Peter Malin

University of Auckland · Department of Physics

Downhole sensors of different types and in various environments provide substantial benefit to signal quality. They also add the depth dimension to measurements performed at the Earths’ surface. Sensor types that particularly benefit from downhole installation due to the absence of near-surface noise include piezometers, seismometers, strainmeters,...

Since 1995 the eruption of the andesitic Soufrie`re Hills Volcano (SHV), Montserrat, has been studied in substantial detail. As an important contribution to this effort, the Seismic Experiment with Airgunsource-Caribbean Andesitic Lava Island Precision Seismogeodetic Observatory (SEA-CALIPSO) experiment was devised to image the arc crust underlying...

Since 1995 the eruption of the andesitic Soufrière Hills Volcano (SHV), Montserrat, has been studied in substantial detail. As an important contribution to this effort, the Seismic Experiment with Airgunsource-Caribbean Andesitic Lava Island Precision Seismo-geodetic Observatory (SEA-CALIPSO) experiment was devised to image the arc crust underlying...

Over the last century the North Anatolian Fault Zone in Turkey has produced a remarkable sequence of large earthquakes. These events have now left an earthquake gap south of Istanbul and beneath the Marmara Sea, a gap that has not been filled for 250 years. Here we investigate the nature of the eastern end of this gap using microearthquakes recorde...

The North Anatolian Fault Zone (NAFZ) below the Sea of Marmara represents a 'seismic gap' where a major earthquake is expected to occur in the near future. The Marmara segment of the NAFZ is located between the 1912 Ganos and 1999 Izmit ruptures and is the only segment that has not ruptured since 1766. The GONAF project (Geophysical Observatory at...

Well-log data for solute species K, Th and U for two wells in the Los Azufres geothermal field in central Mexico show lognormal population distribution systematics that can be understood in terms of in situ fracture-borne flow in a 'geocritical' crustal reservoir. Radionuclide solute well-log data could help build large-scale observationally-constr...

We have developed a new multilevel seismic downhole array for the purpose of ambient seismic noise measurements. The tool substantially widens the bandwidth and lowers the detection threshold for microseismic events at low signal-to-noise levels near the ambient seismic noise floor. We analyse the bandwidth requirements in both frequency and dynami...

The actively producing Puna geothermal system (PGS) is located on the Kilauea East Rift Zone (ERZ), which extends out from the active Kilauea volcano on Hawaii. In the Puna area the rift trend is identified as NE-SW from surface expressions of normal faulting with a corresponding strike; at PGS the surface expression offsets in a left step, but no...

We use fault-zone trapped waves (FZTWs) generated by earthquakes and explosions and recorded at San Andreas Fault Observatory at Depth (SAFOD) borehole seismographs and along a dense linear surface array across the SAF to document fault zone structure and rock damage at seismogenic depths with high-resolution. The seismograph in the SAFOD main-hole...

Five Vulcanian explosions were triggered by collapse of the Soufrière Hills Volcano lava dome in 2003. We report strainmeter data for three explosions, characterized by four stages: a short transition between the onset of disturbance and a pronounced change in strain; a quasi-linear ramp accounting for the majority of strain change; a more gradual...

During the December 2007, SEA-CALIPSO experiment we collected seismic reflection profiles offshore of Montserrat. Off the east coast, we imaged deep fans of volcaniclastic debris from three volcanoes progressively active from ∼2 Ma to present. Near-shelf sedimentation rates of 8–9 cm/ka are approximated following cessation of local volcanic activit...

The CALIPSO collaborative volcano monitoring system on the Caribbean island of Montserrat includes observations of strain at depths ∼200 m using Sacks-Evertson strainmeters. Strain data for the March 2004 explosion of the Soufrière Hills Volcano are characterized by large, roughly equal but opposite polarity changes at the two near sites and much s...

