[ { "id": "authors:97tb8-jta82", "collection": "authors", "collection_id": "97tb8-jta82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200624-130036010", "type": "book_section", "title": "Identification of Sparse Damage in Steel-Frame Buildings Using Dense Seismic Array Measurements", "book_title": "Structural Health Monitoring 2019: Enabling Intelligent Life-cycle Health Management for Industry Internet of Things (IIOT)", "author": [ { "family_name": "Filippitzis", "given_name": "Fillipos", "orcid": "0000-0001-8377-4914", "clpid": "Filippitzis-F" }, { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "editor": [ { "family_name": "Chang", "given_name": "Fu-Kuo", "clpid": "Chang-Fu-Kuo" }, { "family_name": "Kopsaftopoulos", "given_name": "Fotis", "clpid": "Kopsaftopoulos-F" } ], "abstract": "There is an unprecedented increase in the number of real-time measurements produced by permanent, dense accelerometer arrays in buildings, an example being the Community Seismic Network. In the present work, damage identification techniques are developed by coupling such datasets with linear and nonlinear finite-element models of buildings. Damage in steel-frame buildings is manifested in localized areas as cracks in beam-column connections or as an average stiffness reduction. High-fidelity linear or nonlinear finite-element models are developed to allow for realistic behavior, including modeling nonlinearities associated with the opening and closing of cracks. L1 regularization techniques and sparse Bayesian learning tools are further developed fully in the time domain to reduce ill-conditioning and account for the sparsity of damage. The effectiveness of the proposed methods in identifying the location and severity of damage is demonstrated using simulated acceleration data from a three-story steel frame building, and a 15-story building in downtown Los Angeles that is fully instrumented.", "doi": "10.12783/shm2019/32398", "isbn": "9781605956015", "publisher": "Destech Publications", "place_of_publication": "Lancaster, PA", "publication_date": "2019-11", "volume": "1" }, { "id": "authors:69kn8-1s115", "collection": "authors", "collection_id": "69kn8-1s115", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160209-162449879", "type": "book_section", "title": "Structural health monitoring through dense instrumentation by community participants: the Community Seismic Network and Quake-Catcher Network", "author": [ { "family_name": "Kohler", "given_name": "M. D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Heaton", "given_name": "T. H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Cheng", "given_name": "M. H.", "clpid": "Cheng-Ming-Hei" }, { "family_name": "Singh", "given_name": "P.", "clpid": "Singh-P" } ], "abstract": "The Community Seismic Network and Quake-Catcher Network involve participants from communities at large to install low-cost accelerometers in houses and buildings for assessment of shaking intensity due to earthquakes. The seismometers are designed for two types of connec-tions: a USB-connected device which connects to the host's computer, and a stand-alone sensor-plug-computer device that directly connects to the internet. The three-component sensors report both continuous data and amplitude anomalies in local acceleration to a Cloud computing service consisting of data centers geographically distributed across the continent, or to a distributed computing system. The continuous time series waveform data are being used to evaluate response parameters such as peak acceleration, peak velocity, and inter-story drift values. In addition, modal properties such as fundamental and higher mode frequencies and mode shapes are being computed from small and moderate earthquake data from the building. Building motion is computed for every floor of the building using only earthquake records from a single floor. Visualization models that map the instrumented buildings' responses have been construct-ed using SketchUp and an associated plug-in to Matlab with recorded shaking data. This data visualization approach is different from other techniques because each building model is customized to show actual data recorded from that building on varying spatial scales, without the need for large-scale parallel computing facilities or complicated software that requires a steep learning curve.", "publisher": "Earthquake Engineering Research Institute", "publication_date": "2014-07" }, { "id": "authors:0vvy0-1n107", "collection": "authors", "collection_id": "0vvy0-1n107", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130920-082322579", "type": "book_section", "title": "The Community Seismic Network and Quake-Catcher Network: enabling structural health monitoring through instrumentation by community participants", "book_title": "Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems", "author": [ { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Cheng", "given_name": "Ming-Hei", "clpid": "Cheng-Ming-Hei" } ], "contributor": [ { "family_name": "Lynch", "given_name": "Jerome Peter", "clpid": "Lynch-J-P" }, { "family_name": "Yun", "given_name": "Chung-Bang", "clpid": "Yun-Chung-Bang" }, { "family_name": "Wang", "given_name": "Kon-Well", "clpid": "Wang-Kon-Well" } ], "abstract": "A new type of seismic network is in development that takes advantage of community volunteers to install low-cost accelerometers\nin houses and buildings. The Community Seismic Network and Quake-Catcher Network are examples of\nthis, in which observational-based structural monitoring is carried out using records from one to tens of stations in a single\nbuilding. We have deployed about one hundred accelerometers in a number of buildings ranging between five and 23\nstories in the Los Angeles region. In addition to a USB-connected device which connects to the host's computer, we\nhave developed a stand-alone sensor-plug-computer device that directly connects to the internet via Ethernet or wifi. In\nthe case of the Community Seismic Network, the sensors report both continuous data and anomalies in local acceleration\nto a cloud computing service consisting of data centers geographically distributed across the continent. Visualization\nmodels of the instrumented buildings' dynamic linear response have been constructed using Google SketchUp and an\nassociated plug-in to matlab with recorded shaking data. When data are available from only one to a very limited number\nof accelerometers in high rises, the buildings are represented as simple shear beam or prismatic Timoshenko beam models\nwith