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2024-04-05, M4.8, New Jersey

On April 5, 2024 at 14:23:20 UTC (10:23am local time) a M4.8 earthquake occurred near Whitehouse Station, New Jersey, USA, around 60km ESE of New York City. It has been followed by an aftershock sequence of 41 further events of smaller magnitude so far.

This earthquake was caused by a combination of shallow oblique reverse and strike-slip faulting, occurring at a depth of only around 5km. It is an example of an “intraplate” earthquake that occur on existing faults, away from a tectonic plate boundary.

The event was recorded by seismic stations in Ireland operated by DIAS in the Irish National Seismic Network (INSN), see figure below, with the signal just visible above the background noise. An earthquake of magnitude M4.8 at a distance of around 5000km is close to the limit of what can be detected, as the amplitude of the ground motion from the seismic waves reduces with distance as the energy spreads out and is attenuated.

Earthquakes in this part of the US are uncommon but do happen occasionally. 13 earthquakes of M4.5 and larger have been recorded within 500km of this event since 1950, with the largest being the damaging and widely felt M5.8 Mineral Virginia earthquake on 23 August 2011.

While this earthquake was relatively small in global terms, earthquakes of this magnitude are commonly felt more widely in the eastern US (compared to the Western USA) because of the relatively high population density and efficient wave propagation through older cratonic crust. Shaking from this earthquake was felt by millions of people across the Northeast US (see intensity map from the USGS below), but no significant damage to buildings or injuries to people have been reported.

Felt intensity map of the 5 April 2024 M4.8 New Jersey earthquake, showing the effects of ground shaking that occurred during this event, source: USGS

More information is available at the below resources:

https://earthquake.usgs.gov/earthquakes/eventpage/us7000ma74/executive

https://www.earthscope.org/geophysical-event/11825173/

2023-05-06, M2.5, Donegal

At 00:32 UTC on the 6th of May 2023 an M2.5 earthquake occurred at a depth of approximately 10 km. The event occurred near Glenveagh National Park in northwest Donegal, Ireland (see map below). The Irish National Seismic Network (INSN) operated by DIAS has received reports that the event was felt throughout the Donegal area.

The event was recorded by seismic stations operated by DIAS in the Irish National Seismic Network (INSN), see figure below.

If you felt this event, please consider making a report at https://www.insn.ie/you-felt-a-seismic-event/questionnaire/

The map below shows the locations from where the INSN received felt event reports. Nearly 300 reports of the event being felt or heard were received, particularly from Letterkenny, Ballybofey and Dungloe. Approximately 85% of respondents heard the earthquake, 76% felt the earthquake and 32% were awakened by the earthquake.

The earthquake was also detected by several Raspberry Shake seismometers operated in Ireland by citizens and schools. The plot below shows the recorded data, the distance between each station and the epicentre is shown in the top right corner of each sub-panel.

Below we show the seismogram and spectrogram for the the citizen station AM.R0FF0 (located in Sligo) as generated by the Raspberry Shakenet mobile app.

2023-02-24, M3.4, Wales

On the 24st of February 2023 an M3.4 earthquake occurred at 23:59:41 UTC approximately 30 km northwest of Newport in Wales, United Kingdom, see map below. The British Geological Survey (BGS) reported that the event was felt throughout the region, mainly within around 40 km of the earthquake epicentre.

The event was recorded by seismic stations in the Irish National Seismic Network (INSN), see figure below.

More information about the earthquake is available at the following resources:

https://www.emsc-csem.org/Earthquake/earthquake.php?id=1228525

https://earthquakes.bgs.ac.uk/earthquakes/recent_events/20230224235706.htm

2023-02-20, M6.4, Turkey

On the 20th of February 2023 at 17:04:29 (UTC) an M6.4 earthquake occurred in Southern Turkey near the border with Syria, about 15km southwest of Antakya and 5km from the Mediterranean Sea, see map below. The event struck in an area already affected by two strong earthquakes that hit two weeks earlier and caused more than 45,000 deaths and widespread destruction of infrastructure. The M6.4 event occurred at a relatively shallow depth of 10 to 15km and was felt as far as Egypt and Lebanon. Local sources report that several people have been killed and hundreds are injured due to collapsed buildings.

The event was recorded by seismic stations worldwide, including stations in the Irish National Seismic Network (INSN), see figure below.

More information about the earthquake is available at the following resources:

https://www.emsc-csem.org/Earthquake/earthquake.php?id=1226422

https://earthquake.usgs.gov/earthquakes/eventpage/us6000jqcn/

2023-01-09, M7.6, Indonesia

On the 9th of January 2023 an M7.6 earthquake occurred in the Tanimbar region of Indonesia (see map below). Several aftershocks were also reported after the powerful quake that was also felt in some parts of northern Australia.

Indonesia is positioned at the boundary of 3 tectonic plates (the Indian-Australian, Eurasian and Pacific plates). The plate boundaries are long and found beneath the ocean, meaning large and shallow earthquake can be generated from this zone that may potentially generate tsunami.

The event was recorded by seismic stations worldwide, including stations in the Irish National Seismic Network (INSN), see figure below.

