Q_3_06 — Solar Physics and Helioseismology

The Sun is the most thoroughly studied star, yet fundamental mysteries persist about its interior dynamics and outer atmosphere. Helioseismology — the study of solar oscillations — revolutionized solar physics by providi

E_3_11 — Earthquake Archaeology and Seismic Catastrophes

Archaeoseismology — the study of past earthquakes using archaeological evidence — reveals that seismic catastrophes have repeatedly destroyed, reshaped, and sometimes permanently ended ancient urban centers and entire ci

E_3_22 — Historic Mega-Earthquakes: Cascadia, New Madrid, and the Seismic Record

The seismic record of North America reveals two mega-earthquake systems that challenge the common assumption that destructive earthquakes are confined to well-known plate boundaries like the San Andreas Fault: the Cascad

J_2_20 — Zhang Heng's Seismoscope: Ancient Chinese Earthquake Detection

In 132 CE, during the reign of Emperor Shun of Han, the Chinese polymath Zhang Heng (張衡, 78–139 CE) constructed the world's first known instrument for detecting distant earthquakes — the houfeng didong yi (候風地動儀), litera

O_2_10 — Earth's Inner Core: Structure, Rotation, and Seismic Shadow Zones

Earth's inner core — a solid sphere approximately 1,220 km in radius at the center of the planet, composed primarily of an iron-nickel alloy at temperatures of ~5,000-6,000°C and pressures exceeding 330 GPa (~3.3 million

O_2_09 — The Mohorovičić Discontinuity and Earth's Internal Structure

The Mohorovičić Discontinuity (the "Moho") — the boundary between Earth's crust and upper mantle — is one of the most fundamental structural features of our planet and a cornerstone of solid-Earth geophysics. It was disc

O_2_14 — Slow Earthquakes and Episodic Tremor: Silent Seismic Events

Slow earthquakes — a class of seismic events in which fault slip occurs over days to months rather than the seconds to minutes characteristic of conventional earthquakes — represent one of the most significant discoverie

O_2_20 — Hollow Earth Theory

The Hollow Earth theory proposes that the planet's interior is partially or entirely hollow, potentially containing habitable spaces, inner suns, atmospheres, or even advanced civilizations. This idea has ancient roots i

O_2_07 — Anomalous Animal Behavior Before Earthquakes and Storms

Reports of anomalous animal behavior preceding earthquakes and severe weather events span millennia and cultures: the earliest known written account dates to 373 BCE (Diodorus Siculus describing rats, weasels, snakes, an

ZF_1_05 — Tsunami Science and Warning Systems

Tsunamis — long-wavelength ocean waves generated by sudden displacement of the water column — are among the most destructive natural hazards, capable of crossing entire ocean basins and devastating coastlines thousands o

O_0_00 — Earth Science & Anomalies: Section Summary

O_2_00 — Geological Tectonic: Subfolder Summary