Masato Furuya

Hokkaido University | Hokudai · Department of Earth and Planetary Sciences

The Chandler Wobble period is considered a single time-invariable constant, ~ 1.2 years. To confirm the time-invariability of the Chandler period, we preliminarily estimated the Chandler period using 50 years’ long space geodetic data under the minimum excitation assumption. Unexpectedly, the estimated period has been shortened by more than 60 days...

Postseismic‐to‐coseismic moment ratios (PCMR) for strong (M > 6) earthquakes typically do not exceed ∼0.3, but there have been limited estimates for moderate‐to‐small earthquakes. Three M5‐class earthquakes and one M4.7 earthquake occurred along the Chaman fault, Pakistan, on May 13 and July 10, 2016. Using Sentinel‐1A InSAR time‐series from Octobe...

The split-spectrum method (SSM) can largely isolate and correct for the ionospheric contribution in the L-band interferometric synthetic aperture radar (InSAR). The standard SSM is performed on the assumption of only the first-order ionospheric dispersive effect, which is proportional to the total electron content (TEC). It is also known that durin...

The split-spectrum method (SSM) can largely isolate and correct for the ionospheric contribution in the L-band interferometric synthetic aperture radar (InSAR). The standard SSM is performed on the assumption of only the first-order ionospheric dispersive effect, which is proportional to the total electron content (TEC). It is also known that durin...

Environments along the coast of Greenland are rapidly changing under the influence of a warming climate in the Arctic. To better understand the changes in the coastal environments, we performed researches in the Qaanaaq region in northwestern Greenland as a part of the ArCS (Arctic Challenge for Sustainability) Project. Mass loss of ice caps and ma...

We present detailed maps of local-scale 3D deformation preceding the 2018 phreatic eruption at Iwo-yama volcano (south of Kyushu Island, Japan), using a combination of airborne and spaceborne Interferometric Synthetic Aperture Radar (InSAR) data. The 3D and 2.5D deformation maps obtained at different periods allow us to successfully track their spa...

Coseismic and postseismic crustal deformations caused by earthquake episodes are important in understanding the mechanisms of these episodes as well as the fault rheology near an epicentral area. Specifically, interferometric synthetic aperture radar (InSAR) and synthetic aperture radar (SAR) pixel tracking can depict high‐resolution crustal deform...

Interannual modulation of seasonal glacial velocity variations in the Eastern Karakoram detected by ALOS-1/2 data – ERRATUM - Muhammad Usman, Masato Furuya

Thawing of ice‐rich permafrost and subsequent ground subsidence can form characteristic landforms, and the resulting topography they create is collectively called “thermokarst.” The impact of wildfire on thermokarst development remains uncertain. Here, we report on the post‐wildfire ground deformation associated with the 2014 wildfire near Batagay,...

Bárðarbunga is an active volcano beneath the Vatnajökull icecap in Iceland, where a subglacial dike intrusion occurred in 2014. This area has been studied with interferometric synthetic aperture radar (InSAR), an important geodetic method that measures crustal deformation; however, ice/snow cover on volcanoes impedes the mapping of crustal deformat...

Recent advances in the field of atmospheric and ionospheric sensing by GNSS and SAR technologies were discussed during two workshops held in February 2016 and October 2016 in Italy, hosted by GEOlab of Politecnico di Milano under partial support of the JSPS Bilateral Open Partnership Joint Research Projects. Another symposium was held in March 2017...

Abstract Azerbaijan, located on the western edge of the Caspian Sea in Central Asia, has one of the highest populations of mud volcanoes in the world. We used satellite-based synthetic aperture radar (SAR) images derived from two L-band SAR satellites, ALOS/PALSAR along an ascending track from 2006 to 2011, and its successor ALOS-2/PALSAR-2 along b...

Unlike in most other regions, Karakoram glaciers are either stable or advancing, a phenomenon known as the Karakoram anomaly. Despite studies of glacier surges and the derivation of surface velocity maps, the spatiotemporal variability of glacier dynamics still remains poorly understood, particularly in the Eastern Karakoram Range. We use Advanced...

