Wu-Lung Chang

National Central University | NCU · Department of Earth Sciences

The strength of the lithosphere controls tectonic evolution and seismic cycles, but how rocks deform under stress in their natural settings is usually unclear. We constrain the rheological properties beneath the Taiwan orogenic belt using the stress perturbation following the 1999 Chi-Chi earthquake and fourteen-year postseismic geodetic observatio...

Taiwan is located at the boundary between the Philippine Sea plate and the passive continental margin of the Eurasian plate and is one of the most seismically active regions in the world. In an attempt to evaluate the seismogenic potential of active faults in Taiwan, we separated the region into 34 blocks with 27 known active faults as their bounda...

The Mw 5.9 Wutai earthquake of 26 February 2012 occurred at a depth of 26 km in southern Taiwan, where the rupture is not related to any known geologic structures. To illustrate the rupture source of the mainshock, we employ an elastic half-space model and GPS coseismic displacements to invert for optimal fault geometry and coseismic slip distribut...

The University of Utah Wasatch Front, Utah, GPS network is part of the USGS National Earthquake Hazards Reduction Program operating under a Cooperative Agreement for geodetic monitoring of active faults. The principal goal of the Wasatch GPS network is to measure crustal deformation along the populated Wasatch Front, Utah using precision geodetic G...

Final Report for USGS Cooperative Agreement for Regional Geodetic Networks

The Lishan fault has been characterized alternately as a major discontinuity in stratigraphy, structures and metamorphism, a ductile shear zone, a tectonic suture or non-existent. In addition to being a geological boundary, it also marks transitions in subsurface structures. Thus, the seismicity to the west of the fault permeates through the upper...

Predicting how large an earthquake can be, where and when it will strike remains an elusive goal in spite of the ever-increasing volume of data collected by earth scientists. In this paper, we introduce a universal model of fusion-fission processes that can be used to predict earthquakes starting from catalog data. We show how the equilibrium dynam...

We integrate multiple ideas and data from earthquakes, deformation, and volcano/tectonic history to form a new interpretation of the active processes and hazard implication of the Yellowstone volcano-tectonic system. 1) The Yellowstone mantle plume is not vertical beneath Yellowstone and evolving new seismic tomographic data suggests that the plume...

[1] The 1959 Mw 7.3 Hebgen Lake, MT, normal-faulting earthquake occurred in an extensional stress regime near the Yellowstone volcanic field. Time-dependent crustal deformation data following this major earthquake were acquired by precise trilateration and GPS surveys from 1973 to 2000 around the Hebgen Lake fault zone. Modeling the changes of base...

The Yellowstone hotspot results from the interaction of a mantle plume with the overriding N. America plate producing a ~300-m high topographic swell centered on the Late Quaternary Yellowstone volcanic field. The Yellowstone area is dominated by earthquake swarms including a deadly M7.3 earthquake, extraordinary high heat flow up to ~40,000 mWm-2,...

In mid-2004, GPS and InSAR measurements of Yellowstone revealed the initiation of accelerated uplift of the Yellowstone caldera, with maximum rates of ~7 cm/yr near the Sour Creek resurgent dome in the northeastern caldera. From mid-2006 to 2010, the ground uplift rates declined in two distinct phases: in 2006-2009 from 7 to 5 cm/yr in the northeas...

1] Geodetic measurements of Yellowstone ground deformation from 2006 to June 2010 reveal deceleration of the recent uplift of the Yellowstone caldera following an unprecedented period of uplift that began in 2004. In 2006–2008 uplift rates decreased from 7 to 5 cm/yr and 4 to 2 cm/yr in the northern and southwest caldera, respectively, and in 2009...

1] Yellowstone National Park experienced an unusual earthquake swarm in December–January, 2008–2009 that included rapid northward migration of the activity at 1 km per day and shallowing of the maximum focal depths from 12 to 2 km beneath northern Yellowstone Lake. The swarm consisted of 811 earthquakes, 0.5 < M W < 4.1, aligned on a N–S 12‐km‐long...

Dilatational source deformations associated with two unusual M 3+ earthquakes in the area of the 2004-2008 Yellowstone, WY, accelerated uplift episode were identified through detailed analysis of moment tensor inversions. Pressurized hydrothermal fluids are suggested to be associated with the dilatational source processes of these unusual earthquak...

Time-dependent deformation of the Hebgen Lake, MT, normal fault zone was measured by campaign mode GPS and trilateration from 1973 to 2000 following the 18 August 1959 Ms=7.5 Hebgen Lake earthquake that occurred at the northwest edge of the Yellowstone volcanic field in an extensional tectono-volcanic regime. Since 2005, the EarthScope-PBO project...

Integration of geophysical and geological data show that the Yellowstone hotspot resulted from a mantle plume interacting with the overriding North America plate, a process that has highly modified continental lithosphere by magmatic and tectonic processes and produced the 16-17Ma, 700-km-long Yellowstone-Snake River Plain (YSRP) silicic volcanic s...

Dominant dilatational deformations associated with earthquakes in the area of the 2004-2008 Yellowstone accelerated uplift episode were identified through detailed analysis of moment tensor inversions of two unusual M3+ earthquakes characterized by notable coseismic volumetric changes. Highly pressurized hydrothermal fluids are suggested to be asso...

Hydrothermal explosions are a prominent geologic hazard in Yellowstone National Park and are of consideration for park infrastructure and visitor safety. It is estimated that small rock-hurling phreatic explosions occur somewhere in the park almost every year and larger basin-wide events on the order of several hundred years. The Yellowstone Volcan...

Our analysis of split shear waves from local earthquakes on the Yellowstone Plateau is consistent with the complex stress and strain fields determined from previous studies. Splitting fast directions (phi) and delay times were determined using a cross-correlation algorithm for a subset of data from well-located earthquakes recorded from 1993-2006....

The Yellowstone caldera began a rapid episode of ground uplift in mid-2004, revealed by Global Positioning System and interferometric synthetic aperture radar measurements, at rates up to 7 centimeters per year, which is over three times faster than previously observed inflation rates. Source modeling of the deformation data suggests an expanding v...

1] The Yellowstone–Snake River Plain tectonomagmatic province resulted from Late Tertiary volcanism in western North America, producing three large, caldera-forming eruptions at the Yellowstone Plateau in the last 2 Myr. To understand the kinematics and geodynamics of this volcanic system, the University of Utah conducted seven GPS campaigns at 140...

Under the USGS National Earthquake Hazard Program, the University of Utah conducted research focused on evaluating earthquake hazards of the populated Wasatch Front, Utah by operating the Wasatch Front GPS (Global Positioning Systems) network to monitor the surface deformation Utah. High resolution GPS data, acquired by 20 continuous stations and s...

Contemporary strain accumulation rates of the 350-km-long Wasatch fault, Utah, have been determined by GPS measurements and provide key data for evaluating normal fault behavior and related earthquake hazard assessment. This paper presents a complete description of the Wasatch GPS network, data archiving and processing, and the measured ground defo...

Contemporary strain accumulation rates of the 350-km-long Wasatch fault, Utah, have been determined by GPS measurements and provide key data for evaluating normal fault behavior and related earthquake hazard assessment. This paper presents a complete description of the Wasatch GPS network, data archiving and processing, and the measured ground defo...

The development of geodetic methods to measure ground movements using high precision GPS offers a new tool to deduce contemporary crustal deformation and fault-loading rates. Geologic evidence such as paleoearthquakes, on the other hand, provide in-plane, near-vertical displacements of a normal fault that may be used to imply long-term horizontal s...

Interferometric Synthetic Aperture Radar (InSAR) imagery of the Salt Lake Valley shows a northwest-trending, 12- x 17-km elongate subsidence bowl, centered on Salt Lake City, that has an annual subsidence rate of of 12 mm/year and seasonal uplift of ~30 mm. Radar imagery from the European Space Agency's ERS satellites (1992-2000) shows that the sub...

We studied the change of surface deformation after the 1959 Ms=7.5 Hebgen Lake, Montana, earthquake, measured by trilateration and GPS from 1973 to 2000 and the only postseismic observation of large normal-faulting earthquake in the Basin-Range. Time-dependent changes of baseline length across the fault were used to constrain the rheological struct...

Contemporary crustal deformation along the 370 km-long Wasatch fault, Utah, has been measured by the Global Positioning System (GPS) and modeled for elastic and viscoelastic mechanisms. The Wasatch Front GPS network, including 107 campaign sites surveyed in 1992--1995, 1999, and 2001, and 11 permanent stations operating continuously from as early a...

The effects of long-term viscoelastic loading and relaxation of the Earth's lithosphere and asthenosphere should be included to better model the complete earthquake cycle. An earthquake is assumed to generate coseismic stresses that cannot be sustained by the ductile lower crust and upper mantle, leading to postseismic relaxation of these materials...

The 1959, M = 7.5, Hebgen Lake earthquake, the largest historic normal-faulting earthquake in the Basin-Range province, was located 20 miles northwest of the Yellowstone caldera. Models of the fault-stress interaction suggested that the earthquake rupture affected the nearby caldera stress-field and induced long-term aftershock activity, continuing...

We examined the combined effects of different sources that influence earthquake hazard of the populated Wasatch Front, Utah. We first evaluated the fault-stress interaction of the two largest historic earthquakes of the Intermountain Seismic Belt (ISB): the 1959 Hebgen Lake, Montana (M s 7.5) and the 1983 Borah Peak, Idaho (M s 7.3) earthquakes, wh...

As part of a comprehensive neotectonic study of interseismic behavior of active faults, we have done six first order leveling surveys of 50 permanent bench marks in a 22 km-long base line across the Teton fault to characterize its interseismic behavior between 1988 and 2001. This 55 km-long normal fault extends along the eastern base of the Teton R...

The 1959 Hebgen Lake earthquake, the largest historic earthquake in the Intermountain Seismic Belt, simultaneously ruptured two normal faults centered 25 miles northwest of the Yellowstone caldera. The depth of the 90th percentile of earthquake foci approximates the depth of the brittle-ductile transition. This depth increases northwesterly from 7...

As part of a comprehensive : http://repository.uwyo.edu/uwnpsrc_reports/vol25/iss1/13 study of interseismic behavior of active faults, we have done six first order leveling surveys of 50 permanent bench marks in a 22 km-long base line across the Teton fault to characterize its interseismic behavior between 1988 and 2001. This 55 km-long normal faul...

A multidisciplinary approach is employed to evaluate active tectonism of the eastern Basin-Range (BR) and its transition into the stable N. American plate. This intraplate regime is characterized by shallow normal-faulting earthquakes, active volcanism, high heat flow and a thin crust. This zone also coincides with an abrupt change in the elastic t...