Ocean Networks Canada - earthquake

Resilience through preparedness: remembering the 1964 ‘Good Friday’ tsunami

duncanlowrie@uvic.ca — Wed, 08 Apr 2020 21:15:41 +0000

56 years ago, the ‘Good Friday’ earthquake rocked the Gulf of Alaska, causing a major tsunami to roll across the Pacific Ring of Fire on the evening of 27 March 1964. Few in Tofino were aware of the magnitude 9.2 earthquake or the alerts being sent by the US tsunami warning centre. Three and a half hours after the shaking, a series of tsunami waves swept over beaches and strong currents scoured the Pacific northwest coastline (Figure 1). Being early springtime and late at night in a sparsely populated Tofino, the area suffered no fatalities or injuries and only minor damage was reported. The event was a wake-up call for a risk that was not well understood nor well prepared for.

Figure 1. The 1964 earthquake off the coast of Alaska caused multiple tsunami waves to funnel up the narrow Port Alberni Inlet. There were no casualties, but the disaster damaged buildings, downed phone and power lines, and had a lasting impact on the community. Photo credit: Charles Tebby, Alberni Valley Museum.

Today Ocean Networks Canada (ONC) is helping to build resilience in Tofino—and elsewhere in British Columbia—by integrating the latest science and technology into tsunami planning efforts and improving awareness of the risk. Local leaders are partnering with scientists, engineers and tsunami experts to integrate local hazard models, community risk assessments, and tsunami mitigation best practices, to prepare for the next big one. Tofino’s Tsunami Mitigation Plan outlines actionable strategies for decreasing the risks associated with this threat. As a direct result, Tofino has improved understanding of the tsunami risk and what to do to better prepare (Figure 2).

Figure 2. Left: As part of Tofino’s Tsunami Mitigation Plan, the remote Pacific Rim municipality has developed a Tsunami Evacuation Route (left), with a map and information about emergency preparedness for residents and visitors. Right: Installed at Tofino airport in 2015, ONC’s WERA (WavE RAdar) high frequency oceanographic radar array is a shore-based remote sensing system that includes four transmitting and 12 receiving antennas that monitor ocean current speed in real-time.

The future is in real-time. In our highly connected world, tsunami information can be rapidly disseminated across a broad range of communication technologies. For example, technological advances include using high frequency radar to continuously monitor ocean surface levels. Coastal radar, including the WERA radar located at Tofino’s Long Beach Airport, delivers real-time ocean wave height data that can be used for tsunami response decisions and situational awareness (Figure 3).

Figure 3. In October 2016, ONC’s high frequency oceanography WERA radar system provided Tofino with real-time data when Typhoon Songda triggered a tsunami alert. “Real-time data from an instrument like the WERA radar supports critical and lifesaving decision making for coastal communities,” commented Keith Orchiston, Tofino’s Emergency Program Coordinator at that time.

On a broad scale, ONC uses real-time observations of earthquake shaking and tsunami wave heights to support official tsunami alerts and better monitor the tsunami threat. ONC’s Applied Science team uses detailed digital elevation maps and runs tsunami models on high powered computers which inform plans for future tsunamis. Public education on the science of tsunami and public safety best practices support an awareness of the risk and helps people take action to decrease their level of risk. Together, we are moving resilience forward.

Taking appropriate action is key, which is why ONC supports earthquake and tsunami preparedness education and training such as the High Ground Hike tsunami preparedness initiative, Masters of Disasters education program and Great BC ShakeOut earthquake drill.

In a disaster, we’re all in it together. What we do today will influence the outcomes of our next major tsunami event. At ONC, we are doing our part to help coastal communities prepare and become more resilient.

Drop, cover, and hold on

duncanlowrie@uvic.ca — Thu, 14 Nov 2019 23:22:13 +0000

The final land-based Earthquake Early Warning (EEW) sensors have been installed, completing this advanced seismic infrastructure for British Columbia's alerting system. The system, now ready for commissioning, includes eight seafloor EEW sensors installed on the Cascadia subduction zone, providing real time data on earthquakes—a first on the seafloor off the coast of North America. 36 land-based EEW sites on Vancouver Island help to pin down high magnitude earthquakes.

Data integration is done with the Canadian National Seismograph Network and Pacific Northwest Seismic Network. We are currently working with alerting authorities to determine future roll out of the earthquake early warning system.

