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Which type of fault is most likely to produce a Tsunami? (A) Strike-slip fault (B) Normal fault (C) Thrust/Reverse fault (D) Horizontal fault
Strike-slip faults (like the San Andreas) involve horizontal sliding, which doesn't displace much water vertically and thus rarely triggers tsunamis. However, at "Megathrust" boundaries, the overriding plate snaps upward during an earthquake. This act is like lifting the bottom of a bathtub; the watRead more
Strike-slip faults (like the San Andreas) involve horizontal sliding, which doesn’t displace much water vertically and thus rarely triggers tsunamis. However, at “Megathrust” boundaries, the overriding plate snaps upward during an earthquake. This act is like lifting the bottom of a bathtub; the water has no choice but to move. The resulting wave carries the energy of the entire displaced water column. This is why the world’s most destructive tsunamis, like those in 2004 and 2011, are always associated with subduction zone thrust-faulting.
See lessThe ‘Moment Magnitude Scale’ (Mw) is preferred over the Richter Scale for large earthquakes because:
For massive earthquakes, the fault might rupture over hundreds of kilometers for several minutes. A standard seismograph measuring just the highest wave peak (Richter) misses the total duration and scale of the energy release. Mw calculates "Seismic Moment," which is the product of the rock's rigidiRead more
For massive earthquakes, the fault might rupture over hundreds of kilometers for several minutes. A standard seismograph measuring just the highest wave peak (Richter) misses the total duration and scale of the energy release. Mw calculates “Seismic Moment,” which is the product of the rock’s rigidity, the area of the fault that broke and the distance the rocks moved. This makes Mw the scientific standard for modern seismology, as it accurately reflects the true physical size of a catastrophic event like the 9.5 magnitude Valdivia earthquake.
See lessWhy do S-waves disappear at the Gutenberg Discontinuity?
This "disappearance" is one of the most famous observations in geophysics. When an earthquake occurs, a massive "S-wave Shadow Zone" is created on the opposite side of the Earth (beyond 103°). Because P-waves can pass through liquids (by compression) but S-waves cannot, this confirmed that a major pRead more
This “disappearance” is one of the most famous observations in geophysics. When an earthquake occurs, a massive “S-wave Shadow Zone” is created on the opposite side of the Earth (beyond 103°). Because P-waves can pass through liquids (by compression) but S-waves cannot, this confirmed that a major part of the Earth’s interior—the outer core—is liquid. This finding is fundamental to our understanding of the Earth’s magnetic field, which is generated by the movement of this liquid iron.
See lessThe most common depth for ‘Shallow-focus’ earthquakes is: (A) 0 to 70 km (B) 70 to 300 km (C) 300 to 700 km (D) Above 700 km
Most tectonic activity occurs near the surface where rocks are cool and brittle. As you go deeper, the increasing heat makes rocks more "ductile" (pliable), meaning they tend to flow rather than break. Shallow quakes occur along all types of plate boundaries, including transform faults and mid-oceanRead more
Most tectonic activity occurs near the surface where rocks are cool and brittle. As you go deeper, the increasing heat makes rocks more “ductile” (pliable), meaning they tend to flow rather than break. Shallow quakes occur along all types of plate boundaries, including transform faults and mid-ocean ridges. Because the focus is close to the surface, the seismic waves haven’t traveled far enough to lose energy through “attenuation,” which is why shallow quakes like the 2010 Haiti event cause such massive devastation compared to deeper quakes of the same magnitude.
See lessWhich region of the Earth is responsible for the ‘Slow Earthquakes’ or ‘Slow Slip Events’?
SSEs occur in the "transition zone" between the shallow, brittle part of a fault and the deeper, creeping part. In this zone, the rocks are not quite brittle enough for a sudden snap but not soft enough to flow smoothly. These events are crucial for seismologists to study because they shift stress aRead more
SSEs occur in the “transition zone” between the shallow, brittle part of a fault and the deeper, creeping part. In this zone, the rocks are not quite brittle enough for a sudden snap but not soft enough to flow smoothly. These events are crucial for seismologists to study because they shift stress along the fault and might either trigger a major “megathrust” earthquake or help release stress safely. They represent a complex “middle ground” in rock mechanics and are a key area of modern earthquake research.
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