Sporadic-E (Es) is a layer of ionization that irregularly appears within the E region of the ionosphere and is known to generate an unusual propagation of very high frequency waves over long distances. The detailed spatial structure of Es remains unclear due to the limited spatial resolution in the conventional ionosonde observations. We detect mid...

Localized propagation delay signals associated with line-aligned convective cells were detected by the Synthetic Aperture Radar Interferometry (InSAR) technique on 25 August 2010 in Niigata prefecture. The maximum amplitude of the signal reached up to 22.5 cm, which was approximately equivalent to 29 mm anomaly in precipitable water vapor (PWV). Th...

We performed airborne synthetic aperture radar (SAR) observations at two glaciers (San’nomado and Komado glaciers) on the eastern slope of Mt. Tsurugi, Japan, in August and October 2013, and August 2014. The Pi-SAR2 system used in this study consists of two X-band SAR antennas. Taking advantage of single-pass interferometry, we have generated digit...

Series of earthquakes including three Mw > 6 earthquakes occurred in Kumamoto prefecture in the middle of the Kyushu island, Japan. In order to reveal the associated crustal deformation signals, we applied offset tracking technique to ALOS-2/PALSAR-2 data covering three Mw > 6 earthquakes and derived the 3D displacements around the epicenters. We c...

Series of earthquakes including three Mw > 6 earthquakes occurred in Kumamoto prefecture in the middle of the Kyushu island, Japan. In order to reveal the associated crustal deformation signals, we applied offset tracking technique to ALOS-2/PALSAR-2 data covering three Mw > 6 earthquakes and derived the 3D displacements around the epicenters. We c...

Surge-type glaciers repeat their short active phase and their much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to only a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, Canada, indicating remarkably reg...

Kilometer-scale fine structures of midlatitude sporadic-E (Es) plasma patches have been directly imaged for the first time by an interferogram derived from L-band ALOS/PALSAR data obtained over southwestern Japan. The synthetic aperture radar (SAR) interferogram captured the eastern part of a large-scale frontal structure of daytime midlatitude Es...

Surge-type glaciers repeat their short active phase and much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, indicating remarkably regular and short repe...

Here we examine 31 glaciers in the West Kunlun Shan of the northwestern Tibetan Plateau and identify 9 as surge type. The method is based on satellite synthetic aperture radar and Landsat optical images, the former going back to 1992, the latter to 1972. To identify surge-type glaciers, we consider temporal changes in velocity, changes in glacier t...

The Quetta Syntaxis in western Baluchistan, Pakistan, is the result of an oroclinal bend of the western mountain belt and serves as a junction for different faults. As this area also lies close to the left-lateral strike-slip Chaman fault, which marks the boundary between the Indian and Eurasian plates, the resulting seismological behavior of this...

Glacier surges often initiate in winter, but the mechanism remains unclear in contrast to the well-known summer speed-up at normal glaciers. To better understand the mechanism, we used radar images to examine spatial- temporal changes in the ice velocity of surge-type glaciers near the border of Alaska and the Yukon, focusing on their quiescent pha...

Glacier surges often initiate in winter, but the mechanism remains unclear in contrast to the well-known summer speed-up at normal glaciers. To better understand the mechanism, we used radar images to examine spatial-temporal changes in the ice velocity of surge-type glaciers near the border of Alaska and the Yukon, focusing on their quiescent phas...

The Patagonian Ice Fields are known to have undergone rapid retreat of frontal positions and significant thinning of its glaciers over the past decades. However, surface velocities have been measured at only a few of these glaciers. Thus, it remains uncertain if and to what extent the glacier dynamics has changed over time and contributed to ice lo...

This study reports the first detection and analysis of a localized water vapor distribution obtained using interferometric synthetic aperture radar (InSAR) during the Seino heavy rain episode. The InSAR data retrieved during the ALOS/PALSAR emergency observations for the event revealed a radar line-of-sight (LOS) change of up to 130 mm within 10 km...

