Earthquake!! Foreshock, Mainshock, or Aftershock? Which was it?

www.iris.edu/earthquake
There is often confusion surrounding the terminology of earthquakes. Large earthquakes are usually followed by hundreds and even thousands of smaller earthquakes, called aftershocks. In some earthquake sequences, a smaller earthquake called a “foreshock”, precedes the mainshock. Although seismologists have carefully analyzed foreshock/mainshock pairs of earthquakes, and earthquake triggering in general, there are no special characteristics of a foreshock that let us know it is a foreshock until the mainshock occurs. Rate of aftershocks was first studied in detail by Fusakichi Omori, Chairman of Seismology at Imperial University of Tokyo; one of the most important figures in the history of seismology.
Written & directed by Dr. Robert F. Butler, University of Portland
Animation & graphics: Jenda Johnson, Earth Sciences Animated
Narrated by Dr. Wendy Bohon, Education Specialist, IRIS
Reviewed by Dr. Peter Haeussler, U.S. Geological Survey,
Earthquake locations: IRIS Earthquake Browser, (IEB)
Maps: IEB, USGS, Google Earth
Photos from public domain sources
Video clips from FEMA
Music “J-sketches 1” by Andrew Menking
Made with support from the National Science Foundation (NSF)

[@hoimanoy1188]

Who's here because of the earthquake that happened in Southern California a few hours ago?

[@ChadFreeman757]

Hoi Manoy I am. It sparked my interest.

[@hoimanoy1188]

@@ChadFreeman757 same I hope your family is safe ^-^

[@ChadFreeman757]

Hoi Manoy Thanks. We are safe & happy. We’re in Norfolk, Virginia. Definitely didn’t feel it here. But we’re close to hurricane season.😁 I hope you & all of Cali is safe.

[@EuskadiJoloMas]

Well now we know yesterday was the foreshock and today was the mainshock!

[@ChadFreeman757]

JoMas other videos suggest that the main shock is yet to come.

[@beyerdr]

I remember the Denali Fault quake. I was at work standing on a pallet, I thought somebody was trying to move it lol. Lasted a long time.

[@YouCantSeeMeENT]

Good thing i payed attention in high school

[@towakosano5796]

Yes I felt this earthquake in Tokyo. Thnx for this video!

[@BAD5RO]

Foreshock or main shock, we are waiting here in Morocco to know

[@susanyamlean6020]

I Currently in Ambon, Maluku Indonesia. 6.5 Earthquake hits This Island in 26 September 2019 and there are thousand of aftershock with magnitude 2 and 3 poin something until today (10 october 2019) do you think there will be a higher magnitude earthquacke happened after all these aftershock ? 😭

[@charlotte_stevens]

Anyone here trying to brush up on their earthquake knowledge since yesterday's 5.7 quake in Salt Lake City?

[@jiggawhat56]

Pray for Morocco

[@mahlaqa3310]

insha'Allah I will

[@aprendahebraicocomabiblia1090]

הרגשת את רעידת האדמה?

[@CroGirlZg]

Any Zagreb peeps after Sunday's 5,5 quake?

[@aliciaraye]

Well now I know yesterday’s 6.4 was a foreshock... I just hope it wasn’t a foreforeshock 😐😯

[@DawnDawson]

Where is the 4.6 two minutes before the 6.4 in the same area?

[@girlstinkimthere]

Who’s here because of Haiti?

[@cappypharoah]

Who’s here because of the earthquake in NY 😂??

[@cryola787]

Ah shit California

[@beyerdr]

I remember the Denali Fault quake. I was at work standing on a pallet, I thought somebody was trying to move it lol. Lasted a long time.