News Article | November 11, 2015
SANTIAGO A strong, 6.9 magnitude earthquake struck off the coast of Chile on Tuesday night, but there were no immediate reports of damage, the Chilean emergency office said. The U.S. Geological Survey said the quake, initially reported as magnitude 6.8 and then 6.6, was at a very shallow depth of 6.2 miles (10 km) under the seabed. Its epicenter was 58 miles (93 km) northwest of Coquimbo and 290 miles (466 km) northwest of Santiago. The earthquake did not trigger a tsunami, the Pacific Tsunami Warning Center said. Chile's ONEMI emergency office said there were no preliminary reports of damage, while Chile's navy said the quake was not strong enough to generate a tsunami. Chile is prone to earthquakes and was hit in 2010 by a powerful 8.8 magnitude earthquake and in 1960 by the largest earthquake ever recorded, at magnitude 9.5.
Butler R.,University of Hawaii at Manoa |
Burney D.,National Tropical Botanical Garden |
Walsh D.,Pacific Tsunami Warning Center
Geophysical Research Letters | Year: 2014
The Hawaiian Islands' location in the middle of the Pacific Ocean is threatened by tsunamis from great earthquakes in nearly all directions. Historical great earthquakes Mw > 8.5 in the last 100 years have produced large inundations and loss of life in the islands but cannot account for a substantial (≤ 600 m3) paleotsunami deposit in the Makauwahi sinkhole on the Island of Kaua'i. Using high-resolution bathymetry and topography we model tsunami inundation of the sinkhole caused by an earthquake with a moment magnitude of Mw ~9.25 located in the eastern Aleutians. A preponderance of evidence indicates that a giant earthquake in the eastern Aleutian Islands circa 1425-1665 A.D. - located between the source regions of the 1946 and 1957 great tsunamigenic earthquakes - created the paleotsunami deposit in Kaua'i. A tsunami deposit in the Aleutians dated circa 1530-1660 A.D. is consistent with this eastern Aleutian source region. Key Points A Kaua'i tsunami deposit is linked to Mw 9+ earthquake in the eastern AleutiansPaleotsunami evidence in the Aleutians and West Coast U.S. corroborates the timeInundations would be greater than any experienced by Hawai'i in historic times ©2014. American Geophysical Union. All Rights Reserved.
News Article | February 15, 2017
I happened to be in Hawaii last month at the same time that the National Oceanic and Atmospheric Administration(NOAA)'s ship of exploration, the Okeanos Explorer -- of live-streaming, ocean-esplorin’ fame -- was docked in Pearl Harbor. There are several ships that do that, but only one belongs to the American people. This one. On a whim, I wrote to see if I might get a tour of the ship while I was around. Considering the events of the last few weeks, I’m glad I did it while I had the chance. I got to see NOAA Mission Control, the bridge, and the ship’s faithful ROV Deep Discoverer (nicknamed D2)… sort of. When on board, it lives under a protective cover inside a garage. But I was so close to the sampling baskets on the front that I could have reached out and touched one. And I’m kinda sorry now I didn’t! Anyhow, if you’re a regular reader of this blog you’re no doubt aware that I am a booster for ocean exploration. I regularly argue it is every bit as important – perhaps more -- as exploring space. This is our home, after all, and exoplaneteers notwithstanding, it’s the only one we’ve got. I’ve often featured clips from the voyages of the Explorer here on my blog, and I’ve spent hours watching their live feed as they explore strange new worlds, seek out new life and new ecosystems, and boldly go where no one has gone before. ‘Cause that’s their actual job. Here she is the morning I saw her, which happened to be Martin Luther King Jr. Day. That actually presented a problem in getting me in to a military base on a holiday, but fortunately an employee of the Pacific Tsunami Warning Center (also located in Pearl Harbor) offered to give me a lift. Thank you kind sir! I was met by MeMe Lobecker and Mike White, physical scientists and hydrographers who work on the Explorer's mapping projects. Here is the "Wet Lab": It's long and skinny. On the left is a fume hood for sousing specimens in preservative chemicals. On the right toward the rear are dissection lights. On the floor are coolers for the preserved specimens. Can you imagine staring into a microscope here with the smell of formalin in the air (the fume hood never gets it all) while the ship pitches and rolls? Paging Dr. Dramamine. The samples add up fast. Deep Discoverer can retrieve two to three biological samples per dive, so they may end up with around 40 samples by