Interesting this earthquake struck shortly after a solar eclipse, implying significant spring tide forces were present. The earthquake occurred near dawn, when the sun/moon pair, Indonesia, and the Earth's core formed a right angle to each other, creating tidal tension forces on the crust.
Tidal forces have been linked to the Dec. 26, 2004 Sumatra earthquake. This paper claims there's a significant link between tidal forces and earthquakes in the region (https://doi.org/10.1029/2006GL027074). The authors conclude "The observed relationships suggest that the cyclical crustal flexing, which will be at a maximum at full or new moons, might provide sufficient extra force to a plate-boundary region already on the point of rupture to trigger an earthquake that was ‘waiting to happen’."
insaider 1 days ago [-]
Is this big enough to produce a Tsunami? Apparently maybe only a small localised one, but I'm supposed to be getting the ferry from Lombok to Bali shortly and two of those have already burnt down the last 2 weeks!
decimalenough 1 days ago [-]
A ferry in the open ocean is one of the safer places to be during a tsunami. Remember, it's not a surf-style wave, but a gradual increase in water level.
kylecazar 21 hours ago [-]
There's an eerie video that went around of a ship hitting the 2011 tsunami in Japan at open sea. It demonstrates the idea pretty well.
Longer & significantly less edited video from the above's cited source: https://youtu.be/-VcWF8dIDj4. There is a comment with the translations of what's being said that adds a lot of info/meaning. Particularly this was at a relatively shallow depth (38 meters) only a couple miles off the coast, the above ferry would spend most of its time in >200 meter waters according to https://www.arcgis.com/apps/mapviewer/index.html?webmap=019a... so would probably look nothing like this at most points in the trip.
aziaziazi 24 hours ago [-]
After the tsunami, would the current induced by the water drawback disrupt the ferry ability to come back ? I wonder if the ocean “rise” again (water on top of water) or if it’s more a current-style (water push water) movement.
monster_truck 20 hours ago [-]
Extremely. They are quite slow laterally (a couple knots while docking), the lateral currents (which are not constant or unidirectional) reach 2-4x+, throwing them into whatever happens to be in the way.
AFAIK the bigger issue is that the boats are grounded so violently when the water recedes that the hulls get destroyed before they even have a chance.
This tends to be why they put everything they have into getting further out to sea the moment a warning is issued.
throwaway894345 1 days ago [-]
boarding the ferry may not be the most pleasant, however.
They've declared the event over - some waves were generated but nothing particularly large. Bulletin 3 for the recent quake includes wave height observations - maximum reported was 94cm; most were under 50cm.
Grimburger 1 days ago [-]
Tsunamis are only an issue close to shore. In the ocean it's barely a mild wave.
In a boat going further out is the safest thing you can do if there's a tsunami warning.
stelliosk 1 days ago [-]
Depends on how the tsunami was created. By earthquake or by land slide. For example, the following tsunami no boat is safe.
That's a hypothetical "hazard" of a megatsunami and on top of that, seems reaaaally unlikely to happen within the lifetime of any of us:
> Giant landslides are rare events.[117] Humanity has never witnessed enormous collapses on La Palma[59] and there is evidence that the western flank of La Palma is currently stable[65] and a collapse in the near future is unlikely.[133] A worst-case scenario giant landslide like the one modelled by Ward and Day 2001 is a very low probability event, probably much less common than once per 100,000 years[123]
But, never say never, apparently we're ruining the planet faster than anyone of us thought possible just 50 years ago, so who knows what could happen.
stelliosk 18 hours ago [-]
One that happened, earthquake triggered rockslide:
I've seen "possible tsunami" pre-warnings, and a sea level gauge at/near Lembar showing sea level oscillations - so I would recommend keeping a close watch on some information source that's better than HN comment threads, yes.
lostlogin 1 days ago [-]
Correct, but also, I’d bet there is a lurking tsunami expert here somewhere. Nothing is ever too niche for HN.
Melatonic 1 days ago [-]
There's a tsunami warning list you can sign up for. As well as global earthquake alerts. In my experience they arrive very quickly
Usually earthquakes on land don't trigger tsunamis but are more damaging locally
bdickason 1 days ago [-]
I would upgrade the ferry and make sure to get a high quality one given all the swell in the ocean already (most of bali had 6ft+ waves yesterday) and this incident. Not worth the risk.
seanmcdirmid 1 days ago [-]
Lombok will have lots of higher ground at least. You really just have to be careful on and near the beach.
yxhuvud 1 days ago [-]
Easily big enough, but how deep it was generated and how the movements happened do impact the risk a lot.
reilly3000 1 days ago [-]
Safe travels, friend.
pestatije 1 days ago [-]
the tsunami risk is negligible compared to the fire risk
insaider 1 days ago [-]
Agreed, currently aboard and on high alert, pray for me HN
bdickason 1 days ago [-]
Let us know you made it ok!
rootsudo 1 days ago [-]
Interesting times for the ferry indeed
CookieCrisp 1 days ago [-]
I know large earthquakes are effectively random (ignoring aftershocks) but this feels like a lot this year, yeah?
