of moonquakes along with his team at NGRI. He told The Hindu that the largest moonquake ever recorded was 5.5 magnitude by the seismometers deployed on the moon’s surface during Apollo missions in late 1960s and 70s.
4 types of such quakes
Dr. Srinagesh said basically there were four types of moonquakes: deep moonquakes that occur up to 700 km below the surface of the moon and probably caused by tides, vibrations from the impact of meteorites, thermal quakes caused by expansion of the frigid crust of the moon and shallow quakes up to 20-30 km and as many as 28 were recorded between 1972 and 1977.
Dr. Srinagesh said earlier studies found that the first three types were generally harmless. Under the ISRO-NGRI collaborative project, it was intended to characterise moonquakes in terms of their magnitude and depth. One of the focus areas would be to study the causes of shallow quakes and the regions of their occurrence. This was needed because the seismometers deployed during Apollo missions were located in a small region, mostly the front side of the moon.
Pointing out that there was significant difference between moonquakes and earthquakes, he said the energy produced through the former would last longer due to the underlying structure of the moon.
The aim of the study was to help in designing structures with flexible materials to withstand moonquakes. For instance, anything above five magnitude earthquake could cause cracks in plaster and move furniture in a building.
Although one seismometer was being planned to be deployed, there was a possibility for a second instrument, he added.