Seismically Derived Ground Tilts Related to the 2010 Chilean Tsunami

2021 ◽  
Author(s):  
Jui-Chun Freya Chen ◽  
Wu-Cheng Chi ◽  
Chu-Fang Yang
Keyword(s):  
Deep Ocean ◽  
Propagation Model ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Tsunami Propagation ◽  
Ground Tilt ◽  
Tsunami Waves ◽  
The Pacific ◽  
Seismic Networks ◽  
Back Azimuth

Abstract Developing new ways to observe tsunami contributes to tsunami research. Tidal and deep-ocean gauges are typically used for coastal and offshore observations. Recently, tsunami-induced ground tilts offer a new possibility. The ground tilt signal accompanied by 2010 Mw 8.8 Chilean earthquake were observed at a tiltmeter network in Japan. However, tiltmeter stations are usually not as widely installed as broadband seismometers in other countries. Here, we studied broadband seismic records from Japan’s F-net and found ground tilt signals consistent with previously published tiltmeter dataset for this particular tsunamic event. Similar waveforms can also be found in broadband seismic networks in other countries, such as Taiwan, as well as an ocean-bottom seismometer. We documented a consistent time sequence of evolving back-azimuth directions of the tsunami waves at different stages of tsunami propagation through beamforming-frequency–wavenumber analysis and particle-motion analysis; the outcomes are consistent with the tsunami propagation model provided by the Pacific Tsunami Warning Center. These results shown that dense broadband seismic networks can provide a useful complementary dataset, in addition to tiltmeter arrays and other networks, to study or even monitor tsunami propagation using arrayed methods.

scholarly journals TSUNAMI PHASE SPEED REDUCTION DUE TO WATER COMPRESSIBILTY

2018 ◽  
pp. 9
Author(s):  
Ali Abdolali ◽  
James T. Kirby
Keyword(s):  
Arrival Time ◽  
Phase Speed ◽  
Propagation Speed ◽  
Frequency Dispersion ◽  
Wave Theory ◽  
Polar Coordinates ◽  
Ocean Bottom ◽  
Tsunami Propagation ◽  
Boussinesq Model ◽  
Tsunami Waves

Most existing tsunami propagation models consider the ocean to be an incompressible, homogenous medium. Recently, it has been shown that a number of physical features can slow the propagation speed of tsunami waves, including wave frequency dispersion, ocean bottom elasticity, water compressibility and thermal or salinity stratification. These physical effects are secondary to the leading order, shallow water or long wave behavior, but still play a quantifiable role in tsunami arrival time, especially at far distant locations. In this work, we have performed analytical and numerical investigations and have shown that consideration of those effects can actually improve the prediction of arrival time at distant stations, compared to incompressible forms of wave equations. We derive a modified Mild Slope Equation for Weakly Compressible fluid following the method proposed by Sammarco et al. (2013) and Abdolali et al. (2015) using linearized wave theory, and then describe comparable extensions to the Boussinesq model of Kirby et al. (2013). Both models account for water compressibility and compression of static water column to simulate tsunami waves. The mild slope model is formulated in plane Cartesian coordinates and is thus limited to medium propagation distances, while the Boussinesq model is formulated in spherical polar coordinates and is suitable for ocean scale simulations.

The Dellwood knolls and their role in triple junction tectonics off northern Vancouver Island

1980 ◽  
Vol 17 (5) ◽  
pp. 577-593 ◽  
Author(s):  
R. P. Riddihough ◽  
R. G. Currie ◽  
R. D. Hyndman
Keyword(s):  
Triple Junction ◽  
Plate Tectonics ◽  
Vancouver Island ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Geological Evidence ◽  
Topographic Features ◽  
Narrow Valley ◽  
The Pacific ◽  
Geophysical Surveys

The Dellwood knolls are two small topographic features on the ocean floor off northern Vancouver Island. They have been proposed as a spreading centre connecting the Explorer ridge to the Queen Charlotte fault and the location of a triple junction between the Pacific, American, and Juan de Fuca plate systems.Detailed geophysical surveys and ocean-bottom seismometer deployments confirm that they are the site of active seismicity and recent volcanism. Modelling of the magnetic anomaly field shows that it is almost entirely produced by normally magnetized material, supporting geological evidence that the knolls are probably less than 1 Ma old. Although the two knolls are separated by a narrow valley with some downfaulting, they do not form a clearly linear spreading rift.Assessment of their role in the plate tectonics of the region suggests that spreading at the knolls was initiated around 1 Ma ago in crust now 4.5 Ma old as part of a complex, northwesterly ridge migration process at the northern end of the Explorer ridge. Reconstruction of this process, which involves asymmetric spreading and ridge jumping, provides an explanation for the creation of the associated Paul Revere and Winona ridges.

scholarly journals GPS water level measurements for Indonesia's Tsunami Early Warning System

