When was the first instrument that actually recorded an earthquake?
The earliest seismoscope was invented by the Chinese philosopher Chang Heng in A.D. 132. This was a large urn on the outside of which were eight dragon heads facing the eight principal directions of the compass. Below each dragon head was a toad with its mouth opened toward the dragon. When an earthquake occurred, one or more of the eight dragon-mouths would release a ball into the open mouth of the toad sitting below. The direction of the shaking determined which of the dragons released its ball. The instrument is reported to have detected an earthquake 400 miles away that was not felt at the location of the seismoscope. The inside of the seismoscope is unknown: most speculations assume that the motion of some kind of pendulum would activate the dragons.
Learn more: The Early History of Seismometry (to 1900)
What was the duration of the earthquake? Why don't you report the duration of each earthquake? How does the duration affect the magnitude?
What does it mean that the earthquake occurred at a depth of 0 km? How can an earthquake have a negative depth; that would mean it’s in the air. What is the geoid, and what does it have to do with earthquake depth?
How are earthquakes recorded? How are earthquakes measured? How is the magnitude of an earthquake determined?
Moment magnitude, Richter scale - what are the different magnitude scales, and why are there so many?
What is the difference between magnitude and intensity? What is the Modified Mercalli Intensity Scale?
How do you determine the magnitude for an earthquake that occurred prior to the creation of the magnitude scale?
The USGS Earthquake Hazards Program recently released a new strategic plan for earthquake monitoring entitled the “Advanced National Seismic System – Current Status, Development Opportunities, Priorities, 2017-2027.”
The Hawaiian Volcano Observatory’s 1912–2012 Centennial—100 Years of Tracking Eruptions and Earthquakes
HAWAI‘I ISLAND, Hawaii —The history of earthquakes and seismic monitoring in Hawai‘i during the past century will be the topic of a presentation at the University of Hawai‘i at Hilo on Thursday, January 26, at 7:00 p.m.
USGS will Grant Universities $5 Million to Beef Up Public Safety Grants totaling $5 million under the American Recovery and Reinvestment Act are being awarded to 13 universities nationwide to upgrade critical earthquake monitoring networks and increase public safety.
Guided by Japanese writings from an era of shoguns, an international team of scientists today reported new evidence that an earthquake of magnitude 9 struck the northwestern United States and southwestern Canada three centuries ago. The findings are likely to affect the region’s precautions against future earthquakes and tsunamis.
On January 26, 1700, the largest earthquake known to have occurred in the "lower 48" United States, rocked Cascadia, a region 600 miles long that includes northern California, Oregon, Washington, and southern British Columbia.
Block diagram illustrating an idealized geological setting offshore the state of Washington. As the subducting Juan De Fuca tectonic plate dives beneath North America, it can generate an earthquake, and trigger a tsunami.
A seismometer deployed near the epicenter of the Greeley earthquake in 2014.
Map of ANSS free-field seismic stations across the U.S. in 2016 (not shown are additional seismic instruments in buildings and other structures). Map colors show seismic hazard across the United States derived from the National Seismic Hazard Model. Background colors indicate the levels of shaking that have a 2% chance of being exceed in a 50-year period. Shaking is...
Traditional seismic stations such as this one require a source of power (solar here), a poured concrete foundation and several square feet of space. They are not always practical to install in urban areas, and that's where NetQuakes comes in.