We investigate surface deformations associated with two moderate-sized shallow earthquakes that occurred in the southeastern and northwestern stable regions of Mongolia using an analysis of ENVISAT/ASAR and ALOS/PALSAR data, respectively. Differential interferograms generated by a standard two-pass interferometric analysing technique depicted an up...

Interferometric Synthetic Aperture Radar (InSAR) phase data include not only signals due to crustal movements but also those associated with microwave propagation delay through the atmosphere. In particular, the effect of water vapor can generate apparent signals on the order of a few centimeters or more, and prevent us from detecting such geophysi...

We use crustal deformation data sets acquired by the Phased Array-Type L-Band Synthetic Aperture Radar (PALSAR) and the Japanese nationwide Global Positioning System (GPS) Earth Observation Network (GEONET) to develop a fault source model for the 2008 Iwate-Miyagi inland earthquake (M-w 6.9) that occurred on 14 June 2008 in northeastern Honshu, Jap...

Seasonal glacier velocity changes across the High Arctic, including the Greenland Ice Sheet, have been observed and have attracted significant attention over the past decade. However, it remains uncertain how much short-term variability exists in other polythermal glaciers, particularly those in High Asia. Here we report satellite radar image analy...

[1] We present high-resolution measurements of interseismic deformation along the central section of the North Anatolian Fault (NAF) in Turkey using interferometric synthetic aperture radar data from the Advanced Land Observing Satellite and Envisat missions. We generated maps of satellite line-of-sight velocity using five ascending Advanced Land O...

We detected glacier surge in West Kunlun Shan (WKS) located to the northern-western Tibetan plateau. We used several SAR archive data from 1990s and detected surface velocity field based on offset tracking with parallel flow assumption. We also used Landsat optical image from 1970s to detect terminus position of glaciers. Our results revealed veloc...

Synthetic aperture radar SAR has been widely used in crustal deformation studies all over the world. Especially the Japanese Advanced Land Observing Satellite (ALOS) contributed so much to the studies of large earthquakes, volcanic eruptions, landslides and other phenomena, and Japanese researchers presented many remarkable results in international...

Jakobshavn Isbræ in west Greenland has been undergoing dramatic thinning since 1997. Applying the interferometric synthetic aperture radar (InSAR) technique to Radarsat-1 SAR data, we measure crustal uplift near Jakobshavn Isbræ caused by recent ice mass loss. The crustal uplift is predominantly at long spatial wavelengths (larger than 10 km), and...

High mountains at Tibetan plateau and Himalaya are the most glaciated area on the earth except for polar region. Mountain glaciers in High Asia are not only significant contributor to the global sea level rise, but also play an important role as water resource around the nearby densely populated regions. Severe nature and remote place, however, pre...

Glacier surface velocity is a combination of plastic internal deformation of the ice and basal slip, the latter of which consists of basal sliding over the bed and deformation of the bed itself. Because plastic ice cannot deform rapidly, short-term surface velocity variations are attributed to basal slip caused by reduction of the effective overbur...

We present high-resolution measurements of interseismic deformation along the central section of the North Anatolian fault (NAF) in Turkey using L-band Interferometric Synthetic Aperture Radar (InSAR) data collected by the Advanced Land Observing Satellite (ALOS) of the Japan Aerospace Exploration Agency. We generated satellite line-of-sight (LOS)...

Interferometric Synthetic Aperture Radar (InSAR) phase signals are used to map the Earth's surface deformation, but are also affected by Earth's atmosphere. In particular, the heterogeneity of water vapor near the surface causes unpredictable phase changes in InSAR data. In the absence of deformation signals and other errors, InSAR can provide us w...

It is our great regret that the Advanced Land Observing Satellite (ALOS) satellite terminated its operation due to a power failure on 22 April 2011. As part of its final task, the Phased Array type L-band Synthetic Aperture Radar (PALSAR) on ALOS provided invaluable images of the March 2011 Great Tohoku, Japan Earthquake. By analysing images acquir...