soil-structure interaction. Small-magnitude earthquake records are used to identify the first set of horizontal vibrational\nfrequencies. These frequencies are then used to compute the response on every floor of the building, constrained\nby the observed data. These tools are resulting in networking standards that will enable data sharing among entire\ncommunities, facility managers, and emergency response groups.", "doi": "10.1117/12.2010306", "isbn": "9780819494757", "publisher": "International Society for Optical Engineering", "place_of_publication": "Bellingham, WA", "publication_date": "2013-04-19", "pages": "Art. No. 86923X" }, { "id": "authors:79r5g-3y385", "collection": "authors", "collection_id": "79r5g-3y385", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120424-083207598", "type": "book_section", "title": "Mystery Revealed on Natural Frequency Change of a Structure During Rainstorms", "book_title": "Structural Health Monitoring 2011: condition-based maintenance and intelligent structures", "author": [ { "family_name": "Cheng", "given_name": "M. H.", "clpid": "Cheng-Ming-Hei" }, { "family_name": "Heckman", "given_name": "V.", "clpid": "Heckman-V-M" }, { "family_name": "Heaton", "given_name": "T.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "contributor": [ { "family_name": "Chang", "given_name": "Fu-Kuo", "clpid": "Chang-Fu-Kuo" } ], "abstract": "Recent observations as well as previous research show a 2-3% increase in the natural frequencies of Caltech's Millikan Library, a nine-story reinforced concrete frame and shear wall building, during rainstorms. It has been a mystery about whether changes in the building structure or the soil underneath cause the phenomenon. The Southern California Seismic Network lSCSN) installed a 24-bit 3-axis rotational sensor in the basement of the Millikan Library in 2008. It acts as an excellent data source to examine the mode shape changes that accompany frequency changes of the building. During the rainstorm period in late 2010, the authors ran\nseveral shaking tests of the building at its natural frequencies, and the ratio of the roof translational response to the basement rotational response was used to reveal the mystery. Experimental results suggest that the building concrete swells in response to moisture and cracks on the building surface are forced to close. The corresponding increase in the Young's modulus of the building structure causes an increase in the\nmeasured natural frequencies. Furthermore, when the authors watered the ground adjacent to the Millikan Library, no changes in the building's natural frequencies were observed. The irrelevance of \"soil saturation\" supports the suggested hypothesis. Finally, a 1-dimensional\nTimoshenko Beam model with soil-structure interaction is used to verify\nthe proposed explanation for the mystery.", "isbn": "978-1-60595-053-2", "publisher": "Destech Publications", "place_of_publication": "Lancaster, PA", "publication_date": "2011-09", "pages": "1165-1172" }, { "id": "authors:p06xs-d3e28", "collection": "authors", "collection_id": "p06xs-d3e28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140203-102915589", "type": "book_section", "title": "A Method to Detect Structural Damage Using High-Frequency Seismograms", "book_title": "Structural health monitoring 2011: condition based maintenance and intelligent structures", "author": [ { "family_name": "Heckman", "given_name": "Vanessa M.", "clpid": "Heckman-V-M" }, { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "contributor": [ { "family_name": "Chang", "given_name": "Fu-Kuo", "clpid": "Chang-F-K" } ], "abstract": "There has been recent interest in using acoustic techniques to detect damage in instrumented civil structures. An automated damage detection method that analyzes recorded data has application to building types that are susceptible to a signature type of failure, where locations of potential structural damage are known a priori. In particular, this method has application to the detection of brittle fractures in welded beam-column connections in steel moment-resisting frames (MRFs). Such a method would be valuable if it could be used to detect types of damage that are otherwise difficult and costly to identify. \n\nThe method makes use of a prerecorded catalog of Green's function templates and a matched filter method to detect the occurrence and location of structural damage in an instrumented building. This technique is different from existing acoustic methods because it is designed to recognize and use seismic waves radiated by the original brittle failure event where the event is not known to have occurred with certainty and the resulting damage may not be visible. \n\nThe method is outlined as follows. First, identify probable locations of failure in an undamaged building. In pre-Northridge steel MRFs, which are susceptible to brittle failure of welded beam-column connections, those connections would be the locations of probable failure for this type of building. Second, obtain a Green's function template for each identified location of probable failure by applying a short-duration high-frequency pulse (e.g. using a force transducer hammer) at that location. One underlying assumption of this method is that the Green's function template specific to a potential location of failure can be used to approximate the dynamic response of the structure to structural damage at that location. Lastly, after a seismic event, systematically screen the recorded high-frequency seismograms for the presence of waveform similarities to each of the catalogued Green's function templates in order to detect structural damage. This is achieved by performing a running cross-correlation between each Green's function template and a moving window of the continuous data recorded during the earthquake. Damage that occurs at one of the catalogued potential locations is expected to result in a high cross-correlation value when using the correct Green's function template. This method, also known as the matched filter method, has seen recent success in other fields, but has yet to be explored in the context of acoustic damage detection in civil structures. \n\nPreliminary experimental results from tap tests performed on a small-scale laboratory frame are presented. Cross-correlation calculations highlight similarities among events generated at the same source location and expose differences among events generated at different source locations. Finally, a blind tap test is performed to test whether cross-correlation techniques and