The SEA-CALIPSO experiment in December 2007 incorporated a sea-based airgun source, and seismic recorders both on Montserrat and on the adjacent sea floor. A high quality subset of the data was used for a first arrival P-wave velocity tomographic study. A total of more than 115,000 traveltime data from 4413 airgun shots, and 58 recording stations,...

In recent years there has been significant interest in the seismoelectric effect which is the conversion of acoustic energy into electromagnetic energy. At the onset of the earthquake and at layer interfaces, it is postulated that the seismoelectric signal propagates at the speed of light and thus travels much faster than the acoustic wave. The foc...

dd/mm/yyy SUMMARY To better understand the volcanic phenomena acting on Montserrat, the SEA-CALIPSO seis-mic experiment (Seismic Experiment with Airgun-source -Caribbean Andesitic Lava Island Precision Seismo-geodetic Observatory) was conducted in December 2007 with the aim of imaging the upper crust and the magmatic system feeding the active Soufr...

The EGS paradigm is to create geothermal reservoir flow conditions where Nature has not. Unlike oil and gas production, geothermal power production requires rapid fluid flow through significant crustal volumes. From the nature of in situ fracture systems at power‐producing geothermal fields, high EGS flow thus means intersecting faults rather than...

Characterizing internal structures of active volcanoes remains an enigmatic issue in geosciences. Yet studies of such structures can greatly improve hazard assessments, helping scientists to better monitor seismic signatures, geodetic deformation, and gas emissions, data that can be used to improve models and forecasts of future eruptions. Several...

We examined rock damage and healing on the Longmen-Shan Fault (LSF) that ruptured in the 2008 M8 Wenchuan earthquake using the data recorded at Sichuan Seismic Network and portable stations. The Wenchuan mainshock included multiple events with the reverse thrusting at the first stage and then becoming to strike-slip gradually, indicating the comple...

We present the application of joint geophysical imaging (JGI) and interpretation of seismic shear-wave splitting and electrical resistivity polarization due to aligned, fluid-filled fracture zones as targets of drilling exploration and production wells. The method included coupling of physical properties as well as geological structures. The joint...

We seek to develop a robust geofluid flow modeling and data-interpretation process by which inter-well connectivity data acquired during routine flow monitoring can be quantitatively understood in terms of otherwise-unpredictable large-scale reservoir flow structure. To date flow models for both geothermal and hydrocarbon reservoirs have little pre...

Seismic tomography of active volcanic islands can provide information about the size and distribution of intrusions, the response of the lithosphere to edifice loading, the extent to which material has been added on top of versus within the pre-existing crust, and the presence of magma chambers. In December 2007, we carried out such an experiment a...

The collapse of the Soufriere Hills Volcano lava dome on Montserrat in July 2003, the largest such event worldwide in the historical record, was followed by several vulcanian explosions. Here we report on dilatometer data recording pressurisation the magma conduit for three of these explosions. Strain data for these explosions are characterized by...

The Sea-Calipso offshore/onshore experiment was conducted in December 2007 to image the seismic velocity structure of the island of Montserrat. Seismic signals were generated by a towed airgun array at 60 second intervals along a series of circles and radial lines around the island. A total of 4,414 shots were recorded by a network consisting of 20...

The Soufrière Hills Volcano (SHV) on the island of Montserrat, Lesser Antilles, resumed its activity in 1995 and has since been studied in great detail, but knowledge of its deep structure is scarce. In December 2007 the SEA-CALIPSO land-sea seismic experiment was conducted to investigate the seismic velocity structure of the island and better unde...

Seismic reflection profiles provide a cross-sectional view of crustal layers and thus details about local sedimentation rates, chronology, and depositional materials. Based on seismic profiles collected as part of the SEA-CALIPSO seismic experiment, we apply this method to interpreting the volcanic and local tectonic history of the island of Montse...

The geothermal power plant in Puna, in southeastern Hawaii, is located in a section of the Kilauea Lower East Rift Zone that was resurfaced by lava flows as recently as 1955, 1960, and 1972. In 2006 a seismic array consisting of eight 3-component stations was installed around the geothermal field in Puna. The instrument depths range from 24 to 210...