More information is available at the following resources:

https://www.bmkg.go.id/berita/?p=peta-isoseismal-gempabumi-maluku-tenggara-barat-10-januari-2022&lang=ID&s=detil

https://earthquake.usgs.gov/earthquakes/eventpage/us7000j36j/executive?utm_medium=email&utm_source=ENS&utm_campaign=realtime

https://www.emsc-csem.org/Earthquake/earthquake.php?id=1208699

2022-01-15, Eruption in Tonga

The underwater volcano “Hunga Tonga-Hunga Ha’apai” in Tonga has been experiencing ongoing volcanic activity since the 20th December 2021. From the 5th of January 2022 activity had decreased, but on the 15th it increased again with a large eruption occurring with a sonic boom that was heard hundreds of kms away. The event was recorded by seismic stations worldwide, including stations in the Irish National Seismic Network (INSN) (see figure below). The first signals originating from the Tonga event arrived ~15 hours after the event origin. A large plume of ash was visible on satellite images and the eruption was heard in Tonga, the surrounding islands and with reports from as far away as Alaska. The eruption also generated a tidal wave warning for the Pacific region.

Seismic noise changes during Covid19

Instruments operated by the INSN track ground motions from natural phenomena, such as earthquakes, but also human-made ground vibrations, so-called ‘seismic noise’. After the lockdown started on the 28th March 2020, some INSN stations detected seismic noise levels significantly lower than before the lockdown. See figure below for seismic noise data from our station located in the Dublin mountains (click figure to enlarge).


Frequently Asked Questions:

What are seismometers for?
Seismometers respond to ground motion and are traditionally used to detect and locate earthquakes. The earthquake information in turn is used by seismologists and geologists to study the Earth’s interior.

What is seismic noise?
Seismic noise is a relatively persistent ground vibration that is not caused by earthquakes (Note: it is not a vibration in the air). Seismologist termed these signals ‘noise’ because they are a nuisance when trying to detect small earthquakes. Seismic noise has very low amplitude and cannot be felt by humans.

What can a seismometer not tell?
Seismometers do not distinguish between human made seismic noise, naturally made seismic noise (e.g. by strong wind) or seismic waves caused by an earthquake. Seismometers simply record ground vibrations no matter what caused them.

How do you know that the seismic noise is made by human activity?
Seismic noise can be caused by human activities like industrial works (e.g. large building sites, quarries, tunnelling),  road traffic, rail traffic, airports, but it is also caused by natural phenomena like for example wind or water flow in a river. Human induced seismic noise is readily identified by its clear variation between day and night and also lower amplitudes on weekends.

Why does the diagram above stop at Sunday April 26th?
After Sunday 26th April 2020 seismic noise recorded at this station is dominated by more local noise sources (likely related to site machinery) and therefore it no longer gives an average regional picture.

Does human induced seismic noise originate just from traffic?
No. Large building sites, quarries, tunnelling, road traffic, rail traffic and airports are some other examples of sources for human induced seismic noise.

How far away can the vibrations still be detected?
This depends on the type of vibration source, more specifically on the strength and the frequency of the vibration causing the seismic noise waves. It is not possible to determine source distances or locations with a single station, but the spectral content of the data may indicate if the source is near or far. As an approximate guideline here are some numbers: Depending on rock type seismic noise originating from heavy industry can be detected up to distances of (approximately) 25km; from railways up to 15km; from motorways up to 6km; and from smaller roads up to 1km (International Handbook of Earthquake and Engineering Seismology, Part A, 2002, Edited by William H.K. Lee, Hiroo Kanamori, Paul C. Jennings, Carl Kisslinger, ISBN-10: 0124406521, ISBN-13: 978-0124406520).

How do you know its not a disturbance right beside the station?
Disturbances right beside a station show as very large amplitudes and don’t follow the smooth day/night variation that is observed for human induced noise from further afield.

Is this only seen in Ireland?
No. The effect of lockdown measures is observed at seismic stations worldwide, though only stations in or near urbanized areas show the effect, see for example https://www.nationalgeographic.com/science/2020/04/coronavirus-is-quieting-the-world-seismic-data-shows

Can you see this noise change all over Ireland?
No. Most of the seismic stations in Ireland operate at remote locations, away from urban areas, making them less sensitive to human induced seismic noise.

Why are seismologists interested in seismic noise?
In the 1990s methods were developed to derive ground properties from seismic noise data. In addition noise data are now widely used to monitor natural processes, for example ocean wave state, volcano activity and water flow at inaccessible locations like in caves and glaciers.


On the 10th April 2020 Martin Möllhoff gave this interview about seismic ground vibrations on Tipp FM:

 

 

 

2020-01-29, M1.0, Offshore Antrim

On the 29th January 2020 at 07:27:40 GMT a magnitude M1.0 earthquake occurred offshore Co. Antrim, Northern Ireland. The earthquake located close to the epicentres of the M0.9 earthquake, 26th January 2020 and the M1.6 earthquake, 18th of December 2019. In the map below the epicentre of the M1.0 earthquake is indicated with a red marker. Major fault zones in and around Ireland are shown with black lines.

The event was recorded by the Irish National Seismic Network (INSN) and British Geological Survey (BGS) seismometers, for seismograms see the plot below (click image to enlarge).

 

Past Seismograms
follow this link

Live Seismograms
All stations here
Filtered versions here
DSB - Dublin
VAL - Kerry

Past Spectrograms
follow this link
Live Spectrograms
All stations here
ITIP - N. Tipperary
IMAY - Mayo