catalogued Green's function templates can be used to identify the occurrence of and pinpoint the location of an assumed-unknown event.", "isbn": "978-1-60595-053-2", "publisher": "Destech Publications", "place_of_publication": "Lancaster, PA", "publication_date": "2011", "pages": "2504-2511" }, { "id": "authors:kadsn-6gb90", "collection": "authors", "collection_id": "kadsn-6gb90", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160209-162933501", "type": "book_section", "title": "A damage detection method for instrumented civil structures using prerecorded Green's functions and cross-correlation", "author": [ { "family_name": "Heckman", "given_name": "Vanessa", "clpid": "Heckman-V-M" }, { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Heaton", "given_name": "Thomas", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "abstract": "Automated damage detection methods have application to instrumented structures that are\nsusceptible to types of damage that are difficult or costly to detect. The presented method has\napplication to the detection of brittle fracture of welded beam-column connections in steel\nmoment-resisting frames (MRFs), where locations of potential structural damage are known a priori.\nThe method makes use of a prerecorded catalog of Green's function templates and a cross-correlation\nmethod to detect the occurrence, location, and time of structural damage in an instrumented building.\nUnlike existing methods, the method is designed to recognize and use mechanical waves radiated by\nthe original brittle fracture event, where the event is not known to have occurred with certainty and the\nresulting damage may not be visible. An experimental study is conducted to provide insight into\napplying the method to a building. A tap test is performed on a small-scale steel frame to test whether\ncross-correlation techniques and catalogued Green's function templates can be used to identify the\noccurrence and location of an assumed-unknown event. Results support the idea of using a\nnondestructive force to characterize the building response to high-frequency dynamic failure such as\nweld fracture.", "publication_date": "2011" }, { "id": "authors:w0egt-24z63", "collection": "authors", "collection_id": "w0egt-24z63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160209-163237718", "type": "book_section", "title": "Detecting failure events in buildings: a numerical and experimental analysis", "author": [ { "family_name": "Heckman", "given_name": "V. M.", "clpid": "Heckman-V-M" }, { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Heaton", "given_name": "T. H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "abstract": "A numerical method is used to investigate an approach for detecting the brittle fracture of welds associated with beam\n-column connections in instrumented buildings in real time through the use of time-reversed Green's functions and \nwave propagation reciprocity. The approach makes use of a prerecorded catalog of Green's functions for an instrumented building to detect failure events in the \nbuilding during a later seismic event by screening continuous data for the presence of waveform similarities to one of the prerecorded events. This study \naddresses whether a set of Green's functions in response to an impulsive force load can be used to approximate the response of the structure to a localized failure \nevent such as a brittle weld fracture. Specifically, we investigate whether prerecorded Green's functions can be used to determine the absolute time and location of a localized failure event in a building. We also seek to differentiate between sources such as a weld fracture that are structurally damaging and sources such as falling or colliding furniture and other non-structural elements \nthat do not contribute to structural failure. This is explored numerically by comparing the dynamic response of a finite-element cantilevered beam model structure to a variety of loading mechanisms. A finite-element method is \nemployed to determine the behavior of the resulting elastic waves and to obtain a general understanding of the structural response.", "publisher": "Earthquake Engineering Research Institute", "publication_date": "2010" }, { "id": "authors:jy6dj-4xw24", "collection": "authors", "collection_id": "jy6dj-4xw24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160209-163521991", "type": "book_section", "title": "A time-reversed reciprocal method for detecting high-frequency events in civil structures with accelerometer arrays", "book_title": "The Fifth International Workshop on Advanced Smart Material and Smart Structures Technology : proceedings", "author": [ { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Heckman", "given_name": "Vanessa M.", "clpid": "Heckman-V-M" } ], "editor": [ { "family_name": "Wang", "given_name": "M. L.", "clpid": "Wang-M-L" }, { "family_name": "Spencer", "given_name": "B. F.", "clpid": "Spencer-B-F" }, { "family_name": "Cao", "given_name": "Yinghong", "clpid": "Cao-Yinghong" } ], "abstract": "A high-frequency experimental method of detecting a failure event in engineered structures is presented that uses the property of wave propagation reciprocity and time-reversed reciprocal Green's functions. The premise is that if a numerical database of pre-event, source-receiver Green's functions can be compiled for multiple locations of potential damage in a structure, that database can subsequently be used to identify the location and time of occurrence of a real failure event in the structure. \nOnce a fracture source emits a wavefield that is recorded on a distributed set of accelerometers in the structure, time-reversed waves can be obtained by convolving the displacements with the database of time-reversed Green's functions and stacking the results. The correct location and time of the fracture source can be inferred from the subset of Green's functions that exhibits the best focus in the form of a delta function. The 17-story, steel moment-frame UCLA Factor building contains a cutting-edge, continuously recording, 72-channel, seismic array. The accelerometers' 500 sample-per-second recordings \nhave been used to verify the ability to observe impulse-like sources in a full-scale structure. Application of an impulse-like source on the 3rd and 15th floors of the Factor building shows that the associated displacements serve as useful approximations to the building's Green's functions in the far field, and can be used in investigations of scenario fracture location and