There are currently no known means to reliably predict earthquakes, however seismic instruments can rapidly detect an earthquake as it begins to unfold and communicate a warning before shaking arrives.

Earthquakes release energy that travels through the Earth as seismic waves. Primary or ‘P’ waves travel faster than secondary or ‘S’ waves. The latter are the cause of severe damaging ground shaking. It is the ability to detect these first ‘P-waves’ that enables earthquake early warning systems to deliver alerts before the arrival of the ‘S-waves’.

The detection of an earthquake by many sensors can provide rapid estimates of the location and magnitude of an earthquake as it occurs. This information can be used to determine the estimated arrival time and intensity of ground-shaking at specific locations across a region, allowing protective actions to take place before the shaking hits.

ONC is monitoring and observing Cascadia Subduction Zone seismic activity 24/7 with multiple data and system redundancies. Check out ONC’s interactive earthquake data dashboard to explore recent earthquakes around the world.

Read More:
https://www.oceannetworks.ca/innovation-centre/smart-ocean-systems/earthquake-early-warning

Expedition 2019: Highlights Story Map

duncanlowrie@uvic.ca — Thu, 14 Nov 2019 19:36:10 +0000

Click here for the full screen interactive experience.

Data from Alaska’s Magnitude 7.9 Earthquake and Tsunami

kshoemak@uvic.ca — Tue, 23 Jan 2018 19:23:39 +0000

On 23 January 2018, a magnitude 7.9 earthquake occurred in the Gulf of Alaska at 1:35 am PT. A tsunami warning was issued for the west coast of Canada and the United States. The tsunami warning was cancelled at 4:40 am PT.

Ocean Networks Canada’s (ONC) real-time sensors detected the earthquake and the subsequent small tsunami that rippled out across the northeast Pacific (Figure 1).

Figure 1. The relative timing of the magnitude 7.9 Alaskan earthquake and the subsequent small tsunami as detected by ONC real-time sensors.

The resulting tsunami wave was relatively small because this was a strike-slip earthquake characterized by side-to-side motion, which displaces less water than the vertical motion of a subduction zone earthquake.

This morning's 7.9 earthquake occurred along a strike-slip fault. The horizontal movement of the two plates in a strike-slip fault, typically limits the threat of tsunami's pic.twitter.com/o7kgwNHqxS
— Greg Diamond (@gdimeweather) January 23, 2018

the Alaska earthquake generated a small tsunami detected by @Ocean_Networks sensors off Canada's westcoast #tsunami pic.twitter.com/MK0K0SLOi8
— Kate Moran (@katemoran) January 23, 2018

Alaska #tsunami just passed @Ocean_Networks bottom pressure station at Clayoquot Slope: 3-cm sea level drop; not big but there.https://t.co/b27CdUo3as pic.twitter.com/T6A8FT2SdT
— Martin Scherwath (@mscherwath) January 23, 2018

Friday 26 January is the anniversary of the last big Cascadia subduction zone earthquake that occurred in 1700, with an estimated magnitude of 8.7-9.2, which caused a widespread tsunami that devastated coastal Japan (Figure 2).

Figure 2. Modeled tsunami caused by the 26 January 1700 megathrust earthquake. Image courtesy of Kenji Satake.

This close call presents a perfect opportunity for British Columbians to become better prepared. Know the risks, have a plan, get a kit - these are the three major components of preparedness. Get started with help from Prepared BC (Figure 3).

Figure 3. Are you prepared for an emergency?

ONC’s earthquake and tsunami technology, research, data, modelling, and alert systems are being developed in collaboration with partners from government, science, academia, and industry in Canada, the United States, and around the world.

Are earthquakes on the rise?

kshoemak@uvic.ca — Wed, 25 Jan 2017 20:45:05 +0000

With media coverage of the recent earthquakes in Italy (M6.6), New Zealand (M7.8), Japan (M6.9), and Papua New Guinea (M7.9), you might be wondering whether earthquake activity is increasing. Long-term earthquake statistics in the last 12 months indicate that it was an average year: there were no earthquakes of M8.0 or higher (one M8.0+ is the annual average) and 19 earthquakes with M7.0 - 7.9 (17 is the annual average). These statistics (Figure 1) show that earthquake activity is not increasing.

