Space Smurfs: S02E01

Sneak peek into geological events

Geological events such as earthquakes, tsunamis, volcanic eruptions, and underwater landslides are linked to the motion of the crust of the earth. Unlike the skin of an apple or an avocado, the earth’s crust is not a continuous medium. The crust is made of broken plates moving relative to each other at different rates, commonly explained by the theory of plate tectonics. These plates of the crust are of different thicknesses and ages.

Image source: https://media.nationalgeographic.org/assets/photos/330/078/f852cdbc-b970-4881-b1c1-b4e47320f5f4.jpg

The past geological events at Tonga, Haiti, Tohoku are examples of the impacts caused by these disasters. There is a saying, “Earthquakes do not injure or kill people. Poorly built man-made structures injure and kill people”. To avoid such scenarios, seismic codes are established to protect life and property in the buildings.?

There are different metrics to measure the size of the earthquakes: Richter magnitude, body-wave magnitude (Mb), surface-wave magnitude, and moment magnitude. The impact of the earthquake can be measured using shaking intensity which also takes into account the local geology.??

Image source: https://www.usgs.gov/programs/earthquake-hazards/earthquake-magnitude-energy-release-and-shaking-intensity?

The graph in the image shows the shaking intensity in three locations at the same distance from the earthquake epicenter. It can be noted that based on the local geology of the location (bedrock, soft mud, sand, and gravel), the shaking amplitude varies.?

A peek from outer space

Global Position System (GPS) together with seismometers can be used for early warning systems of earthquakes. With high precision GPS data and with appropriate techniques for analysis, the measurement of the movement of plates with a resolution of millimeters can be achieved.?

Earthquake Early Warning (EEW) systems have been in operation in multiple countries such as Japan, Mexico, the United States, Taiwan, Europe, China, and Israel.?

ShakeAlert? Earthquake Early Warning System is a warning system to alert the people that an earthquake has begun and could potentially affect their location. It is to be noted that a warning system is different from a prediction system.?

The Earthquake Hazard Program by the United States Geological Survey (USGS) provides KML feeds to view the earthquake animations on Google Earth for the various periods, ages, and depths. As part of the program, a free Earthquake Notification Service (ENS) is also offered.?

The Geographic Information Systems and Remote Sensing data from Earth Observation satellites also play a major role in the disaster management process. The information from the satellites allows us to study and monitor the situation, assess the damages, and help with decision-making to respond to a disaster.?

The EO image shows a young volcanic island, Nishinoshima, extending since 2013 from the eruption.

Image source: NASA Earth Observatory image by Lauren Dauphin, using MODIS data (of Aqua satellite) from NASA EOSDIS/LANCE and GIBS/Worldview. Date of the image: July 4, 2020. https://earthobservatory.nasa.gov/images/146935/nishinoshima-belches-ash-and-lava?

The recorded EO data from programs such as Landsat and Copernicus are open-source and can be used for analysis and research. Data-sharing policies are increasingly being improved by many EO data providers for such crisis management scenarios.?

European Ground Motion Service (EGMS) is one of the services offered by the Copernicus program. The time series analysis of Copernicus Sentinel-1 data provides the measurement of ground motion which will be complementary data to the Global Navigation Satellite Systems (GNSS) and/or other measurement observations.?

Intense computational power and immense storage are required to process the data generated by EO satellites and seismometers for research purposes which is a significant challenge. However, open-source data can be used for simple visualizations of a specific event or area on Earth.?

Recent research also includes supplementing Earth Observation with Twitter data for disaster management. Twitter data can help in understanding the mental state of people in disaster-prone areas, the type and impact of the destruction.?

Planet Earth vs the rest

During the clubhouse session, Marsquake was brought up as a topic of discussion. A piece of notable news is the low seismic activities recorded by the InSight lander in 2019. Quakes have also been observed on the moon and Venus.

Mars - InSight Lander - Seismometer (Sol 110) Image source: https://ichef.bbci.co.uk/news/976/cpsprodpb/F616/production/_104889926_pia22956-16.jpg, Image credit: NASA/JPL

Unlike Earth’s crust, most planets and their moons in our solar system have comparatively more brittle and rigid crust resulting in a lack of tectonic activities. However, Lo, one of the moons of Jupiter, is the most volcanically active body.?

Volcano: Tvashtar

Image source: https://media.nationalgeographic.org/assets/photos/124/677/5dcbff90-4383-4ef5-9ee6-1a9642f98a73.jpg, Image Courtesy Nasa's Goddard Space Flight Center, Nasa/JPL/the University Of Arizona.