HaloZero 1 days ago [-]
Yeah, I looked this up and USGS literally has a page about this.
According to long-term records (since about 1900), we expect about 16 major earthquakes in any given year. That includes 15 earthquakes in the magnitude 7 range and one earthquake magnitude 8.0 or greater. In the past 40-50 years, our records show that we have exceeded the long-term average number of major earthquakes about a dozen times.
The search filtering is a bit hard to find in the UI but the parameters in the URL can be modified. (We had 16+ 7.0 last year as a comparison)
astrobe_ 1 days ago [-]
I've always wondered if the melting of glaciers would move masses from one place to another and induce some tectonic moves. But the mass is most likely not significant enough; water/ice has a relatively low density after all.
dev1ycan 1 days ago [-]
It's more likely related to planetary positions and or solar cycle/activity, "recent studies suggest a notable statistical correlation between specific solar magnetic milestones and the shifting phases of the El Niño-Southern Oscillation"
Like in theory it doesn't make sense that el niño causes earthquakes, yet there seems to be more prominent ones during el niño however if both are related to sun cycle/activity it would make more sense (seeing how the moon affects earth as well)
smolder 1 days ago [-]
The deep earth isn't all that well studied, so while we know a fair amount about plate tectonics, there could be hidden factors influencing that action in ways we can't anticipate from recorded history. Who's to say there aren't 1000 or 10k year cycles of earthquakes? Something novel could happen too, but our records don't let us set probabilities for 10k year natural disasters the way we can with 100 year tropical storms, floods, or earthquakes.
defrost 1 days ago [-]
> Who's to say there aren't 1000 or 10k year cycles of earthquakes?
The Stratigraphy department of the International Union of Geological Sciences would be the obvious first port of call.
Follow that up with an off book chat with digital archivists for commercial oil and gas exploration geologists.
Melatonic 1 days ago [-]
Or influence by the moon just as it pulls on oceans. Lot of liquid magma down there.
Or maybe some once in a rare incident involving coronal mass ejections somehow affecting the core of the planet. Could even be a delayed effect.
fragmede 20 hours ago [-]
One of the More out there theories is that some earthquakes are caused by high energy cosmic particles going through the Earth.
Earthquakes can occur in swarms[1] (distinct from aftershocks), with many of a similar size (i.e. Not a big quake followed by smaller ones) occurring in a small area over "relatively short" periods of time (i.e. days, weeks, or years).
The USGS map shows the 7.7 quake being followed by about 19 other smaller quakes near or in Indonesia within just a few hours. These are probably aftershocks.
Sure feels like it in my corner of the Bay Area, since we had a prolonged earthquake swarm earlier this year, even hitting a record number of earthquakes per day or something like that.
> Note: While it may look like there have been an increase in total number of earthquakes since about 2020, this is actually due to the increasing number of seismic stations installed in the park since 2020 that are able to detect smaller (<= 0.5 magnitude) earthquakes. If you look at the number of earthquakes >= 1.0, the rate has remained about the same.
jwilber 1 days ago [-]
Somehow I don’t think people are confusing raw seismic station earthquake counts with the three back-to-back high profile/magnitude earthquakes that recently occurred in Venezuela, Colombia, and Indonesia.
I understand the point, maybe those recent earthquakes aren’t ood, but still.
Melatonic 1 days ago [-]
There are also likely a lot of earthquakes we don't notice because they don't effect populated areas. There's a lot of ocean around the ring of fire.
goda90 1 days ago [-]
Why does this page say there have been 0 >2.5mag earthquakes this year?
teraflop 1 days ago [-]
Because this particular sensor network is only monitoring earthquakes in the Pacific Northwest of the USA, not worldwide.
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1 days ago [-]
onion2k 22 hours ago [-]
Randomness without clusters probably isn't random.
This morning, when I woke up, I checked the phone notifications. I saw some alerts from the LastQuake app that a major earthquake occurred on Flores. I didn't feel it here in Bukit, Bali, where I currently reside.