mission end. All those specimens must be properly preserved and documented. By the end of the expedition, Lobecker said, they may also have several hundred pounds of rocks, which have the advantage of needing significantly less dissection and preservation. [Seasick biologists give geologists a slanty eyed side squint] The spirit of Star Trek really does permeate this ship -- and at the captain's behest, no less, according to Lobecker. Here, for example, is the door to Mission Control: While we were there, we heard this sound followed by a message about an upcoming drill. Do you know it? It's the intercom whistle from the original Star Trek TV series. When he came aboard, the current commanding officer asked for the ship to sound like Star Trek, and the crew Made It So. Here is Okeanos Explorer Mission Control. Everything is swathed in black. Here is the front row where the ROV pilot and copilots sit. And those wooden boxes, buttons, and joysticks, my friends, are how you drive an ROV. Note the ropes, which I assume are battening mechanisms to prevent those control panels from going anywhere unauthorized while at sea. Long hours at sea probably provide ample time for the fashioning of a lucky crane ... ...or for the drawing of the ocean invertebrate Glaucus atlanticus, which I wrote about on this blog long ago. This one was spotted on a black dry erase board at the back of Mission Control. Note also the poem, which I assume is an original composition by one of the crew or science team, since a google search turned up nothing like it on the interweb. In case you can't read it, it says, Here is the back row where the mission scientists sit. There are usually two or three, and they chat with dozens of participating scientists on shore as the mission unfolds. There is a mere two second delay between the observations of Deep Discoverer on the bottom of the ocean and their appearance on the screen at mission control, while only five to ten seconds separates what D2 sees from what scientists in America see (where they may sitting up in their jammies in the middle of the night). The three scientists listen to what the shore-side scientists are telling them seems interesting or worth investigating, confer among themselves, and then tell the ROV pilots in the row in front of them what objects and critters should get a closer look. Mapping, the line of work that Lobecker and White are in, although not as sexy in this biologist's opinion as ROV diving, is another of the ship's missions and among the most important. As recently as 2000, up to 95% of the ocean remained unexplored. Lobecker told me scientists have estimated that in the Pacific Ocean there are over 100,000 seamounts -- underwater peaks rising in excess of 1,000 meters from the seabed -- that remain unmapped by any modern equipment. The Navy must be nettled by this, because they created something called the "Red Dot Program" in which they list seamounts they'd really love to have mapped if Okeanos Explorer, you know, ever happens to be in the neighborhood. Lobecker said she has no idea how the Navy picks them. "We don't ask," she said. "We just map." Any data generated by the ship, whether biological, geological, or cartographic, becomes available to the public. We paid for it, after all. Going bow-ward from Mission Control through a hall lined with two to four person "state rooms" where the scientists live while at sea and up two flights of stairs (past the officers' quarters) brought me to the bridge. Here is the floor mat that greets you there. I also spotted this important control panel stuck to the wall toward the rear. I think half of America feels a desperate urge to hit that yellow button right now. Here is where you drive the ship. That machine Lt. Aaron Colohan is standing behind is an extremely expensive piece of equipment originally designed for oil tankers and supply ships called a "Dynamic Positioning System". It can hold the 2000-ton ship in position on the open ocean to within one meter. One meter! In theory, it's no more complex than the trolling motor on my dad's fishing boat, which can accomplish the same feat. In practice: probably a lot more complex. You can imagine how important the ability to nail the ship down, so to speak, might be if you've got a $3.5 million dollar ROV armed with Superbowl-quality cameras trying to do extreme close-ups while plucking delicate creatures from the seabed at the end of a 4,000 meter tether. In high enough seas, the system will eventually fail. It is the captain and crew's job to determine when things are getting dicey enough that it's time to pull the ROV out of the pool. Extraction takes