2011 ◽  
Vol 11 (3) ◽  
pp. 741-749 ◽  
Author(s):  
T. Schöne ◽  
W. Pandoe ◽  
I. Mudita ◽  
S. Roemer ◽  
J. Illigner ◽  
...  
Keyword(s):  
Water Level ◽  
Early Warning ◽  
Early Warning System ◽  
Warning System ◽  
Deep Ocean ◽  
Ocean Bottom ◽  
Tsunami Early Warning ◽  
Tsunami Waves ◽  
Gps Technology ◽  
Water Level Measurements

Abstract. On Boxing Day 2004, a severe tsunami was generated by a strong earthquake in Northern Sumatra causing a large number of casualties. At this time, neither an offshore buoy network was in place to measure tsunami waves, nor a system to disseminate tsunami warnings to local governmental entities. Since then, buoys have been developed by Indonesia and Germany, complemented by NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys, and have been moored offshore Sumatra and Java. The suite of sensors for offshore tsunami detection in Indonesia has been advanced by adding GPS technology for water level measurements. The usage of GPS buoys in tsunami warning systems is a relatively new approach. The concept of the German Indonesian Tsunami Early Warning System (GITEWS) (Rudloff et al., 2009) combines GPS technology and ocean bottom pressure (OBP) measurements. Especially for near-field installations where the seismic noise may deteriorate the OBP data, GPS-derived sea level heights provide additional information. The GPS buoy technology is precise enough to detect medium to large tsunamis of amplitudes larger than 10 cm. The analysis presented here suggests that for about 68% of the time, tsunamis larger than 5 cm may be detectable.

scholarly journals SUSPENSIONS TRANSPORT PREDICTIVE MODELING UNDER VARIOUS SCENARIOS OF FERROMANGANESE NODULES EXTRACTION FROM THE PACIFIC OCEAN BOTTOM

2021 ◽  
pp. 1-9
Author(s):  
A. A. Sukhinov ◽  
A. A. Sukhinov ◽  
S. B. Kirilchik
Keyword(s):  
Pacific Ocean ◽  
Aqueous Medium ◽  
Granulometric Composition ◽  
Water Mass ◽  
Propagation Model ◽  
Ocean Bottom ◽  
Eastern Pacific Ocean ◽  
Ferromanganese Nodules ◽  
The Pacific ◽  
The Pacific Ocean

The article is devoted to the suspensions’ distribution mathematical modeling in the Eastern Pacific Ocean for various scenarios for the ferromanganese nodules extraction. The suspensions propagation model with complex granulometric composition that can interact in an aqueous medium takes into account the suspensions microturbulent diffusion caused by the turbulent aqueous medium movement and the suspensions convection caused by the advective movement of water mass in the ocean; gravitational suspensions deposition under the gravity influence; mutual transitions between different fractions that make up the suspension; interaction of particles with the bottom and with the free surface.

First noise and teleseismic recordings on a new ocean bottom seismometer capsule

1984 ◽  
Vol 74 (3) ◽  
pp. 1043-1058
Author(s):  
William A. Prothero ◽  
William Schaecher
Keyword(s):  
Sea Water ◽  
Low Frequency ◽  
Deep Ocean ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Data Logging ◽  
Santa Barbara Channel ◽  
Noise Levels ◽  
Santa Barbara ◽  
Recording Time

Abstract An ocean bottom seismometer capsule designed specifically for the long-term monitoring of teleseisms has been designed and tested. An efficient triggering algorithm consisting of multiple high-pass filters effectively discriminates between locally generated earthquakes and noise, and teleseisms. During a 1-month deep ocean deployment west of the Santa Barbara Channel, a magnitude 5.9 earthquake at a distance of 76° was recorded, in addition to a number of regional events in the 300- to 450-km range. Noise levels were monitored by automatically recording data at intervals. Vertical noise levels were approximately 20 times greater than those recorded at quiet land sites, and horizontal noise levels were about 5 times greater than that. The instrument consists of a microprocessor-controlled data logging system in three parallel pressure tubes, joined by a common baseplate. Wires between the three tubes are contained within the baseplate. There are no external connectors which are exposed to sea water, allowing the deployment time to extend to 1 yr. Data are recorded on two Braemar cassette recorders with a capacity of 15 Mbits each, for a continuous recording time of approximately 43 hr. This is adequate for the expected data acquisition rate, given the robustness of the triggering algorithm. The sensors are Mark Products L4-C 1-Hz seismometers with useful extended low-frequency response to about 30-sec periods for earthquake signals. The three components are leveled with a mechanical gimbal arrangement. The instrument has been successfully deployed 3 times in the Santa Barbara Channel and deep ocean, and should prove extremely useful for extending teleseismic studies into the ocean.

scholarly journals What fraction of the Pacific and Indian oceans' deep water is formed in the Southern Ocean?