1 days ago [-]
1 days ago [-]
burnt-resistor 1 days ago [-]
So Google Earth says the ocean depth at the epicenter is 6,286 ft / 1,916 m, but I couldn't find a corresponding tsunami alert or evaluation of risk.
mikeyouse 1 days ago [-]
Looks like it was a strike-slip fault, so a much lower tsunami risk compared to a subduction / dip-slip fault.
lightedman 1 days ago [-]
Beachball (moment tensor) says it's a thrust fault with a ton of lateral movement (aka attempted subduction.) https://earthquake.usgs.gov/earthquakes/eventpage/us6000tkt2... eyeballs filled in are pretty much thrust faults and horizontal like that means subduction-possible movement.
ttul 1 days ago [-]
What is the moment tensor in this context?
lightedman 13 hours ago [-]
The moment tensor is the graph on my link which describes the forces that cause an earthquake and is used to analyze the fault movement that generates seismic waves
numb_code 1 days ago [-]
[flagged]
navigate8310 1 days ago [-]
[flagged]
Rendered at 08:15:31 GMT+0000 (Coordinated Universal Time) with Vercel.
Tidal forces have been linked to the Dec. 26, 2004 Sumatra earthquake. This paper claims there's a significant link between tidal forces and earthquakes in the region (https://doi.org/10.1029/2006GL027074). The authors conclude "The observed relationships suggest that the cyclical crustal flexing, which will be at a maximum at full or new moons, might provide sufficient extra force to a plate-boundary region already on the point of rupture to trigger an earthquake that was ‘waiting to happen’."
https://youtube.com/shorts/igfP5CQAkHU?is=TJqk4lxxhYkK8hQV
Longer & significantly less edited video from the above's cited source: https://youtu.be/-VcWF8dIDj4. There is a comment with the translations of what's being said that adds a lot of info/meaning. Particularly this was at a relatively shallow depth (38 meters) only a couple miles off the coast, the above ferry would spend most of its time in >200 meter waters according to https://www.arcgis.com/apps/mapviewer/index.html?webmap=019a... so would probably look nothing like this at most points in the trip.
AFAIK the bigger issue is that the boats are grounded so violently when the water recedes that the hulls get destroyed before they even have a chance.
This tends to be why they put everything they have into getting further out to sea the moment a warning is issued.
https://rtsp.bmkg.go.id/publicbull.php
They've declared the event over - some waves were generated but nothing particularly large. Bulletin 3 for the recent quake includes wave height observations - maximum reported was 94cm; most were under 50cm.
In a boat going further out is the safest thing you can do if there's a tsunami warning.
https://en.wikipedia.org/wiki/Cumbre_Vieja_tsunami_hazard
> Giant landslides are rare events.[117] Humanity has never witnessed enormous collapses on La Palma[59] and there is evidence that the western flank of La Palma is currently stable[65] and a collapse in the near future is unlikely.[133] A worst-case scenario giant landslide like the one modelled by Ward and Day 2001 is a very low probability event, probably much less common than once per 100,000 years[123]
But, never say never, apparently we're ruining the planet faster than anyone of us thought possible just 50 years ago, so who knows what could happen.
https://en.wikipedia.org/wiki/1958_Lituya_Bay_earthquake_and...
https://en.wikipedia.org/wiki/List_of_tsunamis
Usually earthquakes on land don't trigger tsunamis but are more damaging locally
https://www.usgs.gov/faqs/why-are-we-having-so-many-or-so-fe...
According to long-term records (since about 1900), we expect about 16 major earthquakes in any given year. That includes 15 earthquakes in the magnitude 7 range and one earthquake magnitude 8.0 or greater. In the past 40-50 years, our records show that we have exceeded the long-term average number of major earthquakes about a dozen times.
You can see a map of ALL the 7+ here:
https://earthquake.usgs.gov/earthquakes/map/?extent=-89.0318...
The search filtering is a bit hard to find in the UI but the parameters in the URL can be modified. (We had 16+ 7.0 last year as a comparison)
Like in theory it doesn't make sense that el niño causes earthquakes, yet there seems to be more prominent ones during el niño however if both are related to sun cycle/activity it would make more sense (seeing how the moon affects earth as well)
The Stratigraphy department of the International Union of Geological Sciences would be the obvious first port of call.
Follow that up with an off book chat with digital archivists for commercial oil and gas exploration geologists.
Or maybe some once in a rare incident involving coronal mass ejections somehow affecting the core of the planet. Could even be a delayed effect.
2023 also had a strong el-niño event.
https://en.wikipedia.org/wiki/List_of_earthquakes_2021%E2%80...
The USGS map shows the 7.7 quake being followed by about 19 other smaller quakes near or in Indonesia within just a few hours. These are probably aftershocks.
-------
[1]https://en.wikipedia.org/wiki/Earthquake_swarm
I understand the point, maybe those recent earthquakes aren’t ood, but still.