Extracting the vibration response of the subsurface from noise is a rapidly growing field of research [Curtis et al., 2006; Larose et al., 2006]. We carried out broadside imaging of the San Andreas fault zone (SAFZ) using drill bit noise created in the main hole of the San Andreas Fault Observatory at Depth (SAFOD), near Parkfield, Calif. Imaging w...

Highly damaged rocks within the San Andreas fault zone at Parkfield form a low-velocity waveguide for seismic waves, giving rise to fault-guided waves. Prominent fault-guided waves have been observed at the San Andreas Fault Observatory at Depth (SAFOD) site, including a surface array across the fault zone and a borehole seismograph placed in the S...

Borehole seismometer arrays have proven successful in both the exploration and monitoring of geothermal fields. Because the seismometers are located at depth, they are isolated from human noise and record microearthquakes with clearly identifiable seismic phases that can be used for event location. Further analysis of these events can be used to re...

After the M6 Parkfield earthquake that occurred on 28 September 2004, we deployed a dense seismic array at the same sites as used in our experiment in the fall of 2002. The measurements using moving-window cross- correlation of waveforms for the repeated explosions and microearthquakes recorded in 2002 and 2004 show a decrease in shear velocity of...

Highly damaged rocks along the San Andreas Fault at Parkfield create a low-velocity waveguide to trap seismic waves. We recorded prominent fault-zone trapped waves (FZTWs) at the SAFOD mainhole seismograph at 3km depth and the surface seismic array across the fault for microearthquakes. A systematic waveform analysis of borehole and surface seismog...

available. doi:10.2204/iodp.sd.s01.09.2007

The San Andreas Fault Observatory at Depth (SAFOD) is a 3.2-km-deep borehole observatory drilled into the San Andreas fault zone at seismogenic depths to study directly the physical and chemical processes controlling faulting and earthquake generation. SAFOD forms one component of EarthScope, a major Earth Science facility program of the U.S. Natio...

A central goal of seismology is to understand the physics of earthquakes and other sources of seismic waves in the Earth. We would like to understand how dynamic instabilities are nucleated, how they evolve in space and time, and how they come to rest. To achieve this goal, we need observations that are truly broadband with respect to source proces...

No abstract available. doi:10.2204/iodp.sd.s01.39.2007

Pyroclastic flows entering the sea may cause tsunamis at coastal volcanoes worldwide, but geophysically monitored field occurrences are rare. We document the process of tsunami generation during a prolonged gigantic collapse of the Soufrière Hills volcano lava dome on Montserrat on 12 13 July 2003. Tsunamis were initiated by large-volume pyroclasti...

The San Andreas Fault Observatory at Depth provides the most comprehensive set of data on the structure and dynamics of the San Andreas fault. We use two independent experiments recorded by the seismometer arrays of the SAFOD Pilot and Main Holes to resolve the localized structure of the San Andreas fault zone and of an intermediate fault zone at d...

See Abstract volume Istituto Nazionale di Geofisica e Vulcanologia, Italy (INGV) Centre National de la Recherche Scientifique (CNRS) ExxonMobil Upstream Research Company Unpublished Erice, Italy

Our repeated seismic surveys at the San Andreas fault (SAF), Parkfield indicates that the active fault zone, which undergoes strong dynamic stresses and pervasive cracking during earthquakes, has a distinct low- velocity zone that co-seismically weakens and consequently heals. Observations and finite-difference simulations of fault-zone trapped wav...

A new type of seismic wave has been observed on a 3-component downhole seismograph installed in the main borehole of San Andreas Fault Observatory at Depth (SAFOD MH). This phase arrives between the P- and S- waves, is normally dispersed and has a clear Airy phase. It was recorded by 15 Hz seismometers located 2650 m below ground, 3270 m along the...