When any moderate to large earthquakes take place, we can now promptly learn their origin time, location, and its preliminary report on the focal mechanism [e.g., 1]. However, since those seismic data are acquired at “far-field” from epicenters, they assume a point source despite the actual earthquake rupture occurs in a finite domain. The hypocent...

Owing to its average elevation higher than 4000 m, a number of mountain glaciers are developed in Tibetan plateau. Those glaciated areas are thus termed as the Third Pole (TP) region. As is the case for North / South Pole region, the TP glaciers will also sensitively respond to global warming, contributing to global sea level rise. Moreover, the gl...

We detected post-seismic surface deformation following the 2008 Iwate-Miyagi Nairiku Earthquake (2008 June 14 JST, M6.8) by interferometric synthetic aperture radar (InSAR) analysis using ALOS/PALSAR data. The ascending interferograms indicate ∼ 8 cm of length increase in radar line-of-sight (LOS) to the east of Mt. Kurikoma (KRK), and decreases in...

Slow-slip events (SSEs) have occurred at plate-subduction zones throughout the world. Previous studies have revealed that high-pressure fluids supplied from the subducted oceanic plate can generate SSEs. However, the behavior of these fluids during an SSE has not been fully described. In this paper, we discuss the possibility of fluid migration alo...

On 20 March 2008, a normal-faulting earthquake (M7.2/USGS) struck Yutian county, Xinjiang, China. The epicenter is close to the southern-edge of the Tarim basin, where three prominent fault systems, the Altyn-Tagh Fault, Karakax Fault, and Longmu-Gozha Co Fault, meet together at the northwest of the Tibetan plateau. The associated crustal deformati...

Spatio-temporal distribution of glaciers in the Third Pole Environment (TPE) responds sensitively to global climate change. Moreover, meltwater from them plays a critical role for regional industries in the nearby arid areas. It is, therefore, fundamentally important to monitor their spatio-temporal changes. Nevertheless, glacier measurement data i...

Interferometric Synthetic Aperture Radar (InSAR) can measure a spatial distribution of precipitable water vapor with unprecedented spatial resolution, and thus can provide us with unique information about mesoscale weather systems. From the end of August to the beginning of September 2008, torrential rains struck wide areas over central Japan, caus...

Slow-slip events (SSEs) have been observed in many plate-boundary zones along the circum-Pacific seismic belt. Previous studies have revealed that high-pressure fluids supplied from the subducted oceanic plate can generate SSEs. However, the behavior of these fluids during an SSE has not been fully elucidated. This paper discusses possible fluid mi...

We use crustal deformation data sets derived from satellite-based synthetic aperture radar (SAR) to develop a fault source model of the 2008 M-w 7.9 Wenchuan earthquake, China, that occurred at the Longmen Shan fault zone. The data sets include interferometric SAR (InSAR), range offset, and azimuth offset data acquired at seven ascending paths. The...

Numerical weather models offer the possibility to compute corrections for a variety of space geodetic applications, including remote sensing techniques like interferometric SAR. Due to the computational complexity, exact ray-tracing is avoided in many cases and mapping approaches are applied to transform vertically integrated delay corrections into...

In August 1996, an earthquake swarm including 4 earthquakes of magnitudes greater than 5 occurred in and around the Onikobe geothermal area, northeast Japan. While earlier studies detected ground displacements by L-band JERS radar interferograms, there remained certain puzzling discrepancies between the observations and the predictions from a seism...

On June 16 2007 (AM 10:13 in Japan Standard Time), an earthquake of magnitude 6.8 took place about 10 km offshore of Chuetsu area in Niigata, Japan. Using L-band PALSAR InSAR (Interferometric Synthetic Aperture Radar) data, we could detect not only coseismic broad deformation but also significant aseismic deformation nearly 15 km away from the epic...