Figure 1: Annual global earthquakes by magnitude, based on USGS statistics.

When the media focusses attention on something, such as the recent earthquakes in Italy, it’s easy to believe that there’s simply more of it about. This is called a spotlight fallacy, which contributes to the impression that earthquakes are on the rise. In fact, there have been almost 40 quakes of M6.6 or greater in the last year, but most of them did not create as much damage, nor did they receive as much attention.

Similarly, we are also susceptible to the clustering illusion. Our logical brains are wired to seek meaning in clusters or “streaks”, even if the occurrence is totally random. When in doubt, turn to scientific facts—especially during the post-truth era.

Earthquake Facts

A measureable earthquake takes place every 3-4 minutes somewhere on Earth.
Approximately 500,000 earthquakes are detected every year. This animation shows every recorded earthquake in sequence as they occurred from 1 January 2001 to 31 December 2015.
Magnitude and Intensity measure different characteristics of earthquakes. Magnitude indicates the energy released at the source of the earthquake and is measured by seismographs. Intensity indicates the strength of shaking produced by the earthquake at a certain location and is determined from the effects on people, human structures, and the natural environment (USGS).
Recent earthquakes around the world can be explored using the Ocean Networks Canada’s (ONC) interactive earthquake data dashboard (Figure 2). The dashboard includes selected earthquakes that are likely to have been recorded on ONC sensors.

Figure 2: ONC earthquake data dashboard.

The largest earthquake recorded by modern instruments happened in Chile on 22 May 1960 (M9.5).
The deadliest earthquake on record struck Shansi, China on 23 January 1556. An estimated 830,000 people died.
The Pacific northwest is host to three kinds of tectonic earthquakes: M9.0 Cascadia megathrust quakes, M6.5 to 7 deep earthquakes, and shallow crustal-fault earthquakes up to M7.5.
A megathrust earthquake is caused by a sudden slip on the fault between two tectonic plates (Figure 3) when one is forced under the other. On Canada’s west coast for example, the Juan de Fuca plate (Figure 4) is moving eastward underneath the North America plate at a rate of a few centimetres per year.

Figure 3: Global tectonic plates were mapped in the second half of the 20th century. (Image credit: Wikipedia)

Megathrust earthquakes tend to occur in the Pacific northwest region approximately every 300-500 years.
The last megathrust subduction earthquake to occur along the Cascadia subduction zone happened on 26 January 1700. The magnitude was estimated as 9.0, resulting in a tsunami that was recorded in Japan. Evidence of this earthquake is confirmed by geological evidence (land level changes, tsunami traces, turbidite deposits), biological evidence (tree rings), and human records (Indigenous stories and Japanese records). Find out more.

Figure 4: The Cascadia Subduction Zone, where the Juan de Fuca plate is forced under the continental North America Plate. (Image credit: USGS).

In collaboration with the Government of British Columbia, ONC is developing an earthquake early warning system (Figure 5) to alert British Columbians in advance of an earthquake. There are currently no known means to reliably predict earthquakes, however seismic instruments can rapidly detect an earthquake as it begins to unfold and communicate a warning up to 90 seconds before shaking arrives.

Figure 5: Earthquakes release energy that travels through the Earth as seismic waves. Primary or ‘P’ waves travel faster than secondary or ‘S’ waves that cause damaging ground shaking. It is the ability to detect these first ‘P-waves’ that enables earthquake early warning systems to deliver alerts before the arrival of the ‘S-waves’.

Find out more about British Columbia’s earthquake early warning system which will be installed, tested and delivered to Emergency Management BC by March 2019.

Canadian scientist awarded for exceptional contribution to Earth science!

linzhill@uvic.ca — Tue, 23 Aug 2016 21:22:25 +0000

Congratulations to Dr. Kelin Wang for being elected a Fellow of the American Geophysical Union (AGU), an international organization dedicated to advancing Earth and space sciences for the benefit of humanity. Becoming a fellow of AGU is an honour provided to only 0.1% of AGU’s 62,000 plus members from over 140 countries.

Kelin and his students are studying the geodynamics of subduction zones, especially processes related to the generation of large earthquakes and tsunamis around the world. His models for earthquakes inform building codes, risk assessments, and tsunami preparedness along the Pacific coast of North America. This work is relevant to the tsunami research being done at Ocean Networks Canada (ONC).