a mere two hours if the ROV is at 4,000 meters, so they'd better choose well. It could be even longer, since D2's max depth is 6,000 meters, much deeper than the 3,700 meter average depth of the ocean. To put that in perspective, 6,000 meters is nearly 20,000 feet -- 6,500 feet or so higher than the elevation of the tallest mountain in Colorado -- and about four miles deep. Without the dynamic positioning system, Colohan said, it would be impossible to do ROV dives unless the sea were like glass. The ROV itself can take a beating, but the delicate instruments on it not so much. This is the most important feature on the ship: the captain's chair. I note that it lacks cup holders. I saw an uncannily similar one on the bridge of the USS Missouri, also docked in Pearl Harbor. I guess Naval captain's chair technology has not advanced much in 70 years. I also note the convenient proximity of the equal-opportunity toilet. Which is better than the House of Representatives could say, until recently. This is the antenna farm, way up at the top there. Lobecker said that sometimes when they notice they're getting screwy data, they go out to have a look at the farm and there's a bird standing on it. This is how you get internet at sea: It's called the VSAT bubble, and there's a tracking antenna in there that moves as the ship pitches and rolls to stay locked on to the nearest satellite 25,000 miles above. This antenna also beams the ship's data to shore. Here we have Deep Discoverer's camera sled Seirios. They are joined by a tether. Seirios hovers over D2 like a big brother, keeping an eye on the ROV and offering a wider perspective on the scene to the ROV pilots and scientists. As I mentioned, it's wearing its PJs. Here's what it looks like while at sea: This is the crane used to catch and release Deep Discoverer. On the end is a truck tire that has been repurposed as a "swing arrestor". When Deep Discoverer is hauled in, it hits that tire which dampens any lateral motion and allows the ROV to be more safely deposited on deck. Here's what it looks like (note the obvious treads on the tire): Here it is from the front: Unfortunately, I wasn't able to see Deep Discoverer uncovered either. But seeing it in person, even covered, did enable me to make one observation. The ROV is enormous! It's the size of a large room... ... and much bigger than the dinky ROVs I've seen in the movies. In this image, the row of hard hats in the background should give you the scale. On the bottom left you can see the rugged plastic biological specimen collection basket. That is the one I got to stand next to and could have reached out and touched. On the right side of the ROV is a similar looking rock box. Lobecker observed that rocks that look small on camera frequently emerge from the ocean not so wee. I guess Objects in Camera Are Larger Than They Appear. Here is D2 in its garage. You can see the railroad that can be used to slide it in and out. No comment on the enormous ... buoys. Thus ended my tour. I asked my guides what their most surprising, scary, or favorite moments aboard Okeanos Explorer had been. Lobecker recalled a time that oil workers alerted them to a suspected shipwreck of potential archaeological importance. To their surprise, they encountered a nine-foot wide asphalt extrusion/artform on the bottom of the Gulf of Mexico. Only one or two such structures had ever been seen in the world before -- and not in the gulf -- and they had never even been given a name. They dubbed it the "tar lily". White recalled retrieving a device intended to measure the speed of sound in local water -- a shiny silver probe at the end of a long line. To the crew's shock, just as they were pulling it out, a nine-foot swordfish leapt from the water, no doubt perturbed the lunch it had tracked all they way back to the ship had somehow made a miraculous escape. The crew was pleased the swordfish hadn't chomped it first. "What are you going to do [if] you hook a 2,000 pound fish that pulls 10,000 pounds?" White observed. But more mundane moments aboard Explorer also have the abiity to thrill. Nighttime Deep Discoverer retrievals are popular spectator events aboard ship, Lobecker said, as a glow gradually suffuses the deep before the whole contraption is hoisted dripping and lights ablaze to deck. It must be magical. Space is not the final frontier, at least not yet. Nor is it the only one still capable of inspiring surprise and wonder. Let us not, in our understandable haste to reach for the stars, forget that. You can follow the explorations of Okeanos Explorer here. Their live-streaming feed of any explorations in progress is here.