Suwanose-jima is one of the most active volcano of Japan with quasi-continuous unrest since 1957. It is monitored with broadband seismometers and tiltmeters but the difficulty in ground access to the island prohibits us to construct large-enough network to understand the magma plumbing system solely from the ground-based monitoring network. Groud d...

Introduction: A catastrophic earthquake with a moment magnitude of 7.9 struck China's Sichuan area on 12 May 2008. The rupture was thought to proceed northeastward along the Longmen Shan fault zone (LMSFZ), but it remained uncertain where and how the faults were involved in the seismic event. Interferometric SAR (InSAR) analysis has an advantage of...

On 20 March 2008, an earthquake (M7.2) struck northern Tibet, west Kunlun, China. Because of the high altitude (> 4500 meters), no casualties were reported associated with this earthquake. However, the associated crustal deformation signals, if detected and examined in detail, will provide us with important constraints on how the continental crust...

We have detected detailed ground displacements in the proximity of the Longmen Shan fault zone (LMSFZ) by applying a SAR offset-tracking method in the analysis of the 2008 Sichuan earthquake. An elevation-dependent correction is indispensable for achieving sub-meter accuracy. A sharp displacement discontinuity with a relative motion of ~1-2 m appea...

Applying interferometric SAR (InSAR) analysis to the 2008 Iwate-Miyagi Nairiku earthquake, we detected notable ground displacements of several tens of centimeters to about 1.2 m that extend further south of the epicentral area. We explained the InSAR data by constructing a fault model consisting of four WNW dipping and one ESE dipping reverse fault...

Glaciers are among the most visible indicators of the effects of climate change. Jakobshavn Isbrae, the largest outlet glacier in Greenland, is observed to have been undergoing dramatic thinning and acceleration in speed in recent years. The changes in Jakobshavn Isbrae are likely important indicators of the dynamic response of the Greenland ice sh...

Suwanose-jima is one of the most active volcano of Japan with quasi-continuous unrest since 1957. It is monitored with broadband seismometers and tiltmeters but the difficulty in ground access to the island prohibits us to construct large-enough network to understand the magma plumbing system solely from the ground-based monitoring network. Groud d...

We analyzed SAR (Synthetic Aperture Radar) data to derive the crustal deformation due to the Solomon Islands earthquake (Mw8.1) that occurred on April 1st, 2007. Three tracks that cover the source areas were used and the image data taken before and after the earthquake were processed to make interferograms. Then, we examined the obtained interferog...

Niigata basin is located at a diffuse plate boundary between Eurasian plate and North American plate. Although there are no clear plate boundaries, GPS data indicate that a broad area from Niigata to Kobe is undergoing significant strain concentrations (Sagiya et al. 2000, PAGEOPH). Over the past 50 years, there have been a couple of large inland e...

Introduction: A catastrophic earthquake struck China"fs Sichuan area on May 12, 2008, with the moment magnitude of 7.9 (USGS). The hypocenter and their aftershocks are distributed along the western edge of the Sichuan Basin, suggesting that this seismic event occurred at the Longmeng Shan fault zone which is constituted of major three active faults...

Global Positioning System (GPS) and Synthetic Aperture Radar Interferometry (InSAR) detected substantial ground deformation due to the 2007 Chuetsu-oki earthquake (M w = 6.8); GPS observation detected a horizontal deformation of up to about 170 mm and subsidence of up to 30 mm, and InSAR detected up to 290 mm of line-of-sight changes. A fault model...

The termination of the Japanese Earth Resources Satellite (JERS 1) in October 1998 and the subsequent delay of the launch of its successor, the Advanced Land Observing Satellite (ALOS), caused a troublesome interruption in the availability of L-band synthetic aperture radar (SAR) data to the several research institutions and government agencies in...

The Chaman fault system forms a prominent ∼900-km-long left-lateral transform plate boundary between the Indian and Eurasian plates in Afghanistan and Pakistan. Here we show satellite radar interferometry data that revealed an afterslip (or slow earthquake) signal following an earthquake of magnitude 5.0. This slow slip episode lasted for more than...