timing.", "isbn": "9788989693277", "publisher": "Techno-Press", "place_of_publication": "Taejon, Korea", "publication_date": "2009" }, { "id": "authors:e78v0-ztg11", "collection": "authors", "collection_id": "e78v0-ztg11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120904-164125964", "type": "book_section", "title": "Early Warning Systems for Large Earthquakes: Classification of Near-source and Far-source Stations by using the Bayesian Model Class Selection", "book_title": "Applications of statistics and probability in civil engineering : proceedings of the 10th International Conference on Applications of Statistics and Probability in Civil Engineering, ICASP10, Tokyo, Japan, 31-July-3 August, 2007", "author": [ { "family_name": "Yamada", "given_name": "M.", "clpid": "Yamada-Masumi" }, { "family_name": "Heaton", "given_name": "T. H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Beck", "given_name": "J. L.", "clpid": "Beck-J-L" } ], "contributor": [ { "family_name": "Kanda", "given_name": "Jun", "clpid": "Kanda-Jun" }, { "family_name": "Takada", "given_name": "Tsuyoshi", "clpid": "Takada-Tsuyoshi" }, { "family_name": "Furuta", "given_name": "Hitoshi", "clpid": "Furuta-Hitoshi" } ], "abstract": "To estimate the fault dimension of an earthquake in real time, we present a methodology to\nclassify seismic records into near-source or far-source records. This study analyzes peak ground motions and\nfinds the function which best classifies near-source and far-source records based on these parameters. We\nperform: Bayesian methods to find the coefficients of the linear discriminant function; and Bayesian model class\nselection to find the best combination of the peak ground motion parameters. Bayesian model class selection\nshows that the combination of vertical acceleration and horizontal velocity produces the best performance for the\nclassification. The linear discriminant function produced classifies near-source and far-source data and it gives\nthe probability for a station to be near-source, based on the ground motion measurements. This discriminant\nfunction is useful to estimate the fault rupture dimension in real time, especially for large earthquakes", "isbn": "978-0-415-45211-3", "publisher": "Taylor & Francis", "place_of_publication": "London", "publication_date": "2007-07", "pages": "19-26" }, { "id": "authors:jsv2r-rny47", "collection": "authors", "collection_id": "jsv2r-rny47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160209-164557445", "type": "book_section", "title": "Using embedded wired and wireless seismic networks in the moment-resisting steel frame Factor building for damage identification", "book_title": "SSCM' 2006 : safety and durability of structure : proceeding of the 4th China-Japan-US Symposium on Structural Control and Monitoring, Oct. 16-17, 2006, Hangzhou, China", "author": [ { "family_name": "Kohler", "given_name": "Monica D.", "orcid": "0000-0002-4703-190X", "clpid": "Kohler-M-D" }, { "family_name": "Heaton", "given_name": "Thomas", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Govindan", "given_name": "Ramesh", "clpid": "Govindan-R" }, { "family_name": "Davis", "given_name": "Paul", "clpid": "Davis-P" }, { "family_name": "Estrin", "given_name": "Deborah", "clpid": "Estrin-D" } ], "abstract": "Ideally both spectral and time domain data could be used to compute the total building response and to make predictions of damage patterns based on various input scenarios. The combination of frequency change information coupled with that provided by wavefield properties can pinpoint the time and location of damage more accurately, especially for densely instrumented structures such as the 17-story UCLA Factor building. The 72-sensor embedded seismic array in the Factor building, recording continuous waveforms at 500 Hz, makes it possible to observe subtle changes in dynamic characteristics between pairs of floors and to relate the measurements to system properties such as changes in stiffness due to a column failure. The high dynamic range of the 24-bit digitizers allows both strong motions and ambient vibrations to be recorded with reasonable signal-to-noise ratios. Temporary decreases in frequencies of Factor building modes of vibration have been correlated with moderate-to-strong shaking, and spectral amplitudes of ambient vibrations have clear daily and weekly patterns that correlate with working hours, wind speeds, and non-seismic vibrations. Waveform data from the Factor array are also being used in comparison with finite element calculations for predictive damage behavior. A three-dimensional model of the Factor building has been developed based on structural drawings. Observed displacements for 20 small and moderate, local and regional earthquakes were used to compute the impulse response functions of the building by deconvolving the subbasement records as a proxy for the free field. It can be shown that small but significant changes in the travel times, mode shapes, and frequencies are observed in the simulation results for strong ground shaking and for modifications to the structural model for hypothesized damage patterns such as broken welds on a particular floor. Wireless untethered devices whose design is guided by data analysis and simulations such as these can significantly increase the spatial resolution of structural response to earthquakes. A Mica-Z mote network controlled by Wisden software that monitors a local area such as a building is being assembled and tested. The software system addresses some of the challenges associated with high sample rates and limited radio bandwidth, yet allows structural data acquisition from a relatively large network of wireless sensors.", "isbn": "7894902942", "publisher": "Zhejiang University Press", "place_of_publication": "Hangzhou, China", "publication_date": "2006" }, { "id": "authors:ddby1-1v431", "collection": "authors", "collection_id": "ddby1-1v431", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120912-145915845", "type": "book_section", "title": "Structural Monitoring and Evaluation Tools at Caltech: Instrumentation and Real-Time Data Analysis", "author": [ { "family_name": "Bradford", "given_name": "S. C.", "clpid": "Bradford-S-C" }, { "family_name": "Heaton", "given_name": "T. H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Beck", "given_name": "J. L.", "clpid": "Beck-J-L" } ], "abstract": "This paper presents a summary of the structural monitoring tools available at the California\nInstitute of Technology (Caltech) and selected research using these tools.