18 March 2005 TTRC

The Hawaiian Islands Seismic NetworkLocal Tsunami Warnings from Earthquake Early Warning and Mwp.

Barry Hirshorn and Gerard Fryer,

Richard Hagemeyer Pacific Tsunami Warning Center

University of Hawaii at Manoa

Tsunamis from the Big Island

Major coastal earthquakes shaded

Largest confirmed eathquakes and tsunamis: 1868, 1975

1929 produced no tsunami The ~1600AD earthquake

is required to explain deposits at Maha’ulepu, Kauai

Tsunami travel times (minutes) from a South Kona earthquake

Tsunami Sources (cross section of a Hawaiian volcano)

Present warning timeline (ideal)

INTERACTIVE TOOL TO

DETERMINEMWP

MOMENTMAGNITUDE

The Effect using Longer Period Data on Mwp.

Mwp and Local Earthquakes

Mwp is limited by the trade off between the S-P travel time, and the source duration of the event.

Appears to work well at less than 5 degrees epicentral distance. Depending on

the Mw and source length, Mwp provides an estimate that is low by an amount that decreases between 1-5 degrees epicentral distance.

Will automate it for local earthquakes.

ISSUE TIME OF PTWC INITIAL BULLETINS FOR TELESEISMS

0

10

20

30

40

50

60

70

80

90

100

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

EVENT TIME (YEAR)

MIN

UT

ES

SIN

CE

QU

AK

E

ISSUE TIME OF PTWC BULLETINS FOR HAWAII EVENTS

0

5

10

15

20

25

30

1994 1996 1998 2000 2002 2004 2006

EVENT TIME (YEAR)

EL

AP

SE

D M

INU

TE

S

84 Mwp Observations Within 5 Degrees of The Epicenter

Warning timeline after upgrade

All big, shallow earthquakes have the same mechanism.

So all we need is epicenter and magnitude?

All big, shallow earthquakes have the same mechanism.

So all we need is epicenter and magnitude?

Earthquake depths are bimodalEarthquake depths are bimodal

We want to issue warnings for large shallow earthquakes near a coastline, but not large deep earthquakes

Crude depth determination?

We want to issue warnings for large shallow earthquakes near a coastline, but not large deep earthquakes

Crude depth determination?

The Hawaiian Islands Seismic Network

Funding requested by the President, recommended by House Committee on Science, included in Senate Bill 50, The Tsunami Preparedness Act.

Funding FY05: $0.5 million FY06: $1.0 million Maintenance in NWS budget

Working Committee Charles McCreery (NOAA) Harley Benz (USGS) Robert Cessaro (NOAA) Gerard Fryer (UHM) Barry Hirshorn (NOAA) David Oppenheimer (USGS) Paul Okubo (USGS)

Special thanks to Senator Daniel Inouye Jeff LaDouce, NOAA Rhett Butler, IRIS Kent Anderson, IRIS

The Future?

PTWC is interested in more Interaction with the Seismological Community.

Held a Workshop in Ewa Beach, June 8 2005 with USGS and others to co-ordinate and plan out upgrade.

More staff to look at these problems soon.

Software: prototyping and testing EEW systems in Hawaii, in particular for the Local Earthquake/Tsunami problem.