News Article | January 24, 2016
JUNEAU, Alaska A powerful 7.1 magnitude earthquake struck remote southern Alaska early on Sunday, unleashing shudders felt several hundred miles (km) from the tremor's lakefront epicenter at the far end of Cook Inlet from Anchorage, the state's largest city. No injuries were reported, but several neighborhoods in the town of Kenai - roughly halfway between the quake's center and Anchorage - were temporarily evacuated after a gas explosion damaged four homes several hours later, a city spokesman said. As of Sunday night, local utility company Enstar was still investigating whether the earthquake triggered a gas leak believed to have caused the blast, company spokesman John Sims said. There were also reports of brief power outages in Anchorage, about 160 miles (257 km) southwest of the epicenter, and cities immediately to the north and south. The quake, initially reported at a 7.3 magnitude, struck at 1:30 a.m. about 30 miles (48 km) east-southeast of Pedro Bay on the shore of Iliamna Lake, at the foot of a mountain chain just west of Cook Inlet, the U.S. Geological Survey (USGS) reported. The quake was felt as far away as Whitehorse, the capital of Canada's Yukon Territory more than 600 miles (966 km) east of Anchorage, according to the USGS. It was recorded 79 miles (128 km) beneath the surface, a depth that helped keep damage to a minimum, said Dara Merz, a research technician with the Alaska Earthquake Center in Fairbanks. "If you take into account how deep it was, that's a lot of earth and rock that seismic waves have to work through to get to the surface," Merz said. The Fairbanks agency reported a series of aftershocks reaching magnitudes of up to 4.7, though Merz said even larger tremors could follow. Alaska, a seismically active state, records anywhere from 80 to 100 quakes daily, most of them hardly ever noticed. One of the more powerful quakes to hit Alaska in recent years was a 7.9 magnitude temblor that struck beneath the ocean floor near the Aleutian Islands chain in June 2014, but it caused no injuries or major damage. Following Sunday's quake, jittery Anchorage residents and hotel guests who briefly fled their buildings took to social media sites to share their experiences. Some posted photos of stores with aisles littered by fallen merchandise knocked off shelves to the floor. The quake produced no tsunami threat, according to the U.S. Pacific Tsunami Warning Center.
News Article | January 11, 2016
LONDON A 6.9 magnitude earthquake struck on Monday, around 330 km (205 miles) north-northwest of Indonesia's Molucca islands, the U.S. Geological Survey said. The USGS said the quake was 102 km deep. The NOOA Pacific Tsunami Warning Center said that, based on available information, "a destructive Pacific-wide tsunami is not expected".
News Article | March 21, 2016
WASHINGTON A large, magnitude 6.6 earthquake hit in the Pacific Ocean off Russia's Kamchatka Peninsula, the U.S. Geological Survey said on Sunday. There was no danger of a Pacific-wide tsunami from the quake, the Pacific Tsunami Warning Center said. The quake struck at a depth of 18.4 miles (30 km) and was centered 140 miles (225 km) west-southwest of Nilol'skoye, Komandorskiye Ostrova, Russia, the USGS said.
Becker N.C.,Pacific Tsunami Warning Center |
Fryer P.,University of Hawaii at Manoa |
Moore G.F.,University of Hawaii at Manoa
Geochemistry, Geophysics, Geosystems | Year: 2010
Six-channel seismic reflection data reveal a magma chamber reflector beneath the Malaguana-Gadao Ridge, the southernmost segment of the spreading center in the Mariana Trough. For most of its length the spreading center in this active back-arc basin is morphologically similar to slow spreading mid-ocean ridges, having a deep central graben flanked by a zone of abyssal hill fabric. This southernmost segment, however, has a broad, smooth cross section, lacks a deep central graben, and is thus similar in morphology to fast spreading ridges (e.g., the East Pacific Rise). We identify a magma chamber at 1.5 s two-way travel time below the crest of the ridge. Observations from remotely operated vehicles along the ridge reveal not only fresh pillows, lobate, and sheet lava flows but also an abundance of volcaniclastic debris and intense hydrothermal activity. These observations, together with the "fast spreading" morphology of the ridge, suggest that this segment has a considerably higher magma supply than is typical in the Mariana Trough. We suggest that the volcanic arc or enhanced melting of a hydrated mantle is supplying volatile-rich magma as evidenced by a highly negative coefficient of reflection, -0.42, for this MCR and the presence of evolved, highly vesicular lava and volcaniclastic materials. The southeastern Mariana back-arc basin spreading ridge does not compare readily with mechanical models for global mid-ocean ridge data sets because of marked asymmetry in both volcanism and deformation that may be the consequence of slab-related geometry in this part of the convergent margin system. Copyright 2010 by the American Geophysical Union.