\n\nThe Caltech Online Monitoring and Evaluation Testbeds (COMET) site is an educational and\nresearch tool that archives real-time data from the Southern California Earthquake Data Center\n(SCEDC) stations MIK (Millikan Library) and CBC (Broad Center). The COMET site allows users\nto view and download real-time data, as well as perform dynamic analysis using Caltech's MODEID\nsoftware.\n\nAmbient analysis of data from Millikan Library has revealed a change in dynamic properties\nbased on weather conditions, especially rainfall and windstorms. During heavy rains, the\nfundamental E-W and Torsional frequencies of Millikan Library can increase by 3-5%. Strong\nwinds can decrease all fundamental frequencies by 2-4%. Results such as these have important\nimplications in the development of structural health monitoring methods that use changes in modal\nparameters to infer damage.", "publisher": "ANCER", "publication_date": "2004-07" }, { "id": "authors:z745f-50k14", "collection": "authors", "collection_id": "z745f-50k14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121220-152414173", "type": "book_section", "title": "Simulation of near-source ground motions with dynamic failure", "book_title": "Advanced technology in structural engineering", "author": [ { "family_name": "Aagaard", "given_name": "Brad T.", "orcid": "0000-0002-8795-9833", "clpid": "Aagaard-B-T" }, { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "contributor": [ { "family_name": "Elgaaly", "given_name": "Mohamed", "clpid": "Elgaaly-M" } ], "abstract": "We simulate long-period near-source ground motions due to hypothetical events\non a strike-slip fault (M_w 6.9) and a buried thrust fault (M_w 7.0). We include the dynamics\nof the rupture process using a model of sliding friction. The directivity of the rupture\ncreates large displacement and velocity pulses in the ground motions in the forward\ndirection. For the strike-slip fault the peak values occur near the tip of the fault, while for\nthe buried thrust fault the peak values occur up-dip from the top of the fault. The\nacceleration response spectra in the 2.0 sec to 3.0 sec range exceed 1.0 g near the\nstrike-slip fault in the forward direction, and 0.5 g up-dip from the top of the thrust fault.\nThese results quantify the threat posed to long-period structures near faults.", "doi": "10.1061/40492(2000)113", "isbn": "978-0-7844-0492-8", "publisher": "American Society of Civil Engineers", "place_of_publication": "Reston, VA", "publication_date": "2000-05", "pages": "1-8" }, { "id": "authors:2e91m-7pt62", "collection": "authors", "collection_id": "2e91m-7pt62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121121-084449316", "type": "book_section", "title": "Microscopic and macroscopic physics of earthquakes", "book_title": "Geocomplexity and the Physics of Earthquakes", "author": [ { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "contributor": [ { "family_name": "Rundle", "given_name": "John B.", "clpid": "Rundle-J-B" }, { "family_name": "Turcotte", "given_name": "Donald L.", "clpid": "Turcotte-D-L" }, { "family_name": "Klein", "given_name": "William", "clpid": "Klein-W-H" } ], "abstract": "Frictional melting and fluid pressurization can play a key role in rupture dynamics of large earthquakes. For faulting under frictional stress \u03c3_\u0192, the temperature increases with \u03c3_\u0192 and the earthquake magnitude, M_w. If the thickness of the heated zone, w, is of the order of a few mm, then, even for a modest \u03c3_\u0192, the temperature rise, \u0394T, would exceed 1000\u00b0 for earthquakes with M_w = 5 to 6, and melting is likely to occur, and reduce friction during faulting. If fluid exists in a fault zone, a modest \u0394T of 100 to 200\u00b0 would likely increase the pore pressure enough to significantly reduce friction for earthquakes with M_w = 3 to 4. The microscopic state of stress can be tied to macroscopic seismic parameters such as the seismic moment, M_0, and the radiated energy, E_R, by averaging the stresses in the microscopic states. Since the thermal process is important only for large earthquakes, the dynamics of small and large earthquakes can be very different. This difference is reflected in the observed relation between the scaled energy \u1ebd = E_R/M_0 and M_W. The observed \u1ebd for large earthquakes is 10 to 100 times larger than for small earthquakes. Mature fault zones such as the San Andreas are at relatively moderate stress levels, but the stress in the plate interior can be high. Once slip exceeds a threshold, runaway rupture could occur, and could explain the anomalous magnitude-frequency relationship observed for some mature faults. The thermally controlled slip mechanism would produce a non-linear behavior, and under certain circumstances, the slip behavior at the same location may vary from event to event. Also, slip velocity during a large earthquake could be faster than what one would extrapolate from smaller earthquakes.", "doi": "10.1029/GM120p0147", "isbn": "9780875909783", "publisher": "American Geophysical Union", "place_of_publication": "Washington, DC", "publication_date": "2000", "pages": "147-163" }, { "id": "authors:ajhsw-5y970", "collection": "authors", "collection_id": "ajhsw-5y970", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121218-110709492", "type": "book_section", "title": "Sensitivity study of near-source ground motion", "book_title": "12th World Conference on Earthquake Engineering", "author": [ { "family_name": "Aagaard", "given_name": "Brad T.", "orcid": "0000-0002-8795-9833", "clpid": "Aagaard-B-T" }, { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "abstract": "We studied the sensitivity of near-source ground motions for hypothetical events on a thrust fault\n(M_w 6.6 to 7.0) and a strike-slip fault (M_w 7.0 to 7.1) to five earthquake source parameters. We\nsystematically varied the rupture speed, maximum slip rate, hypocentre location, distribution of\nfinal slip, and fault depth. We used the finite element method to discretize a homogeneous or\nlayered half-space into an unstructured mesh to model the wave propagation in the domain\nsurrounding the fault.