On New Year’s Day, a powerful 7.5 magnitude earthquake rocked western Japan, wrecking roads and knocking out power to thousands of homes. Tsunami warnings were initially issued; these have since been lifted.
Wajima City saw firemen searching through collapsed buildings for survivors after being shaken awake by an earthquake which rocked homes and schools throughout Ishikawa Prefecture and sent students fleeing classrooms in fear.
An earthquake can have serious repercussions, from collapsed buildings and fires to disrupting power and water supplies. To protect yourself and your family during such a catastrophic event, prepare beforehand. Learn coping techniques and stockpile emergency supplies as soon as an earthquake hits; additionally locate all gas, electric, and water mains so you can turn them off swiftly in case of emergency situations.
earthquake
Shaking of Earth’s surface caused by earthquakes results from underground rock or material moving along a fault, often breaking apart and releasing energy that causes shaking – this place underground known as the focus or hypocenter is where such energy release happens and causes earth-shaking events.
This set off tsunami waves reaching several meters high near the coast, as well as damaging buildings and roads across western Japan. Following its main temblor, some 155 aftershocks followed suit, prompting many families to spend the New Year holiday either in evacuation centers or their cars.
Some may think earthquakes occur more frequently in certain kinds of weather conditions, like heavy rainfall or extreme heat, but there’s no proof to support that belief. It can happen at any time and anywhere – being ready means understanding their formation as well as having emergency plans in place for your region.
magnitude of an earthquake
The magnitude of an earthquake allows scientists to compare its power. It is calculated using seismograph measurements of seismic waves with maximum amplitude recorded, taking into account both distance between earthquake site and recording instrument as well as time before shaking begins.
Earthquake magnitude differs from intensity, which measures its strength of shaking and damage caused. Intensity varies based on where an earthquake hits; its ground-bending waves dissipate as its energy dissipates away from its source fault.
USGS now uses Moment Magnitude (Mw) scale for large teleseismic earthquakes; it uses modeling recordings from multiple stations to provide more accurate estimates than Richter scale. Other scales exist for smaller earthquakes including Richter Scale, ML, Mb and short-period surface wave magnitude, which portray earthquake energy logarithmically to approximately base 32; for instance an earthquake of magnitude 6 releases 31 times more energy than one with magnitude 5. This energy release factor.
epicenter of an earthquake
Epicenter of an earthquake refers to the point directly above a fault line where rocks begin to fracture, and is also referred to as focus or hypocenter. Earthquake waves travel outward from this focus in all directions and are recorded on seismographs by scientists who triangulate (identify) its epicenter.
Seismograph stations measure how long it takes P and S waves to arrive at that station. Scientists can then use this data to ascertain their speed by measuring S-P interval on charts; using this information they are then able to draw circles on maps showing each seismograph station’s location, measure distance from their epicenters to each circle and mark them accordingly on maps.
An earthquake’s intensity is determined by how it shakes people and structures on the ground and any damage it causes, while its magnitude can be determined by measuring its amplitude using instruments with known calibration.