2018 ◽  
Vol 15 (12) ◽  
pp. 3779-3794 ◽  
Author(s):  
James W. B. Rae ◽  
Wally Broecker
Keyword(s):  
Southern Ocean ◽  
Deep Water ◽  
Large Scale ◽  
Bottom Water ◽  
Deep Ocean ◽  
Ocean Bottom ◽  
Biological Pump ◽  
Water Value ◽  
The Pacific ◽  
Northern Atlantic

Abstract. In this contribution we explore constraints on the fractions of deep water present in the Indian and Pacific oceans which originated in the northern Atlantic and in the Southern Ocean. Based on PO4* we show that if ventilated Antarctic shelf waters characterize the Southern contribution, then the proportions could be close to 50–50. If instead a Southern Ocean bottom water value is used, the Southern contribution is increased to 75 %. While this larger estimate may best characterize the volume of water entering the Indo-Pacific from the Southern Ocean, it contains a significant portion of entrained northern water. We also note that ventilation may be highly tracer dependent: for instance Southern Ocean waters may contribute only 35 % of the deep radiocarbon budget, even if their volumetric contribution is 75 %. In our estimation, the most promising approaches involve using CFC-11 to constrain the amount of deep water formed in the Southern Ocean. Finally, we highlight the broad utility of PO4* as a tracer of deep water masses, including descending plumes of Antarctic Bottom Water and large-scale patterns of deep ocean mixing, and as a tracer of the efficiency of the biological pump.

scholarly journals Precise aftershock distribution of the 2011 off the Pacific coast of Tohoku Earthquake revealed by an ocean-bottom seismometer network

2012 ◽  
Vol 64 (12) ◽  
pp. 1137-1148 ◽  
Author(s):  
Masanao Shinohara ◽  
Yuya Machida ◽  
Tomoaki Yamada ◽  
Kazuo Nakahigashi ◽  
Takashi Shinbo ◽  
...  
Keyword(s):  
Pacific Coast ◽  
Tohoku Earthquake ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Aftershock Distribution ◽  
The Pacific ◽  
Precise Aftershock Distribution

scholarly journals Aftershock observation of the 2011 off the Pacific coast of Tohoku Earthquake by using ocean bottom seismometer network

2011 ◽  
Vol 63 (7) ◽  
pp. 835-840 ◽  
Author(s):  
Masanao Shinohara ◽  
Tomoaki Yamada ◽  
Kazuo Nakahigashi ◽  
Shin’ichi Sakai ◽  
Kimihiro Mochizuki ◽  
...  
Keyword(s):  
Pacific Coast ◽  
Tohoku Earthquake ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
The Pacific ◽  
Aftershock Observation

The Pacific OBS Research into Convecting Asthenosphere (ORCA) Experiment

2021 ◽  
Author(s):  
Zachary C. Eilon ◽  
James B. Gaherty ◽  
Lun Zhang ◽  
Joshua Russell ◽  
Sean McPeak ◽  
...  
Keyword(s):  
Data Quality ◽  
Recovery Rate ◽  
Body Wave ◽  
Spectral Characteristics ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Central Pacific ◽  
Seismic Arrays ◽  
Daily Data ◽  
The Pacific

Abstract The Pacific ocean-bottom seismometer (OBS) Research into Convecting Asthenosphere (ORCA) experiment deployed two 30-station seismic arrays between 2018 and 2020—a US contribution to the international PacificArray project. The “Young ORCA” array deployed on ∼40 Ma central Pacific seafloor had a ∼68% data recovery rate, whereas the “Old ORCA” array deployed on ∼120 Ma southwest Pacific seafloor had a ∼80% recovery rate. We detail here the seismic data quality, spectral characteristics, and engineering challenges of this experiment. We provide information to assist users of this dataset, including OBS orientations and tables of daily data quality for all channels. Preliminary analysis illustrates the utility of these data for surface- and body-wave seismic imaging.

scholarly journals Combining the All-Source Green's Functions and the GPS-Derived Source Functions for Fast Tsunami Predictions—Illustrated by the March 2011 Japan Tsunami

2013 ◽  
Vol 30 (7) ◽  
pp. 1542-1554 ◽  
Author(s):  
Zhigang Xu ◽  
Y. Tony Song
Keyword(s):  
Green's Functions ◽  
Source Function ◽  
Green’S Functions ◽  
Geographic Origin ◽  
Deep Ocean ◽  
Propagation Model ◽  
Tsunami Source ◽  
Tsunami Propagation ◽  
2011 Tohoku Tsunami ◽  
Using Data

Abstract This paper proposes an effective approach on how to predict tsunamis rapidly following a submarine earthquake by combining a real-time GPS-derived tsunami source function with a set of precalculated all-source Green's functions (ASGFs). The approach uses the data from both teleseismic and coastal GPS networks to constrain a tsunami source function consisting of both sea surface elevation and horizontal velocity field, and uses the ASGFs to instantaneously transfer the source function to the arrival time series at the destination points. The ASGF can take a tsunami source of arbitrary geographic origin and resolve it as fine as the native resolution of a tsunami propagation model from which the ASGF is derived. This new approach is verified by the 2011 Tohoku tsunami using data measured by the Deep-Ocean Assessment and Reporting of Tsunamis (DART) buoys.

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