GEOL 106 Lecture Notes - Lecture 43: Mass Wasting, Global Catastrophic Risk, Grand Banks Of Newfoundland
26 May 2018
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14.4 Linkages with Other Natural Hazards
- impact or airburst of asteroid or comet is a direct cause for number of other natural hazards including
tsunamis, wildfires, earthquakes, mass wasting, climate change, volcanic eruptions (possibly)
- most impacting ojets lad i world’s oeas, ad large ojets will ause tsuais
- asteroid that hit Yucatan Peninsula close to 65 million years ago created large, complex tsunamis that
spread across Gulf of Mexico and are recorded in sedimentary deposits in Mexico, Texas, Alabama,
Cuba
o waves 200 – 300m high originated from impact blast and subsequent landslides in Gulf of
Mexico
- wildfires of regional or global extent have resulted from 3 well documented airbursts of impact events:
o K-Pg boundary
o Younger ryas boundary
o Tunguska events
- superheated clouds of gas and debris reach temperatures capable of drying out and then igniting living
vegetation
o wildfire patterns following large impact are complex and involve rock lasted into space
that then returns to Earth on other side of planet
o simulations suggest that these wildfires did not burn entire land surface of Earth
- seismic waves from large impact most likely activate numerous landslides both on land and under
water
o e.g. asteroid that formed Chicxulub impact on Yucantan Peninsula appears to have
produced a M10 earthquake and caused mass wasting of continental slope of NA as far
as north as Grand Banks of Newfoundland
- both asteroid that created Chicxulub Crater at K-Pg boundary and probably airburst at end of
Pleistocene Epoch caused global changes in climate
o impacts on land can inject large quantities of dust into atmosphere
o dust combines with smoke from wildfires → global cooling for number of years after
o after cooling → prolonged period of global warming from large amounts of CO2 and other
greenhouse gases produced by post-impact wildfires
- extraterrestrial impacts can also produce large volcanic eruptions by causing melting and instability
i earth’s atle
o could result in huge eruptions of lava called flood basalts and create large igneous
provinces on land
▪ provinces contain 100X more lava than from any other volcanic eruptions
▪ these eruptions appear to have produced global changes to atmosphere and
oceans and contributed to major extinctions of life
14.5 Minimizing the Impact Hazard
RISK RELATED TO IMPACTS
- risk of event = probability it will occur X consequences should it take place
o consequences of airburst or direct impact: catastrophic
▪ 7/10 would likely occur in oceans → effect of enormous size of asteroid or comet
would still be felt worldwide
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