Fault-guided waves reveal a low-velocity fault segment a few hundred meters southwest of the main strand of the San Andreas Fault (SAF) system. In 2004, the San Andreas Fault Observatory at Depth (SAFOD) Main Hole was drilled 2.5 km underground and 0.7 km west of the SAF surface trace. A 3-component, 4.5-Hz seismograph was installed near the bottom...

Deep within an active fault zone, the San Andreas Fault Observatory at Depth will measure changes in rock properties before, during and after earthquakes. Linked with other measurements at the Earth's surface, these direct observations will, for the first time, monitor how an active fault and the surrounding environment respond to local and regiona...

The collapse of the Soufrière Hills Volcano lava dome on Montserrat in July 2003 is the largest such event worldwide in the historical record. Here we report on borehole dilatometer data recording a remarkable and unprecedented rapid (~600s) pressurisation of a magma chamber, triggered by this surface collapse. The chamber expansion is indicated by...

The dome-building volcano Soufriere Hills on Montserrat in the Carribean has been active since about 1995. By the end of January 2003, the CALIPSO group had established a small network of 4 borehole sites with the instrumentation including Sacks-Evertson dilatometers. Major dome collapse in July 2003, reported elsewhere, was accompanied by increase...

We have used the drill bit seismic technique to develop preliminary images of fracture and shear zones associated with the San Andreas Fault at the SAFOD site, Parkfield, California. Our study included the interpretation of the USGS PSINE surface seismic profile and the drill bit seismic data recorded by three different geophone arrays. Three-compo...

In 2004, drilling in the San Andreas Fault Observatory at Depth Main Hole (MH) stopped at ~2.5 km underground and ~0.7 m short of the SAF surface trace. A seismograph temporarily placed there recorded fault zone guided waves from SAF earthquakes, but only from events more than ~2 km northwest and ~3 km southeast of the seismograph. P-wave tomograph...

Extending 4 km into the Earth along a diagonal path that crosses the divide between Salinian basement accreted to the Pacific Plate and Cretaceous sediments of North America, the main hole at the San Andreas Fault Observatory at Depth (SAFOD) was designed to provide a portal into the inner workings of a major plate boundary fault. The successful dr...

We use fault-zone guided waves recorded at surface seismic arrays deployed across and along the San Andreas fault for explosions and local earthquakes combined with the guided waves recorded at borehole instrument in the SAFOD main hole to delineate the low-velocity structure of the SAF at seismogenic depths. The data from events occurring within t...

Scientists recently used the drillbit seismic technique to image fractures and shear zones associated with the San Andreas fault near Parkfield, Calif. Low-level energy produced by the drillbit served as a downhole seismic source, and the wave response was measured by an array of geophones at the surface. In the complex structural environment under...

Analysis of long-period (LP) seismic events provides information about the internal state of a volcano because LP events are attributed mainly to fluid dynamics between magma and hydrothermal reservoirs in its volcano (e.g., Chouet, 1992). We analyzed LP events recorded by three borehole seismic stations (AIRS, OLVN, and TRNT) at Soufriere Hills Vo...

The CALIPSO Project (Caribbean Andesite Lava Island-volcano Precision Seismo-geodetic Observatory) has greatly enhanced the monitoring and scientific infrastructure at the Soufrière Hills Volcano, Montserrat with the recent installation of an integrated array of borehole and surface geophysical instrumentation at four sites (Mattioli et al., 2004)...

The main objective of this study is to contribute to the continued development of Joint Geophysical Imaging (JGI) methods for the combined use of seismic and electrical resistivity measurements to guide the drilling of high-production geothermal wells. For competitive production of geothermal power, it is essential to develop well-targeting techniq...

We deployed an array twenty PASSCAL L-28 4.5-Hz sensors for forty days during the summer of 2004 at the Krafla Geothermal field. During this time, twenty GeoSpace 1-Hz instruments recorded the seismicity for fifteen days. The Krafla Geothermal field is located approximately 60 km East of Akureyri in northern Iceland. The arrays recorded approximate...