\nOur sensitivity study of near-source ground motion indicates it is very important to include\ndirectivity effects when modelling near-source ground motion. In the thrust fault scenarios a\ndouble velocity pulse sweeps along the surface in the direction of the propagating rupture. For\nmost of the scenarios the peak velocity, filtered to periods longer than 2.0 sec, exceeds 1.0 m/sec\nover an area of 100 square kilometres. In the strike-slip scenarios a complex series of pulses\ninvolving the shear wave and Rayleigh waves propagates in the direction of the rupture with the\nmost severe motion confined to a narrow region along the fault. The peak, filtered velocity\nexceeds 1.0 m/sec over an area of 700 square kilometres. We found the ground motions strongly\nsensitive to the material properties and fault depth, moderately sensitive to the hypocentre\nlocation, rupture speed, and maximum slip rate, and relatively insensitive to the distribution of\nfinal slip. The shape of the near-source factor, N_v, from the 1997 Uniform Building Code does not\ncorrelate with the zone of severe shaking in the case of blind thrust faults, because the maximum\ndisplacements and maximum velocities tend to occur up-dip from the top of the fault.", "isbn": "9780958215435", "publisher": "New Zealand National Society for Earthquake Engineering", "place_of_publication": "Upper Hutt, New Zealand", "publication_date": "2000", "pages": "Art. No. 0722" }, { "id": "authors:n9qp7-n8894", "collection": "authors", "collection_id": "n9qp7-n8894", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121022-111806120", "type": "book_section", "title": "The TriNet Project", "book_title": "Eleventh World Conference on Earthquake Engineering : Acapulco, Mexico, June 23-28, 1996 : 11WCEE", "author": [ { "family_name": "Heaton", "given_name": "Thomas", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Clayton", "given_name": "Robert", "orcid": "0000-0003-3323-3508", "clpid": "Clayton-R-W" }, { "family_name": "Davis", "given_name": "James", "clpid": "Davis-J" }, { "family_name": "Hauksson", "given_name": "Egill", "orcid": "0000-0002-6834-5051", "clpid": "Hauksson-E" }, { "family_name": "Jones", "given_name": "Lucille", "orcid": "0000-0002-2690-3051", "clpid": "Jones-L-M" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Mori", "given_name": "James", "clpid": "Mori-Jim" }, { "family_name": "Porcella", "given_name": "Ron", "clpid": "Porcella-R-L" }, { "family_name": "Shakal", "given_name": "Tony", "clpid": "Shakal-A-K" } ], "abstract": "TriNet is a collaborative project of the California Institute of Technology, the California Division of\nMines and Geology, and the U.S. Geological Survey to develop a digital seismographic network in\nsouthern California. TriNet will provide ground motion data having unprecedented frequency bandwidth\nand dynamic range throughout southern California, including urbanized areas. All stations will have 3-\ncomponent, high-dynamic-range, strong-motion force balance accelerometers. Ill addition, all stations\nwill have either real-time or dial-up digital telemetry. Many stations will have high-gain seismometers,\nmany of which will be of the force-balance type with broad frequency responses. TriNet will enhance the\ntraditional products of the existing regional seismographic network and strong-motion networks, and\nimportant new products will be developed. Major products of the TriNet project are: 1) near-real-time\nmonitoring and cataloging of earthquakes in southern California, 2) broad-band ground motions from\nteleseismic earthquakes and other seismic sources, 3) strong-motion recordings from significant\nearthquakes, 4) near-real-time shaking intensity maps for emergency management, and 5) a pilot system\nfor early warning of seismic shaking. Many other agencies (e.g., lifeline operators, emergency\nmanagement agencies, etc.) are being included in the TriNet development.", "isbn": "9780080428222", "publisher": "Elsevier Science", "publication_date": "1996", "pages": "Paper No. 2136" }, { "id": "authors:6mbme-6ns80", "collection": "authors", "collection_id": "6mbme-6ns80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121126-145417758", "type": "book_section", "title": "Strong-Motion and Broadband Teleseismic Analysis of the Earthquake for Rupture Process and Hazards Assessment", "author": [ { "family_name": "Wald", "given_name": "David J.", "clpid": "Wald-D-J" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Helmberger", "given_name": "Donald V.", "clpid": "Helmberger-D-V" } ], "contributor": [ { "family_name": "Spudich", "given_name": "Paul", "clpid": "Spudich-P" }, { "family_name": "Bakun", "given_name": "W. H.", "clpid": "Bakun-W-H" }, { "family_name": "Prescott", "given_name": "William H.", "clpid": "Prescott-W-H" }, { "family_name": "Havach", "given_name": "George A.", "clpid": "Havach-G-A" } ], "abstract": "We have used broadband records from 18 teleseismic\nstations and three-component records from 16 local strongmotion\nstations in a formal inversion to determine the\ntemporal and spatial distribution of slip during the earthquake.\nSeparate inversions of the teleseismic (periods, 3-30 s) \nand strong-motion (periods, 1-5 s) data sets result in\nsimilar source models. The data require bilateral rupture,\nwith relatively little slip in the region directly updip from\nthe hypocenter. Slip is concentrated in two patches: one\ncentered 6 km northwest of the hypocenter at 12-km depth\nwith an average slip amplitude of 250 cm, and the other\ncentered about 5 km southeast of the hypocenter at 16-km\ndepth with an average slip amplitude of 180 cm. This\nbilateral rupture results in large-amplitude ground motions\nat sites both to the northwest and southeast along\nthe fault strike. The northwestern patch, however, has a\nlarger seismic moment and overall stress drop and thus is\nthe source of the highest ground-motion velocities, a result\nconsistent with observations. The bilateral rupture also\nresults in relatively moderate ground motion directly updip\nfrom the hypocenter, in agreement with the ground motions\nobserved at Corralitos, Calif. Furthermore, there is\nclear evidence of a foreshock (M~4.5-5.0) or slow rupture\nnucleation about 2 s before the main rupture; the\norigin time implied by strong-motion trigger times is systematically\nnearly 2 s later than that predicted from the\nhigh-gain regional-network data. The seismic moment obtained\nfrom either or both data sets is about 3.0x10^(26)\ndyne-cm, and the seismic potency is 0.95 km^3. Our analysis\nindicates that the rupture model determined from the\nteleseismic data set alone, independent of the strong-motion\ndata set, is adequate to predict many characteristics\nof the local-strong-motion recordings.", "publisher": "Untied States Government Printing Office", "publication_date": "1996" }, { "id": "authors:04ps4-c4k28", "collection": "authors", "collection_id": "04ps4-c4k28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130108-074900309", "type": "book_section", "title": "The