Dr. Kelin Wang, senior scientist with Natural Resources Canada and adjunct professor at the University of Victoria

ONC recently collaborated with Kelin and his student, Dawei Gao, whose research on rupture scenarios along the Cascasdia fault, together with ONC’s work on Digital Elevation Models, will provide the necessary pieces to develop tsunami inundation maps and tools for preparedness for British Columbia coastal communities.

ONC’s tsunami research will continue to advance with instrument development and more detailed propagation models in collaboration with world-class scientists and organizations such as IBM Canada, the Natural Sciences and Engineering Research Council’s Collaborative Research and Development Grant, Fisheries and Oceans Canada, Emergency Management BC, Alberni-Clayoquot Regional District, NOAA, and GeoBC.

Kelin Wang is a senior scientist with Natural Resources Canada and adjunct professor at the University of Victoria who has published more than 200 publications and nearly 10,000 citations.

Some of his recent publications linked to ONC include:

Nykolaishen, L., H. Dragert, K. Wang, T. S. James, and M. Schmidt (2015), GPS Observations of Crustal Deformation Associated with the 2012 Mw 7.8 Haida Gwaii Earthquake, Bull Seismol Soc Am, 0120140177–, doi:10.1785/0120140177.

Obana, K., M. Scherwath, Y. Yamamoto, S. Kodaira, K. Wang, G. Spence, M. Riedel, and H. Kao (2015), Earthquake Activity in Northern Cascadia Subduction Zone Off Vancouver Island Revealed by Ocean-Bottom Seismograph Observations, Bull Seismol Soc Am, 0120140095–, doi:10.1785/0120140095.

Insua, T. L. et al. (2015), Advancing Tsunami Detection: The Ocean Networks Canada Tsunami Project, in 11th Canadian Conference on Earthquake Engineering, Canadian Association for Earthquake Engineering, Victoria.

Insua, T. L. et al. (2015), Preliminary tsunami hazard assessment in British Columbia, Canada, in Fall Meeting, AGU, American Geophysical Union, San Francisco.

Gao, D., K. Wang, M. Riedel, T. Sun, T. L. Insua, C. Goldfinger, and G. R. Priest (2015), On the Possibility of Slip-to-trench Rupture in Cascadia Megathrust Earthquakes, in Fall Meeting, AGU, American Geophysical Union, San Francisco.

ONC detects M6.1 earthquake near Haida Gwaii

vkeast@uvic.ca — Fri, 24 Apr 2015 22:41:22 +0000

Seismic sensors on Ocean Networks Canada’s seafloor observatory installed offshore Vancouver Island detected an earthquake in the Northeast Pacific Ocean on the morning of 24 April 13:56:16 UTC (7:00 a.m. PDT)

The magnitude 6.1 earthquake struck offshore the Haida Gwaii Region, with its epicentre about 280 kilometres south west of Prince Rupert, British Columbia.

Figure1: ONC Earthquake Sensors and 24 April earthquake epicentre

The Haida Gwaii event was preceded by a magnitude 5.5 earthquake off the coast of Northern California twelve and a half hours earlier. It is unclear whether these earthquakes, occurring about 1300 km away from each other, are in some way related. It is, however, intriguing that the events were located at the southern and northern reaches of the Cascadia subduction zone and that the ONC seismometer at Endeavour detected numerous small local events during the same period of time.

Figure2. Seismic activity recorded by Endeavour seismometer on 24 April. Each horizontal line represents one hour of vertical ground motion (even hour black; odd hour blue). Bigger earthquakes show as large excursions crossing several rows. Small events right after each fourth hour are caused by electrical interference from the camera that observes hot vent fauna at the Endeavour location.

For more information: Martin Heesemann, ONC staff scientist

Sign up for alerts via the USGS Earthquake Hazards Program
Check for recent significant earthquakes in Canada

Magnitude 6.6 Earthquake

dwowens@uvic.ca — Thu, 24 Apr 2014 20:06:29 +0000

Multiple Ocean Networks Canada instruments recorded a magnitude 6.6 earthquake that struck beneath the seafloor off northern Vancouver Island at 8:10 PM (Pacific Daylight Time), 23 April 2014. Shaking from the earthquake was felt throughout Vancouver Island and by many people on the lower mainland in southwestern British Columbia.