Project CALIPSO (Caribbean Andesite Lava Island Precision Seismo-geodetic Observatory) aims to investigate the magmatic system at the active Soufriere Hills Volcano (SHV), Montserrat. The collaborative project involves several institutions acting in partnership with the Montserrat Volcano Observatory (MVO), and is funded by NSF with assistance by N...

Since we installed it in July 2002 and its demise in July 2004, we used a 32 level array of 3-component, 15 Hz seismographs in the Pilot Hole to study the structure and properties of the SAFOD site. The array levels were spaced at 40 m intervals, with the deepest level at 2096 m. A catalogue of several hundred earthquakes and explosions was recorde...

Seismic waves from the September 28th Parkfield event and its aftershocks were recorded by the SAFOD Pilot Hole seismic array. This array currently consists of seven levels of 3-component 15 Hz seismometers within the Salinian granite. Its sensors are spaced at 40 m intervals between depths of 856 to 1156 meters below ground. Our deep borehole reco...

In July 2002, scientists from Duke University successfully installed a downhole seismic array at the SAFOD site in collaboration with SAFOD Principal Investigators Bill Ellsworth (USGS), Steve Hickman (USGS), and Mark Zoback (Stanford University). As part of ongoing seismic studies at SAFOD, the vertical array of three component seismometers is cur...

Receiver functions are now routinely calculated from teleseismic P-waveform records to investigate the subsurface geology. For these calculations broad-band seismometers are generally used since only the low end of the frequency spectrum (f < 1.5 Hz) can be interpreted. With a number of ongoing efforts of deep drilling and monitoring of earthquakes...

We present a simultaneous interpretation of coincident magnetotelluric (MT) and seismic refraction lines near the Parkfield, CA, San Andreas Fault Observatory at Depth site. The MT data set was acquired with Phoenix 4-channel systems with average station spacing of about 250 m over a profile length of ( ˜5000) m. The time-domain recording scheme wa...

The July 12-13, 2003 eruption (dome collapse plus explosions) of Soufriere Hills Volcano in Montserrat, WI, is the largest historical lava dome collapse with ˜120 million cubic meters of the dome lost. Pyroclastic flows entered the sea at 18:00 AST 12 July at the Tar River Valley (TRV) and continued until the early hours of 13 July. Low-amplitude t...

This article is an update on the status of an innovative new project designed to enhance generally our understanding of andesitic volcano eruption dynamics and, specifically, the monitoring and scientific infrastructure at the active Soufriàre Hills Volcano (SHV), Montserrat. The project has been designated as the Caribbean Andesite Lava Island Pre...

In August 2002, an array of 32 three-component geophones was installed in the San Andreas Fault Observatory at Depth (SAFOD) Pilot Hole (PH) at Parkfield, CA. As an independent test of surface-observation-based microearthquake locations, we have located such events using only data recorded on the PH array. We then compared these locations with loca...

In July 2002 we installed a vertical array of seismometers in the San Andreas Fault Observatory at Depth (SAFOD) Pilot Hole (PH). The bottom of this 32 level, 1240 m long array of 3- components is located at a depth of ~2100 m below ground. Surface-explosion and microearthquake seismograms recorded by the array give valuable insights into the struc...

Most of 26 small (0.4≲M≲3.1) microearthquakes at Long Valley caldera in mid-1997, analyzed using data from a dense temporary network of 69 digital three-component seismometers, have significantly non-double-couple focal mechanisms, inconsistent with simple shear faulting. We determined their mechanisms by inverting P- and S-wave polarities and ampl...

In this project we developed a method for using seismic S-wave data to map the patterns and densities of sub-surface fractures in the NW Geysers Geothermal Field/ (1) This project adds to both the general methods needed to characterize the geothermal production fractures that supply steam for power generation and to the specific knowledge of these...