Southern California Seismographic Network", "author": [ { "family_name": "Hauksson", "given_name": "Egill", "orcid": "0000-0002-6834-5051", "clpid": "Hauksson-E" }, { "family_name": "Heaton", "given_name": "Thomas", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "contributor": [ { "family_name": "Blackford", "given_name": "Michael", "clpid": "Blackford-M" }, { "family_name": "Kanamori", "given_name": "H.", "clpid": "Kanamori-H" } ], "abstract": "The Southern California Seismographic Network (SCSN) is jointly operated by the Pasadena Office of the U. S. Geological Survey and the Seismological Laboratory of the California Institute of Technology. The SCSN has 224 remote sites (with 434 components) and gathers data from local, regional and teleseismic earthquakes. These data are used for earthquake hazards reduction as well as for basic scientific research. The earthquake hazards reduction effort has become more important as moderate-sized earthquakes continue to occur within densely populated areas in southern California. Although the USGS operates most of the remote stations in the SCSN, Caltech operates 24 short-period telemetered stations and 15 very broad-band TERRAscope stations. In 1994-1995 we plan to install four more TERRAscope stations. Caltech also maintains drum recorders and other equipment at the central site located in the Seismological Laboratory at Caltech.", "publisher": "Dept. of Commerce, National Oceanic and Atmospheric Administration", "publication_date": "1994-09" }, { "id": "authors:9tjaj-dv037", "collection": "authors", "collection_id": "9tjaj-dv037", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140919-104627916", "type": "book_section", "title": "Real-time earthquake hazard assessment in California; the early post-earthquake damage assessment tool and the Caltech-USGS broadcast of earthquakes", "book_title": "Proceedings of the U. S. National Conference on Earthquake Engineering", "author": [ { "family_name": "Eguchi", "given_name": "Ronald T.", "clpid": "Eguchi-R-T" }, { "family_name": "Goltz", "given_name": "James D.", "clpid": "Goltz-J-D" }, { "family_name": "Seligson", "given_name": "Hope A.", "clpid": "Seligson-H-A" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "abstract": "A real-time earthquake monitoring system which provides source parameters\nto user groups through a commercial paging service is now in place in California.\nA GIS-based system to predict and display near real-time damage and casualty\nestimates is currently being developed by EQE International under contract with\nthe State of California. These new technologies offer immediate tangible benefits\nto state and local governments, utilities, lifelines and corporations with facilities\nor operations at risk. This paper will outline the development of these new\ntechnologies, identify the contributions they will make to emergency management\nand explore some directions these innovative systems may take in the future.", "isbn": "0943198461", "publisher": "Earthquake Engineering Research Institute", "place_of_publication": "Oakland, CA", "publication_date": "1994", "pages": "55-63" }, { "id": "authors:576gg-rzz15", "collection": "authors", "collection_id": "576gg-rzz15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121127-134135015", "type": "book_section", "title": "Seismological research issues in the San Diego region", "author": [ { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Jones", "given_name": "Lucile M.", "orcid": "0000-0002-2690-3051", "clpid": "Jones-L-M" } ], "contributor": [ { "family_name": "Roquemore", "given_name": "Glenn", "clpid": "Roquemore-G" } ], "abstract": "What is the nature of earthquake ground motions that can be expected in San Diego's\nforeseeable future? Although this is the most basic of questions underlying the adequate design\nof structures to resist earthquakes, answers to this question are disturbingly uncertain. A\nreasonable assumption is that future earthquake ground motions will be similar to those that have\noccurred in the past. When compared with San Francisco or Los Angeles, San Diego has\nhistorically experienced relatively mild earthquake shaking. Unfortunately, San Diego's written\nhistory is very short compared to the time scales of earthquake repetition. Are there sources of\nearthquakes that may cause damage in San Diego and what is their frequency? Mapping of\ngeologic structures and the study of patterns of small earthquakes are the primary tools for\nrecognizing potentially active faults. There are features in both the geologic structure and the\nseismicity that are suggestive of major active faults that could pose a serious hazard to San\nDiego. Furthermore, there is evidence that the rate of occurrence of small earthquakes has\nincreased within the last 5 years when compared with the previous 50 years. However, these\nfeatures are not well studied or understood.\nEven if the potential sources of earthquakes were well understood, the problem of anticipating the\nrange of future ground motions is difficult. The nature of shaking from earthquakes is strongly\naffected by the nature of seismic wave propagation through complex geologic structures (path\neffects). Although path effects are likely to be of great importance in San Diego, relatively little\nspecific information is available.", "publisher": "Southern California Earthquake Preparedness Project", "publication_date": "1989-06" }, { "id": "authors:teg55-19178", "collection": "authors", "collection_id": "teg55-19178", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121127-080122692", "type": "book_section", "title": "Anomalous Seismicity in the San Diego Coastal Region", "author": [ { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "contributor": [ { "family_name": "Aki", "given_name": "Keiiti", "clpid": "Aki-Keiiti" }, { "family_name": "Stuart", "given_name": "W. D.", "clpid": "Stuart-W-D" } ], "abstract": "This short note documents recent seismic activity in the\ncoastal region adjacent to San Diego. Seismic activity in the\nregion has increased dramatically since 1983 when compared with\nprevious historic activity. Similar increases in seismicity, that\noccurred prior to significant earthquakes in California, are also\ndocumented. It is speculated that the tectonic style in the\ncontinental borderland off of San Diego is very similar to that in\nthe Basin and Range province.", "doi": "10.3133/ofr87591", "publisher": "U.S. Dept. of the Interior, Geological Survey", "publication_date": "1987" }, { "id": "authors:aaen5-d6n64", "collection": "authors", "collection_id": "aaen5-d6n64", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121126-154909069", "type": "book_section", "title": "Teleseismic mechanism of the May 02, 1983 Coalinga, California, earthquake from long-period P-waves", "author": [ { "family_name": "Hartzell", "given_name": "Stephen H.", "clpid": "Hartzell-S-H" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "contributor": [ { "family_name": "Bennett", "given_name": "John H.", "clpid": "Bennett-J-H" }, { "family_name": "Sherburne", "given_name": "Roger W.", "clpid": "Sherburne-R-W" } ], "abstract": "Teleseismic, long-period P-waveforms are modeled to obtain estimates\nof the source parameters for the May 2, 1983 Coalinga earthquake.