Anthony Lomax @ALomax@social.cleverlibre.org

Seismic intensity map (Japanese scale) from JMA website. M6.1, 350km depth (along the subducting Pacific Plate), not a damaging #earthquake but widely felt in Kanto and Tohoku to the North because the wave propagated efficiently along the Pacific Plate. https://www.data.jma.go.jp/multi/quake/quake_detail.html?eventID=20221114171426&lang=en

Can lots of small #earthquakes prevent a larger one from happening?

I get this question a lot and unfortunately the answer is no.

It would take 32 magnitude 5's, 1000 M4's, or 32,000 M3's to equal the energy of just one magnitude 6 event.

@freemo at well as downloading and playing with #obspy, which is highly recommended, you can see professionally produced versions of this plot, using more seismometers at #iris here: http://ds.iris.edu/spud/eventplot/20633642 and lots of further information from them here: http://ds.iris.edu/ds/nodes/dmc/tools/event/. My plot uses citizen science data collected from many private #raspishake seismometers across the globe.

Okay, there appears to be a sequence of #earthquakes in #Tonga. Here is a #map of the significant earthquakes in the area in the last 30 days. The three clusters are located > 300 km apart. Source: https://earthquake.usgs.gov/earthquakes/map/?extent=-28.70959,-187.11914&extent=-12.89718,-166.02539&range=month&magnitude=significant&sort=oldest&listOnlyShown=true&settings=true 1/N

M 6.5, Fiji Islands Region
2022-11-12 07:09:14 -20.18 -178.28 595 km A
http://geofon.gfz-potsdam.de/eqinfo/event.php?from=rss&id=gfz2022webq

Today's M7.3 #earthquake near #Tonga was a different type of event, generated by compression in the outer rise due to the bending of the #subducting slab. The shallow part of the outer rise is usually experiencing tensional #stresses and produces normal faulting quakes. The deeper section is in compression, causing reverse #faulting #earthquakes, usually with low #tsunami generating potential due to their depth.

A large M=7.3 #earthquake occurred today to the west of #Tonga islands. The #focal #mechanism shows that it involved a #thrust fault (contraction). However, its location (to the east of the trench) is somehow unusual, as the #subduction dips to west. This "outer rise" region produces earthquakes related to bending/loading of the plate, but most of them have #normal (extension) focal mechanisms. Mecanism from Geoscope/IPGP.
http://geoscope.ipgp.fr/index.php/en/catalog/earthquake-description?seis=us7000ip0l

Magnitude 7.3 #earthquake offshore Tonga 45 minutes ago (2022-11-11Z10:48) - Normal faulting. Incredible signal at station IU.CTAO (Charters Towers, Australia, available via IRIS)

https://earthquake.usgs.gov/earthquakes/eventpage/us7000ip0l/executive

See https://www.tsunami.gov/ for #tsunami information. Advisory in place

M 7.6, Tonga Islands Region
2022-11-11 10:48:44 -19.25 -172.35 15 km M
http://geofon.gfz-potsdam.de/eqinfo/event.php?from=rss&id=gfz2022wcnj

Large earthquakes in #Canada??
Not so often, but yes, some of the world’s largest #earthquakes, including:
M9 (offshore #VancouverIsland in 1700)
M8.1 and M7.8 (offshore #HaidaGwaii in 1949 and 2012, respectively).
More than 4000 earthquakes are located across Canada each year, from coast to coast to coast.

More on Canada’s earthquakes and how we minimize the impacts:
https://earthquakescanada.nrcan.gc.ca/historic-historique/GeoScienceCanada2010_Cassidyetal.pdf

https://earthquakescanada.nrcan.gc.ca/pprs-pprp/pubs/GF-GI/GEOFACT_largest-earthquakes_e.pdf

Wow. This needs to be read by everyone who joined Mastodon in the last week: https://www.hughrundle.net/home-invasion/

The largest earthquake I’ve felt was the 2016 M7.8 Kaikōura NZ. I was in Wellington and although the rupture started >200 km away, it travelled northwards towards us. The earthquake really kicked in at the top of the South Island with shaking of MMI IX (Violent), finally stopping in Cook Strait ~50 km away. More than 20 faults ruptured; the Papatea Fault displaced the coast by ~1.5 m👇 The fact that earthquakes can produce changes to our landscape in seconds is, to me, awe-inspiring and humbling.

In North America, there are numerous sites that allow us to visualise the history of #OurPlanet📜

⬇️The Goosenecks State Park in Utah provides a spectacular view of the goosenecks (or entrenched meanders) even when observed from above🌍

#EarthArt by #Copernicus #Sentinel2 🇪🇺🛰️

🐦🔗: https://nitter.eu/CopernicusEU/status/1590348216436142080

The choices facing the world at #COP27.

The planet has already warmed by around 1.2°C.

Current policies set us on track for around 3°C of warming.

Only making radically different choices will give the world a chance of not exceeding the 1.5 or 2°C limits of the Paris Agreement

M5.6 #earthquake Italy at 06.07 UTC on 9 November 2022. Recorded in Nottingham using "slinky" (top) and horizontal pendulum school seismometers
https://earthquake.usgs.gov/earthquakes/eventpage/us7000infp/executive

Just a reminder about Mastodon.

Try not to directly upload videos here.
You have to remember that these videos have to be stored on the server that you're hosted on.

This would also eat up on available bandwidth, storage and memory resources of said servers and slow them down. Which would force server hosts to upgrade at a substantial cost.

Suggested idea...

Upload to YouTube, Vimeo or other video streaming services and share the link to the video here instead.

#IPGP #Geoscope focal mechanism for today Mw5.8 #earthquake in #CentralItaly http://geoscope.ipgp.fr/index.php/en/catalog/earthquake-description?seis=us7000infp