Maps showing earthquake epicentre and aftershock locations (above, detail map shown above-right) and moderate to light shaking felt across northern Vancouver Island (lower map). The epicentre was 94 km south of Port Hardy, British Columbia and approximately 250 km north of NEPTUNE installations at Cascadia Basin. (Click to enlarge.)

Seismic Data

The main shock and numerous subsequent aftershocks were clearly recorded by seismometers at Cascadia Basin and Endeavour, as shown in data below. (Some of the smaller aftershocks shown in the seismic data from Endeavour may be associated with unrelated small local earthquakes that are frequently observed in this seismically active region.)

Earthquake initial shock and subsequent aftershocks recorded by the Cascadia Basin and Endeavour seismometers between 3:10-5:30AM, 24 April 2014 (UTC time) or 8:10-10:30 PM, 23 April 2014 (Pacific Daylight Time).

Bottom Pressure Recordings

Seafloor shaking was recorded by bottom pressure recorders at Cascadia Basin, Clayoquot Slope and Barkley Canyon shortly after the earthquake struck. However, there was no indication of a tsunami in the pressure data.

Seafloor pressure measured by bottom pressure recorders at three sites on the NEPTUNE Observatory. These recorders are situated at depths of 1285 m, 2706 m and 411 m. Pressure disturbances indicate seafloor shaking beginning approximately 3:11 AM, 24 April 2014 (UTC time) or 8:11 PM, 23 April 2014 Pacific Daylight Time).

Seafloor pressure anomalies (dBar) measured by bottom pressure recorders at three sites on the NEPTUNE Observatory. These recorders are situated at depths of 1285 m, 2706 m and 411 m. Blue lines show unfiltered wave height anomalies, while red lines are filtered to highlight longer-period waves such as tsunamis. Pressure disturbances indicate seafloor shaking (in blue) as the seismic waves passed, but there was no subsequent indication of a tsunami in the pressure data.

Ocean Networks Canada instruments on (and in) the seabed of the Fraser River Delta also registered the shaking, providing scientists at Natural Resources Canada information on how the delta sediments, and pressures within, respond to large earthquakes. An unproven, but commonplace, perception is that earthquakes could cause failure on the delta; Natural Resources Canada scientists are testing this hypothesis.

Rumbles and Crackles

The sound of the earthquake was recorded by Ocean Networks Canada's low-frequency hydrophone in Cascadia Basin, approximately 250 km away from the epicentre. The noise generated was so loud it saturated the hydrophone input. The spectrogram and audio recording of the earthquake are shown below. This recording has been sped up 400% to make the earthquake audible. The crackling sounds were caused when the hydrophone sensor was saturated.

Strike-slip Earthquakes

Seismologist analyses and the absence of a tsunami suggest that this earthquake likely occured on a strike-slip (lateral) fault. Vertical displacement for strike-slip earthquakes is typically much less than may be expected from a major subduction earthquake. The following short video illustrates the distinction between strike-slip and subduction earthquakes.

Chilean quake detected by ONC seafloor instruments

vkeast@uvic.ca — Wed, 02 Apr 2014 15:24:58 +0000

On April 1 at 4:46:45 PM, a magnitude 8.2 earthquake occurred off Chile's Pacific coastline. Shortly afterward, Ocean Networks Canada seismometers detected the tremors as they crossed the North Pacific.

Travel times for tsunami propagation were also modeled by the National Tsunami Warning Center, with expected arrival of a small (2-4 cm) tsunami in coastal British Columbia beginning 15 hours after the event, around 7:00 AM Pacific Daylight Time.

For full story, see: Tsunami Alert follows 8.2 quake off Chile

Updates to come...

No stranger to seismic activity, Chile is one of the world¹s most earthquake-prone countries. In 2010, a magnitude-8.8 quake and ensuing tsunami in central Chile killed more than 500 people and destroyed several hundred thousand homes along the coast.

Tsunami alert follows 8.2 quake off Chile

dwowens@uvic.ca — Wed, 02 Apr 2014 04:25:42 +0000

On April 1 at 4:46:45 PM Pacific Daylight Time (23:46:45 UTC), a magnitude 8.2 earthquake occurred off Chile's Pacific coastline, according to the US Geological Survey. Ocean Networks Canada instrumenatation captured both ground shaking and a very small tsunami as they crossed the northeast Pacific.