The San Andreas Fault Observatory at Depth pilot hole is located on the southwestern side of the Parkfield San Andreas fault. This observatory includes a vertical seismic profiling (VSP) array. VSP seismograms from nearby microearthquakes contain signals between the P and S waves. These signals may be P and S waves scattered by the local geologic s...

During November 2002 to February 2003, 4 borehole sites were established on Montserrat in order to provide data to investigate the on-going eruption of Soufriere Hills as part of the multi-institutional CALIPSO project that also included participation by the Monserrat Volcano Observatory. In the boreholes we installed a Sacks-Evertson strainmeter,...

The CALIPSO Project (Caribbean Andesite Lava Island-volcano Precision Seismo-geodetic Observatory) has greatly enhanced the monitoring and scientific infrastructure at the Soufriere Hills Volcano, Montserrat with the recent installation of an integrated array of borehole and surface geophysical instrumentation at four sites. Each site was designed...

Project CALIPSO (Caribbean Andesite Lava Island-volcano Precision Seismo-geodetic Observatory) investigates with borehole and surface instruments the magmatic system at the very active Soufriere Hills Volcano (SHV), Montserrat, supplementing surface monitoring systems of the Montserrat Volcano Observatory, and those of other institutions including...

Project CALIPSO (Caribbean Andesite Lava Island-volcano Precision Seismo-geodetic Observatory) was developed in order to investigate the magmatic system at the exceedingly active Soufriere Hills Volcano (SHV), Montserrat. The collaborative project involves a number of institutions acting in partnership with the Montserrat Volcano Observatory (MVO),...

It has been shown that accurate predictions of compressional and shear‐wave velocities can be derived from measurements of clay content, porosity, and bulk density. In this paper, we test the efficacy of using a sequence of established petrophysical formulations to go a step further and predict porosity and bulk density as well as velocity from cla...

A temporary network of 69 three-component seismic stations captured a major seismic sequence in Long Valley caldera in 1997. We performed a tomographic inversion for crustal structure beneath a 28 km x 16 km area encompassing part of the resurgent dome, the south moat, and Mammoth Mountain. Resolution of crustal structure beneath the center of the...

The Long Valley Exploratory Well, drilled in the middle of the resurgent dome in the Long Valley caldera, was started in 1989 and after rather checkered progress eventually reached a depth of about 9,831 feet. The hole is cased to a depth of 7178 feet with bare rock below that. At 8,500 feet there is an open fracture system with substantial permeab...

The prolonged and ongoing volcanic activity at SoufriSre Hills Volcano (SHV), Montserrat, provides a rare chance for collecting multi-stream monitoring data in support of volcano research. Conventional surface geophysical instrumentation and detailed observational and geochemical data have enabled the development of a good understanding of surface...

The Long Valley Exploratory Well is located in the resurgent dome of the Long Valley Caldera in California. It has been characterized as hydrothermally active and for the last 20 years it's seismicity as well as deformation have been monitored by the USGS and other groups. In November 2001 we completed the installation of a 2 Hz three component sei...

Arrival-time data from about 1000 local earthquakes and a number of shots are inverted for earthquake locations and three-dimensional Vp and Vp/Vs structure of the San Andreas fault zone at Parkfield, CA. Included are data from a temporary array of surface seismic stations installed around the SAFOD site as well as from a vertical array of geophone...

In the summer of 2000, Duke University and the Kenyan power generation company, KenGen, conducted a microearthquake monitoring experiment at Longonot volcano in Kenya. Longonot is one of several major late Quaternary trachyte volcanoes in the Kenya Rift. They study was aimed at developing seismic methods for locating buried hydrothermal areas in th...

Abstract. A simple, fast, moment-tensor inversion method using bandpass-filtered P-amplitudes was used to study the moment-tensor statistics of Long Valley caldera microearthquakes. The events were recorded in the summer of 1997, during a swarm in the caldera. The swarm was associated with geodetic extension, uplift, and subsequent moderate earthqu...