\nThe best fitting focal mechanism is: strike = 297 \u00b1 5\u00b0, dip = 64 \u00b1 1\u00b0,\nrake = 70 \u00b1 10\u00b0. The moment is estimated to be 3.8 \u00b1 1.5 X 10^(25) dyne-cm\nwith a slip duration of 5 \u00b1 1 sec. The depth is estimated at 12 \u00b1 2 km.", "publisher": "California Dept. of Conservation, Division of Mines and Geology", "publication_date": "1983" }, { "id": "authors:pcvzy-7hc95", "collection": "authors", "collection_id": "pcvzy-7hc95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121119-104007993", "type": "book_section", "title": "Aftershock Accelerograms Recorded on a Temporary Array", "author": [ { "family_name": "Anderson", "given_name": "J. G.", "clpid": "Anderson-J-G" }, { "family_name": "Heaton", "given_name": "T. H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "abstract": "We recovered 52 timed analog accelerograms from 25 aftershocks of\nthe 1979 Imperial Valley earthquake, between 3:33p.m. P.d.t. October\n16 and 5:43 a.m. October 31. The largest aftershock that we\nrecorded (M_L =4.9) occurred at 4:16p.m. October 16. This aftershock\ntriggered eight accelerographs; preliminary estimates of epicentral\ndistance range from 7 to 35 km. The data from this aftershock may be\nuseful for study of both source and wave-propagation phenomena in\nthe Imperial Valley.", "publisher": "United States Geological Survey", "publication_date": "1982" }, { "id": "authors:ehfxb-f0392", "collection": "authors", "collection_id": "ehfxb-f0392", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121127-101407169", "type": "book_section", "title": "Synthesis of San Fernando strong-motion records", "author": [ { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Helmberger", "given_name": "Donald V.", "clpid": "Helmberger-D-V" } ], "abstract": "Three-dimensional models of a finite fault located in a half-space are constructed to\nstudy the ground motions from the 9 February 1971 earthquake as observed at JPL, Palmdale,\nand Lake Hughes (Array Station #4). The Cagniard-De Hoop Technique is used to compute the\nground motions due to infinitesimal point sources which are evenly distributed (0.5 km\nspacing) on the fault plane. The responses are summed with time lags determined by the\nassumed hypocentral solution and rupture velocity. Nonuniform fault displacement is\nmodeled by varying the weights of individual point sources. By investigating the motion\ndue to small sections of the fault it is possible to understand how various wave types\ninterfere to produce the motion due to the total fault. Recent modeling of teleseismic\nbody waves by Langston has indicated that the fault changes dip from 50\u00b0 to 30\u00b0 at a depth\nof approximately 5 km. This feature has been incorporated into our models. The assumed\nfault geometry and station locations are shown in Figure 1. In Figure 2, we display\nassumed fault displacements for a preliminary model which is used to explain the motions\nat JPL, PLM, and LKH. The overall moment for this model is 1.5 x 10^(26) ergs. The hypocenter\nis assumed to lie in the region of maximum displacement and a rupture velocity of\n1.8 km/sec (as suggested by Langston) is also assumed. Although stations LKH and JPL are\nsituated at roughly equal epicentral distances, there appears to be a dramatic difference\nin the character and amplitudes of ground motion seen for these stations. This can be\nseen in Figures 3 and 4. In these figures, the synthetic ground motions for the fault\nmodel described above are compared with the integrated accelerograms for these stations.\nBecause the integrated accelerograms have been filtered with an 8 sec. Ormsby filter, the\nsynthetics are displayed both with and without the inclusion of this filter. Although it\nappears that the particular fault model used for Figures 3 and 4 is not, in detail, correct,\nit does well at explaining the differences in character and amplitude of ground motions as\nseen between JPL and LKH. An examination of Figure 5 helps one to appreciate the complex\ninterplay between source and wave propagational effects. In this figure the fault is\nsubdivided into 5 strips each of which has a width of 4 km. Also shown are synthetic\nmotions (JPL, North) for a single point source located in the middle of each subfault.\nAlthough these point sources produce easily interpreted specific arrivals, it is clear\nthat the JPL record results from complex and not easily interpreted interaction of both\nsource and propagation effects. These synthetics also demonstrate the dramatic effect\nof the free-surface. Rayleigh wave and sP head wave contributions are of great importance.", "publisher": "National Science Foundation", "publication_date": "1978" }, { "id": "authors:h9dfp-d4117", "collection": "authors", "collection_id": "h9dfp-d4117", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121126-151711821", "type": "book_section", "title": "Tilts associated with the Pt. Mugu earthquake", "author": [ { "family_name": "Alewine", "given_name": "R. W., III", "clpid": "Alewine-R-W-III" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" } ], "contributor": [ { "family_name": "Kovach", "given_name": "Robert L.", "clpid": "Kovach-R-L" }, { "family_name": "Nur", "given_name": "Amos", "clpid": "Nur-A" } ], "abstract": "Anomalously large far field tilts were observed\nduring the Pt. Mugu earthquake of February 21, 1973. The\nmagnitude and pattern of tilting is not explained by a simple\nelastic dislocation model using reasonable source parameters\nfor this event. Dynamical triggering of small displacements\non a fault well exterior to the epicentral region is offered\nas an alternative explanation to the observed large tilts.", "publisher": "Stanford University, School of Earth Sciences", "publication_date": "1973" } ]