Map of the epicentre and 16 aftershocks along the subduction zone between the Nazsca and South American plates, 1 April 2014. Data provided by USGS and plotted using Google Earth. (Click to enlarge.)

At a depth of 20.0 km below the seabed, the shallow near-field quake struck 86 km northwest of the mining area of Iquique, hitting a region that has been rocked by numerous quakes over the past two weeks. According to the USGS, this earthquake occurred as the result of thrust faulting at shallow depths near the Chilean coast. The location and mechanism of the earthquake are consistent with slip on the primary plate boundary interface, or megathrust, between the Nazca and South America plates. In this area, the Nazca plate subducts eastward beneath the South America plate at a rate of 65 mm/yr. Subduction along the Peru-Chile Trench to the west of Chile has generated the uplift of the Andes mountain range.

Ocean Networks Canada's seismometer in Cascadia Basin recorded the tremors as they crossed the North Pacific. Seismic data clearly indicate arrival of the initial P waves approximately 750 seconds (12.5 minutes) after the earthquake, and following S waves about 1375 seconds (23 minutes) after the earthquake struck. Bottom Pressure Recorders on the NEPTUNE Observatory also detected passage of the tsunami in real time, as it crosses our observing stations in the northeast Pacific.

Data from the Cascadia Basin ocean-bottom seismometer indicating arrival of P and S waves. The top trace shows East-West motions, the centre trace shows North-South motions, and the lower trace shows vertical motions. (Click to enlarge.)

A 1.9-metre tsunami was recorded at a northern Chilean port Tuesday evening. The Pacific Tsunami Warning Center issued an alert for all of Latin America's Pacific coast. There was no threat issued to the Pacific coast along North America.

NOAA issued a forecast of tsunami heights as the energy propagated away from the source region, indicating heights up to 100 cm close to the epicenter, with rays of 2-10 cm wave heights extending across portions of the South Pacific Ocean toward New Zealand and archipelegos in the South-Central Pacific.

Tsunami wave energy propagation forecast issued by the Pacific Tsunami Warning Center, showing contours of maximum wave amplitudes (in cm) associated with the 1 April 2014 earthquake.

Predicted travel times for tsunami waves generated by the 1 April 2014 earthquake. Three-hour intervals are marked by the heavy white lines, intermediary hours are marked by blue shades and dashed white lines indicate half-hour boundaries. Arrival in both New Zealand and British Columbia was predicted to begin approximately 15 hours after the initial earthquake.

Seafloor pressure traces from the CORK pressure instrument at Cascadia Basin, 1-2 April 2014. The upper plot shows initial passage of the earthquake just past 00 UTC (indicated by the blue lines), followed by passage of the small tsunami beginning at 14 UTC. The lower plot focuses on the tsunami onset period, 11-15:20 UTC. Wave amplitudes at this deep-water site (2660 m) were approximately 8 mm.

No stranger to seismic activity, Chile is one of the world¹s most earthquake-pronecountries. In 2010, a magnitude-8.8 quake and ensuing tsunami in central Chile killed more than 500 people and destroyed several hundred thousand homes along the coast.

Ocean Networks Canada - earthquake

Resilience through preparedness: remembering the 1964 ‘Good Friday’ tsunami

Tags:

Categories:

Drop, cover, and hold on

Tags:

Categories:

Expedition 2019: Highlights Story Map

Tags:

Categories:

Data from Alaska’s Magnitude 7.9 Earthquake and Tsunami

Tags:

Categories:

Are earthquakes on the rise?

Earthquake Facts

Related posts:

Tags:

Categories:

Canadian scientist awarded for exceptional contribution to Earth science!

Tags:

Categories:

ONC detects M6.1 earthquake near Haida Gwaii

Tags:

Categories:

Magnitude 6.6 Earthquake

Seismic Data

Bottom Pressure Recordings

Rumbles and Crackles

Strike-slip Earthquakes

Tags:

Categories:

Chilean quake detected by ONC seafloor instruments

Tags:

Categories:

Tsunami alert follows 8.2 quake off Chile

Tags:

Categories: