312 research outputs found

    Introduction to the Special Issue on the 2004 Sumatra–Andaman Earthquake and the Indian Ocean Tsunami

    Get PDF
    The great Sumatra–Andaman earthquake of 26 December 2004 (UTC 00:58:53) was a momentous event, whether measured by scientific or human standards. Sadly, what is currently regarded as the third largest earthquake in recorded history led to the worst tsunami disaster in recorded history, with the loss of more than 200,000 lives and devastation throughout the Bay of Bengal. About three months later, on 28 March 2005, the Nias–Simeulue earthquake, near the southern end of the 2004 rupture, shocked the region again. Fortunately, this M_w 8.7 earthquake, the second largest earthquake in the past decade, was less destructive. These earthquakes and resulting tsunamis have been a sobering reminder to many in the community of earthquake scientists that the subject of our professional lives can have enormous impact on humanity. Hopefully, the legacy of the science presented in this volume will be a greater understanding of earthquake and tsunami processes that will be useful in advancing the resilience of our communities to Nature’s violence

    Effects of subducted seamounts on megathrust earthquake nucleation and rupture propagation

    Get PDF
    Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 39 (2012): L24302, doi:10.1029/2012GL053892.Subducted seamounts have been linked to interplate earthquakes, but their specific effects on earthquake mechanism remain controversial. A key question is under what conditions a subducted seamount will generate or stop megathrust earthquakes. Here we show results from numerical experiments in the framework of rate- and state-dependent friction law in which a seamount is characterized as a patch of elevated effective normal stress on the thrust interface. We find that whether subducted seamounts generate or impede megathrust earthquakes depends critically on their relative locations to the earthquake nucleation zone defined by depth-variable friction parameters. A seamount may act as a rupture barrier and such barrier effect is most prominent when the seamount sits at an intermediate range of the seamount-to-trench distances (20–100% of the nucleation-zone-to-trench distance). Moreover, we observe that seamount-induced barriers can turn into asperities on which megathrust earthquakes can nucleate at shallow depths and rupture the entire seismogenic zone. These results suggest that a strong barrier patch may not necessarily reduce the maximum size of earthquakes. Instead, the barrier could experience large coseismic slip when it is ruptured.This work is supported by the NSF Grant EAR-1015221 and WHOI Deep Ocean Exploration Institute awards 27071150 and 25051162.2013-06-1

    Analysis of the 23 June 2001 M w = 8.4 Peru underthrusting earthquake and its aftershocks

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95298/1/grl16079.pd

    Risk of progression in complex and atypical endometrial hyperplasia: clinicopathologic analysis in cases with and without progestogen treatment

    Get PDF
    Abstract. Horn L-C, Schnurrbusch U, Bilek K, Hentschel B, Einenkel J. Risk of progression in complex and atypical endometrial hyperplasia: clinicopathologic analysis in cases with and without progestogen treatment. Int J Gynecol Cancer 2004;14:348-353. In most cases, the endometrioid adenocarcinoma of the endometrium is preceded by hyperplasia with different risk of progression into carcinoma. The original histologic slides from 560 consecutive cases with complex and atypical hyperplasia were re-examined to assess the interobservercorrelation. The hyperplasias were analyzed separately for their likelihood of progression to carcinoma in patients with and without progestogen hormonal therapy. In all cases, a fractional re-curreting was performed to establish the state of the disease. The leading symptom was vaginal bleeding in 65.5% of the cases in the postmenopausal period. Eighty-six percent of the patients presented with obesity (BMI > 30 kg/m 2 ), 23% had had an exogeneous use of estrogens. Twenty-two cases were reclassified as simple hyperplasia and excluded from further analysis. The interobserver-correlation was 91% for complex, 92% for atypical hyperplasia, and 89% for endometrioid carcinoma, representing an overall correlation of 90%. Two percent of the cases with complex hyperplasia (8/390) progressed into carcinoma and 10.5% into atypical hyperplasia. Fifty-two percent of the atypical hyperplasias (58/112) progressed into carcinomas. In the case of progestogen treatment (n = 208; P < 0.0001) 61.5% showed remission confirmed by re-curetting, compared with 20.3% of the cases without hormonal treatment (n = 182; P < 0.0001). Endometrial hyperplasia without atypia is likely to respond to hormonal treatment. Especially in postmenopausal situation, atypical hyperplasia should be treated with total hysterectomy

    Synthesis of highly tetrahedral amorphous carbon by mixed-mode HiPIMS sputtering

    Get PDF
    Tetrahedral amorphous carbon films with an sp 3 content of 80% have been produced by high power impulse magnetron sputtering (HiPIMS) operating in a mixed sputtering/arc mode. In this mode, short-lived cathode spots form in the magnetic racetrack and produce large numbers of carbon ions. The spots move rapidly, inhibiting the formation of macroparticles. An argon pressure below 2.5 mTorr was critical for obtaining films with high sp 3 content, high stress, large Tauc gap and symmetrical Raman spectra, and all four quantities were strongly correlated
    corecore