McMurtry G.M.,University of Hawaii at Manoa |
Campbell J.F.,University of Hawaii at Manoa |
Fryer G.J.,University of Hawaii at Manoa |
Fryer G.J.,Pacific Tsunami Warning Center |
Fietzke J.,Leibniz Institute of Marine Science
Geology | Year: 2010
Studies of paleo-sea level and past climate have focused upon proxy methods in ice and deep-sea cores and more direct information provided by past shorelines, in some cases preserved as raised or submerged reef deposits in tropical areas. Paleo-shorelines need to be constrained by accurate tectonic history because these environments and their marine deposits can be confused with past tsunami deposits and vice versa. A maximum 21-m-high extensive emerged reef on Oahu, Hawaii, U-series dated to 334 ± 17 ka, together with a mean U-series age of 335 ± 22 ka (n = 5) for slightly higher, energetic shoreline deposits nearby, suggest a marine isotope stage 9 (MIS 9) highstand, and extend the earlier work indicating a linear uplift for Oahu of 0.060 ± 0.001 mmlyr over the past 500 k.y. Five of the past six major emerged interglacial highstand reefs on Oahu have been identified, and these data provide little evidence for past maximum sea levels significantly greater than 2 m above the sea level datum at that time. There is currently no evidence for a MIS 11 highstand on Oahu. © 2010 Geological Society of America.
Hirshorn B.,Pacific Tsunami Warning Center |
Weinstein S.,Pacific Tsunami Warning Center |
Tsuboi S.,Japan Agency for Marine - Earth Science and Technology
Pure and Applied Geophysics | Year: 2013
Tsunami Warning Centers issue rapid and accurate tsunami warnings to coastal populations by estimating the location and size of the causative earthquake as soon as possible after rupture initiation. Both US Tsunami Warning Centers have therefore been using Mwp to issue Tsunami Warnings 5-10 min after Earthquake origin time since 2002. However, because Mwp (Tsuboi et al., Bulletin of the Seismological society of America 85:606-613, 1995) is based on the far-field approximation to the P-wave displacement due to a double couple point source, we should only very carefully apply Mwp to data obtained in the near field, at distances of less than a few wavelengths from the fault. On the other hand, the surface waves from Great Earthquakes, including those that occur just offshore of populated areas, such as the 2011 Tohoku earthquake, clip seismographs located near the fault. Because the first arriving P-waves from such large events are often on scale, Mwp should provide useful information, even for these Great Earthquakes. We therefore calculate Mwp from 18 unclipped STS-1 broadband P-wave seismograms, recorded at 2-15° distance from the Tohoku epicenter to determine if Mwp can usefully estimate Mw for this earthquake, using data obtained close to the epicenter. In this case there should be a good chance to get reliable Mwp values for stations at epicentral distances of 9-10°, since the source duration for the Tohoku earthquake is less than 200 s and the time window used to estimate Mwp is 120 s in duration. Our analysis indicates that Mwp does indeed give reliable results (Mw ~ 9.1) beginning at about 11° distance from the epicenter. The values of Mwp from seismic waveforms obtained at 11-15° epicentral distance from the Mw 9.1 off the east coast of Tohuku earthquake of March 11, 2011 fell within the range 9.1-9.3, and were available within 4-5 min after origin time. Even the Mwp values of 7.7-8.4, obtained at less than 5° epicentral distance, exceed the PTWC's threshold of Mw 7.6 for issuing a regional tsunami warning to coastal populations within 1,000 km of the epicenter, and of Mw 6.9 for issuing a local tsunami warning to the coastal populations of Hawaii. © 2012 Springer Basel AG.
Fryer G.J.,Pacific Tsunami Warning Center
Earth-Science Reviews | Year: 2011
With any handheld GPS unit and a modest investment of time, typically about one hour per kilometer, it is possible to walk along the debris line and so map the inundation limit of a tsunami. These measurements are not adequate to define runup, but with an accuracy of three meters or better (one meter with simple processing) they are quite adequate for all scientific uses of inundation. The same data are invaluable to emergency managers planning recovery efforts. This short note uses the examples of Amanave and Tula in American Samoa, both affected by the 2009 South Pacific tsunami, to encourage the routine collection of such data in future post-tsunami surveys. © 2011.