HR: 0800h
AN: S31A-0206    [Abstracts]
TI: The 2006 Acadia National Park, Maine Earthquake Sequence
AU: * Kim, W
EM: wykim@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964, United States
AU: Gold, M E
EM: goldm@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964, United States
AB: A sequence of small to moderate sized earthquakes shook the Bar Harbor, Maine region in Acadia National Park starting on September 2006. The earthquake sequence started with a magnitude 3.4 event on September 22, 2006 which was preceded by four earthquakes with magnitude ranges of 1.8 to 2.4. Many aftershocks of magnitude about 2 followed the September 22 shock, then a magnitude Mw 4.0 earthquake occurred in the same epicentral area on October 3, 2006. A four-station local seismographic network was deployed on October 5, 2006, by a field crew from Lamont-Doherty Earth Observatory (LDEO) in collaboration with staff at Acadia National Park around Mount Desert Island for aftershock monitoring. The focal mechanism of the mainshock on October 3, 2006 shows the P-axis with trend=86 degree and plunge=10 degree and the T-axis with trend=289 degree and plunge=79 degree. Hence, the P-axis orientation is consistent with the stress axis in the northeastern United States - E-W to ENE-WSW trending horizontal compression. During October 5 through November 30, 2006 about 45 aftershocks with magnitude ranging from Mw 0.4 to 2.4 were located by the local network. Preliminary locations of the aftershocks indicate that these shocks occurred at three clusters around Champlain Mountain close to the east coast of Mount Desert Island. The focal depths of the aftershocks range from 0.5 to 2.5 km. The hypocenters show a complex distribution and do not delineate a simple fault plane. The static stress-drops of 0.1-10 MPa are obtained for these aftershocks, whereas the source radii estimates range 0.05-0.2 km for aftershocks with seismic moment 1.0e+10 Nm to 1.0e+13 Nm (Mw 0.4-2.4).
DE: 7205 Continental crust (1219)
DE: 7215 Earthquake source observations (1240)
SC: Seismology [S]
MN: 2007 Fall Meeting