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Latest Earthquake | Chat Share
There is nothing different about a cave that would make it immune to the shaking from an earthquake. Just as there are safer and less safe places to be on the surface of the earth during an earthquake, there are also various characteristics inside caves that make some cave locations safer or less safe than others. First of all, whether or not you feel an earthquake in a cave depends chiefly upon the magnitude or size of the earthquake and the distance from the earthquake source to the cave in question. The closer and larger the earthquake, the more shaking you’ll feel. The rest of the information about cave stability and shaking effects is based on limited observations and is a major area of active research.
The complexity of the cave seems to be a very important factor with regard to issues of cave passage "stability". A small tube-like passage appears to be a relatively safe location that doesn’t tend to collapse or sustain much, if any, damage from earthquake shaking. However, large cave passages or “rooms” are notably less stable places. It is in these areas where fallen chunks of limestone or marble are commonly observed, and where broken or toppled cave formations tend to be found.
Shaking effects inside caves include damage to delicate formations like soda straw stalactites that effectively “die” and top growing. Sometimes stalagmites or columns can be toppled. Toppled or not, renewed growth on them can occur. These effects are far short of a total passage collapse, but collapse of portions of cave ceilings has been observed in caves, notably from caves in Missouri and Indiana near the New Madrid and Wabash seismic zones.
So are caves safe in earthquakes? Generally yes, but it depends on the cave characteristics and where you are in it.
An interesting note: Cavers who witnessed earthquakes while underground have described sounds as if a distant aircraft was passing by, as in becoming perceptibly louder, then fading away.
It isn't that simple. There is not one magnitude above which damage will occur. It depends on other variables, such as the distance from the earthquake, what type of soil you are on, etc. That being said, damage does not usually occur until the earthquake magnitude reaches somewhere above 4 or 5.Learn more: Earthquake Magnitude, Energy Release, and Shaking Intensity
The way an earthquake feels depends on where you are, where the earthquake is, and how big the earthquake is:A large earthquake nearby will feel like a sudden large jolt followed quickly by more strong shaking that may last a few seconds or up to a couple of minutes if it's a rare great event. The shaking will feel violent and it will be difficult to stand up. The contents of your house will be a...
"Booms" have been reported for a long time, and they tend to occur more in the Northeastern US and along the East Coast. Of course, most "booms" that people hear or experience are actually some type of cultural noise, such as some type of explosion, a large vehicle going by, or sometimes a sonic boom, but there have been many reports of "booms" that cannot be explained by man-made sources. No one...
There is more damage and more deaths from earthquakes in other parts of the world primarily because of buildings which are poorly designed and constructed for earthquake regions, and population density.
Groundwater levels in wells may oscillate up and down while seismic waves pass, and in some cases, the water level may remain higher or lower for a period of time after the seismic wavetrain has ended.Learn more:Groundwater Effects from EarthquakesGroundwater Response to Earthquakes
Two sources for photographs that show earthquake damage are:Earthquake Hazards Program - Earthquake Photo CollectionsU.S. Geological Survey Photographic Library (see 'earthquakes' in the categories left column)
Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes. For example, the 1964 Niigata earthquake caused widespread liquefaction in Niigata, Japan which destroyed many buildings. Also, during the...
Phenomena such as sheet lightning, balls of light, streamers, and steady glows, reported in association with earthquakes are called earthquake lights (EQL). Geophysicists differ on the extent to which they think that individual reports of unusual lighting near the time and epicenter of an earthquake actually represent EQL: some doubt that any of the reports constitute solid evidence for EQL...
Steps to identification of a sonic boom:The USGS sees either nothing on our seismic records or a fairly short high-frequency signal that doesn't look like an earthquake.On rare occasions, we see the event on multiple stations, and the time difference between stations matches the speed of sound in air, which is slower than the speed of seismic waves in rock.Felt reports come from a wide area, which...
The central United States has undergone a dramatic increase in seismicity over the past 6 years. From 1973-2008, there was an average of 24...